Two-year mortality of primary angioplasty for acute myocardial infarction during regular working hours versus off-hours

Background: Studies with short-term follow-up found higher mortality in patients with STEMI who underwent primary PCI during off-hours as compared to regular working hours. We analyzed the interaction between one and two-year survival of patients with STEMI who underwent primary PCI during regular working hours and off-hours in a tertiary care academic teaching hospital. Methods: A total of 1126 STEMI patients treated with primary PCI between 2008 and 2013 were analyzed. Two-years follow-up were available in 941 (83%) patients. Multivariable survival analysis was used to estimate the relationship between treatment during off-hours versus regular hours and the incidence of all-cause mortality at 2-years follow-up. Logistic regression was used to calculate interaction p-values between time of admission and time (between ≤1 year and ≤2 year). Results: At 2-years, the mortality rate of patients admitted during off-hours and regular hours was similar (15% vs. 19%; adjusted hazard ratio 0.77; 95% confidence interval 0.52–1.16). Of the 941 patients, those who admitted during off-hours (N = 717) had similar median door-to-device time (94 min vs. 91 min), final Thrombolysis In Myocardial Infarction 3 flow grade (93% vs. 91%) and use of dual antiplatelet within 24 h (96% vs. 98% respectively) as compared with regular hours admission (N = 224). There were no mortality difference observed between one year and two years (p interaction >0.05). Conclusion: In this analysis, the similar mortality observed at one year between patients with STEMI treated by primary PCI during off-hour and regular hour were maintained at two years.