CMR Feature Tracking-based Left Atrial Mechanics Predicts Response to Cardiac Resynchronization Therapy and Adverse Outcomes

Background Cardiac resynchronization therapy (CRT) is an established therapy for advanced heart failure with prolonged QRS duration. However, 30% of patients have shown no benefit from the treatment. Objectives This study aimed to examine the value of left atrial (LA) mechanics by cardiac magnetic resonance (CMR), to predict response to CRT and clinical outcomes. Methods A total of 163 CRT recipients with pre-implantation CMR examination were retrospectively recruited. CMR feature-tracking was used to evaluate LA size and function. Endpoints include: 1)improvement of at least 5% in left ventricular ejection fraction combined with a reduction of at least 1 NYHA functional class reduction at 6-month follow-up, 2) any all-cause death or heart failure (HF) hospitalization during follow-up. Results Overall, 82 (50.3%) were CRT responders. CRT non-responders had larger LA, and worse LA reservoir and booster function than responders (all P <0.001). LA structural (maximum volume index <47 ml/m2) and functional (booster strain >8.5%) criteria were incremental to traditional indicators in detecting CRT response (Chi-square: 40.83 vs. 9.98, P <0.001). During follow-up (median: 41 months), survival free from death or HF hospitalization increased with the number of positive LA criteria (log-rank p <0.001). After adjustment for clinical confounders, the absence of the 2 criteria remained associated with a considerably increased risk of death or HF hospitalization (adjusted HR: 6.2 [95% CI: 2.15-17.88]; P =0.001). Conclusions The pre-procedure LA mechanics evaluated by CMR may be useful to predict response to CRT and improve risk stratification in CRT recipients.