Cardioversion strategy impacts quality of rate control during recurrences of atrial fibrillation

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Netherlands Organization for Health Research and Development INTRODUCTION: In the Rate Control versus Electrical Cardioversion Trial 7–Acute Cardioversion versus Wait and See, patients with recent-onset atrial fibrillation (AF) were randomised to either early or delayed cardioversion. PURPOSE: This pre-specified sub-analysis aimed to evaluate heart rate during AF recurrences after an emergency department (ED) visit identified by an electrocardiogram (ECG)-based handheld device. METHODS: After the ED visit, included patients (n=437) were asked to use an ECG-based handheld device to monitor for recurrences during the four-week follow-up period. 335 patients used the handheld device and were included in this analysis. Recordings from the device were collected and assessed for heart rhythm and rate. Optimal rate control was defined as a target resting heart rate of <110 bpm. RESULTS: In 99 patients (29.6%, mean age 67±10 years, 39.4% female, median 6 [3-12] AF recordings) a total of 314 AF recurrences (median 2 [1-3] per patient) were identified during the follow-up. The average median resting heart rate at recurrence was 100±21 bpm in the delayed vs 112±25 bpm in the early cardioversion group (p=0.011). Additionally, the maximum heart rate was also significantly lower in the delayed cardioversion group (115 [94-131] vs 136 [118-147], p=0.001). Optimal rate control was seen in 68.4% [21.3-100%] of the performed recordings per patient in the delayed, and 33.3% [0-77.5%] of the performed recordings per patient in the early cardioversion group (p=0.01). Randomisation group (coefficient -12.09 (-20.55 - -3.63, p=0.006) for delayed versus early cardioversion) and heart rate on index ECG (coefficient 0.46 (0.29-0.63, p<0.001) per bpm increase) were identified as multivariable adjusted factors associated with lower median heart rate during AF recurrences. CONCLUSION: A delayed cardioversion strategy translated into lower median heart rates as well as lower peak heart rates during AF recurrences. Apart from the randomized treatment, heart rate at recurrence was influenced by the intrinsic heart rate on presentation.