Abstract 13438: Additive Value of Free Wall Activation Delay for Risk Stratification of Cardiac Resynchronization Therapy Patients
Background: Free wall activation delay (FWAD) is a new simplified tissue Doppler index of mechanical dyssynchrony applied to free wall segments. Septal to posterior wall delay (SPWD) by speckle tracking radial strain is more widely used in cardiac resynchronization therapy (CRT) patients, but the comparative significance of FWAD is unknown.
Objective: To test the hypothesis that baseline dyssynchrony assessed by FWAD is additive to SPWD in predicting outcome in CRT patients.
Methods: We studied 321 consecutive heart failure patients for CRT. Color-coded tissue Doppler measured FWAD as the average time-to peak longitudinal ejection velocity from QRS onset in 8 basal and mid free wall segments from 3 apical views. FWAD was corrected for heart rate using Bazett's formula. Speckle tracking radial strain was used for SPWD at the midventricular short axis level. Significant dyssynchrony by FWAD was pre-defined as > 240 ms and by SPWD was pre-defined as > 130ms. Pre-defined outcome end-points were death, heart transplant or left ventricular assist device (LVAD).
Results: Both FWAD and SPWD were feasible in 278 patients (84%), aged 65±11 yrs. Their QRS width was 159 ± 27 ms, and ejection fraction 24±6%. There were 63 events (44 deaths, 12 transplants, and 7 LVADs) over 2 yrs. Both FWAD and SPWD were independently associated with long term outcome (p=0.0007 and p=0.003) and remained significantly associated after correcting for ischemic status and QRS duration (p=0.002 and p=0.01). Combined FWAD and SPWD measures of dyssynchrony were additive for predicting outcome events; p <0.0001 overall, HR 0.32 (95 CI 0.14-0.73) for both FWAD and SPWD positive vs. either positive and HR 0.48 (95 CI 0.28-0.83) for either positive vs. neither positive (Fig).
Conclusion: FWAD is a simple tissue Doppler dyssynchrony index that has additive value to SPWD by speckle tracking echo. Combined stratification adds important prognostic information with promise for clinical application to CRT patients.
- © 2012 by American Heart Association, Inc.