Abstract 1647: Can Left Ventricular Dyssynchrony as evaluated by Phase Analysis on Gated Myocardial Perfusion SPECT predict Response to Cardiac Resynchronization Therapy?
Purpose: Cardiac resynchronization therapy (CRT) is now a well established therapeutic option for patients with end-stage heart failure. However, not all patients respond to CRT, and therefore preimplantation identification of responders is desirable. The purpose of the present study was to investigate whether the degree of left ventricular (LV) dyssynchrony as assessed with phase analysis from gated myocardial perfusion single photon emission computed tomography (GMPS), can predict which patients will respond to CRT.
Methods: Forty-two patients with severe heart failure, depressed LV ejection fraction and wide QRS complex, were prospectively included for implantation of a CRT device and underwent GMPS and 2D echocardiography as part of clinical protocol. Clinical status was evaluated using New York Heart Association (NYHA) classification, 6-minute walk test and quality-of-life score. The histogram bandwidth and phase standard deviation (SD) (parameters indicating LV dyssynchrony) were assessed from GMPS, and clinical status and echocardiographic variables were re-assessed at 6 months follow-up.
Results: Responders (71%) and non-responders (29%) had comparable baseline characteristics, except for histogram bandwidth (175±63° vs 117±51°, P <0.01) and phase SD (56.3±19.9° vs 37.1±14.4°, P <0.01) which were significantly larger in responders as compared to non-responders. Moreover, receiver-operator characteristic curve analysis demonstrated an optimal cutoff value of 135° for histogram bandwidth (sensitivity and specificity of 70%) and of 43° for phase SD (sensitivity and specificity of 74%) for the prediction of response to CRT.
Conclusion: Response to CRT is related to the presence of LV dyssynchrony assessed by phase analysis with GMPS. A cutoff value of 135° for histogram bandwidth and of 43° for phase SD could be used to predict response to CRT. Larger prospective studies are warranted to confirm the present findings.