Left atrial function and long-term survival after cardiac resynchronization therapy

Abstract Background Left atrial (LA) reservoir strain after CRT has been linked to long-term outcome, but the role of LA function in response to cardiac resynchronization therapy (CRT) is incompletely understood. LA dyssynchrony during left bundle branch block has negative effects on LA function beyond LA reservoir strain. We hypothesized that correction of LA dyssynchrony after CRT has added value to LA reservoir strain as a marker of long-term outcome. Purpose To explore the role of LA function in long-term survival after CRT. Methods In a recent prospective multicenter study of 168 patients, LA segmental and global strains were measured by speckle-tracking echocardiography before and 7 ± 1 months after CRT. LA reservoir strain was measured as the difference between peak and minimum global strain during the atrial cycle and LA dyssynchrony as the time delay between onset systolic stretch of the interatrial septum and LA lateral wall. Since LA reservoir strain < 18% is associated with elevated LV filling pressure, we used 18% as cutoff and for LA dyssynchrony 43 ms (mean after CRT in the present study). All-cause mortality was used as clinical endpoint during follow-up. Results After 6 years ± 21 months (mean ± SD) follow-up, 35 (21%) patients died. LA reservoir strain was significantly lower (15 ± 9% vs 20 ± 10%, p = 0.003) and LA dyssynchrony numerically higher (61 ± 68 ms vs 39 ± 69 ms, p = 0.099) in patients who died compared to survivors. LA reservoir strain ≥ 18% after CRT was associated with favorable long-term survival (HR: 0.51, 95% CI: 0.26 - 0.98) (upper panel in the Figure). LA dyssynchrony was not independently associated with mortality. However, when used in concert with LA reservoir strain ≥ 18% after CRT, it identified patients with perticularly excellent long-term survival (HR: 0.17, 95% CI: 0.05 - 0.58 vs patients with reservoir strain ≥ 18% and persistent LA dyssynchrony) (lower panel in the Figure). Patients with preserved LA reservoir strain but persistent LA dyssynchrony had similar outcome as patients with reduced LA reservoir strain (HR: 0.98, 95% CI: 0.45 - 2.12). Conclusion LA reservoir strain ≥ 18% and absence of LA dyssynchrony is associated with excellent long-term survival after CRT.LA strain after CRT and survival