At the time that it was halted, a multicenter randomized trial was associating venoarterial extracorporeal membrane oxygenation (VA-ECMO) with an intriguing signal of benefit for patients in cardiogenic shock undergoing percutaneous intervention (PCI) for acute myocardial infarction.

Stopped early because of the pandemic, the EURO SHOCK trial has data on only 35 patients, but all-cause mortality at 30 days was nearly 30% lower in the VA-ECMO arm than in the standard-therapy arm, reported Manel Sabate, MD, PhD, chief of the interventional cardiology unit, Clinic University Hospital, Barcelona.

When patients were followed out to 12 months, the numerical survival advantage appeared to persist.

Yet, because of the early trial termination, “there really are no definite conclusions to be drawn from these results,” acknowledged Dr. Sabate, who noted that less than 10% of the planned enrollment had been reached. In addition, the survival benefit in the VA-ECMO arm was achieved at the cost of a higher rate of complications.

Despite the small numbers, results from the halted trial were presented as a late-breaker at the annual meeting of the European Association of Percutaneous Cardiovascular Interventions. They were also simultaneously published in EuroIntervention.

The interest is based on an important unmet need, said Dr. Sabate. Cardiogenic shock occurs in about 10% of acute MI patients. Of those that continue on to revascularization, the 30-day mortality can approach 50%.

Meanwhile, the potential of mechanical circulatory support to maintain perfusion during cardiogenic shock makes it one of the most attractive, if unproven, approaches for improving outcomes.

Major multicenter trial terminated

The EURO SHOCK trial had a planned enrollment of 428 patients when it was initiated; 15 centers in six European countries participated. Recruitment and the trial were brought to a halt by the COVID-19 pandemic.

When trial recruitment was stopped, 18 patients had been assigned to standard supportive care and 17 patients to VA-ECMO. The primary endpoint of the trial was all-cause mortality at 30 days. Mortality at 12 months along with bleeding complications, cerebrovascular events, and readmission for heart failure, were among secondary endpoints.

At 30 days, the mortality rate was 61.1% among patients randomized to standard care, versus 43.8% among patients randomized to VA ECMO (hazard ratio, 0.56; 95% confidence interval, 0.21-01.45; P = 0.22).

At 12 months, the numerical advantage of VA-ECMO persisted (81.5% vs. 51.8%) with a similar nonsignificant signal for potential benefit despite the small sample size (HR, 0.52; 95% CI, 0.21-1.26; P = 0.14).

There were also numerically lower rates of cardiovascular death, ischemic stroke, recurrent MI, and acute kidney injury among patients in the VA-ECMO group relative to those in the standard-care group, Dr. Sabate reported.

However, VA-ECMO was associated with more vascular complications (21.4% vs. 0%) and bleeding events (35.7% vs. 5.6%).

Furthermore, although quality of life data were limited, Dr. Sabate noted that about half of patients in the VA-ECMO group reported problems with mobility, self-care, or usual activities on the basis of the EQ-5D-3L questionnaire at 30 days. None of the patients in the standard-care group reported any such difficulties.

When standard care was compared with VA-ECMO, rates of readmission for heart failure over 12 months (8.0% vs. 6.9%) were not different.

To be enrolled in this study, patients being treated for MI had to be in cardiogenic shock for at least 30 minutes following primary PCI. The median time from onset of cardiogenic shock to VA-ECMO in the active treatment arm was 4.8 hours.

Patient enrollment was challenging

Even independent of the COVID-19 pandemic, enrolling patients proved to be difficult. The 35 patients enrolled represented about 10% of the 333 patients screened at the participating centers. Unwitnessed out-of-hospital cardiac arrest, cardiogenic shock from a cause other than MI, and recovery from cardiogenic shock after the PCI was performed were among reasons for the high rate of exclusions.

The difficulty of identifying and engaging appropriate candidates for VA-ECMO, along with a substantial crossover rate, should be among lessons for investigators planning the next trial, said Dr. Sabate, who pointed out that 5 of the 17 patients assigned to VA-ECMO were never treated due to complications or patient refusal.

“We cannot associate VA-ECMO with a favorable benefit-to-risk ratio on the basis of this study, but it sets the state for a larger randomized controlled trial to address this question,” Dr. Sabate said.

Davide Capodanno, MD, PhD, a professor of cardiology and interventional cardiologist at the University of Catania (Italy), agreed.

“It was a good decision to publish these results,” he said. Noting that there were challenges in conducting the trial unrelated to COVID-19, Dr. Capodanno acknowledged the promise of mechanical ventilatory support for a relatively common and life-threatening complication.

“This study must be read for the lessons it will provide for future trials,” he said.

Dr. Sabate reported he has no potential conflicts of interest. Dr. Capodanno reported financial relationships with Amgen, Daiichi Sankyo, and Sanofi.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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