Atherosclerosis quantification and cardiovascular risk: the ISCHEMIA trial

Area of Science:

• Cardiology
• Radiology
• Medical Imaging

Background:

• The ISCHEMIA trial investigated optimal invasive or conservative strategies for stable ischemic heart disease.
• Coronary computed tomography angiography (CCTA) is a key imaging modality in cardiology.
• Assessing atherosclerotic plaque characteristics beyond stenosis severity is crucial for risk stratification.

Purpose of the Study:

• To determine the prognostic value of CCTA-derived atherosclerotic plaque analysis in the ISCHEMIA trial.
• To evaluate if quantitative plaque analysis improves cardiovascular risk prediction in a high-risk population.

Main Methods:

• Atherosclerosis imaging quantitative CT (AI-QCT) was used to quantify plaque volume, composition, and distribution from baseline CCTAs.
• Multivariable Cox regression analyzed associations between baseline risk factors, AI-QCT plaque characteristics, and a composite outcome of cardiovascular death or myocardial infarction.
• Area under the curve (AUC) analysis compared the predictive value of plaque quantification added to traditional risk factors.

Main Results:

• Analyzable CCTA data were available from 3711 participants, with 79% having multivessel coronary artery disease.
• Total plaque volume was strongly associated with the primary outcome (aHR 1.56 per IQR increase; P = .001).
• AI-QCT plaque quantification improved the predictive model's value for the primary outcome at 6 months, 2 years, and 4 years (e.g., AUC 0.688 vs. 0.637 at 6 months; P = .006).

Conclusions:

• Total plaque volume quantified by AI-QCT is significantly associated with major adverse cardiovascular events in the ISCHEMIA population.
• Enhanced assessment of atherosclerotic burden using AI-QCT measures modestly improves cardiovascular event prediction in this high-risk cohort.
• CCTA-derived plaque analysis provides incremental prognostic information beyond traditional risk factors and coronary anatomy.