Clinical Significance of Global Wasted Work in patients receiving Cardiac Resynchronization Therapy for Heart Failure

Abstract

Risk stratification remains key in the management of patients with heart failure (HF). Besides enduring standards such as left ventricular (LV) ejection fraction, the amount of LV myocardial global wasted work (GWW) might better predict outcome in HF patients who are eligible for cardiac resynchronization therapy (CRT). The aim of this study is to evaluate the relation between preoperative GWW and outcome in a large prospective cohort of patients with heart failure and reduced ejection fraction (HFrEF) receiving CRT. The study included 249 HF patients. GWW was calculated by speckle tracking strain two-dimensional echocardiography using pressure-strain loops. The primary outcome of the study was all-cause death. A combined response to CRT defined as LV reverse remodeling and/or absence of hospitalization for HF was also studied. Median follow-up was 48 months (interquartile range 43-54). Median preoperative GWW was 281 (184-388) mmHg%. Preoperative GWW correlated with mortality during follow-up (hazard ratio (HR) 1.5 (1.1-2.0) per SD decrement, P = 0.006). After adjustment on established predictors of outcome in HFrEF patients receiving CRT, patients with GWW < 200 mmHg% remained at increased risk for all-cause death compared with those with GWW ≥ 200 mmHg% (adjusted HR, 2.0; 95%CI, 1.1–3.9; P = 0.0245). GWW had significant additional prognostic value for mortality prediction over the baseline model (Chi 2 to improve 4.85, P = 0.028). Preoperative GWW < 200 mmHg% also independently predicted absence of CRT response ( Fig. 1 ). A low preoperative GWW (< 200 mmHg%) increases the risk of all-cause death by two-fold and predicts the absence of CRT response in CRT recipients.