Long-term clinical outcomes of type 1 vs. type 2 myocardial infarction in patients who underwent angiography: data from the Korea acute myocardial infarction-national institute of health registry

Background: In the cause of increase the clinical research observational evidence on type 2 myocardial infraction (T2MI), the study compared the characteristics of T2MI and T1MI with respect to major adverse cardiac events (MACE) and mortality as long-term outcomes from a large, nationwide, prospective Korean cohort registry. Methods: From 13,105 consecutively enrolled individuals in the Korea Acute Myocardial Infarction-National Institute of Health (KAMIR-NIH) registry between October 2011 and December 2015, 11,053 acute myocardial infarction (AMI) patients were divided into the T1MI (n=10,545) and T2MI (n=508) groups. All patients completed ≥3 years of follow-up. Results: The Kaplan-Meier curve analysis and Cox proportional hazard regression models showed that the cumulative rate of MACE was similar between the 2 groups (11.4% vs. 13.4%, log-rank P=0.185) at 3 years. However, the T2MI group showed higher rates of all-cause death [12.6% vs. 9.4%, log-rank P=0.019; hazard ratio (HR), 1.42; 95% CI: 1.08–1.85; P=0.012] and non-cardiac death (3.5% vs. 5.3%, log-rank P=0.043; HR, 1.55; 95% CI: 1.01–2.37; P=0.043) than the T1MI group. Male sex (HR 1.540; 95% CI: 1.218–1.947, P<0.001), old age (≥65 years; HR, 3.546; 95% CI: 2.645–4.753, P<0.001), low hemoglobin level (<12 g/dL; HR, 2.335; 95% CI: 1.841–2.961, P<0.001), high heart rate (>100 beats/min; HR, 1.852; 95% CI: 1.436–2.388, P<0.001), low glomerular filtration rate (GFR) (<60 mL/min/1.73 m²; HR, 2.373; 95% CI: 1.874–3.005, P<0.001), high body mass index (>25 kg/m²; HR, 0.644; 95% CI: 0.514–0.805, P<0.001), and low left ventricular ejection fraction (LVEF) (<40%; HR, 1.487; 95% CI: 1.095–2.020, P=0.011) were the independent predictors for 3-year non-cardiac mortality. Conclusions: Although the 2 groups did not differ in MACE, the total mortality rate was higher in T2MI than in T1MI, especially non-cardiac mortality. The independent predictors for non-cardiac mortality were male sex, old age, anemia, low GFR, tachycardia, obesity, and low LVEF.