Short-term outcome of cardiac resynchronization therapy - A comparison between newly implanted and chronically right ventricle-paced patients

Background Cardiac resynchronization therapy (CRT) is considered as a standard adjunct therapy in symptomatic patients with congestive heart failure (CHF) who have a prolonged QRS. There is an increasing number of patients who do not receive de novo CRT devices but are upgraded from right ventricular (RV) pacing to biventricular stimulation. We wanted to evaluate the benefit of CRT in patients with chronic RV pacing in comparison to previously non-paced heart failure patients. Methods One hundred and sixty-five patients who had their device newly implanted (group I) and 116 who were upgraded from previously implanted RV pacing systems (group II) at Mayo Clinic Hospital were retrospectively analyzed. Clinical and echocardiographic response to CRT was evaluated. Mean follow-up time was 290 ± 250 days. Results Baseline characteristics did not differ between the two groups of patients. Clinical response rate was identical in Groups I and II (65 vs. 65%, respectively; P = 0.98) and echocardiographic response rate was similar in both groups of patients (64 vs. 62%; P = 0.80). Post-implant QRS increased in group I and was reduced in group II (5 (27.4) vs. - 20.0 (33.9) ms; P < 0.001). NYHA class improvement (- 0.7 (0.6) vs. - 0.7 (0.6), P = 0.81), LV ejection fraction increase (9.2 (12.9) vs. 8.2 (9.9)%; P = 0.55) and LV end-systolic volume reduction (- 34.5 (50.7) vs. - 25.7 (47.4)%; P = 0.28) were comparable in both groups. Conclusions Chronically RV-paced patients who receive CRT have similar short-term benefits when compared with patients with new CRT implantations.