This study compared the time course and outcomes of acute myocardial infarction, including mechanical complications and hospital mortality, before and after the coronavirus disease 2019 (COVID-19) pandemic at a regional core hospital in South Osaka, Japan. Moreover, it identified predictors for hospital mortality and mechanical complications. In total, 503 patients who underwent emergency percutaneous coronary intervention between January 2011 and December 2021 at our institution were examined retrospectively. The time course of acute myocardial infarction, mechanical complications, and mortality rate before and after the COVID-19 emergency declaration were compared. Overall, 426 patients with ST-segment elevation myocardial infarction and 77 patients with non-ST-segment elevation myocardial infarction were identified. For patients with ST-segment elevation myocardial infarction, the onset-to-door time was longer (181 vs. 156 min, P = 0.001) and mechanical complications were worse (7.8% vs. 2.6%, P = 0.025) after the emergency declaration of COVID-19 than before the pandemic. Age, low ejection fraction, out-of-hospital cardiac arrest, and mechanical complications were identified as independent risk factors for hospital mortality among patients with ST-segment elevation myocardial infarction, using multivariable analysis. Post-declaration, age, walk-ins, referrals, and intra-aortic balloon pump use were independent predictors of mechanical complications among patients with ST-segment elevation myocardial infarction. Onset-to-door time and mechanical complication rate increased after the COVID-19 declaration among patients with ST-segment elevation myocardial infarction. Arrival by walk-in and a referral that caused treatment delay were identified as independent risk factors for mechanical complication, in addition to age, use of intra-aortic balloon pump, and post-declaration of COVID-19. Therefore, the risks posed by the COVID-19 pandemic might have a polarization tendency resulting from the relief or worsening of cardiac symptoms.

The authors have declared no competing interest.

The authors received no specific funding for this work.

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The Ethics Committee of the Matsubara Tokushukai Hospital (approval number: 22-01)

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