DOI:10.2214/AJR.06.0626
AJR 2007; 188:W93
© American Roentgen Ray Society
Identification of Severe Left Main Trunk Coronary Stenosis on MDCT Coronary Angiography
Emil R. Hayek,
Harold A. White and
Robert W. Kamienski
Akron General Medical Center Akron, OH 44307
WEB—This is a Web exclusive article.
MDCT coronary angiography is a rapidly emerging technique for the accurate
noninvasive detection of coronary arterial disease (CAD). We report the
diagnosis of a severe left main trunk stenosis based on MDCT in a minimally
symptomatic individual.
A 60-year-old man with no risk factors for premature CAD other than mildly
elevated low-density lipoprotein cholesterol noticed loss of exercise
endurance during upright stationary rowing over the preceding month. He denied
anginal symptoms, and ECG showed normal findings. He underwent a
technetium-99m-tetrofosmin SPECT myocardial perfusion stress test that was
terminated after 4 minutes of treadmill exercise (heart rate, 150 beats per
minute, 94% of the maximum predicted heart rate) due to the development of
2-mm ST-segment depression. During exercise, he had no anginal symptoms and
the hemodynamic response to exercise was normal. The Duke treadmill score was
-6, corresponding to intermediate cardiac risk.
Both the rest and stress perfusion images were normal, and there was no
evidence of significant transient ischemic left ventricular dilatation
(Fig. 1A). The ECG-gated images
showed normal wall motion and thickening with a left ventricular ejection
fraction of 57%. MDCT coronary angiography (64-detector) was subsequently
performed and depicted severe stenoses of the left main trunk, left anterior
descending, and circumflex coronary arteries. Invasive coronary angiography
confirmed the MDCT findings, and the patient underwent uncomplicated
two-vessel coronary artery bypass grafting the next day (Figs.
1B and
1C).
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Fig. 1A —60-year-old man with no risk factors for premature coronary
arterial disease other than mildly elevated low-density lipoprotein
cholesterol noticed loss of exercise endurance during upright stationary
rowing over preceding month. He denied anginal symptoms, and ECG showed normal
findings. During exercise, he had no anginal symptoms and hemodynamic response
to exercise was normal. Duke treadmill score was -6, corresponding to
intermediate cardiac risk. Stress and rest myocardial perfusion SPECT images
were normal. VLA = vertical long axis, HLA = horizontal long axis, SA = short
axis.
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Fig. 1B —60-year-old man with no risk factors for premature coronary
arterial disease other than mildly elevated low-density lipoprotein
cholesterol noticed loss of exercise endurance during upright stationary
rowing over preceding month. He denied anginal symptoms, and ECG showed normal
findings. During exercise, he had no anginal symptoms and hemodynamic response
to exercise was normal. Duke treadmill score was -6, corresponding to
intermediate cardiac risk. MDCT coronary angiogram (B) and coronary
angiogram (C) show severe ostial left main trunk (LMT) stenosis
(arrowhead, C). LCx = left circumflex coronary artery, LAD =
left anterior descending coronary artery.
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Fig. 1C —60-year-old man with no risk factors for premature coronary
arterial disease other than mildly elevated low-density lipoprotein
cholesterol noticed loss of exercise endurance during upright stationary
rowing over preceding month. He denied anginal symptoms, and ECG showed normal
findings. During exercise, he had no anginal symptoms and hemodynamic response
to exercise was normal. Duke treadmill score was -6, corresponding to
intermediate cardiac risk. MDCT coronary angiogram (B) and coronary
angiogram (C) show severe ostial left main trunk (LMT) stenosis
(arrowhead, C). LCx = left circumflex coronary artery, LAD =
left anterior descending coronary artery.
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Although SPECT myocardial perfusion imaging (MPI) has been invaluable both
in the noninvasive detection of CAD and in risk stratification, the extent of
perfusion abnormalities often underestimates the severity of CAD. Because
SPECT MPI estimates relative rather than absolute myocardial perfusion, in the
presence of three-vessel CAD (3VD), or left main trunk stenosis, global left
ventricular (LV) hypoperfusion (termed "balanced ischemia") is
associated with the failure to identify perfusion abnormalities in all of the
affected coronary territories in as many as 81% of patients
[1].
Both clinical information, including the presence of diabetes or
hypertension, and exercise variables, including the magnitude of ST-segment
depression, exercise heart rate, and decreasing blood pressure during
exercise, independently predict the presence of 3VD or left main trunk
stenosis [2,
3]. In addition, scintigraphic
findings including multiple perfusion defects, transient LV cavity dilatation,
increased thallium-201 pulmonary uptake, and increased right ventricular
uptake are associated with severe multivessel or left main trunk disease
[3]. Although our patient did
have an intermediate-risk Duke treadmill score, none of the high-risk
clinical, exercise, or scintigraphic findings associated with 3VD or left main
trunk disease was present.
64-MDCT coronary angiography offers excellent temporal and spatial
resolution, making it a clinically useful tool in the noninvasive detection of
coronary stenoses. When compared with conventional invasive coronary
angiography in the identification of significant CAD, both 16- and 64-MDCT
exhibit excellent sensitivity and specificity
[4]. Among patients with
atypical symptoms and intermediate-risk exercise SPECT studies, MDCT may have
a role in the noninvasive identification of severe multivessel or left main
trunk CAD.
References
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myocardial imaging in left main coronary artery disease: sensitive but not
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