Abstract 2781: Role of Scar Tissue on Response to Cardiac Resynchronization Therapy
Introduction: The response to cardiac resynchronization therapy (CRT) varies significantly among individuals.
Hypothesis: We hypothesized that the presence of scar tissue may be important for non-response to CRT. Also, pacing the LV in scarred myocardium may result in ineffective pacing and non-response after 6 months.
Methods: We evaluated fifty-one consecutive patients with ischemic heart failure and substantial LV dyssynchrony eligible for CRT. To determine the extent and location of scar tissue, all patients underwent nuclear imaging with technetium−99m tetrofosmin SPECT before implant. In all patients 17 segments were scored using a 4-point model, with the higher scores indicating more scar tissue. Clinical and echocardiographic parameters were assessed at baseline and after 6 months of CRT.
Results: The improvement in echocardiographic parameters after 6 months of CRT was inversely related to the extent of scar tissue. Moreover, when the scar score exceeded 22, the response rate to CRT was <10%. Fifteen patients (29%) had transmural scar tissue (<50% tracer activity on SPECT) in the region were the LV pacing lead was positioned. These patients showed neither clinical nor echocardiographic improvement after 6 months, whereas patients without scar tissue in the LV pacing lead region improved significantly.
Conclusions: Scar formation is frequently observed in patients with ischemic cardiomyopathy and is inversely related to the response to CRT. In addition, scar tissue in the region of the LV pacing lead may prohibit response to CRT. Therefore, evaluation for scar tissue may be considered in the selection process for CRT.