Figure 1. Study Flow and Matching of Patients With ST-Segment Elevation Myocardial Infarction (STEMI) With or Without COVID-19.

Out-of-hospital STEMI was defined through International Classification of Diseases, Tenth Revision coding (see eTable 1 in the Supplement) as being both present on admission and the primary diagnosis, while in-hospital STEMI was defined as nonprimary diagnosis coding and not present on admission. Patients in whom these were mixed (eg, STEMI present on admission but not the primary diagnosis) were excluded. Patients who presented to centers not capable of percutaneous coronary intervention (PCI), and were therefore excluded, may have entered the analysis if they subsequently transferred to a PCI-capable center.