Clinical Significance of Electromechanical Dyssynchrony and QRS Narrowing in Patients With Heart Failure Receiving Cardiac Resynchronization Therapy.

BACKGROUND: We hypothesized that preoperative electromechanical dyssynchrony amenable to cardiac resynchronization therapy (CRT) and QRS narrowing immediately after CRT are both correlated and have a cumulative impact on response and outcome after CRT. METHODS: A total of 233 CRT candidates (heart failure New York Heart Association classes II-IV, ejection fraction < 35%, QRS ≥ 120 milliseconds, 44% women, 71 ± 11 years old) were prospectively included. Preoperative electromechanical dyssynchrony amenable to CRT was assessed by septal deformation patterns using speckle tracking echocardiography. QRS narrowing was calculated from 12-lead electrocardiograms before and immediately after CRT implantation. The primary endpoint was overall mortality during long-term follow-up. The NTC clinical trial number is NCT02986633. RESULTS: Eighty-seven percent of patients with preoperative electromechanical dyssynchrony experienced QRS narrowing after CRT (118/136), whereas 69% of patients without preoperative electromechanical dyssynchrony (67/97) experienced QRS narrowing after CRT (P < 0.001). By Cox multivariate analysis, both preoperative electromechanical dyssynchrony and lack of postoperative QRS narrowing were independently associated with an increased risk of mortality during follow-up (adjusted hazards ratio [HR] 2.24, 95% confidence interval [CI] 1.43-3.50 and HR 1.90, 95% CI 1.06-3.38, respectively). Compared with patients with preoperative electromechanical dyssynchrony, patients without both electromechanical dyssynchrony and postoperative QRS narrowing experienced a considerable increased risk of mortality during follow-up (adjusted HR 3.70, 95% CI 1.96-6.97). CONCLUSIONS: Lack of postoperative QRS narrowing after CRT is associated with preoperative electromechanical dyssynchrony. Both preoperative electromechanical dyssynchrony and postoperative QRS narrowing have a favourable cumulative impact on outcome after CRT.

Prognostic importance of postoperative QRS widening in patients with heart failure receiving cardiac resynchronization therapy.

BACKGROUND: Landmark reports have suggested that patients with QRS widening immediately after cardiac resynchronization therapy (CRT) experienced less frequently reverse left ventricular remodeling during follow-up. OBJECTIVE: We sought to investigate the relationship between postoperative QRS widening relative to baseline and mortality in a prospective cohort of heart failure patients receiving CRT. METHODS: A 12-lead electrocardiogram was recorded for 237 heart failure patients (New York Heart Association class II to IV, left ventricular ejection fraction ≤35%, and QRS width ≥120 ms) before and immediately after CRT device implantation. The relationships between QRS widening, all-cause and cardiovascular mortality, and echocardiographic response to CRT were studied. RESULTS: During a median follow-up of 24 months, 39 patients died. Fifty patients (21%) experienced QRS widening after CRT [QRS(+) group]. During follow-up, all-cause mortality was higher in QRS(+) patients than in QRS(-) patients (36-month survival free from death 81% ± 7% vs 64% ± 16%; log rank, P = .029). After adjustment for important prognostic confounders, QRS(+) patients remained associated with an excess overall mortality (adjusted hazard ratio [HR] 2.67; 95% confidence interval 1.07-6.65; P = .035) and cardiovascular mortality (adjusted hazard ratio 3.63; 95% confidence interval 1.13-11.65; P = .03). QRS(+) patients were less frequent responders to CRT than were QRS(-) patients (20 [47%] vs 136 [83%]; P < .0001). CONCLUSION: Postoperative QRS widening relative to baseline after CRT is associated with a considerable increased mortality risk during follow-up. Whether QRS narrowing should be achieved to optimize CRT placement, and thereby increase the rate of CRT responders and improve outcome, deserves further research.