DOI:10.2214/AJR.07.2287
AJR 2007; 189:1344-1352
© American Roentgen Ray Society
MRI of Hypertrophic Cardiomyopathy: Part 2, Differential Diagnosis, Risk Stratification, and Posttreatment MRI Appearances
Mark W. Hansen1,2 and
Naeem Merchant2
1 Department of Medical Imaging, The Prince Charles Hospital, Rode Rd.,
Chermside, Brisbane, Queensland 4032, Australia.
2 Department of Medical Imaging, Toronto General Hospital, University Health
Network and Mt. Sinai Hospital, Toronto, ON, Canada.
Received March 20, 2007;
revised June 29, 2007;
Address correspondence to M. W. Hansen
(mark.hansen{at}qscan.com.au).
Abstract
OBJECTIVE. We present a two-part review about the use of MRI in
patients with hypertrophic cardiomyopathy (HCM). This article, Part 2, covers
the differential diagnosis, risk stratification, and posttreatment MRI
follow-up appearances in these patients.
CONCLUSION. Cardiovascular MRI is a useful imaging tool for the
diagnosis of HCM and follow-up of patients after either surgical myomectomy or
septal ablation therapy. In addition, MRI can help to discriminate HCM from
the differential diagnoses of other cardiomyopathies and cardiac disorders,
and it can potentially identify the subset of patients at risk of sudden
cardiac death.
Keywords: cardiac imaging • cardiomyopathy • cardiovascular imaging • Fabry's disease • hypertrophic cardiomyopathy • MRI • sarcoidosis • sports medicine
Introduction
Cardiovascular MRI is now accepted as a valuable tool in the initial
assessment and follow-up of many acquired and congenital disorders. In
particular, assessment of cardiomyopathies with MRI has been successful owing
to its unique ability to characterize different enhancement patterns in
diseased myocardium with inversion recovery gadolinium-enhanced imaging. We
present a two-part review about the use of MRI in hypertrophic cardiomyopathy
(HCM). Part 1 of the review focuses on the MRI appearances of HCM
[1]. This article, Part 2,
covers the differential diagnosis, risk stratification, and posttreatment MRI
follow-up appearances in these patients.
Differential Diagnosis
In this section, we discuss the major differential diagnoses for HCM.
Amyloid
The presence of a thickened left ventricle with marked global systolic
dysfunction should raise suspicion of HCM and of other diseases such as
amyloidosis [2]. Researchers
have suggested that all myocardial biopsies for thickened ventricular
myocardium in patients older than 65 years should be assessed for cardiac
amyloid given the prevalence of the disease in that age group
[3]. Some imaging features,
however, may help to distinguish this infiltrative cardiomyopathy from other
causes of thickened left ventricles before biopsy.
Cardiac amyloidosis most commonly presents with symmetric left ventricular
thickening, and although HCM more typically shows asymmetric left ventricular
hypertrophy (LVH), symmetric disease is known to occur in up to 42% of HCM
cases [3] (Figs.
1A,
1B,
1C,
1D,
2,
3A,
3B). Poorer ventricular wall
contractility and lower ECG voltages should alert the physician to the
diagnosis of amyloidosis [4,
5]. Both diseases may exhibit
restrictive physiology and poor compliance. Morphologic changes of a thickened
nodular right atrial free wall and interatrial septum are helpful in
distinguishing cardiac amyloid from HCM
(Fig. 2). In particular,
thickening of the right atrial free wall of more than 6 mm has been shown to
be a specific marker in diagnosing cardiac amyloid in suspected cases
[4].
View larger version (165K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1A —64-year-old woman with cardiac amyloid. Inversion recovery
delayed gadolinium-enhanced images (A and B) and steady-state
free precession images (C and D) in the axial and short-axis
oblique projections show extensive mid wall enhancement and symmetric
thickening of the left ventricle that are typical of amyloid. Mild right
ventricular wall thickening is also present. Although subendocardial extension
of delayed enhancement is common in cardiac amyloid, large areas of mid wall
enhancement, such as in this patient, are also commonly found.
|
|
View larger version (166K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1B —64-year-old woman with cardiac amyloid. Inversion recovery
delayed gadolinium-enhanced images (A and B) and steady-state
free precession images (C and D) in the axial and short-axis
oblique projections show extensive mid wall enhancement and symmetric
thickening of the left ventricle that are typical of amyloid. Mild right
ventricular wall thickening is also present. Although subendocardial extension
of delayed enhancement is common in cardiac amyloid, large areas of mid wall
enhancement, such as in this patient, are also commonly found.
|
|
View larger version (130K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1C —64-year-old woman with cardiac amyloid. Inversion recovery
delayed gadolinium-enhanced images (A and B) and steady-state
free precession images (C and D) in the axial and short-axis
oblique projections show extensive mid wall enhancement and symmetric
thickening of the left ventricle that are typical of amyloid. Mild right
ventricular wall thickening is also present. Although subendocardial extension
of delayed enhancement is common in cardiac amyloid, large areas of mid wall
enhancement, such as in this patient, are also commonly found.
|
|
View larger version (134K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1D —64-year-old woman with cardiac amyloid. Inversion recovery
delayed gadolinium-enhanced images (A and B) and steady-state
free precession images (C and D) in the axial and short-axis
oblique projections show extensive mid wall enhancement and symmetric
thickening of the left ventricle that are typical of amyloid. Mild right
ventricular wall thickening is also present. Although subendocardial extension
of delayed enhancement is common in cardiac amyloid, large areas of mid wall
enhancement, such as in this patient, are also commonly found.
|
|
View larger version (129K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3B —61-year-old man with biopsy-proven amyloid infiltration of
the liver and spleen. Delayed inversion recovery gadolinium-enhanced image
shows there is no evidence of convincing delayed enhancement after
administration of gadolinium within the heart; however, there is hepatomegaly
with diffuse homogeneous enhancement of both the liver and spleen. This
finding shows the ability of gadolinium to accumulate within expanded
extracellular space not only in the heart but also in the remainder of the
body.
|
|
Right ventricular wall thickening is less helpful in distinguishing between
the two entities. One feature that may be helpful in assessing right
ventricular free wall involvement is the distribution of hypertrophy. As with
HCM involvement within the left ventricle, right ventricular involvement with
HCM is typically asymmetric with thickening more commonly identified apically.
