Cardiogenic shock is the leading cause of death amongst patients hospitalized with acute myocardial infarction. Immediate revascularization of the culprit lesion is the only treatment available but mortality still remains high. The use of extracorporeal life support (ECLS), which enables full circulatory and respiratory support, have increased with the aim to achieve haemodynamic stabilization in patients with severe or rapidly deteriorating infarct-related cardiogenic shock.
Evidence on the use of ECLS in cardiogenic shock resulting from acute myocardial infarction is scarce and quality of existing studies are low. Use of ECLS is also associated with complications such as bleed, stroke, limb ischemia and hemolysis. As such, the ECLS-SHOCK study was conducted to evaluate if use of early ECLS intervention will result in improved survival outcomes for patients with acute myocardial infarction complicated with cardiogenic shock, with planned early revascularization by either percutaneous coronary intervention (PCI) or coronary-artery bypass grafting (CABG).
Trial information
A total of 420 patients were enrolled in the trial and they were split between ECLS intervention group and usual medical therapy group in a 1:1 ratio. Patients had to have acute myocardial infarction complicated by cardiogenic shock and planned for early revascularization. These patient groups were chosen as they were thought to be most likely to benefit from ECLS. Patients who had undergone cardiopulmonary resuscitation for more than 45 minutes prior to randomization or who has a mechanical cause of cardiogenic shock or severe peripheral-artery disease precluding the insertion of ECLS cannulae were excluded.
About 60% of the patients presented with ST elevation myocardial infarction and left anterior descending artery was the most common infarct site. Majority (96.6%) of the patients underwent PCI. ECLS was initiated during the index angiography in 92% of the patients in the treatment group and median duration of ECLS therapy was 2.7 days.
What do the results tell us?
The results from the study showed that ECLS use did not significantly reduce death from any cause at 30 days, which was the primary outcome (RR = 0.98, P = 0.81). Duration of catecholamine therapy and time until haemodynamic stabilization was similar between both groups. Patients in the ECLS group also experienced higher incidence of moderate or severe bleeding as compared to the control group (23.4% vs 9.6%). Incidence of peripheral complications warranting intervention was also higher in the ECLS group (11% vs 3.8% in the control group).
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Based on the results of this study, early routine ECLS was not superior to usual medical therapy in reducing death from any cause at 30 days for patients with acute myocardial infarction complicated by cardiogenic shock. The use of ECLS also resulted in higher risk of bleeding and peripheral vascular complications. These results are also in line with other trials that have evaluated the effect of ECLS in patients with cardiogenic shock.
The reasons for the lack of benefits of ECLS seen is this trial can be attributed to multiple factors, such as ECLS complications leading to poorer outcomes, risk of left ventricular unloading and risk of cerebral injury due cardiac arrest, which may negatively affect the patient’s prognosis (about 77% of patients in both groups underwent resuscitation before randomization). Patients with cardiogenic shock after acute myocardial infarction often differ in terms of clinical presentation and course, thus it would be difficult to determine the exact subgroup of patients that may benefit from ECLS intervention. With these findings, the routine early initiation of ECLS in patients with acute myocardial infarction complicated by cardiogenic shock should be re-evaluated and reserved for patients in which benefits clearly outweigh the risk.
References:
- Thiele H, Zeymer U, Akin I, Behnes M, Rassaf T, Mahabadi AA, et al. Extracorporeal life support in infarct-related cardiogenic shock. New England Journal of Medicine. 2023; doi:10.1056/nejmoa2307227
