Clinical outcomes associated with temporary mechanical circulatory support in the AltShock-2 registry: a propensity score matching analysis

Nationwide data on temporary mechanical circulatory support (tMCS) for cardiogenic shock (CS) have shown mixed results, likely due to variations in the etiology of CS, timing of device implantation, and access to advanced therapies like permanent support or heart transplantation. This study uses propensity score matching (PSM) to compare clinical characteristics and outcomes between patients with undifferentiated CS managed with either medical therapy or tMCS.

The objective is to evaluate whether tMCS provides a mortality benefit over medical therapy alone in a real-world population of undifferentiated CS patients enrolled in the ALT-SHOCK registry.

This study included adult patients (≥18 years) with CS admitted to 12 cardiac intensive care units (CICUs) from March 2020 to November 2023. Patients were categorized by treatment type (tMCS or medical therapy). PSM was conducted to evaluate the impact of tMCS on outcomes while accounting for potential confounders.

Among 725 patients admitted to the ALT-SHOCK registry, 655 had complete mid-term follow-up: 428 (65%) received tMCS, and 227 (35%) were treated with medical therapy alone. Compared to those managed with medical therapy, tMCS patients were younger, had more comorbidities, presented more commonly with acute myocardial infarction-related CS (AMI-CS), and had higher SCAI classes, often receiving higher vasoactive-inotropic scores and more frequent invasive monitoring. The most common tMCS device used was the Intra-Aortic Balloon Pump (IABP; 56%), followed by Venoarterial Extracorporeal Membrane Oxygenation (VA-ECMO; 17%) and Impella (4%). In-hospital mortality rates were 35.0% in the tMCS group and 39.2% in the medical therapy group (p = 0.29). Notably, in patients with acute decompensated heart failure-related CS (ADHF-CS), tMCS was associated with lower mortality compared to medical therapy alone (27.3% vs. 48.4%, p = 0.003). However, PSM revealed no significant mortality difference between matched cohorts (34.5% vs. 39.3%, p = 0.366). Survival analysis at mid-term showed that tMCS was not associated with a lower mortality.