Head to head comparison of Impella with extracorporeal veno-arterial membrane oxygenation in myocardial infarction-related cardiogenic shock: a systematic review and meta-analysis

Background Recent studies increasingly point to the significance of mechanical circulatory support (MCS) devices in treating refractory cardiogenic shock (CS) due to an acute myocardial infarction (AMI). Nevertheless, there is a notable absence of large, randomized trials focusing on the direct head-to-head comparison of Impella and extracorporeal veno-arterial membrane oxygenation (VA-ECMO) in managing AMI-related CS. Consequently, evidence from thorough retrospective studies or meta-analyses plays a crucial role in clarifying the utility of these devices in such circumstances. Purpose This meta-analysis aims to a head-to-head comparison Impella vs VA-ECMO in 30-day mortality rates and device-related complications, including limb ischemia and bleeding rates, in the specific subgroup of patients with an AMI-CS. Method This meta-analysis included only clinical trials and observational studies focusing on patients treated with Impella or VA-ECMO for managing CS resulting from an AMI, aiming to a crude head-to-head comparison of these devices in the setting of AMI-mediated CS. The main outcome evaluated was the 30-day mortality rate, with secondary outcomes including major bleeding and ischemic vascular complications. Results Ten studies comprising a total of 3,949 patients were included in the present meta-analysis (Figure 1). Impella showed a statistically significant lower 30-day mortality rate compared to VA-ECMO (0.91, Confidence Interval (CI) 0.84 to 0.99). Moreover, vascular complications (0.41, CI 0.31 to 0.57) and major bleeding events (0.67, CI 0.49 to 0.93) were also significantly lower in the Impella-group (Figure 2). Lactate levels on admission, consistently recorded in seven of ten studies, ranged between 3.3 and 8.6 mmol/l in the Impella cohort and 5.5 to 14.1 mmol/l in the ECMO cohort, indicating a severe state of shock. The comparison of these two groups showed a statistically significant between the two groups (SMD -0.68, 95% C.I.: -1.03 to -0.33, p-value < 0.0001). Furthermore, the available data on ejection fraction on admission indicated severe impairment, with values ranging from 21% to 36% (Impella group) and 20% to 35% (VA-ECMO group) (SMD 0.05, 95% C.I.: -0.28 to 0.38; p=0.6). pH values were on average to a similar extent (7.25 ± 0.16 in Impella- and 7.2 ± 0.2 in the ECMO group), p=0.8. In a subgroup analysis of patients with similar lactate levels, Impella continued to offer superior 30-day survival (0.89, CI 0.84 to 0.98, p=0.04). Conclusion This meta-analysis suggests that Impella may be associated with a lower mortality compared to VA-ECMO in AMI-mediated CS, mainly due to less vascular complications and bleeding events. Though not evident, our data may suggest a possible mode of escalation therapy in the setting of AMI-associated CS.Figure 1Figure 2