In cases of amyloid, the right ventricular involvement is more commonly
symmetric.
Patients with cardiac amyloid have been shown to have pericardial and
pleural effusions in up to 50% of the cases
[4]
(Fig. 2).
A study of 29 patients with known cardiac amyloidosis by Maceira et al.
[6] looked at both delayed
enhancement and T1 mapping of the left ventricular myocardium. Those
investigators found delayed enhancement in 69% of patients, with the dominant
distribution of enhancement being predominantly subendocardial, diffuse, and
not confined to one clear vascular territory (Fig.
1A,
1B,
1C,
1D). At autopsy, the
distribution of delayed enhancement within the left ventricular myocardium of
one patient premortem was found to coincide with the distribution of amyloid
protein histologically. The authors concluded that it was the amyloid protein
itself that was responsible for the delayed enhancement and not the minor
accompanying diffuse interstitial fibrosis. The presence of delayed
enhancement was also shown in that study to be associated with a higher left
ventricular mass index and the presence of left ventricular systolic
dysfunction [6].
Another feature noted in cardiac amyloid by Maceira et al.
[6] was the rapid washout of
gadolinium from blood and myocardium, probably as a result of distribution
into the total body amyloid load (Fig.
3A,
3B). This washout was noted to
occur in patients with reduced creatinine clearance; however, comparison of
gadolinium clearance with estimates of total body amyloid load showed no
direct correlation. The poor correlation was considered to be secondary to
inaccuracies with serum amyloid P component scintigraphy as a technique for
making this estimate [6].
The alteration in distribution kinetics of gadolinium chelates within both
the blood and myocardium and the diffuse myocardial delayed enhancement in
patients with amyloidosis may result in perceived difficulties in selecting an
appropriate inversion time for the delayed enhancement imaging pulse sequence,
a point to keep in mind when imaging patients with LVH
[7].
Athlete's Heart
Although sudden cardiac death is rare among the athletic population
(estimated to be less than 1:200,000), it is nonetheless a devastating
occurrence [8,
9]. Up to 90% of deaths occur
during training or competition, which suggests that vigorous physical activity
in the setting of certain cardiovascular diseases is a trigger for sudden
cardiac death [9]. HCM is known
to be the most common cause of sudden death in young athletes, usually male
[2,
8,
10]. In the United States, HCM
is the most common culprit accounting for one third of deaths, whereas
arrhythmogenic right ventricular dysplasia (ARVD) has been found to be more
common in Italian athletes [8,
9].
Morphologic adaptations of an athlete's heart may mimic cardiovascular
diseases such as HCM, dilated cardiomyopathy, and ARVD. Approximately 2% of
highly trained male athletes will have mild symmetric increase in wall
thickness (usually < 16 mm), increased left ventricular volumes, and
increased left ventricular mass, but no evidence of diastolic dysfunction
[2,
5,
9,
11]. Similar changes may be
seen within the right ventricle.
The diastolic wall thickness (DWT) divided by the left ventricular
end-diastolic volume (LVEDV) ratio (DWT/LVEDV) was identified by Petersen et
al. [12] as the best parameter
to differentiate an athlete's heart from all other pathologic causes of
hypertrophy. Those investigators found that by using the various geometric
indexes of LVEDV, left ventricular end-systolic volume (LVESV), left
ventricular ejection fraction (LVEF), wall thickness, and the DWT/LVEDV ratio,
they were able to correctly identify an athlete's heart in 100% of the cases.
Most important, no athlete was misdiagnosed with a pathologic form of LVH,
despite wall thicknesses of up to 16 mm in some athletes
[12]. A cutoff for the
DWT/LVEDV ratio of less than 0.15 mm/m2/mL gave a sensitivity of
80% and a specificity of 99%
[12] (Fig.
4A,
4B,
4C,
4D,
4E,
4F).
View larger version (147K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4A —28-year-old male athlete with athlete's heart. Steady-state
free precession images show maximal left ventricular wall thickness was
measured as 16 mm. Note biventricular dilatation (E). This male
athlete's end-diastolic volume (EDV) was calculated as 325 mL (120
mL/m2). Diastolic wall thickness (DWT) and left ventricular
end-diastolic volume (LVEDV) ratio (DWT/LVEDV) of 0.13 falls below the cutoff
of 0.15 suggested by Petersen et al.
[12]. This quantitative
evaluation makes diagnosis of athlete's heart more likely than other
pathologic causes of thickened left ventricles.
|
|
View larger version (143K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4B —28-year-old male athlete with athlete's heart. Steady-state
free precession images show maximal left ventricular wall thickness was
measured as 16 mm. Note biventricular dilatation (E). This male
athlete's end-diastolic volume (EDV) was calculated as 325 mL (120
mL/m2). Diastolic wall thickness (DWT) and left ventricular
end-diastolic volume (LVEDV) ratio (DWT/LVEDV) of 0.13 falls below the cutoff
of 0.15 suggested by Petersen et al.
