Prognostic Implications of Bleeding and Ischemic Complications in Acute Myocardial Infarction-Related Cardiogenic Shock Managed With Microaxial Flow Pump

BACKGROUND: Microaxial flow pumps are emerging therapeutic devices for acute myocardial infarction-related cardiogenic shock. However, prognostic implications of hemorrhagic and ischemic complications on mortality remain limited. We aim to clarify the incidence of these complications in acute myocardial infarction-related cardiogenic shock requiring a microaxial flow pump and their associations with mortality. METHODS: We analyzed patients from the J-PVAD (Japan Registry for Percutaneous Ventricular Assist Device) who underwent microaxial flow pump implantation for acute myocardial infarction-related cardiogenic shock between 2020 and 2023. Primary composite exposures were bleeding complications (nonintracranial bleeding, including access site bleeding and nonintracranial bleeding requiring blood transfusion, and intracranial hemorrhage) and ischemic complications (lower limb ischemia, recurrent myocardial infarction, noncerebral embolism, or ischemic stroke). The primary outcome was in-hospital all-cause mortality. Cumulative incidences were estimated with death as a competing event. Cox regression with time-varying exposures assessed associations between complications and mortality, adjusting for clinical characteristics. Population attributable fractions of complications for death were calculated, indicating the proportion of mortality that could theoretically be prevented if the complications were eliminated. RESULTS: Of 2034 patients (mean age, 69.2±11.7 years; 17.6% women), 840 (41.3%) died during hospitalization. The 30-day cumulative incidence was 23.2% (95% CI, 21.4%–25.0%) for bleeding complications and 10.5% (95% CI, 9.1%–11.8%) for ischemic complications. Both complications were independently associated with increased mortality (adjusted hazard ratio, 1.60 [95% CI, 1.30–1.97] for bleeding; adjusted hazard ratio, 1.74 [95% CI, 1.24–2.44] for ischemic complications). The population attributable fraction of bleeding complications was 10.7% (95% CI, 6.6%–14.0%), compared with 4.0% (1.8%–5.6%) for ischemic complications, suggesting that bleeding events contributed substantially to the mortality burden. CONCLUSIONS: Both bleeding and ischemic complications remain frequent adverse events in acute myocardial infarction-related cardiogenic shock requiring a microaxial flow pump. While both complications were significantly associated with mortality, the higher incidence of bleeding complications contributed to a greater mortality burden. This underscores the importance of bleeding prevention strategies alongside ischemic complication management in this high-risk population.