Restoration of sinus rhythm results in early and late improvements in the functional reserve of the heart following direct current cardioversion of persistent AF: FRESH-AF

Background: The improvement in cardiac physiological parameters after restoration of sinus rhythm in patients with persistent atrial fibrillation (AF) can be challenging to quantify. Overall cardiac function assessment is better assessed by peak cardiac power output (CPOpeak), rather than indirect measures of cardiac performance such as peak oxygen consumption (VO2peak). CPO was used to quantify improvement in cardiac function early and later following electrical cardioversion.

Methods and results: 29 patients with persistent AF underwent maximal treadmill cardiopulmonary exercise (CPEx) testing within 14days (±3) 8weeks (±3) following electrical cardioversion (DCCv). This enabled measurement of VO2peak, cardiac output (COpeak) and calculation of CPOpeak. Quality of life (QoL) data (EQ5D) was also recorded. Three patients attended for 2 CPEx tests and 3 were lost to follow-up (total n=26). Fourteen were successfully cardioverted and 12 remained in AF. In patients successfully cardioverted exercise duration increased significantly between all tests. CPOpeak, VO2peak, CO peak and QoL were improved significantly between Tests 1 and 2 (p<0.02) and Tests 1 and 3 (p<0.05). QoL improved by 15%.

Conclusions: Restoration of SR confers significant, early and sustained cardiac functional improvement following DCCv with a significant 14% increase in the calculated peak power output of the heart. Such increase in functional reserve suggests that pursuit of a rhythm control strategy in the treatment of AF may be warranted in terms of both improving quality of life and cardiac function with objective improvement of cardiac function.