[12]. This quantitative
evaluation makes diagnosis of athlete's heart more likely than other
pathologic causes of thickened left ventricles.
|
|
View larger version (153K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4C —28-year-old male athlete with athlete's heart. Steady-state
free precession images show maximal left ventricular wall thickness was
measured as 16 mm. Note biventricular dilatation (E). This male
athlete's end-diastolic volume (EDV) was calculated as 325 mL (120
mL/m2). Diastolic wall thickness (DWT) and left ventricular
end-diastolic volume (LVEDV) ratio (DWT/LVEDV) of 0.13 falls below the cutoff
of 0.15 suggested by Petersen et al.
[12]. This quantitative
evaluation makes diagnosis of athlete's heart more likely than other
pathologic causes of thickened left ventricles.
|
|
View larger version (155K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4D —28-year-old male athlete with athlete's heart. Steady-state
free precession images show maximal left ventricular wall thickness was
measured as 16 mm. Note biventricular dilatation (E). This male
athlete's end-diastolic volume (EDV) was calculated as 325 mL (120
mL/m2). Diastolic wall thickness (DWT) and left ventricular
end-diastolic volume (LVEDV) ratio (DWT/LVEDV) of 0.13 falls below the cutoff
of 0.15 suggested by Petersen et al.
[12]. This quantitative
evaluation makes diagnosis of athlete's heart more likely than other
pathologic causes of thickened left ventricles.
|
|
View larger version (171K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4E —28-year-old male athlete with athlete's heart. Steady-state
free precession images show maximal left ventricular wall thickness was
measured as 16 mm. Note biventricular dilatation (E). This male
athlete's end-diastolic volume (EDV) was calculated as 325 mL (120
mL/m2). Diastolic wall thickness (DWT) and left ventricular
end-diastolic volume (LVEDV) ratio (DWT/LVEDV) of 0.13 falls below the cutoff
of 0.15 suggested by Petersen et al.
[12]. This quantitative
evaluation makes diagnosis of athlete's heart more likely than other
pathologic causes of thickened left ventricles.
|
|
View larger version (169K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4F —28-year-old male athlete with athlete's heart. Steady-state
free precession images show maximal left ventricular wall thickness was
measured as 16 mm. Note biventricular dilatation (E). This male
athlete's end-diastolic volume (EDV) was calculated as 325 mL (120
mL/m2). Diastolic wall thickness (DWT) and left ventricular
end-diastolic volume (LVEDV) ratio (DWT/LVEDV) of 0.13 falls below the cutoff
of 0.15 suggested by Petersen et al.
[12]. This quantitative
evaluation makes diagnosis of athlete's heart more likely than other
pathologic causes of thickened left ventricles.
|
|
In cases that cannot be distinguished, a period of deconditioning to assess
for a return to more normal cardiac dimensions may be necessary
[2]. Most (90%) athletes with
dilated left ventricles will show a reduction in LVEDV after a period of
deconditioning [11].
Similarly, nearly all athletes with an increased left ventricular wall
thickness will show a return to normal left ventricular wall thickness, some
in as little as 13 weeks [9,
11]. This period of
deconditioning is, however, unacceptable to many athletes.
Another feature of the cardiac remodeling identified in athletes is the
lack of areas of delayed enhancement within the left ventricular myocardium.
However, it should be noted that the absence of myocardial delayed enhancement
does not exclude the diagnosis of HCM.
Fabry's Disease
Fabry's disease is a rare X-linked autosomal recessive metabolic storage
disorder caused by a lack of lysosomal 
-galactosidase A, leading to
accumulation of glycosphingolipid in various tissues. Histologic
ultrastructural findings include concentric lamellar bodies or myelin figures
within the sarcoplasm of myocytes. The disease is more typically systemic in
onset, but one variant may cause predominant heart involvement, typically
later in life [3,
13]. Studies suggest a
prevalence of 3% in all male patients who present with LVH. This prevalence
increases to 6% in male patients and 12% in female patients referred to
tertiary referral centers for late-onset HCM evaluation
[3,
13,
14].
Fabry's disease leads to increased, usually concentric, left ventricular
wall thickening [13,
15] (Fig.
5A,
5B,
5C,
5D). However, asymmetric
septal thickening mimicking HCM can occur
[13,
16].
View larger version (144K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5A —60-year-old man with Fabry's disease and cardiac involvement.
Steady-state free precession and delayed inversion recovery
gadolinium-enhanced images show symmetric left and right ventricular
hypertrophy with mid wall delayed enhancement of the basal posterolateral wall
(C and D). Further enhancement of the basal left ventricular
septum (C) is noted.
|
|
View larger version (167K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5B —60-year-old man with Fabry's disease and cardiac involvement.
Steady-state free precession and delayed inversion recovery
gadolinium-enhanced images show symmetric left and right ventricular
hypertrophy with mid wall delayed enhancement of the basal posterolateral wall
(C and D). Further enhancement of the basal left ventricular
septum (C) is noted.
|
|
View larger version (158K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5C —60-year-old man with Fabry's disease and cardiac involvement.
Steady-state free precession and delayed inversion recovery
gadolinium-enhanced images show symmetric left and right ventricular
hypertrophy with mid wall delayed enhancement of the basal posterolateral wall
(C and D). Further enhancement of the basal left ventricular
septum (C) is noted.
|
|
View larger version (159K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5D —60-year-old man with Fabry's disease and cardiac involvement.
