Background: Recent studies have shown that myocardial constructive work (CW) assessed by pressure strain loops (PSLs) is an independent predictor of the response to cardiac resynchronization therapy (CRT). Aim of our study is to assess if CW has an additive value in the prediction of long-term outcome of patients undergoing CRT, in addition to CRT response (CRT+) and left ventricular (LV) dyssynchrony.
Methods: 2D standard and speckle tracking echocardiography were performed in 166 CRT candidates (mean age: 66±10 years, males: 69%, QRS duration: 165±19 ms) before CRT implantation and at 6-month follow-up. Myocardial constructive work (CW) was assessed by PSLs. CRT+ was defined by a >15% reduction in left-ventricular end-systolic volume at 6-month follow-up and was observed in 48 (29%) patients. LV dyssynchrony was visually assessed by septal flash.
Results: After a median FU of 4 years (range: 1.3–5 years), all-cause death occurred in 28 patients (17%). At multivariable Cox-regression analysis, CW and age were the only prognostic predictors of cardiac death (Table 1). At ROC curve analysis, CW≤888 mmHg% was the best cut-off to predict all-cause mortality (AUC 0.67, p=0.004). Variables with a p-value <0.05 at univariable Cox-regression analysis were used to test the prognostic power of different nested models. Only the addition of CW≤888 mmHg% to a model including clinical variables (age and ischemic etiology for heart failure), SF, and CRT+ caused a significantly increase in model power for the prediction of prognosis cardiac (χ2: 13.2 vs 28.1, p=0.004) (Figure 1).
Conclusions: The estimation of myocardial CW has an additive value for the prediction of mortality in CRT candidates, over SF and volumetric CRT-response.