Predicting Survival in Patients Treated With Extracorporeal Membrane Oxygenation After Myocardial Infarction

Acute myocardial infarction is the most common cause of cardiogenic shock. Although the number of patients with acute myocardial infarction complicated by cardiogenic shock who were treated with venoarterial extracorporeal membrane oxygenation increased during the last decade, detailed data on survival are lacking. We sought to analyze covariates that were independently associated with survival in this patient population and to externally validate the newly developed prEdictioN of Cardiogenic shock OUtcome foR Acute myocardial infarction patients salvaGed by venoarterial Extracorporeal membrane oxygenation (ENCOURAGE) score.

Retrospective clinical study.

A single academic teaching hospital.

Adult patients with acute myocardial infarction complicated by cardiogenic shock who were supported by venoarterial extracorporeal membrane oxygenation from June 2008 to September 2016.

Fourteen individual variables were assessed for their association with the primary endpoint. These variables were prespecified by the study team as being the most likely to affect survival. A receiver operating characteristic analysis was also performed to test the ability of the ENCOURAGE score to predict survival in this patient cohort.

The primary endpoint of the study was in-hospital survival. A total of 61 patients were included in the analysis. Thirty-seven (60.7%) could be weaned from venoarterial extracorporeal membrane oxygenation and 36 (59.0%) survived. Survival was significantly higher in patients less than 65 years old (odds ratio, 14.6 [CI, 2.5-84.0]; p = 0.003), whose body mass index was less than 32 kg/m (odds ratio, 5.5 [CI, 1.2-25.4]; p = 0.029) and international normalized ratio was less than 2 (odds ratio, 7.3 [CI, 1.3-40.1]; p = 0.022). In patients where the first lactate drawn was less than 3 mmol/L, the survival was not significantly higher (odds ratio, 4.4 [CI, 0.6-32.6]; p = 0.147). The C-statistic for predicting survival using a modified version of the ENCOURAGE score, which replaced prothrombin activity less than 50% with an international normalized ratio greater than 2, was 0.74 (95% CI, 0.61-0.87).

In this single-center study, several important covariates were associated with improved survival in patients with acute myocardial infarction complicated by cardiogenic shock who were supported by venoarterial extracorporeal membrane oxygenation and the ENCOURAGE score was found to be externally valid for predicting survival to hospital discharge.