Steady-state free precession and delayed inversion recovery
gadolinium-enhanced images show symmetric left and right ventricular
hypertrophy with mid wall delayed enhancement of the basal posterolateral wall
(C and D). Further enhancement of the basal left ventricular
septum (C) is noted.
|
|
Delayed gadolinium-enhanced imaging has been shown to be useful in
diagnosing Fabry's disease. Moon et al.
[17] found that delayed
contrast enhancement occurred in up to 50% of patients with Fabry's disease.
Enhancement was typically mid wall and occurred in the basal inferolateral
segment in 92% of patients
[17] (Fig.
5A,
5B,
5C,
5D). Distinction between
Fabry's disease and HCM is important because enzyme replacement or enhancement
therapy for patients with Fabry's disease is now available
[3].
Other inherited metabolic disorders, such as mitochondrial myopathy and
glycogen storage disease, are considered in the differential diagnosis of HCM
but are not discussed here.
Thickened Left Ventricular Apex
The differential diagnosis of a thickened left ventricular apex on
echocardiography includes apical HCM, mural thrombus, hypertrabeculation or
noncompaction, and hypereosinophilic cardiomyopathy. These entities may be
evaluated more clearly on MRI using steady-state free precession (SSFP)
imaging techniques and delayed gadolinium-enhanced imaging
[18]. Contrast-enhanced
echocardiography is superior to standard transthoracic echocardiography but is
no substitute for MRI
[19].
Mural thrombus can be easily detected on delayed gadolinium-enhanced
imaging when it is associated with an underlying myocardial infarct. The low
signal of the mural thrombus in these instances stands out against a
background of intermediate blood pool signal and the underlying hyperintense
area of infarcted subendocardium.
Patients with left ventricular apical hypertrabeculation or noncompaction
are well suited to imaging with cardiovascular MR. The high signal intensity
of the blood pool achieved by SSFP imaging techniques allows reliable
differentiation of compacted and noncompacted layers of the left ventricular
myocardium (Fig. 6A,
6B). The presence of
echogenicity within the blood pool trapped between the interstices of the
trabeculae on echocardiography can sometimes lead to the incorrect diagnosis
of apical HCM.
View larger version (160K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6A —36-year-old man with biventricular dilatation and reduced
function. Steady-state free precession four-chamber (A) and short-axis
oblique (B) projection images show left ventricular noncompaction. Note
presence of prominent trabeculae within the right ventricle as well.
Echocardiography (not shown) suggested possible left ventricular apical
thickening; however, the diagnosis of left ventricular noncompaction was
considered, and MRI was requested to investigate further.
|
|
View larger version (138K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6B —36-year-old man with biventricular dilatation and reduced
function. Steady-state free precession four-chamber (A) and short-axis
oblique (B) projection images show left ventricular noncompaction. Note
presence of prominent trabeculae within the right ventricle as well.
Echocardiography (not shown) suggested possible left ventricular apical
thickening; however, the diagnosis of left ventricular noncompaction was
considered, and MRI was requested to investigate further.
|
|
Hypereosinophilic syndrome with cardiac involvement and endomyocardial
fibrosis (with or without peripheral hypereosinophilia) are a complex group of
disorders that may lead to both endomyocardial fibrosis and obliteration of
the left ventricular apical cavity. Imaging appearances may mimic apical HCM;
therefore, these disorders should be considered in the differential diagnosis
[20–24].
Hypereosinophilic syndrome typically induces cardiac damage through three
distinct phases: an acute necrotic stage, a thrombotic stage, and a fibrotic
stage. The disorder may result in endomyocardial fibrosis, valvular lesions,
mural thrombus formation, infiltration of the myocardium with eosinophils, and
pericardial effusions
[24–27]
(Fig. 7A,
7B).
View larger version (145K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 7A —49-year-old man with hypereosinophilic syndrome
cardiomyopathy. Steady-state free precession four-chamber view shows apparent
apical left ventricular thickening, small pericardial effusion, and bilateral
pleural effusions.
|
|
View larger version (58K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 7B —49-year-old man with hypereosinophilic syndrome
cardiomyopathy. Delayed enhancement four-chamber view clearly shows diffuse
subendocardial enhancement and triangular-shaped apical thrombus. These
findings are typical of hypereosinophilic syndrome cardiomyopathy.
|
|
The imaging appearances of hypereosinophilic syndrome on cardiovascular MR
are therefore characterized by subendocardial enhancement; distortion of the
mitral valve apparatus, with resultant regurgitation; and mural thrombus
formation [24,
27,
28]. Fibrosis at the cardiac
apex frequently results in obliteration of the apical cavity. These changes,
when combined with apical mural thrombus, commonly lead to a misdiagnosis of
apical HCM (Fig. 7A,
7B).
Cardiac Sarcoidosis
Sarcoidosis is a multisystem disorder that shows cardiac involvement in up
to 27% of patients with the disorder at autopsy
[29]. Clinical evidence of
myocardial involvement is apparent during life in only 5% of affected
patients. Sarcoidosis is characterized by the presence of noncaseating
granulomatous infiltration. Sudden death is the most common cardiac
manifestation of patients with severe cardiac sarcoid involvement, with ECG
changes being the most predictive of cardiac sarcoid in general
[29]. The incidence of sudden
cardiac death in these patients highlights the importance of identifying
cardiac sarcoid early because prompt initiation of corticosteroid therapy has
been shown to improve left ventricular function and prevent malignant
arrhythmia [30,
31].
