ABSTRACT
BACKGROUND: Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in selected patients with heart failure, but up to one third of patients may not respond to CRT. A transmural postero-lateral (TMPL) wall scar in the left ventricle (LV) or over the LV pacing site may attenuate clinical and echocardiographic response to CRT. METHODS AND RESULTS: We systematically searched PubMed, EMBASE, and Cochrane databases for studies examining the association between Cardiac magnetic resonance (CMR)-determined postero-lateral or LV pacing site scar and clinical and echocardiographic response to CRT. Eleven prospective studies were included. The presence of TMPL scar on pre-implant CMR was associated with a 75% lower chance of echocardiographic response to CRT, and a similarly lower chance of clinical response. Significant scar over LV pacing site on pre-implant CMR was also associated with a 46% lower chance of echocardiographic response to CRT, and a 67% lower chance of clinical response. CONCLUSIONS: The presence of transmural postero-lateral scar or significant scar within the LV pacing site detected by pre-implant CMR is associated with a lower rate of clinical or echocardiographic response to CRT.
