Impact of statin use on major adverse cardiovascular events in patients with normal stress myocardial perfusion imaging and elevated coronary artery calcium score.

Introduction: Normal stress myocardial perfusion imaging (MPI) carries a favourable prognosis. Conversely, elevated coronary artery calcium (CAC) is associated with increased major adverse cardiovascular events (MACE). There is limited information on the prognosis and management of patients with elevated CAC and normal MPI. We aimed to assess the outcomes of patients with elevated CAC and normal MPI in relation to post-MPI statin use. Methods: A retrospective review of normal MPI with CAC score >300 was performed between 1 March 2016 and 31 January 2017 in a Singapore tertiary hospital. Patients with known atherosclerotic cardiovascular disease or left ventricular ejection fraction <50% on MPI were excluded. Patient demographics, prescriptions and MACE (cardiac death, nonfatal myocardial infarction and/or ischaemic stroke) at 24 months after MPI were traced using electronic records. Binary logistic regression was used to evaluate for independent predictors of MACE. Results: We included 311 patients (median age 71 years, 56.3% male), of whom 65.0% were on moderate to high-intensity statins (MHIS) after MPI. MACE was significantly lower in the post-MPI MHIS group (3.5% vs. 9.2%, P = 0.035). On univariate binary logistic regression, post-MPI MHIS use was the only significant predictor for MACE (odds ratio [OR] 0.355 [95% confidence interval (CI) 0.131-0.962], P = 0.042), even after multivariate adjustment (adjusted OR 0.363, 95% confidence interval 0.134-0.984, P = 0.046). Conclusion: Post-MPI MHIS use is associated with lower MACE and is an independent negative predictor for 24-month MACE among patients with normal MPI and CAC >300.