Pre-operative prediction of post-VAD implant mortality using easily accessible clinical parameters

Abstract

Background: Mortality rates are high after implantation of a ventricular assist device (VAD), occurring mainly in the early phase post-implant during the time in the intensive care unit (ICU). Pre-operative selection criteria, which predict successful outcome, are difficult to evaluate. We implemented a pre-operative risk score to predict mortality in the ICU after VAD implantation by using easily obtained and quickly accessible clinical parameters.

Methods: In 241 VAD patients, 100 pre-operative markers were related to mortality in the ICU using univariate analysis and ROC curves, followed by multinomial logistic regression analyses.

Results: The mortality rate in the ICU was 32.0%. Univariate statistical analysis revealed 34 parameters that were significantly associated with mortality in the ICU. Of these, multinomial logistic regression identified 13 markers as significant risk factors. These included demographic data (age >50 years); clinically/procedurally relevant data (ischemic cardiomyopathy [ICM], re-do surgery, on extracorporeal membrane oxygenation [ECMO], on intra-aortic balloon pump [IABP], previous cardiac surgery, ventilation, emergency implant, inotropic support, renal replacement therapy, pre-operative resuscitation, transfusion) and laboratory values (blood urea nitrogen [BUN] >40 mg/dl, creatinine >1.5 mg/dl, lactate >3 mg/dl, platelets <100 x 10(3)/microl, white blood cell [WBC] count >13 x 10(3)/microl, C-reactive protein [CRP] >8 mg/dl, hemoglobin <12 g/dl, hematocrit <35%, lactate dehydrogenase [LDH] >500 U/liter, creatine kinase [CK] >200 U/liter, troponin >20 ng/ml). A weighted risk score was implemented with a maximum of 50 points. The risk for mortality in the ICU was as follows: low (15.8%), <15 points; medium (48.2%), 16 to 30 points; and high (65.2%), >30 points.

Conclusions: Easily obtained and quickly accessible clinical parameters can inform potential patients, relatives, and physicians pre-operatively about the risk of death in the ICU after VAD implantation.