Abstract 14750: Free Wall Activation Delay is Predictive of Outcome After Cardiac Resynchronization Therapy in Patients With Narrower QRS Width or Non-Left Bundle Branch Block Morphology
Background: Response to cardiac resynchronization therapy (CRT) is best in patients with QRS width > 150ms and left bundle branch block (LBBB). It is unclear how to improve selection of patients for CRT with QRS 120-149ms or non-LBBB (Guideline Class IIa/IIb CRT indications). Free Wall Activation Delay (FWD) is a new index of left ventricular (LV) mechanics associated with response to CRT.[[Unable to Display Character:
Methods: To test the hypothesis that FWD was associated with outcome following CRT in those with narrower QRS or non-LBBB, we studied 263 NYHA III-IV heart failure (HF) patients with QRS ≥ 120ms and ejection fraction ≤ 35%. FWD was defined by color-coded tissue Doppler as the average time-to peak longitudinal ejection velocity from QRS onset in 4 basal and mid posterior and lateral wall segments from apical 4 and 3 chamber views, corrected for heart rate using Bazett’s formula. Significant FWD was pre-defined as ≥ 240 ms. Pre-defined outcome end-points were death or hospitalization for HF.[[Unable to Display Character:
Results: Of 263 patients, 112 patients had QRS ≥ 150 ms and LBBB (Guideline Class I CRT indication) and 151 patients had QRS < 150 ms and/or non-LBBB morphology (Guideline Class II CRT indication). Patients with QRS ≥150 ms and LBBB had significantly better long-term outcome (p=0.001). Among patients with QRS < 150ms and/or non-LBBB, those with baseline FWD ≥ 240 ms had significantly better long-term outcome than patients with FWD < 240 ms (p = 0.017).[[Unable to Display Character:
Conclusion: Baseline FWD before CRT is associated with more favorable long-term outcome in patients with QRS 120-150ms and/or non-LBBB. These findings are of clinical importance for CRT.
- © 2013 by American Heart Association, Inc.