Abstract 14532: The Off-Hour Effect on Clinical Outcomes of ST-Segment Elevation Myocardial Infarction Complicated by Cardiogenic Shock Patients Treated With Impella: Insight From Japanese Registry for Percutaneous Ventricular Assist Device (J-PVAD)

Introduction: The off-hours effect is a contentious issue in that patients admitted on weekends or nighttime have worse outcomes than on weekday daytime. The off-hours effect in patients with ST-segment elevation myocardial infarction complicated by cardiogenic shock (STEMI-CS) treated with Impella has not been fully evaluated. Hypothesis: The off-hours admission is associated with longer door-to-unload (DTU) time, door-to-balloon (DTB) time, and higher mortality in this population.

Methods: We used the Japanese large-scale registry data for Percutaneous Ventricular Assist Device (J-PVAD), which registered all consecutive patients treated with Impella from December 2019 to July 2022. We compared the effects of on-hours and off-hours admissions on DTU time, DTB time, and 30-day mortality. We defined “on-hours” as between 8:00 and 19:59 on weekdays and the other time as “off-hours”. A multiple linear regression model was used to reveal the independent factors of prolonged DTU and DTB times. The Cox proportional hazards model was applied to calculate adjusted hazard ratios [aHR] for 30-day mortality, controlling for conventional cardiac risk factors.

Results: Of 2,453 patients, 775 (32%) (mean age 68 years, 628 (81%) male) STEMI-CS patients treated with Impella were included. Among them, 401 (39%) were admitted during off-hours. We observed 155 deaths (49%) among patients admitted off-hours and 134 deaths (36%) among patients admitted on-hours during the follow-up period (median: 23 days). The DTU and DTB times were significantly longer in patients admitted off-hours than in patients admitted on-hours (91 (IQR 74-164) vs. 74 (62-151) minutes, p<0.001; 104 (77-134) vs. 89 (61-122), p<0.001, respectively). The linear regression model showed that the off-hours admission was associated with longer DTU time (β=14.3 minutes, 95% CI 4.8-23.8, p=0.003) and DTB time (15.4, 5.0-25.7, p=0.004). The Cox proportional hazards model showed that off-hours admission was associated with a higher risk of 30-day mortality than on-hours admission (aHR=1.42, 95% CI: 1.03-1.96, p=0.03).

Conclusion: Our findings implied that the off-hours effect existed in DTU time, DTB time, and 30-day mortality among STEMI-CS patients treated with Impella.