Abstract 13288: Baseline Radial Dyssynchrony by Speckle Tracking Echocardiography is Associated with Favorable Clinical Outcomes after Cardiac Resynchronization Therapy: Analysis from the MADIT-CRT Trial
Background: The importance of echocardiographic dyssynchrony as a predictor of response to cardiac resynchronization therapy (CRT) has been unclear.
Objective: To test the hypothesis that patients with mechanical dyssynchrony determined by speckle tracking radial strain will have a more favorable outcome after CRT.
Methods: The Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT) trial randomized patients with NHYA class I-II heart failure, QRS > 130 ms, and EF < 30% to either CRT-defibrillator or defibrillator (ICD) alone. A subgroup of 1,106 patients had baseline digital echocardiograms analyzed by speckle tracking radial strain (TomTec Inc.) for radial dyssynchrony defined as the time difference between peak anteroseptal to posterior wall strain. Dyssynchrony by quartiles and the pre-defined cut-off of > 130 ms were studied. The primary end-point was the first heart failure hospitalization or death.
Results: Data were available on 668 CRT and 438 ICD patients. The patient's degree of radial dyssynchrony by quartiles were: <96ms, 96-200ms, 200-330ms, and>330ms. CRT patients who lacked radial dyssynchrony (<96 ms) had a similar unfavorable event rate per 100 patient-years at 11.7% as did the ICD controls at 12.4% p=NS. In patients with > 200 ms of dyssynchrony, CRT was associated with a reduction in event rate to 4.7%; significantly lower than 13.3% for ICD. (Figure). Using a radial dyssynchrony cut-off of >130ms, CRT had a reduction in HF hospitalization or death: hazard ratio (HR) 0.45 (0.32-0.64), in contrast to CRT patients with <130ms :HR 0.96 (0.63-1.46).
Conclusion: Baseline radial dyssynchrony by speckle tracking strain was associated with more favorable outcomes after CRT with a significant reduction in HF hospitalizations or death, compared with those patients who lacked baseline dyssynchrony. Lack of radial dyssynchrony appears to be an important factor associated with non-response to CRT.
- © 2012 by American Heart Association, Inc.