Absence of subclinical atherosclerosis is considered safe to defer statin therapy in general population. However, impact of statins on atherosclerotic cardiovascular disease in patients with diabetes stratified by coronary artery calcium (CAC) scores and extent of non-obstructive CAD on coronary computed tomography angiography (CCTA) has not been evaluated.

CONFIRM (Coronary CT Angiography EvaluatioN For Clinical Outcomes: An InteRnational Multi-center Registry) study enrolled consecutive adults 18 years of age between 2005 and 2009 who underwent 364-detector row CCTA for suspected CAD. The long-term registry includes data on 12,086 subjects who underwent CCTA at 17 centers in 9 countries. In this sub-study of CONFIRM registry, patients with diabetes mellitus (DM) and without diabetes mellitus with normal CCTA or non-obstructive plaque (<50 % diameter stenosis) for whom data on baseline statin use was available were included. CAC score was calculated using Agatston score. The magnitude of non-obstructive coronary artery disease on CCTA was quantified using segment involvement score (SIS). Primary outcome was major cardiovascular events (MACE) which included all-cause mortality, myocardial infarction, and target vessel re-vascularization.

A total of 7247 patients (Mean age 56.8 years) with a median follow up of 5 years were included. For DM patients, baseline statin therapy significantly reduced MACE for patients with CAC ≥100 (HR: 0.24; 95 % CI 0.07–0.87; p = 0.03) and SIS≥3 (HR: 0.23; 95 % CI 0.06–0.83; p = 0.024) compared to those not on statin therapy. Among Diabetics with lower CAC (<100) and SIS (≤3) scores, MACE was similar in statin and non-statin groups. In contrast, among non-DM patients, MACE was similar in statin and no statin groups irrespective of baseline CAC (1–99 or ≥100) and SIS.

In this large multicenter cohort of patients, the presence and extent of subclinical atherosclerosis as assessed by CAC and SIS identified patients most likely to derive benefit from statin therapy.