Paroxysmal atrial fibrillation (PAF) is broadly defined despite high variability in the occurrence and duration of PAF episodes.

The purpose of this study was to identify rhythm patterns in a large cohort of individuals with PAF who wore an ambulatory single-lead electrocardiogram (ECG) patch sensor as part of standard clinical care.

We performed a retrospective analysis of longitudinal rhythm data obtained from 13,293 individuals with PAF.

In this study, 7934 men and 5359 women with PAF wore an ambulatory single-lead ECG patch sensor for 11.4 days on average, experiencing 1,041,504 PAF episodes. The median daily rate of PAF was 1.21 episodes per day (interquartile range [IQR] 0.31-4.99), and the median maximum duration per individual was 7.5 hours (IQR 2.4-18.6 hours). There was an inverse relationship between the duration of PAF episodes and the frequency in which they occurred, which became pronounced at moderate and high overall burdens of AF. This produced a spectrum of PAF flanked by 2 distinct subtypes of the disease: the staccato subtype, characterized by many, short AF episodes; and the legato subtype, characterized by fewer, longer episodes. Longer but less frequent episodes became more common with increasing age. Only 49.4% of individuals experienced an episode in the first 24 hours of monitoring, increasing to 89.7% after 1 week of monitoring.

We identified subtypes of the disease that we labeled staccato and legato. Although further study is required, these subtypes may result from differing elements of pathophysiology and disease progression, and may confer differing stroke risks.