Door-to-unload time and mortality in patients with ST-segment elevation myocardial infarction complicated by...

Microaxial flow pumps (mAFPs) provide left ventricular unloading and haemodynamic stabilisation, with evidence suggesting a survival benefit in patients with ST-segment elevation myocardial infarction (STEMI) complicated by cardiogenic shock (CS). The prognostic impact of early mAFP placement after hospital arrival remains unclear. Aims: We aimed to investigate the association between door-to-unload time and in-hospital mortality in patients with STEMI-CS. Methods: We analysed data from the Japan Registry for Percutaneous Ventricular Assist Devices, including consecutive patients with STEMI-CS who underwent mAFP placement between February 2020 and December 2023. The primary outcome was in-hospital mortality. Results: Among 1,783 patients, the median door-to-unload time was 99 min. The overall in-hospital mortality rate was 39.2%, and this increased with longer door-to-unload times: 32.9% (≤60 min), 33.0% (61-90 min), 40.1% (91-150 min), and 48.3% (>150 min). Using a 90 min cutoff, delayed placement (>90 min) was associated with higher mortality (adjusted odds ratio 1.56, 95% confidence interval: 1.26-1.95). A restricted cubic spline model showed that mortality remained stable when placement was within 90 min, followed by an increase. When stratified by no prior mechanical circulatory support and prior venoarterial extracorporeal membrane oxygenation (VA-ECMO) only, the patients with prior VA-ECMO only had more severe baseline characteristics and higher mortality; however, the association of longer door-to-unload time with higher mortality was consistent. Predictors of delayed mAFP placement included older age, lower institutional volume, higher heart rate, higher creatinine levels, prior use of an intra-aortic balloon pump or VA-ECMO, and percutaneous coronary intervention before mAFP placement. Conclusions: A shorter door-to-unload time, particularly within 90 min, is associated with better survival in patients with STEMI-CS..