High heart rates during paroxysmal atrial fibrillation: continuous rhythm monitoring data of the RACE V study

BACKGROUND: Preventing high heart rates in patients with atrial fibrillation (AF) is a key objective of AF management. Data regarding heart rates in patients with paroxysmal AF (PAF) is lacking. This analysis aimed to provide insight into heart rates during PAF episodes measured with continuous implantable loop monitoring.

METHODS: In present analysis of the Interaction between hyperCoagulability, Electrical remodeling, and Vascular Destabilization in the Progression of AF study, we included 349 patients with at least one year of continuous rhythm monitoring and an episode of AF. Mean heart rates and duration of AF episodes were used to calculate total AF duration and AF duration above different heart rate cut-offs.

RESULTS: The median age was 64.0 (58.4 to 70.5) years, 152 (44%) were women and CHA 2DS 2-VASc score ≥2 or higher in 255 (73%) patients. During 28.3 (21.3 to 35.0) months of follow-up, the median number of AF episodes was 62 (12 to 293) with a median total AF duration of 4.6 (0.8 to 26.8) days. At baseline, 172 (49%) patients used beta-blockers, 64 (18%) used diltiazem or verapamil and 5 (1%) used digoxin. A total of 133 patients (38%) experienced a heart rate >110 bpm for more than 50% of the time during AF. Fifty-six (16%) patients had a heart rate >130 bpm for more than 50% of the time while in AF. During follow-up, 39 patients (11%) received an increase of rate-controlling medication.

CONCLUSION: Continuous rhythm monitoring revealed that more than a third of PAF patients had heart rates above 110 bpm for more than half of their time in AF.

TRIAL REGISTRATION NUMBER: Clinicaltrials.gov identifier NCT02726698.