Eligibility for MCS Based on Cardiogenic Shock RCTs

Benedikt Schrage, M.D., discusses his paper titled “Eligibility for Mechanical Circulatory Support Devices Based on Current and Past Randomized Cardiogenic Shock Trials” published in European Journal of Heart Failure in June 2021. Dr. Schrage is an interventional cardiologist at University Heart and Vascular Center in Hamburg, Germany.

Dr. Schrage and his colleagues retrospectively applied pragmatic enrollment criteria (criteria most likely to affect the decision to implant MCS) from the IABP-SHOCK II, DanGer-SHOCK, ECLS-SHOCK, and EURO-SHOCK trials to 1305 “classic” cardiogenic shock patients (typically between SCAI C and D classification) admitted to a tertiary care hospital between 2009 and 2019. The study sought to determine how many of these patients would meet eligibility requirements for these trials.

Referring to figure 1 in the paper, "This was a bit shocking to all of us," states Dr. Schrage."Barely one third of these would be eligible for any of the cardiogenic shock trials. Generally, if we looked at inclusion verses exclusion criteria, we found that inclusion criteria were a bit more restrictive. A patient was more likely to not be included than excluded."

The most restrictive inclusion which was not met was the cause of cardiogenic shock. Dr. Schrage continued, "About half of the patients do have acute myocardial infarction as the cause of cardiogenic shock, but the other half does not have that so all these patients are excluded."

In addition to identifying major enrollment criteria, this study assessed outcome between eligible and ineligible patients and found that 30-day mortality was high across all patients and trials, regardless of eligibility or ineligibility. Dr. Schrage hypothesizes that this equality in mortality rate reflects the full spectrum of heart failure patients in the ineligible group. Referring to these ineligible patients, Dr. Schrage states, “They also deserve to be covered by randomized evidence; they also need to be covered because we do need to make good treatment decisions for these patients to lower the mortality rate.”

“We do need more randomized trials in this field,” Dr. Schrage emphasizes. “We maybe cannot rely too much on extrapolating findings from acute myocardial infarction shock trials for these patients because they are so different. So this means we need to think about pathophysiology. We need to think about hemodynamics. We need to judge the patients at the bedside and then decide who might benefit or not benefit from a device, until, maybe in the future, we have the data.”