Cardiac resynchronization therapy in patients with postero-lateral scar by cardiac magnetic resonance: A systematic review and meta-analysis

- Cardiac magnetic resonance (CMR) has the potential to discriminate response to cardiac resynchronization therapy (CRT).
- Pre-implant CMR is useful for the assessment of left ventricle (LV) scar burden.
- Presence of transmural postero-lateral (TMPL) scar or significant scar at the LV pacing site is associated with a lower response rate.

BackgroundCardiac 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 resultsWe 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.ConclusionsThe 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.