Analysis of the outcome for patients experiencing myocardial infarction and cardiopulmonary resuscitation refractory to conventional therapies necessitating extracorporeal life support rescue

Abstract

Objective: To analyze the results of acute myocardial infarction (AMI) complicated with refractory shock necessitating extracorporeal life support (ECLS) rescue and to search for associated risk factors.

Design: Retrospective review of our 9-yr experience with patients initially presenting with AMI with shock necessitating ECLS rescue; analysis of patient outcomes.

Setting: A university-affiliated tertiary referral medical center.

Patients: Between 1994 and 2003 inclusively, 36 consecutive patients (age [mean +/- sd], 57 +/- 10 yrs) with AMI complicated by refractory shock and undergoing cardiopulmonary resuscitation (CPR) necessitating emergent ECLS rescue were enrolled in this study.

Intervention: All patients underwent CPR before ECLS, although 30 patients (83.3%) received ECLS during CPR because spontaneous circulation failed to return. All patients underwent intraaortic counterpulsation either before or following rescue. Seven patients underwent angioplasty only, and one underwent heart transplantation without any intervention. Twenty-eight patients underwent coronary artery bypass grafting (CABG), in which the beating-heart technique was used for 20 patients.

Measurements and main results: The pre-ECLS blood lactate level was high (13.4 +/- 8.5 mmol/L), as was the inotropic score (121.4 +/- 117.3 microg/kg/min). Twenty-five patients (69.4%) were successfully weaned off ECLS, and 12 (48%) survived to discharge (one had a neurologic deficit). The overall mortality rate was 66.7%. A lower inotropic score, reduced blood lactate level, shorter CPR duration, surgical revascularization, and a reduced total maximal Sepsis-related Organ Failure Assessment (SOFA) score were noted among survivors. Liver failure, central nervous system failure, and renal failure mainly occurred in nonsurvivors after ECLS. The technique used for surgical revascularization (beating heart or arrested heart) did not influence the outcome. ECLS is associated with a lower mortality rate than that expected (>90%) from the resultant total maximal SOFA score (16.6 +/- 3.0).

Conclusions: : AMI complicated with refractory shock remains associated with a high mortality rate, even following ECLS rescue, although ECLS might afford a better chance of survival. The SOFA score can be applied to ECLS condition as a reference point for predicting outcome.