Noncalcified plaque: Relationship between results of multislice computed tomography, risk factors, and late clinical outcome

Background: Contrast-enhanced multislice computed tomographic angiography (MSCTA) detects noncalcified plaque (NCP) in coronary arteries and associated coronary stenoses. However, the clinical relevance of NCP is poorly defined. Objectives: Our goal was to examine the relationship NCP, risk factors (RFs), and clinical follow-up in unselected outpatients undergoing MSCTA. Methods: Five hundred six patients undergoing contrast MSCTA were evaluated for NCP (intraluminal density 25 < Hounsfield units < 130). One hundred twenty-four patients (24.5%) had calcium scores (CAC) of zero. Of these, 111 patients were examined for RFs and followed clinically for a mean of 34 months. Results: Of 124 patients with zero CAC, 111 (89.5%) included 52 (46.8%) with no NCP, 40 (36.0%) with NCP, and mild luminal stenosis, 14 (12.6%) and 5 (4.5%) with NCP causing significant and severe stenosis, respectively. Patients in each group were similar in age but differed significantly in number of RFs. Current or former smokers, hypertensive, and obese patients had more NCP and associated stenosis. At a mean of 34 months, there were no events in the no NCP group, 2/54 (3.7%) events in the NCP without severe stenosis group (one sudden cardiac death and one ventricular tachycardia), and 2/5 (40.0%) patients had revascularization in the NCP with severe stenosis group. Conclusions: (1) In patients with zero CAC, presence of NCP on MSCTA was associated with more RFs, especially smoking, obesity, and hypertension. (2) NCP can result in severe coronary stenosis. (3) NCP detected by MSCTA in patients with zero CAC may identify patients with late cardiac events. (c) 2011 Wiley Periodicals, Inc.