Atrial resynchronization: an overlooked concept in heart failure and conduction system pacing: review of selected literature with emphasis on atrial anatomy

Unlike ventricular electrical disease, the impact of similar atrial disease on cardiac function has received insufficient importance. We aimed to examine data on atrial anatomy, electrical disease, and pacing to ameliorate abnormalities, offering pointers towards future practice.

We used PubMed to explore atrial anatomy, activation, and pacing aiming to improve function. From inception of pacing, causes of deterioration in ventricular systolic function went unrecognized. Their eventual recognition led to fresh pacing strategies, termed conduction system pacing, which have yielded improved and preserved long-term ventricular function: now standard practice. Study of atrial anatomy/conduction implies that similar approaches may improve atrial function and also reduce incidence of atrial fibrillation. Impact of atrial electrical disease on diastolic and subsequent ventricular systolic function has been ignored, despite data showing how pacing alternative atrial sites can abbreviate atrial activation and improve ventricular filling: methods that have not been widely adopted. Comprehension of atrial anatomy/conduction underpins abandonment of right atrial appendage pacing paralleling the move away from right ventricular apical pacing on similar principles.

When treating heart failure, atrial resynchronization should be considered along with ventricular resynchronization. Crucially, convenient pacing sites have been outmoded by active-fixation leads that can be placed at stimulation sites approximating normal conduction, including the atria; achievement hinges on understanding atrial anatomy and activation. Atrial resynchronization may significantly improve cardiac function where dyssynchrony relates to atrial disease/conduction delay, but more evidence of benefits must be collected. As resynchronization therapy moves forward, there should be parallel focus on evaluating coordination of atrial activation and timing with respect to the ventricles.