Improvement in Left Atrial Function Critical for Atrial Fibrillation-Free Survival After Cardiac Resynchronization Therapy

Following cardiac resynchronization therapy (CRT), left atrial (LA) functional improvement independently predicted atrial fibrillation (AF)-free survival in a new study.

“The improvement in LA systolic and diastolic strain as a means of LA mechanical reserve also predicts long-term event-free survival after CRT independently from [left ventricular (LV)] volume response and new-onset AF,” the researchers wrote.

Since the effect of CRT on new AF development is unknown, researchers sought to evaluate the factors associated with AF development and the effect of these factors on long-term outcome after CRT.

During 5 years of follow-up, researchers performed regular clinical assessment, 12-lead electrocardiograms, echocardiography with speckle tracking strain imaging, and device interrogation before CRT implantation and every 6 months afterward.

New-onset AF served as the primary end point, with transplantation, assist device implantation, and death serving as pre-specified outcome events.

Overall, 29 (27.4%) of the 106 patients experienced AF during follow-up (mean, 38 ± 19 months).

According to results, the following parameters of LA mechanics improved at 6 months compared with baseline, but only in patients who remained free of AF: mitral annular late diastolic velocity; LA volume index; LA ejection fraction; LA active emptying fraction; and mean systolic and late diastolic LA strain.

The most accurate predictor of new-onset AF was change in mean systolic (area under curve [AUC]= 0.793) and late diastolic (AUC=0.815; P for both <.0001) LA strain from baseline to 6 months after CRT; these values predicted outcome events independent of new-onset AF and LV volume response.

“[LA] compliance and contractile function can be readily assessed by speckle tracking strain,” the researchers wrote. “[LA] reverse remodeling and improvements in [LA] compliance and contractile function are necessary for [AF]-free survival after [CRT]. [LA] systolic and diastolic strain is a predictor of AF-free survival irrespective of LV reverse remodeling and also important for long-term outcome.”

The researchers added that further validation of this data in CRT patients “will provide important clinical implications to differentiate patients who are expected to derive atrial anti-arrhythmic effect from those who are at high risk of developing [AF], necessitating more aggressive measures or additional therapies addressing [AF] such as atrio-ventricular node ablation.”

Reference

Sade EL, Atar I, Ozin B, et al. Determinants of new-onset atrial fibrillation in patients receiving cardiac resynchronization therapy: Mechanistic insights from speckle tracking imaging. JACC Cardiovasc Imaging.2015. doi: doi:10.1016/j.jcmg.2015.05.011.