Introduction Myocardial scar measured by nuclear imaging has become a promising predictor to outcome of cardiac resynchronization therapy (CRT),however, with mixed results in literature.Methods We recruited 213 CRT recipients with nuclear cardiac imaging before CRT (mean age70.2 ± 9.4 years, 84％ male, 72.8％ ischemic cardiomyopathy).The scar localization and myocardial vitality were analyzed using a 17-segment polar map and a 5-point scale for each segment (0, orl were defined as scar; 2, 3, or 4 were defined as viable tissue).Echo variables were recorded at baseline and6-months follow-up.Left ventricular (LV) lead positions were categorized using echocardiographic map in which territories are consistent with 17-segment nuclear model.Responder was defined as an absolute improvement in ejection fraction (EF)≥ 5％ after CRT.