Regional myocardial wall asymmetry as a novel echocardiographic predictor of response to resynchronization, preliminary single-centre data

Background According to current guidelines, the indications for cardiac resynchronization therapy (CRT) are determined based on the morphology and duration of QRS complexes in the ECG. Despite the advancements in cardiology, approximately 30-40% of patients turn out to be non-responders. Therefore, assessing dyssynchrony based solely on ECG is insufficient. Echocardiographic assessment of left ventricular (LV) mechanical dyssynchrony using new speckle tracking techniques may be promising for improving the criteria for CRT implantation. Purpose The aim of this preliminary analysis was to evaluate echocardiographic predictors of a positive response to CRT in patients with chronic heart failure with reduced left ventricular ejection fraction. Methods In a prospective single-centre study, CRT recipients were assessed for myocardial work parameters using speckle tracking echocardiography. All patients underwent conventional and 2D speckle-tracking echocardiography one day before and 12 months after the procedure. Patients were qualified for the procedure according to the current guidelines.CRT positive response was defined as ≥15% reduction in left ventricular end-systolic volume and ≥5% increase in left ventricular ejection fraction, evaluated together after 12 months of follow-up. Results A total of 45 patients (68.5% of men) were included in the analysis. Positive echocardiographic response for CRT therapy was established in 28 subjects (62.9%). All assessed myocardial work parameters (Global Constructive Work, GCW; Global Wasted Work, GWW; Global Work Index, GWI; Global Work Efficiency, GWE; work difference between septum and lateral wall of the LV, S-L Work Asymmetry; work difference between antero-septal and posterior wall, AS-P Work Asymmetry) significantly improved after CRT implantation. However, the improvement was significantly higher in CRT responders compared to the non-responder group (p<0.001). Univariableregression analysis identified GCW, GWW, S-L Work Asymmetry, and AS-P Work Asymmetry assessed in baseline echocardiography as predictors of CRT response. In multivariable regression analysis, only AS-P Work Asymmetry proved to be a significant independent predictor of CRT response (OR 1.003; 95%CI 1.001-1.006; p=0.005) (Table 1). The diagnostic accuracy of AS-P Work Asymmetry in predicting CRT responders, calculated as AUC, was 0.92 (95% CI; 0.83-1). ROC analysis identified an AS-P Work Asymmetry threshold of 908mmHg%, with 91% sensitivity and 85% specificity in predicting CRT responders (Fig 1). Conclusions Echocardiographic assessment of LV function based on AS-P work difference was found to be the strongest independent predictor of response to CRT. The presented pilot results encourage further research conducted on a larger group of patients.