Brady- and tachyarrhythmias in paroxysmal atrial fibrillation: results from long-term continuous electrocardiographic monitoring in RACE V

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The Netherlands Cardiovascular Research Initiative: an initiative with support of the Dutch Heart Foundation, and grant support from Medtronic to the institution. MHJPF was funded by a grant from the Karen Elise Jensen Foundation. JCN was supported by a grant from the Novo Nordisk Foundation Background Atrial fibrillation (AF) has been associated with adverse events and constitutes a significant, global healthcare challenge. Paucity exists on the occurrence of brady- and ventricular tachyarrhythmias. Purpose The aim of this predefined sub-analysis of the Reappraisal of Atrial Fibrillation: interaction between hyperCoagulability, Electrical remodelling, and Vascular destabilization in the progression of AF (RACE V) study was to examine the prevalence of brady- and tachyarrhythmias using continuous rhythm monitoring in patients with paroxysmal self-terminating AF (PAF). Methods We identified 417 patients with PAF and at least two years of follow-up in RACE V; 25 patients with pacemakers at baseline were excluded. All remaining patients (n=392) received an implantable loop recorder and performed daily automated and weekly manual transmissions. Throughout follow-up, all detected episodes of tachycardia ≥182 BPM (cycle length ≤330ms) of ≥24 beats, bradycardia ≤30 BPM (cycle length ≥2000ms) of ≥12 beats, and pauses ≥5 seconds were adjudicated by three cardiologists. Results Over 1,272 patient years of continuous rhythm monitoring, we validated 1,940 episodes in 175 patients with paroxysmal self-terminating PAF (45%); 106 (27%) patients experienced AF or atrial flutter (AFL) with a rapid rate, pauses ≥5 seconds or bradycardias ≤30 BPM occurred in 47 (12%) patients (figure 1), and in 22 (6%) patients, both rapid AF/AFL and bradyarrhythmias were observed. No sustained ventricular tachycardias occurred. In the multivariable analysis, age >70 years (HR 2.4, 95% CI 1.4-3.9), longer PQ interval (HR 1.9, 1.1-3.1), CHA2DS2-VASc score ≥2 (HR 2.2, 1.1-4.5), and treatment with verapamil or diltiazem (HR 0.4, 0.2-1.0) were significantly associated with bradyarrhythmia episodes. For tachyarrhythmia episodes, age >70 years was associated with a significantly lower tachyarrhythmia risk (HR 0.4, 95% CI 0.2-0.7) in the multivariable analysis. Conclusions In a cohort exclusive to patients with self-terminating PAF, severe bradyarrhythmia episodes or AF/AFL with rapid ventricular rates occurred in 45% of patients. Our data highlight a higher than anticipated bradyarrhythmia risk in PAF.