Creatine kinase isoenzyme MB relative index as predictor of mortality on extracorporeal membrane oxygenation support for postcardiotomy cardiogenic shock in adult patients

Abstract

Objective: Extracorporeal membrane oxygenation (ECMO) has been used as initial, biventricular circulatory support for patients with severe postcardiotomy cardiogenic shock (PCS). Due to its aggressiveness and limited weaning quote, concerns have been raised about maintenance of ECMO support regarding duration. However, it is frequently hazardous for physicians to make an individualized decision, whether and when discontinuation of ECMO support should be considered. We tried to find measurable values during ECMO support that could predict the patient mortality on ECMO support.

Methods: During a 9-year period, 32 patients (mean age 55.4+/-11.9; ranging from 30 to 75 years) with ECMO support for postcardiotomy cardiogenic shock were included in this study.

Results: Eighteen patients died without weaning (group I, 56.25%), while 14 patients could be weaned off the ECMO support (group II, 43.75%). In the group II, six patients (18.75%) died later in the postoperative course and eight patients (25%) survived to be discharged from hospital. The overall survival of all 32 patients at 30 days was 31.25% (n=10). At a follow-up period of 3.88+/-1.58 years, the overall survival rate was 12.5% (n=4). Mean duration of ECMO support was 2.7+/-1.7 days. The following variables were significantly different between the two groups: blood lactate level and the level of MB isoenzyme of creatine kinase (CK-MB) 48 h after ECMO initiation (p<0.01, p=0.001) as well as the CK-MB relative index as the ratio of CK-MB to total CK (p<0.001). Logistic regression identified that only the CK-MB relative index 48 h after ECMO initiation was associated with mortality on ECMO support (p=0.011, odds ratio=1.219, 95% confidence interval: 1.046-1.421).

Conclusion: For adult non-transplantation patients with postcardiotomy cardiogenic shock, the CK-MB relative index 48 h after ECMO initiation can be a predictor of mortality on ECMO support. This might be a useful tool for considering a patient either for discontinuation of ECMO support or further treatment.