Plaque Morphology as Predictor of Late Plaque Events in Patients With Asymptomatic Type 2 Diabetes: A Long-Term Observational Study

Abstract

Objectives: The authors used coronary computed tomography angiography (CTA) to determine plaque characteristics predicting individual late plaque events precipitating acute coronary syndromes (ACS) in a cohort of asymptomatic type 2 diabetic patients.

Background: In patients with coronary artery disease, CTA plaque characteristics may predict mid-term patient events.

Methods: Asymptomatic patients with diabetes 55 to 74 years of age with no history of coronary artery disease (N = 630) underwent baseline 64-slice CTA and detailed plaque level analysis. All subsequent clinical events were recorded and adjudicated. In patients who developed ACS, culprit plaque was identified at invasive angiography and its precursor located on the baseline CTA. Plaque characteristics predicting an ACS-associated culprit plaque event were analyzed by time to event accounting for inpatient clustering of plaques and competing events.

Results: Among 2,242 plaques in 499 subjects, 24 ACS culprit plaques were identified in 24 subjects during median follow-up of 9.2 years (interquartile range: 8.4 to 9.8 years). Plaque volume (upper vs. lower quartile hazard ratio [HR]: 6.9; 95% confidence interval [CI]: 1.6 to 30.8; p = 0.011), percentage of low-density plaque content <50 Hounsfield units (HR: 14.2; 95% CI: 1.9 to 108; p = 0.010), and mild plaque calcification (HR vs. all other plaques 3.3 [95% CI: 1.5 to 7.3]; p = 0.004) predicted plaque events univariately and after adjustment by clinical risk score. A culprit plaque event occurred in 13 of 376 (3.5%) high-risk plaques (HRP) (plaques with ≥2 risk predictors) versus 11 of 1,866 (0.6%) in non-HRPs (p < 0.0001), at 12 of 343 (3.5%) stenotic sites (≥50%) versus 12 of 1,899 (0.6%) nonstenotic sites (p < 0.0001) and in 7 of 131 (5.3%) HRP with stenosis (p < 0.0001 vs. all others). In 130 (20.6%) subjects, no coronary plaque was present on baseline CTA.

Conclusions: In asymptomatic patients with type 2 diabetes, CTA plaque volume, percent low-density plaque content, and mild calcification predicted late plaque events. The additional presence of luminal stenosis increased the probability of an acute event.

Keywords: CT angiography; acute coronary syndrome; coronary plaque; diabetes mellitus; primary prevention.