Long-term effects of upgrading from right ventricular pacing to cardiac resynchronization therapy in patients with heart failure.

AIMS: To determine the effects of upgrading from right ventricular (RV) pacing to cardiac resynchronization therapy (CRT) in patients with heart failure. METHODS AND RESULTS: Patients with heart failure [age 67.3 +/- 9.6 years (mean +/- SD), NYHA class III or IV, left ventricular ejection fraction (LVEF) or= 120 ms] underwent de novo CRT (n = 336) or upgrading from RV pacing [n = 58; VVIR in 24, DDDR in 34] to CRT. The endpoint of death from any cause or major cardiovascular events, cardiovascular death or hospitalization for heart failure, and cardiovascular death or death from any cause was determined after a maximum follow-up of 7.7 years. No differences emerged between the de novo CRT and the upgrade-to-CRT groups with respect to any of the clinical endpoints. The de novo CRT and upgrade-to-CRT groups derived similar improvements in NYHA class [-1.2 vs. -1.3 (mean), both P <0.0001), 6 min walking distance [75.9 (P <0.0001) vs. 46.4 (P = 0.0205) m], and quality of life scores [-25.2 vs. -18.7 (both P <0.0001)] 1 year after implantation. Response rates using a combined clinical score (>or=1 NYHA classes or >or=25% increase in 6 min walking distance plus survival with freedom from heart failure hospitalizations for 1 year) were 73.2% and 75.4%, respectively (P = NS). There were reductions in left ventricular end-systolic volume [median of 20.3 mL (P = 0.0012) and 22.7 mL (P = 0.0066), respectively] and improvements in LVEF [median of 2.9% and 9.3%, respectively (both P <0.0001)]. CONCLUSION: In patients with heart failure who are RV-paced, upgrading to CRT is associated with a similar long-term risk of mortality and morbidity to patients undergoing de novo CRT. Symptomatic improvements and degree of reverse remodelling are also comparable.