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 […]