Clinical characteristics and outcomes of patients with coronary artery spasm who initially presented with acute myocardial infarction

Background The long-term clinical outcomes of coronary artery spasm (CAS) patients presented with acute myocardial infarction (AMI) compared to those who did not present with AMI has rarely been investigated. Methods From November 2004 to May 2014, a total of 3360 patients who were confirmed as CAS by the acetylcholine (Ach) provocation test and without significant coronary lesion were retrospectively analyzed. AMI was an initial presentation in 34 patients [CAS-myocardial infarction (MI) group], and not in other 3326 patients (CAS group). The clinical outcomes up to 5 years were compared between the two groups. Results Baseline characteristics and cardiovascular risk factors did not differ between the two groups, except the higher smoking rate in CAS-MI group (38.2 vs. 23.5%, P=0.046). During a mean follow-up period of 1211±583 days, the cumulative incidence of recurrent angina [hazard ratio (HR): 2.71; 95% confidence interval (CI): 1.20-6.13; P=0.016], MI (HR: 33.89; 95% CI: 8.76-131.1; P<0.001) and major adverse cardiovascular events (MACE; HR: 10.94; 95% CI: 3.83-31.22; P<0.001) were significantly higher in the CAS-MI group. After propensity score matched analysis (1: 5 matching; n=186, C-statistic=0.834), the incidences of recurrent angina (HR; 4.68; 95% CI: 1.62-13.5; P=0.004) and MACE (HR: 12.2; 95% CI: 2.23-67.3; P=0.003) remained higher in the CAS-MI group. Conclusion The CAS-MI group patients were associated with higher incidence of recurrent angina, MI, and MACE compared to CAS group patients. More intensive antispastic medication might be needed for these patients, and further study will be necessary to determine which treatment can improve the prognosis of CAS-MI patients.