Association of Shock-to-Balloon Time With Outcomes in Acute Myocardial Infarction With Cardiogenic Shock Requiring VA-ECMO

The optimal timing of percutaneous coronary intervention (PCI) in patients with acute myocardial infarction complicated by cardiogenic shock (AMI-CS) who are supported with venoarterial extracorporeal membrane oxygenation (VA-ECMO) remains uncertain. We aimed to evaluate the prognostic impact of shock-to-balloon time (STB) in AMI-CS patients supported with VA-ECMO before revascularization. This study included patient-pooled data from CS-dedicated registries, including the SMART-RESCUE and the SMC-ECMO. A total of 256 patients were included. Patients were stratified according to STB (<120 min, n = 140; ≥120 min, n = 116). Among the study population, all-cause mortality was significantly higher in the ≥120 minutes group compared with the <120 minutes group (65.2% vs. 44.6%; adjusted hazard ratio [HR]: 1.59, 95% confidence interval [CI]: 1.03-2.45, p = 0.037). This association was significant in the ST-segment elevation myocardial infarction (STEMI) subgroup (adjusted HR: 2.22, 95% CI: 1.26-3.93), and in patients with earlier (<60 min) VA-ECMO initiation (adjusted HR: 2.50, 95% CI: 1.42-4.38), whereas in the non-ST-segment elevation myocardial infarction (NSTEMI) subgroup a directionally consistent but nonsignificant trend was observed, without significant interaction (p-for-interaction = 0.164). In AMI-CS patients who underwent VA-ECMO, a prolonged STB was associated with higher all-cause mortality, with a consistent but exploratory trend in NSTEMI. These findings support STB as a prognostic marker and warrant prospective evaluation of coordinated ECMO-revascularization pathways.