Junior General Coordinator, Health Sciences Research Program (INVESTIGA) Anáhuac University Mexico State, Distrito Federal, Mexico
Disclosure(s):
Diego Aguirre, Sr.: No financial relationships to disclose
Background: Optimal timing for initiation of mechanical circulatory support (MCS) in cardiogenic shock remains uncertain. While early support has been proposed to improve outcomes by stabilizing hemodynamics and preventing end-organ failure, evidence has been inconsistent. This systematic review and meta-analysis evaluated the association between MCS timing and mortality in cardiogenic shock.
Methods: A systematic search was performed in PubMed from database inception until the final search date. We included studies involving adult patients with cardiogenic shock comparing early versus late MCS initiation that reported mortality. Two reviewers independently screened the titles and abstracts using broad sensitivity criteria. For the final synthesis, data on study characteristics, device types, and effect estimates (OR, HR, or RR) were extracted. Statistical analysis was conducted using Review Manager (RevMan) version 5.4. We calculated pooled effect estimates through a random-effects model with the inverse variance method, which was chosen due to the expected clinical heterogeneity. To assess the inconsistency between studies, the I² statistic was used. Furthermore, a predefined subgroup analysis was carried out for studies specifically reporting outcomes for VA-ECMO. Studies with mixed devices that did not provide stratified data were analyzed in a narrative way. This systematic review followed the PRISMA recommendations to ensure a rigorous reporting of the results.
Outcome: The systematic search identified 1,236 records, with 9 studies meeting the criteria for qualitative synthesis and 5 for the final meta-analysis. In the primary analysis, early initiation of MCS was not associated with a statistically significant reduction in mortality compared to delayed support (pooled OR 1.08; 95% CI 0.91–1.28; p = 0.40). A moderate-to-high heterogeneity was observed (I² = 68%), reflecting the clinical diversity of the included populations. Regarding the VA-ECMO subgroup, which included three specific studies, the pooled effect showed a directional trend toward lower mortality with early initiation (OR 0.78; 95% CI 0.40–1.49). However, this result did not reach statistical significance (p = 0.45) and presented a high heterogeneity (I² = 76%). Additionally, the narrative synthesis of studies with mixed devices suggested that while timing might influence clinical outcomes, the lack of stratified data prevents a definitive quantitative conclusion for these cases. These findings provide a comprehensive assessment of current evidence, suggesting that timing alone is not a guarantee of survival without considering other clinical factors.
Conclusion: In cardiogenic shock, early initiation of MCS wasn't associated with significantly reduced in mortality versus delayed support. Timing alone seems insufficient to improve outcomes and emphasizing patient selection, device-specific strategies, and adjunctive management. These results should guide future prospective randomized trials toward identifying optimal intervention windows
