Two-year post-discharge outcomes after acute myocardial infarction in the contemporary era: Ten-year temporal trends from the Mie ACS Registry

Background Advances in primary percutaneous coronary intervention (PCI) have substantially reduced in-hospital mortality in patients with acute myocardial infarction (AMI). However, real-world data regarding mid-term post-discharge outcomes, particularly among Japanese patients treated in the contemporary era, remain limited. A precise assessment of post-discharge events is essential to optimize secondary prevention strategies after AMI. Purpose To elucidate 2-year post-discharge outcomes in Japanese patients with AMI in the contemporary era. Methods We analyzed 6,394 consecutive patients with AMI who were enrolled in the Mie ACS Registry between January 2013 and December 2022 and survived to hospital discharge. The study endpoints were all-cause death and major adverse cardiac and cerebrovascular events (MACCE), defined as cardiovascular death, non-fatal myocardial infarction, or non-fatal stroke occurring after discharge. Cumulative event rates up to 2 years were estimated using the Kaplan–Meier method. Temporal comparisons were performed between the early period (2013–2017) and the late period (2018–2022). Event rates were also compared between the first year (0–365 days) and the second year (366–730 days) after discharge. In addition, outcomes were stratified according to Killip class at presentation. Results The 2-year cumulative incidence of all-cause death after discharge was similar between the early and late periods (7.0% vs. 6.3%; log-rank P = 0.58; Figure 1A). Likewise, the 2-year cumulative incidence of MACCE did not differ significantly between periods (5.2% vs. 5.3%; log-rank P = 0.95; Figure 1B). For both endpoints, event accumulation was steeper during the first year after discharge than during the second year, with significantly higher incidence rates in the first year (all-cause death: incidence rate ratio 0.64, 95% CI 0.52–0.77, p < 0.001; MACCE: incidence rate ratio 0.55, 95% CI 0.44–0.69, p < 0.001), indicating attenuation of risk beyond the first year. When stratified by Killip class, the cumulative incidence of all-cause death increased stepwise with increasing Killip severity (Killip I, Killip II/III, and Killip IV; log-rank P < 0.001; Figure 2A). Similarly, MACCE incidence was significantly higher among patients with more advanced Killip class (log-rank P < 0.001; Figure 2B). Conclusions In this contemporary Japanese cohort, no significant temporal improvement in 2-year post-discharge outcomes was observed over the past decade. The first year after discharge represents a particularly vulnerable period, and Killip class at presentation remains a strong determinant of long-term prognosis. These findings underscore the importance of early and intensive secondary prevention, especially in patients presenting with higher Killip class.