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 (HF) with prolonged QRS duration. However, 30% of patients have shown no benefit from the treatment.

Objective: 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 preimplantation CMR examination were retrospectively recruited. CMR feature tracking was used to evaluate LA size and function. The end points include (1) improvement of at least 5% in left ventricular ejection fraction combined with a reduction of at least 1 New York Heart Association functional class at 6-month follow-up and (2) any all-cause death or HF hospitalization during follow-up.

Results: Overall, 82 (50.3%) were CRT responders. CRT nonresponders had larger LA and worse LA reservoir and booster pump function than did responders (P < .001 for all). LA structural (maximum volume index < 47 mL/m) and functional (booster pump strain > 8.5%) criteria were incremental to traditional indicators in detecting CRT response (χ, 40.83 vs 9.98; P < .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 < .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 hazard ratio 6.2; 95% confidence interval 2.15-17.88; P = .001).

Conclusion: The preprocedure LA mechanics evaluated using CMR may be useful to predict response to CRT and improve risk stratification in CRT recipients.