Common MRI findings in patients with cardiac sarcoid include delayed
enhancement, which may be either mid wall or transmural; nodular mid wall
hyperintense foci on black blood T2-weighted imaging; and areas of focal
myocardial thickening (Fig.
8A,
8B). Disease may involve
either the left or the right ventricle but more commonly involves the left
ventricle, where the basal septum is often involved, giving an appearance that
can mimic asymmetric HCM [30,
32–36].
View larger version (151K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 8A —54-year-old man with heart block and confirmed cardiac
sarcoid. Steady-state free precession four-chamber view shows three separate
areas of nodular left ventricular thickening. Two nodules are noted within the
left ventricular septum and a third at the lateral apical left ventricular
free wall.
|
|
View larger version (140K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 8B —54-year-old man with heart block and confirmed cardiac
sarcoid. After gadolinium administration, the three areas seen in A
show nodular delayed enhancement. Note also delayed enhancement and
inflammatory thickening of the right ventricular trabeculae.
|
|
In a study by Tadamura et al.
[36], 10 patients with cardiac
sarcoidosis were imaged with MRI, 201Tl scintigraphy, and
67Ga scintigraphy. They found delayed gadolinium enhancement in all
patients. Assessment for wall motion abnormalities, 201Tl perfusion
defects, and abnormal 67Ga uptake was shown to be less sensitive in
detecting disease [35,
36]. Patients in whom
transmural delayed gadolinium enhancement was identified were more likely to
show abnormalities on both 201Tl and 67Ga scintigraphy
and to show region wall motion abnormalities
[36].
Imaging features that should alert the radiologist to a diagnosis of
cardiac sarcoid over HCM include clinical, hematologic, pulmonary, and
mediastinal manifestations of sarcoidosis; nodular myocardial thickening
confined to areas of myocardial delayed enhancement (Fig.
8A,
8B) or T2 hyperintensity;
associated 67Ga scintigraphy changes; and pericardial granulomatous
disease characterized by effusions, thickening, and delayed enhancement.
Aortic Stenosis and Hypertensive Heart Disease
These diseases tend to cause symmetric left ventricular wall thickening and
are a diagnosis of exclusion. Aortic stenosis is readily evaluated on
cardiovascular MR, and evidence of this finding should be sought when imaging
patients for suspected HCM.
Sudden Cardiac Death and Risk Stratification in Patients with HCM
Sudden cardiac death occurs in 1% or less per year of adult patients,
rising to 2–4% per year in children and adolescents
[2]. Disorganized cellular
architecture, myocardial replacement scarring, and an expanded interstitial
collagen compartment are thought to be the primary arrhythmogenic substrate in
some susceptible patients
[37]. The best clinical
correlate of sudden cardiac death is ventricular tachyarrhythmias
[2,
3]. Appendix 1 includes a list
of classic predictors of sudden cardiac death in HCM patients
[37].
The ability to detect areas of myocardial enhancement in hearts with HCM
has generated interest in trying to identify patients who harbor an
"arrhythmogenic substrate." Teraoka et al.
[38] found that the presence
of delayed enhancement and the number of involved segments correlated with the
presence of ventricular tachycardia. Furthermore, delayed enhancement has been
shown to be increased in patients with more clinical risk factors for sudden
cardiac death
[39–41].
View larger version (29K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 9B —Diagrams looking at the left ventricular interventricular
septum and outflow tract. Diagram depicts area of iatrogenic infarction
resulting from injection of ethanol into an appropriate septal perforator as
shown.
|
|
Treatment of HCM
Although most patients with HCM are treated medically, septal reduction
techniques involving either surgical septal myomectomy or catheter-based
septal alcohol ablation are generally indicated in patients who do not respond
to medical therapy and have either resting or inducible left ventricular
outflow tract (LVOT) gradients. Other techniques involving atrioventricular
sequential pacing and insertion of an implantable cardioverter-defibrillator
are used in certain circumstances; however, because these patients do not
undergo follow-up cardiovascular MR, they are not discussed here.
View larger version (131K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 10A —52-year-old man with hypertrophic cardiomyopathy and left
ventricular outflow tract (LVOT) obstruction treated with alcohol septal
ablation. Steady-state free precession (A and B) and delayed
enhancement (C and D) images of the basal left ventricular
septum show full-thickness infarction. The area of delayed enhancement
(C and D) is well remodeled with marked thinning of the involved
septum. This remodeling creates a greater cross-sectional dimension of the
LVOT and reduces gradients in this region.
|
|
View larger version (159K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 10B —52-year-old man with hypertrophic cardiomyopathy and left
ventricular outflow tract (LVOT) obstruction treated with alcohol septal
ablation. Steady-state free precession (A and B) and delayed
enhancement (C and D) images of the basal left ventricular
septum show full-thickness infarction. The area of delayed enhancement
(C and D) is well remodeled with marked thinning of the involved
septum. This remodeling creates a greater cross-sectional dimension of the
LVOT and reduces gradients in this region.
|
|
View larger version (148K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 10C —52-year-old man with hypertrophic cardiomyopathy and left
ventricular outflow tract (LVOT) obstruction treated with alcohol septal
ablation. Steady-state free precession (A and B) and delayed
enhancement (C and D) images of the basal left ventricular
septum show full-thickness infarction. The area of delayed enhancement
(C and D) is well remodeled with marked thinning of the involved
septum. This remodeling creates a greater cross-sectional dimension of the
LVOT and reduces gradients in this region.
