Benefit of statin therapy in patients with coronary spasm-induced acute myocardial infarction

Background: Coronary artery spasm is associated with vascular smooth muscle hyper-reactivity. Statins suppress coronary spasm by inhibiting the vascular smooth muscle contraction. However, it is unclear whether statin therapy benefits patients with coronary spasm-induced acute myocardial infarction (AMI). Methods and results: We analyzed 501 (median age 57 years; male/female, 346/155) patients with coronary spasm-induced AMI with nonobstructive coronary arteries (stenosis severity <50%) from the Korea AMI Registry between November 2005 and October 2013. They were divided into two groups according to statin prescription at discharge (statin group n = 292; nonstatin group n = 209). The primary endpoint was the composite of 12-month major adverse cardiac events, including all causes of death, non-fatal myocardial infarction, and target vessel revascularization. The primary endpoint occurred in 17 patients during 12 months of follow-up. Statin therapy significantly reduced the risk of the composite primary endpoint [adjusted hazard ratio (HR): 0.30; 95% confidence interval (CI): 0.09-0.97; p = 0.045]. Statin therapy reduced the risk of myocardial infarction (HR: 0.19; 95% CI: 0.04-0.93; p = 0.040). However, we found no significant difference in the risk of the composite of all-cause death. Conclusion: Statin therapy in patients with coronary spasm-induced AMI with nonobstructive coronary arteries was associated with improved clinical outcome, which was predominantly accounted for by reducing the incidence of myocardial infarction. (C) 2016 Published by Elsevier Ltd on behalf of Japanese College of Cardiology.