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

To determine the effects of upgrading from right ventricular (RV) pacing to cardiac resynchronization therapy (CRT) in patients with heart failure. Patients with heart failure [age 67.3 +/- 9.6 years (mean +/- SD), NYHA class III or IV, left ventricular ejection fraction (LVEF) <= 35%, QRS >= 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 (>= 1 NYHA classes 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)]. 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.