|
|
View larger version (151K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 10D —52-year-old man with hypertrophic cardiomyopathy and left
ventricular outflow tract (LVOT) obstruction treated with alcohol septal
ablation. Steady-state free precession (A and B) and delayed
enhancement (C and D) images of the basal left ventricular
septum show full-thickness infarction. The area of delayed enhancement
(C and D) is well remodeled with marked thinning of the involved
septum. This remodeling creates a greater cross-sectional dimension of the
LVOT and reduces gradients in this region.
|
|
Septal Myomectomy
Septal myomectomy is considered the gold standard of septal reduction
techniques currently in use [2,
42]. This procedure, performed
through an aortotomy, creates a rectangular trough in the myocardium via two
parallel longitudinal incisions in the basal septum. Incisions are connected
proximally below the aortic valve and are extended distally just beyond the
level of mitral valve–septum contact and subaortic obstruction
(Fig. 9A) or, in some
patients, are extended to the base of the papillary muscles (extended
myomectomy) [43].
Mortality at expert centers is approximately 1–1.5% for myomectomy
alone and 1–5% for combined myomectomy and coronary artery bypass
grafting [2,
44]. Complications such as
complete heart block, requiring insertion of a permanent pacemaker, and
iatrogenic ventricular septal perforation have become uncommon (
1–2%) as surgical techniques have improved. Partial or complete left
bundle branch block is a common consequence of the muscular resection and is
not associated with adverse sequelae
[37].
Septal Alcohol Ablation
Septal alcohol ablation involves iatrogenic infarction of the basal
interventricular septum. Initially, a coronary angiogram is obtained, followed
by placement of a balloon catheter into the first major septal perforator
(Fig. 9B). A temporary pacing
catheter is positioned in the right ventricle. After the balloon is inflated,
another angiogram is obtained to verify the position of the balloon and to
ensure that no alcohol will leak into the left anterior descending coronary
artery or the coronary venous system. Contrast-enhanced echocardiography is
used to define the perfusion territory of the targeted septal perforator
before alcohol embolization
[2]. ECG is used to closely
monitor for signs of bradycardia or heart block
[45,
46].
Postprocedure MRI with delayed contrast-enhanced imaging reliably shows the
area of infarcted septal myocardium
[47] (Fig.
10A,
10B,
10C,
10D). For visualization of the
LVOT diameter, MRI is best performed 3 months after the procedure because
remodeling may not yet be complete before this time. In addition, LVOT
gradients may continue to decrease for up to 1 year after surgical ablation
because of left ventricular septal remodeling over time
[2]. Having said this, delayed
contrast-enhanced imaging performed less than 3 months after the procedure
will adequately show the extent of infarction and any areas of microvascular
obstruction [47,
48].
Postprocedure complications of septal alcohol ablation include ventricular
septal defect formation, heart block (5–30%), and coronary artery
dissection [2]. Current
modifications to the procedure, which use a slower injection of alcohol and
contrast-enhanced transesophageal echocardiography, have shown a reduction in
occurrence of complete heart block from 22% before modifying the procedure to
8.6% after modification. This lower occurrence is still high compared with
that of myomectomy in which complete heart block occurs in approximately
1–2% [46]. Not
surprisingly, there is a reported higher incidence of permanent pacemaker
implantation after alcohol septal ablation than after myomectomy—on the
order of 14–25%
[49].
The long-term arrhythmogenic potential of scarred myocardium is not yet
clear, but short-term results show no increase in arrhythmogenesis.
LVOT gradients, septal thickness, left atrial dimensions, mitral
regurgitation, and patient symptoms have been shown to decrease after ablation
[47,
50]. Some studies show no
significant differences in functional outcome between alcohol septal ablation
and surgical myomectomy when considering resting LVOT gradients, LVEDV, LVESV,
and left ventricular mass. Other reports however show greater reductions in
LVOT gradients and reduction in systolic anterior motion (both resting and
provocable) in patients who have undergone myomectomy
[51].
Whether alcohol septal ablation can create a permanent arrhythmogenic
substrate in the form of a healed intramyocardial septal scar is
controversial. This issue is particularly relevant because many patients with
HCM already possess an unstable electrophysiologic substrate as part of their
underlying disease. Reports however suggest that there is no evidence that
septal ablation increases the incidence of ventricular arrhythmias, the
incidence of sudden cardiac death, or the rate of discharge of implantable
cardioverter-defibrillators
[42,
52,
53].
Screening for HCM
Screening programs for HCM in the past have considered a normal imaging
study and ECG as proof that an adult is genetically unaffected. However,
certain genotypes of HCM have been shown to exhibit age-related penetrance and
delayed appearance of LVH—that is, in midlife or later
[54,
55].
The American College of Cardiology/European Society of Cardiology clinical
expert consensus document on HCM suggests that relatives of affected
individuals be screened yearly by means of echocardiography and that relatives
who are 12–18 years old undergo ECG examinations. Because of the
possibility of delayed adult-onset LVH, they also recommend that adult
relatives with normal echocardiograms who are 18 years old or older undergo
subsequent clinical studies every 5 years. This document also suggests that
affected patients identified through family screening or otherwise be
evaluated every 12–18 months
[37].
Summary
Cardiovascular MRI is a useful imaging tool for the diagnosis of HCM and
follow-up of patients after either surgical myomectomy or septal ablation
therapy. In addition, MRI can help to discriminate HCM from the differential
diagnoses of other cardiomyopathies and cardiac disorders.
The strengths of MRI include accuracy and reproducibility when measuring
left ventricular mass, volumes, and function and its ability to identify
macroscopic areas of abnormal myocardium with delayed gadolinium-enhanced
imaging.
