Left atrial strain compared to volume in long-term flecainide treated patients with atrial fibrillation – a retrospective cohort study

Left atrial volume index (LAVI) is associated with recurrent atrial fibrillation (AF) during flecainide treatment. Nevertheless, AF patients with normal LAVI experience rhythm control failure. Our study sought to compare the association between left atrial strain and LAVI with rhythm control failure, in flecainide treated patients with AF. This retrospective cohort study included consecutive patients ≥ 18 years of age with AF who were discharged after in-hospital initiation of flecainide. Patients without an echocardiogram in sinus rhythm within one year of initiation of flecainide were excluded. The primary endpoint was discontinuations due to rhythm control failure. Receiver operating characteristics determined optimal cutoffs for reservoir (LASr), conduit (LAScd) and contractile (LASct) left atrial longitudinal strains for the primary endpoint. These cutoffs were analysed using Cox regression, with 95% confidence intervals. Seventy patients were followed for a mean of 1.71 ± 1.56 years (mean age 59.4 ± 11.5 years; 66% male; 8.6% had persistent AF). The area under the curve for LASr was 0.764 (0.595–0.933), for LAScd 0.784 (0.634–0.934), and for LAVI 0.497 (0.345–0.795). Optimal cutoffs for LASr were < 23% and LAScd < 14.5%. These cutoffs had similar specificity (LASr 85% and LAScd 73%) but higher sensitivity (70% and 90%, respectively) compared to ≥moderately increased LAVI (84% and 36%) for the primary endpoint. Hazard ratios for LASr < 23% and LAScd < 14.5% were 9.09 (2.34–35.3) and 18.3 (2.31–145), respectively. Impaired left atrial strain was associated, independently from LAVI, with discontinuations due to rhythm control failure in patients receiving long-term flecainide treatment for AF.