Changes in left atrial function in patients undergoing cardioversion for atrial fibrillation: relevance of left atrial strain in heart failure

Background: Left atrial (LA) reservoir strain provides prognostic information in patients with and without heart failure (HF), but might be altered by atrial fibrillation (AF). The aim of the current study was to investigate changes of LA deformation in patients undergoing cardioversion (CV) for first-time diagnosis of AF.

Methods and results: We performed 3D-echocardiography and strain analysis before CV (Baseline), after 25 ± 10 days (FU-1) and after 190 ± 20 days (FU-2). LA volumes, reservoir, conduit and active function were measured. In total, 51 patients were included of whom 35 were in SR at FU-1 (12 HF and preserved ejection fraction (HFpEF)), while 16 had ongoing recurrence of AF (9 HFpEF). LA maximum volume was unaffected by cardioversion (Baseline vs. FU-2: 41 ± 11 vs 40 ± 10 ml/m²; p = 0.85). Restored SR led to a significant increase in LA reservoir strain (Baseline vs FU-1: 12.9 ± 6.8 vs 24.6 ± 9.4, p < 0.0001), mediated by restored LA active strain (SR group Baseline vs. FU-1: 0 ± 0 vs. 12.3 ± 5.3%, p < 0.0001), while LA conduit strain remained unchanged (Baseline vs. FU-1: 12.9 ± 6.8 vs 13.1 ± 6.2, p = 0.78). Age-controlled LA active strain remained the only significant predictor of LA reservoir strain on multivariable analysis (β 1.2, CI 1.04-1.4, p < 0.0001). HFpEF patients exhibited a significant increase in LA active (8.2 ± 4.3 vs 12.2 ± 6.6%, p = 0.004) and reservoir strain (18.3 ± 5.7 vs. 22.8 ± 8.8, p = 0.04) between FU-1 and FU-2, associated with improved LV filling (r = 0.77, p = 0.005).

Conclusion: Reestablished SR improves LA reservoir strain by restoring LA active strain. Despite prolonged atrial stunning following CV, preserved SR might be of hemodynamic and prognostic benefit in HFpEF.