Long-term follow-up of patients with myocardial infarction and myocardial injury
Authors: Haller P M , Soerensen N A , Kellner C , Lehmacher J , Toprak B , Schock A , Hartikainen T S , Zeller T , Westermann D , Blankenberg S , Twerenbold R , Neumann J T 
Published: November 2023

Abstract

Introduction
Patients with symptoms indicative of acute myocardial infarction (MI) frequently present to the emergency department (ED) and undergo a structured diagnostic assessment. Apart from MI, other diagnoses are frequently identified, including myocardial injury. In these patients estimation of long-term risk is crucial to guide preventive strategies.

Purpose
To assess and compare the long-term incidence of all-cause death and cardiovascular events in patients with MI, myocardial injury and other causes of acute chest pain.

Methods
We conducted a prospective, observational cohort study enrolling consecutive patients presenting with suspected MI to the ED of a tertiary hospital. The final diagnoses were adjudicated by two independent cardiologists according to the 4th Universal Definition of MI using high-sensitivity cardiac troponin T (hs-cTnT). Patients were followed to assess incidental all-cause death and a composite endpoint (cardiovascular death, MI, or myocardial revascularization). We used Kaplan-Meier plots for crude and Cox regression models (providing hazard ratios [95% confidence intervals]) for adjusted (sex, age, cardiovascular risk factors, heart failure, renal function) time-to-event analyses, respectively, using patients with other causes of chest pain as reference.

Results
Overall, we prospectively included 2,714 patients with a median age of 64 (25th, 75th: 51, 75) years, of whom 1,745 (64.3%) were male. In total, 143 (5.3%) had ST-elevation MI (STEMI), 128 (4.7%) Type 1 Non-ST-elevation MI (NSTEMI), 236 (8.7%) Type 2 NSTEMI, 86 (3.2%) acute myocardial injury, 677 (24.9%) chronic myocardial injury, and 1,444 (53.2%) other diagnoses of chest pain not involving hs-cTn elevation. The median follow-up time was 4.6 (4.5, 7.3) years. The highest rates of all-cause death were observed in patients with myocardial injury (81.6 [71.7, 92.3] events/1000 patient-years) and infarction (55.9 [46.3, 66.7]), compared to other diagnoses (12.2 (9.8, 15.1). Figure 1 provides the Kaplain-Meier estimates for the final diagnoses. In adjusted Cox regression analyses, all patients with MI or myocardial injury were at significantly higher risk for all-cause death, compared to patients with other causes of chest pain (Figure 2A). Additionally, the risk for the secondary composite endpoint (cardiovascular death, MI, revascularization) was significantly increased in those with acute or chronic myocardial injury, and patients with Type 1 NSTEMI or STEMI, but not Type 2 NSTEMI (Figure 2B).

Conclusion
Patients with acute myocardial infarction and acute or chronic myocardial injury are at high long-term risk for death and incident cardiovascular events. Importantly, those patients with acute myocardial injury showed the highest mortality rate. Further studies need to determine appropriate management strategies for patients with myocardial injury.Kaplan-Meier plot for final diagnosesForest plot of adjusted outcome analysis