Current research studies comparing traditional clinical indicators for
predicting sudden cardiac death with cardiovascular MRI findings and delayed
enhancement imaging highlight MRI's future potential in moving toward patient
risk stratification in HCM. Further research in this area is necessary,
however, to determine how best to manage this subset of patients with delayed
enhancement and the impact of management on reducing the incidence of sudden
cardiac death.
References
- Hansen MW, Merchant N. MRI of hypertrophic cardiomyopathy: part 1,
MRI appearances. AJR 2007;189
:1335
–1343[Abstract/Free Full Text]
- Elliott P, McKenna WJ. Hypertrophic cardiomyopathy.
Lancet 2004; 363:1881
–1891[CrossRef][Medline]
- Hughes SE. The pathology of hypertrophic cardiomyopathy.
Histopathology 2004;44
: 412–427[CrossRef][Medline]
- Fattori R, Rocchi G, Celletti F, Bertaccini P, Rapezzi C, Gavelli
G. Contribution of magnetic resonance imaging in the differential diagnosis of
cardiac amyloidosis and symmetric hypertrophic cardiomyopathy. Am
Heart J 1998; 136:824
–830[CrossRef][Medline]
- Prasad K, Atherton J, Smith GC, McKenna WJ, Frenneaux MP,
Nihoyannopoulos P. Echocardiographic pitfalls in the diagnosis of hypertrophic
cardiomyopathy. Heart 1999;82
[suppl 3]:III8
–III15[Medline]
- Maceira AM, Joshi J, Prasad SK, et al. Cardiovascular magnetic
resonance in cardiac amyloidosis. Circulation2005; 111:186
–193[Abstract/Free Full Text]
- Mahrholdt H, Wagner A, Judd RM, Sechtem U, Kim RJ. Delayed
enhancement cardiovascular magnetic resonance assessment of non-ischaemic
cardiomyopathies. Eur Heart J 2005;26
:1461
–1474[Abstract/Free Full Text]
- Beckerman J, Wang P, Hlatky M. Cardiovascular screening of
athletes. Clin J Sport Med 2004;14
: 127–133[CrossRef][Medline]
- Maron BJ. Sudden death in young athletes. N Engl J
Med 2003; 349:1064
–1075[Free Full Text]
- Pelliccia A, Maron BJ, Culasso F, Spataro A, Caselli G. Athlete's
heart in women: echocardiographic characterization of highly trained elite
female athletes. JAMA 1996;276
: 211–215[Abstract]
- Pelliccia A, Maron BJ, De Luca R, Di Paolo FM, Spataro A, Culasso
F. Remodeling of left ventricular hypertrophy in elite athletes after
long-term deconditioning. Circulation2002; 105:944
–949[Abstract/Free Full Text]
- Petersen SE, Selvanayagam JB, Francis JM, et al. Differentiation of
athlete's heart from pathological forms of cardiac hypertrophy by means of
geometric indices derived from cardiovascular magnetic resonance. J
Cardiovasc Magn Reson 2005;7
: 551–558[Medline]
- Sachdev B, Takenaka T, Teraguchi H, et al. Prevalence of
Anderson-Fabry disease in male patients with late onset hypertrophic
cardiomyopathy. Circulation 2002;105
:1407
–1411[Abstract/Free Full Text]
- Chimenti C, Pieroni M, Morgante E, et al. Prevalence of Fabry
disease in female patients with late-onset hypertrophic cardiomyopathy.
Circulation 2004;110
:1047
–1053[Abstract/Free Full Text]
- Goldman ME, Cantor R, Schwartz MF, Baker M, Desnick RJ.
Echocardiographic abnormalities and disease severity in Fabry's disease.
J Am Coll Cardiol 1986;7
: 1157–1161[Abstract]
- Linhart A, Palecek T, Bultas J, et al. New insights in cardiac
structural changes in patients with Fabry's disease. Am Heart
J 2000; 139:1101
–1108[CrossRef][Medline]
- Moon JC, Sachdev B, Elkington AG, et al. Gadolinium enhanced
cardiovascular magnetic resonance in Anderson-Fabry disease: evidence for a
disease specific abnormality of the myocardial interstitium. Eur
Heart J 2003; 24:2151
–2155[Abstract/Free Full Text]
- Sperling RT, Parker JA, Manning WJ, Danias PG. Apical hypertrophic
cardiomyopathy: clinical, electrocardiographic, scintigraphic,
echocardiographic, and magnetic resonance imaging findings of a case.
J Cardiovasc Magn Reson 2002;4
: 291–295[CrossRef][Medline]
- Dijkmans PA, Visser CA, Kamp O. An abnormal ECG with inverted T
waves in the precordial leads: confirming the diagnosis with contrast enhanced
echocardiography. Heart 2005;91
: 913[Free Full Text]
- Anderson KR, Sutton MG, Lie JT. Histopathological types of cardiac
fibrosis in myocardial disease. J Pathol1979; 128:79
–85[CrossRef][Medline]
- Andy JJ. Aetiology of endomyocardial fibrosis (EMF).
West Afr J Med 2001;20
: 199–207[Medline]
- Felice PV, Sawicki J, Anto J. Endomyocardial disease and
eosinophilia. Angiology 1993;44
: 869–874[Medline]
- Hassan WM, Fawzy ME, Al Helaly S, Hegazy H, Malik S. Pitfalls in
diagnosis and clinical, echocardiographic, and hemodynamic findings in
endomyocardial fibrosis: a 25-year experience. Chest2005; 128:3985
–3992[CrossRef][Medline]
- Puvaneswary M, Joshua F, Ratnarajah S. Idiopathic hypereosinophilic
syndrome: magnetic resonance imaging findings in endomyocardial fibrosis.
