Impact of Plaque Burden Versus Stenosis on Ischemic Events in Patients With Coronary Atherosclerosis

Patients with obstructive coronary artery disease (CAD) are at high risk for cardiovascular disease (CVD) events. However, it remains unclear whether the high risk is due to high atherosclerotic disease burden or if presence of stenosis has independent predictive value. The purpose of this study was to evaluate if obstructive CAD provides predictive value beyond its association with total calcified atherosclerotic plaque burden as assessed by coronary artery calcium (CAC). Among 23,759 symptomatic patients from the Western Denmark Heart Registry who underwent diagnostic computed tomography angiography (CTA), we assessed the risk of major CVD (myocardial infarction, stroke, and all-cause death) stratified by CAC burden and number of vessels with obstructive disease. During a median follow-up of 4.3 years, 1,054 patients experienced a first major CVD event. The event rate increased stepwise with both higher CAC scores and number of vessels with obstructive disease (by CAC scores: 6.2 per 1,000 person-years (PY) for CAC = 0 to 42.3 per 1,000 PY for CAC >1,000; by number of vessels with obstructive disease: 6.1 per 1,000 PY for no CAD to 34.7 per 1,000 PY for 3-vessel disease). When stratified by 5 groups of CAC scores (0, 1 to 99, 100 to 399, 400 to 1,000, and >1,000), the presence of obstructive CAD was not associated with higher risk than presence of nonobstructive CAD. Plaque burden, not stenosis per se, is the main predictor of risk for CVD events and death. Thus, patients with a comparable calcified atherosclerosis burden generally carry a similar risk for CVD events regardless of whether they have nonobstructive or obstructive CAD.