Background:
Patients with low or moderate pre-test probability of significant coronary artery disease (CAD) and equivocal or mildly abnormal non-invasive cardiac stress tests represent a frequent management challenge. Coronary multidetector computed tomography (MDCT) has been shown to have excellent diagnostic accuracy to exclude the presence of significant CAD.
Methods:
The study included 218 patients (mean age 59±12 years, 60% male) with equivocal or mildly abnormal exercise electrocardiography (n=93), stress SPECT perfusion scans (n=121), stress echocardiography (n=3) and stress cardiac MRI (n=1). Patients were either asymptomatic (n=113) or had atypical chest pain (n=105). All patients underwent contrast-enhanced 64-slice MDCT coronary angiography and datasets were evaluated for the presence of coronary atherosclerotic plaques and significant coronary artery stenosis. Patients were followed for 8±3 months and the endpoints evaluated were: cardiac death, myocardial infarction, revascularization procedure performed >3 months after MDCT coronary angiography and unstable angina requiring hospitalization.
Results:
MDCT coronary angiography was either normal (n=90; 41%), demonstrated non-obstructive coronary atherosclerotic plaques (n=66; 30%) or exhibited significant coronary stenosis (n=62; 29%). Event-free survival was 100% for patients with normal coronary angiography, 98% for patients with non-obstructive plaques and 92% for patients with coronary stenosis (log-rank test P=0.01). One patient with a non-obstructive plaque involving the left main coronary artery died following an AMI (hazard ratio, 0.38; 95% confidence interval, 0.04 to 3.24). Among patients with coronary stenosis, 3 underwent revascularization procedures and 2 died (hazard ratio, 12.59; 95% confidence interval, 1.47 to 107.86).
Conclusion:
Among patients with equivocal or mildly abnormal non-invasive cardiac stress tests, a normal MDCT coronary angiography is associated with a very low risk for subsequent cardiac events. Further studies are necessary to determine the clinical significance of non-obstructive atherosclerotic plaques detected by MDCT coronary angiography in this patient population.
Non-invasive molecular imaging of vulnerable atherosclerotic plaques
