Myocardial Viability and Resynchronization Therapy

Several studies in the literature have shown that the absence of myocardial viability at the site where the electrode was positioned reduces the efficacy of CRT. Ypenburg et al. evaluated the presence of fibrosis using GATED-SPECT with Tc-99m-tetrofosmin before CRT. Patients without fibrosis at the electrode implantation site showed improvement in NYHA class, quality of life, 6-minute walk test, ventricular volumes, and ejection fraction at a 6-month follow-up compared to patients with fibrosis at the electrode implantation site for CRT RT. The extent of the viable myocardial area was related to the reduction of ventricular volumes and ejection fraction. Bose et al. also demonstrated in a retrospective study involving 160 patients with ischemic cardiomyopathy that those patients in which electrode placement was in a site with fibrosis or fibrosis and ischemia more often had the primary outcome (hospitalization for HF and death) at 3 years compared to those patients with normal myocardium. Therefore, the fibrosis and myocardial viability evaluation at the electrode implementation site should be considered before CRT.

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