Australas Radiol 2001;45
: 524–527[CrossRef][Medline]
- Mayet J, Kanagaratnam P, Lincoln C, Oldershaw P. Hypereosinophilic
syndrome: endomyocardial fibrosis. Heart1997; 77:391[Free Full Text]
- Pitt M, Davies MK, Brady AJ. Hypereosinophilic syndrome:
endomyocardial fibrosis. Heart 1996;76
: 377–378[Free Full Text]
- Salanitri GC. Endomyocardial fibrosis and intracardiac thrombus
occurring in idiopathic hypereosinophilic syndrome.
AJR 2005; 184:1432
–1433[Free Full Text]
- Alter P, Maisch B. Endomyocardial fibrosis in Churg-Strauss
syndrome assessed by cardiac magnetic resonance imaging. Int J
Cardiol 2006; 108:112
–113[CrossRef][Medline]
- Silverman KJ, Hutchins GM, Bulkley BH. Cardiac sarcoid: a
clinicopathologic study of 84 unselected patients with systemic sarcoidosis.
Circulation 1978;58
:1204
–1211[Abstract/Free Full Text]
- Stauder NI, Bader B, Fenchel M, Kramer U, Kühlkamp V, Miller
S. Images in cardiovascular medicine: follow-up of cardiac sarcoidosis by
magnetic resonance imaging. Circulation2005; 111:e158
–e160[Free Full Text]
- Sharma OP. Cardiac and neurologic dysfunction in sarcoidosis.
Clin Chest Med 1997;18
: 813–825[CrossRef][Medline]
- Vignaux O. Cardiac sarcoidosis: spectrum of MRI features.
AJR 2005; 184:249
–254[Free Full Text]
- Dubrey SW, Grocott-Mason R, Mittal TK. Images in cardiology:
cardiac sarcoidosis with delayed enhanced MRI. Heart2005; 91:1185[Free Full Text]
- Kiuchi S, Teraoka K, Koizumi K, Takazawa K, Yamashita A. Usefulness
of late gadolinium enhancement combined with MRI and 67-Ga scintigraphy in the
diagnosis of cardiac sarcoidosis and disease activity evaluation.
Int J Cardiovasc Imaging 2007;23
: 237–241[CrossRef][Medline]
- Smedema JP, Snoep G, van Kroonenburgh MP, et al. Evaluation of the
accuracy of gadolinium-enhanced cardiovascular magnetic resonance in the
diagnosis of cardiac sarcoidosis. J Am Coll Cardiol2005; 45:1683
–1690[Abstract/Free Full Text]
- Tadamura E, Yamamuro M, Kubo S, et al. Effectiveness of delayed
enhanced MRI for identification of cardiac sarcoidosis: comparison with
radionuclide imaging. AJR 2005;185
: 110–115[Abstract/Free Full Text]
- Maron BJ, McKenna WJ, Danielson GK, et al. American College of
Cardiology/European Society of Cardiology clinical expert consensus document
on hypertrophic cardiomyopathy. A report of the American College of Cardiology
Foundation Task Force on Clinical Expert Consensus Documents and the European
Society of Cardiology Committee for Practice Guidelines. J Am Coll
Cardiol 2003; 42:1687
–1713[Free Full Text]
- Teraoka K, Hirano M, Ookubo H, et al. Delayed contrast enhancement
of MRI in hypertrophic cardiomyopathy. Magn Reson
Imaging 2004; 22:155
–161 [Erratum in Magn Reson Imaging
2004; 22:901][CrossRef][Medline]
- Moon JC, Mogensen J, Elliott PM, et al. Myocardial late gadolinium
enhancement cardiovascular magnetic resonance in hypertrophic cardiomyopathy
caused by mutations in troponin I. Heart2005; 91:1036
–1040[Abstract/Free Full Text]
- Moon JC, McKenna WJ, McCrohon JA, Elliott PM, Smith GC, Pennell DJ.
Toward clinical risk assessment in hypertrophic cardiomyopathy with gadolinium
cardiovascular magnetic resonance. J Am Coll Cardiol2003; 41:1561
–1567[Abstract/Free Full Text]
- Elliott PM, Gimeno Blanes JR, Mahon NG, Poloniecki JD, McKenna WJ.
Relation between severity of left-ventricular hypertrophy and prognosis in
patients with hypertrophic cardiomyopathy. Lancet2001; 357:420
–424[CrossRef][Medline]
- Kovacic JC, Muller D. Hypertrophic cardiomyopathy: state-of-the-art
review, with focus on the management of outflow obstruction. Intern
Med J 2003; 33:521
–529[CrossRef][Medline]
- Ommen SR, Maron BJ, Olivotto I, et al. Long-term effects of
surgical septal myectomy on survival in patients with obstructive hypertrophic
cardiomyopathy. J Am Coll Cardiol 2005;46
: 470–476[Abstract/Free Full Text]
- Woo A, Williams WG, Choi R, et al. Clinical and echocardiographic
determinants of long-term survival after surgical myectomy in obstructive
hypertrophic cardiomyopathy. Circulation2005; 111:2033
–2041[Abstract/Free Full Text]
- Faber L, Seggewiss H, Gleichmann U. Percutaneous transluminal
septal myocardial ablation in hypertrophic obstructive cardiomyopathy: results
with respect to intraprocedural myocardial contrast echocardiography.
Circulation 1998;98
:2415
–2421
Top
Abstract
Introduction
