Objectives: To identify preoperative predictors of post-cardiotomy cardiogenic shock in patients with ischemic and non-ischemic cardiomyopathy and evaluate trajectory of postoperative ventricular function.
Methods: From 1/2017-1/2020, 238 patients with ejection fraction <30% (206/238) or 30-34% with at least moderately severe mitral regurgitation (32/238) underwent conventional cardiac surgery at Cleveland Clinic, 125 with ischemic and 113 with non-ischemic cardiomyopathy. Preoperative ejection fraction was 25±4.5%. The primary outcome was post-cardiotomy cardiogenic shock, defined as need for microaxial temporary left ventricular assist device, extracorporeal membrane oxygenation, or vasoactive-inotropic score >25. RandomForestSRC was used to identify its predictors.
Results: Post-cardiotomy cardiogenic shock occurred in 27% (65/238). Pulmonary artery pulsatility index <3.5 and pulmonary capillary wedge pressure >19 mmHg were the most important factors predictive of post-cardiotomy cardiogenic shock in ischemic cardiomyopathy. Cardiac index <2.2 L∙min-1∙m-2 and pulmonary capillary wedge pressure >21 mmHg were the most important predictive factors in non-ischemic cardiomyopathy. Operative mortality was 1.7%. Ejection fraction at 12 months post-surgery increased to 39% (CI: 35-40) in the ischemic group and 37% (CI: 35-38) in the non-ischemic cardiomyopathy group.
Conclusions: Predictors of post-cardiotomy cardiogenic shock were different in ischemic and non-ischemic cardiomyopathy. Right heart dysfunction, indicated by low pulmonary artery pulsatility index, was the most important predictor in ischemic cardiomyopathy, whereas greater degree of cardiac decompensation was the most important in nonischemic cardiomyopathy. Therefore preoperative right heart catheterization will help identify patients with low ejection fraction that are at higher risk of post-cardiotomy cardiogenic shock.
Keywords: cardiac surgery; low ejection fraction; mechanical circulatory support; right heart catheterization.
