Background: ST-segment elevation myocardial infarction (STEMI) complicated by cardiogenic shock (STEMI-CS) is associated with high mortality rates. Patients admitted during off-hours, specifically on weekends and at night, show higher mortality rates, which is called the "off-hours effect". The off-hours effect in patients with STEMI-CS treated with mechanical circulatory support, especially Impella, has not been fully evaluated.
Aims: We aimed to investigate whether off-hours admissions were associated with higher mortality rates in this population.
Methods: We used large-scale Japanese registry data for consecutive patients treated with Impella between February 2020 and December 2021 and compared on- and off-hours admissions. On- and off-hours were defined as the time between 8:00 and 19:59 on weekdays and the remaining time, respectively. The Cox proportional hazards model was used to calculate the adjusted hazard ratios (aHRs) for 30-day mortality.
Results: Of the 1,207 STEMI patients, 566 (46.9%) patients (mean age: 69 years; 107 females) with STEMI-CS treated with Impella were included. Of these, 300 (53.0%) were admitted during on-hours. During the follow-up period (median 22 days [interquartile range 13-38 days]), 112 (42.1%) and 91 (30.3%) deaths were observed among patients admitted during off- and on-hours, respectively. Off-hours admissions were independently associated with a higher risk of 30-day mortality than on-hours admissions (aHR 1.60, 95% confidence interval: 1.07-2.39; p=0.02).
Conclusions: Our findings indicated the persistence of the "off-hours effect" in STEMI-CS patients treated with Impella. Healthcare professionals should continue to address the disparities in cardiovascular care by improving the timely provision of evidence-based treatments and enhancing off-hours medical services.