Abstract 2650: Do Changes In Surface Ekg Predict The Clinical Response To Cardiac Resynchronisation Therapy: Data From The Care-hf Study
Background : The CARE-HF study showed that cardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients with heart failure and markers of dyssynchrony. This analysis investigated whether baseline EKG and EKG changes after biventricular pacing influences the clinical response to CRT.
Methods: Four hundred and nine patients (age 66 ± 6; 75% male; mean LVEF 25 ± 4%) were included in the CRT group and 404 in the medical therapy group (age 66 ± 6; 73% male; mean LVEF 25 ± 4%). EKG’s were analyzed in both groups before implantation (intrinsic conduction), and after 3 and 18 months of biventricular pacing. Patients who were alive, had not had an emergency heart transplantation or an unplanned cardiovascular hospitalisation by the end of the study were defined as responders
Results: Amongst patients assigned to CRT, 250 (61%) had a positive response and 159 (39 %) did not, including 19 patients in whom a device could not be implanted and 55 who had died by 18 months. In univariate analyses baseline QRS duration didn’t predict a positive response to CRT. Baseline PR and QTc durations, the presence of LBBB, QTc and QRS durations at 3 months were predictive of response (table 1). In the multivariate model, baseline PR interval (Chi-square 10.6; p<0,01) and presence of RBBB (Chi-square 10.52; p<0,01) were predictive of response to CRT as was QTc duration at 3months (Chi-square 10.14; p<0,01).
Conclusion: Based on the definition used, a positive clinical response to CRT was observed in 61% of patients at 18 months. Shorter paced QRS and QTc durations at 3 months were somewhat predictive of better long term outcome. Patients with RBBB are not good candidates to CRT.