Abstract Aims COVID-19 might have affected the care and outcomes of hospitalized acute myocardial infarction (AMI). We aimed to determine whether the COVID-19 pandemic changed patient response, hospital treatment, and mortality from AMI. Methods and results Admission was classified as non-ST-elevation myocardial infarction (NSTEMI) or STEMI at 99 hospitals in England through live feeding from the Myocardial Ischaemia National Audit Project between 1 January 2019 and 22 May 2020. Time series plots were estimated using a 7-day simple moving average, adjusted for seasonality. From 23 March 2020 (UK lockdown), median daily hospitalizations decreased more for NSTEMI 69 to 35; incidence risk ratios (IRR) 0.51, 95% confidence interval (CI) 0.47–0.54 than STEMI (35 to 25; IRR 0.74, 95% CI 0.69–0.80) to a nadir on 19 April 2020. During lockdown, patients were younger (mean age 68.7 vs. 66.9 years), less frequently diabetic (24.6% vs. 28.1%), or had cerebrovascular disease (7.0% vs. 8.6%). ST-elevation myocardial infarction more frequently received primary percutaneous coronary intervention (81.8% vs. 78.8%), thrombolysis was negligible (0.5% vs. 0.3%), median admission-to-coronary angiography duration for NSTEMI decreased (26.2 vs. 64.0 h), median duration of hospitalization decreased (4 to 2 days), secondary prevention pharmacotherapy prescription remained unchanged (each > 94.7%). Mortality at 30 days increased for NSTEMI from 5.4% to 7.5%; odds ratio (OR) 1.41, 95% CI 1.08–1.80, but decreased for STEMI (from 10.2% to 7.7%; OR 0.73, 95% CI 0.54–0.97). Conclusion During COVID-19, there was a substantial decline in admissions with AMI. Those who presented to hospital were younger, less comorbid and, for NSTEMI, had higher 30-day mortality.