Abstract 3321: Comparison of Long-Term Response to Resynchronization Therapy in Patients With Chronic Right Ventricular Pacing to Those With Intrinsic Left Bundle Branch Block
Background: Current guidelines for cardiac resynchronization therapy (CRT) are for heart failure (HF) patients with intrinsic widened QRS. The objective was to compare dyssynchrony and response to CRT and long-term outcome after CRT in patients with right ventricular (RV) pacing induced QRS widening to those with intrinsic left bundle branch block (LBBB).
Methods: We studied 288 HF patients referred for CRT with ejection fraction (EF) 24±7% (all ≤35%), and QRS 159±27ms (all ≥120ms), 48% ischemic disease. CRT implants occurred in 174 with LBBB and in 60 with chronic RV pacing upgraded to CRT; 54 had attempted but failed CRT as a control group. Long-term outcome after CRT including event-free survival from heart transplantation, ventricular assist device or death for approximately 5 years was available in all and EF follow-up was available in 163 patients 7±4 after CRT. Response to CRT was defined as a ≥15% increase in EF.
Results: Both RV paced and LBBB patients had similar EF responses (from 24±7 to 32±11* and from 24±6 to 33±11*, *p<0.01 vs. baseline) and EF response rate (70% vs. 66%). Furthermore, both groups had a similar long-term outcome after CRT, which was significantly better than the failed CRT control group (p<0.001).
Conclusions: Similar favorable EF response and long-term survival was observed in chronic RV paced patients upgraded to CRT and LBBB patients. Chronically RV paced HF patients with low EF appear to be similar candidates for CRT.