The use of extracorporeal life support (ECLS) in patients with myocardial infarction (MI) and cardiogenic shock who underwent revascularization did not improve survival rates compared to those receiving medical therapy alone, a new study concludes. Findings from the ECLS-SHOCK trial, which were observed in patients at 30 days, call into question the benefits of ECLS which is increasingly being used in the treatment of infarct-related cardiogenic shock. The trial results were presented Saturday at the European Society of Cardiology (ESC) congress 2023 in Amsterdam, and a manuscript reporting the results was simultaneously published Saturday online in The New England Journal of Medicine. “The use of ECLS and other techniques for mechanical circulatory support increased substantially when percutaneous systems became widely available and after studies showed a lack of survival benefit for the intraaortic balloon pump as a former standard of hemodynamic support,” the paper says. “On the basis of findings from observational studies, current international guidelines and scientific statements support a strategy of mechanical circulatory support, albeit based on weak levels of evidence.” Main trial results The trial included a total of 417 patients in the final analyses. At 30 days, death from any cause occurred in 100 of 209 patients (47.8%) in the ECLS group and in 102 of 208 patients (49.0%) in the control group (relative risk, 0.98; 95% confidence interval [CI], 0.80 to 1.19; P=0.81). The median duration of mechanical ventilation was 7 days (interquartile range [IQR], 4 to 12) in the ECLS group and 5 days (interquartile range, 3 to 9) in the control group (median difference, 1 day; 95% CI, 0 to 2). The safety outcome, consisting of moderate or severe bleeding, occurred in 23.4% of the patients in the ECLS group and in 9.6% of those in the control group (relative risk, 2.44; 95% CI, 1.50 to 3.95). Further findings revealed that peripheral vascular complications warranting intervention occurred in 11.0% of the ECLS group and 3.8% in the control group (relative risk, 2.86; 95% CI, 1.31 to 6.25). “Reasons for the absence of benefit of ECLS in cardiogenic shock could be multifactorial,” suggested the research team, led by Holger Thiele, MD, from the University of Leipzig in Germany. “First, the risk and associated device-related complications may counterbalance any potential benefit. In our trial, major bleeding episodes were considerably more frequent in the ECLS group than in the control group, and it is well known that bleeding has a major negative effect on the outcome in acute coronary syndromes and cardiogenic shock.” Discussion at ESC The research team’s observations were further discussed during a press conference at ESC, where Thiele said he believed that the study results were relatively generalizable. “I think this is very important for the interpretation,” he said. “We included patients based on the SCAI [Society for Cardiovascular Angiography and Interventions definition for cardiogenic shock, which we currently have available. Roughly 50% of the patients were in classical cardiogenic shock, and the other 25% were in stage D (deteriorating) or E (extremes). “Based on this, we could not find any subgroup receiving a benefit. We were looking for age subgroups, sex differences, and patients with higher lactate versus lower lactate. But the p-value for interaction, which is important for the interpretation of subgroups, was not significant for any of the subgroups we were looking for.” Thiele added that this was true not only for the ECS SHOCK trial but also for the individual patient-level meta-analysis of this trial with other studies, the results of which were also simultaneously published online Saturday in The Lancet. “And that's the reason why if you ask me is there are any groups benefiting, I will answer that if there was any, it's less than 1% of the patients you are asking.” Lack of ECLS mortality benefits consistent In accompanying editorial commentary to the main paper published online Saturday in The New England Journal of Medicine, Jane A. Leopold, MD, and Darren B. Taichman, MD, PhD, elaborated on this lack of apparent mortality benefit given by ECLS, which appeared to be consistent across multiple subgroup analyses. These subgroups included those performed according to sex, age, the presence or absence of diabetes, STEMI or non-STEMI, anterior MI, a lactate level of more than 6 mmol/L, or receipt of cardiopulmonary resuscitation. The two commentators added that the lack of a mortality benefit with ECLS in the trial corresponded to findings of other randomized trials of mechanical circulatory support devices in patients with myocardial infarction and cardiogenic shock. Asking whether the trial results would change current clinical practice, they said that if the goal of ECLS was to improve 30-day mortality, these data should “steer interventional and critical care cardiologists away from its early routine implementation for all or most patients with MI and cardiogenic shock.” “There will be some patients in this population for whom ECLS is necessary and lifesaving, but the results of the ECLS-SHOCK trial do not tell us which ones,” the experts added. “For now, the best course may be to reserve the early initiation of ECLS for those patients with infarct-related cardiogenic shock in whom the likely benefits more clearly outweigh the potential harms.” Study methodology The multicenter trial identified a total of 420 patients, who underwent randomization of which 417 patients were included in the final analyses. These patients with acute myocardial infarction complicated by cardiogenic shock for whom early revascularization was planned. They were then randomly assigned to receive early ECLS plus usual medical treatment (ECLS group; n=209) or usual medical treatment alone (control group; n=208). The primary outcome was defined as death from any cause at 30 days. Safety outcomes included bleeding, stroke, and peripheral vascular complications warranting interventional or surgical therapy. Sources: Thiele H, Zeymer U, Akin I, et al. Extracorporeal Life Support in Infarct-Related Cardiogenic Shock. N Engl J Med. 2023 Aug 26 (Article in press). Leopold JA, Taichman DB. Routine Early ECLS in Infarct-Related Cardiogenic Shock? N Engl J Med 2023 Aug 26 (Article in press). Zeymer U, Freund A., Hochadel M, et al. Venoarterial extracorporeal membrane oxygenation in patients with infarct-related cardiogenic shock: an individual patient data meta-analysis of randomised trials. Lancet. 2023 Aug 26 (Article in press). Image Caption: Image Caption: Holger Thiele, MD, speaks during a press conference at the European Society of Cardiology congress 2023 in Amsterdam. (Screenshot)