Aims: At present, 20-30% of patients do not respond to cardiac resynchronization therapy (CRT). In this study, the relation between the extent of viable myocardium and scar tissue vs. response to CRT was evaluated. In addition, the presence of scar tissue in the left ventricular (LV) lead position was specifically related to response to CRT. Methods and results: A total of 51 consecutive patients with ischaemic heart failure and substantial LV dyssynchrony undergoing CRT were included. All patients underwent gated SPECT before CRT implantation to determine the extent of scar tissue and viable myocardium. Clinical and echocardiographic parameters were assessed at baseline and after 6 months of CRT. The results demonstrated direct relations between the response to CRT and the extent of viable myocardium and scar tissue. In addition, the 15 patients (29%) with transmural scar tissue (< 50% tracer activity) in the region of the LV pacing lead showed no improvement after 6 months of CRT. Conclusion: The extent of scar tissue and viable myocardium were directly related to the response to CRT. Furthermore, scar tissue in the LV pacing lead region may prohibit response to CRT. Evaluation for viability and scar tissue may be considered in the selection process for CRT.

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European Heart Journal
Erasmus MC: University Medical Center Rotterdam

Ypenburg, C., Schalij, M. J., Bleeker, G., Steendijk, P., Boersma, E., Dibbets-Schneider, P., … Bax, J. (2007). Impact of viability and scar tissue on response to cardiac resynchronization therapy in ischaemic heart failure patients. European Heart Journal, 28(1), 33–41. doi:10.1093/eurheartj/ehl379