A major randomised trial showed no mortality difference with extracorporeal membrane oxygenation versus supportive care alone.
Respite great strides in managing acute myocardial infarction (AMI), 30 day mortality rates remain at 40 to 50% when cardiogenic shock complicates AMI (AMI-CS). Several percutaneous devices can provide substantial, temporary circulatory support to vital organs (about 3 to 5L/min blood flow). Given their relative safety and ease of insertion, short-term circulatory support with these devices has been hypothesised to offer potential benefit in patients with AMI-CS as cardiac function recovers.
To assess whether this approach improves survival, investigators randomised 420 patients (mean age, 63 years; 19% women) with AMI-CS who were undergoing planned coronary revascularisation (almost all with percutaneous coronary intervention) to mechanical circulatory support using extracorporeal membrane oxygenation (ECMO) or supportive care alone (NCT03637205). About 78% of participants had under gone cardiopulmonary resuscitation before randomisation.
The primary endpoint – allcause mortality at 30 days – was virtually identical with ECMO (47.8%) and suppor tive care alone (49.0%). The ECMO group had higher rates of moderate-to-severe bleeding (23%, vs 10% with supportive care alone) and vascular complications requiring treatment (11% vs 4%, respectively). Findings were consistent across age and clinical subgroups.
Comment: These data are a sobering reminder that pathophysiological principles do not necessarily predict clinical benefit. Despite providing near-normal cardiac output, ECMO did not improve survival in patients with AMI-CS. Potential explanations include high rates of bleeding and vascular complications with ECMO (potentially offsetting any benefit of circulatory support) and the fact that ECMO leads to increased cardiac afterload and ventricular volume overload, which may impair myocardial recovery. Several ongoing trials are testing whether a percutaneous microaxial left ventricular assist device (which does not increase afterload) can improve survival after AMI-CS. For now, though, we should temper enthusiasm for use of mechanical circulatory support in these patients, given its cost, associated complications and uncertain benefit.
David J. Cohen, MD, MSc, Director of Clinical and Outcomes Research, Cardiovascular Research Foundation, New York City; Director of Academic Affairs, St. Francis Hospital, Roslyn, USA.
This summary is taken from the following Journal Watch titles: Cardiology, Emergency Medicine, Hospital Medicine.