Difference in the in-hospital prognosis between ST-segment elevation myocardial infarction and non-ST-segment elevation myocardial infarction with high Killip class: Data from the Japan Acute Myocardial Infarction Registry

Background: ST-segment elevation myocardial infarction is known to be associated with worse short-term outcome than non-ST-segment elevation myocardial infarction. However, whether or not this trend holds true in patients with a high Killip class has been unclear.

Methods: We analyzed 3704 acute myocardial infarction patients with Killip II-IV class from the Japan Acute Myocardial Infarction Registry and compared the short-term outcomes between ST-segment elevation myocardial infarction (n = 2943) and non-ST-segment elevation myocardial infarction (n = 761). In addition, we also performed the same analysis in different age subgroups: <80 years and ≥80 years.

Results: In the overall population, there were no significant difference in the in-hospital mortality (20.0% vs 17.1%, p = 0.065) between ST-segment elevation myocardial infarction and non-ST-segment elevation myocardial infarction groups. Patients <80 years of age also showed no difference in the in-hospital mortality (15.7% vs 15.2%, p = 0.807) between ST-segment elevation myocardial infarction (n = 2001) and non-ST-segment elevation myocardial infarction (n = 453) groups, whereas among those ≥80 years of age, ST-segment elevation myocardial infarction (n = 942) was associated with significantly higher in-hospital mortality (29.3% vs 19.8%, p = 0.001) and in-hospital cardiac mortality (23.3% vs 15.0%, p = 0.002) than non-ST-segment elevation myocardial infarction (n = 308). After adjusting for covariates, ST-segment elevation myocardial infarction was a significant predictor for in-hospital mortality (odds ratio 2.117; 95% confidence interval, 1.204-3.722; p = 0.009) in patients ≥80 years of age.

Conclusion: Among cases of acute myocardial infarction with a high Killip class, there was no marked difference in the short-term outcomes between ST-segment elevation myocardial infarction and non-ST-segment elevation myocardial infarction in younger patients, while ST-segment elevation myocardial infarction showed worse short-term outcomes in elderly patients than non-ST-segment elevation myocardial infarction. Future study identifying the prognostic factors for the specific anticipation intensive cares is needed in this high-risk group.