Impact of Door-to-Balloon Time Reduction Depending on the Killip Classification in Patients with ST-Segment Elevation Myocardial Infarction Transported by Emergency Medical Services.

The coronavirus disease 2019 pandemic occurred in several countries, making the conventional medical system difficult to maintain. Recent recommendations aim to prevent nosocomial infections and infections among health care workers. Therefore, establishing a cardiovascular medical system under an emergency for patients with ST-segment elevation myocardial infarction (STEMI) is desired. This study aimed to determine the relationship between prognosis and door-to-balloon time (DBT) shortening based on the severity on arrival.This retrospective, multi-center, observational study included 1,127 consecutive patients with STEMI. These patients were transported by emergency medical services and underwent primary percutaneous coronary intervention. Patients were stratified according to the Killip classification: Killip 1 (n = 738) and Killip ≥ 2 (n = 389) groups.Patients in the Killip ≥ 2 group were older, with more females, and more severity on arrival than those in the Killip 1 group. The 30-day mortality rate in the Killip 1 and Killip ≥ 2 groups was 2.2% and 18.0%, respectively. The Killip ≥ 2 group had a significant difference in the 30-day mortality between patients with DBT ≤ 90 minutes and those with DBT > 90 minutes; however, this did not occur in the Killip 1 group. Furthermore, multivariate analysis revealed that DBT ≤ 90 minutes was not a significant predictive factor in the Killip 1 group; however, it was an independent predictive factor in the Killip ≥ 2 group.DBT shortening affected the 30-day mortality in STEMI patients with Killip ≥ 2, although not those with Killip 1.