Monitoring time-to-detection of recurrent atrial fibrillation in patients with transient new-onset atrial fibrillation detected initially during hospitalization for noncardiac surgery or medical illness

BACKGROUND: Approximately one-third-of patients with transient new-onset atrial fibrillation (AF) during hospitalization for noncardiac surgery or medical illness will have recurrent AF within 1 year when assessed using two 14-day ECG monitors. The proportion of patients that would be diagnosed with recurrent AF with less monitoring is unknown. METHODS: We used data from a prospective cohort of participants with transient new-onset AF while hospitalized for noncardiac surgery or medical illness, who wore one or two 14-day ECG monitors. We calculated the proportion of patients that would be diagnosed with recurrent AF with different durations of ECG monitoring and the median time-to-detection of recurrent AF lasting ≥30 s. RESULTS: A total of 139 participants (41.0 % female, median CHA₂DS₂-VASc 3) wore an ECG monitor a median of 1.5 months following hospital discharge; 83 (59.7 %) wore a second monitor at median of 5.8 months after the first monitor. Recurrent AF was detected in 5.0 % of participants by 1 day, 5.8 % by 2 days, 6.5 % by 3 days, 12.2 % by 7 days, 21.6 % by 14 days and in 28.8 % by the end of the second 14-day monitor. Median monitoring time to recurrent AF was 5.3 (IQR 1.4-9.7) days. CONCLUSIONS: In patients with transient new-onset AF during hospitalization for another reason, the rate of detection of recurrent AF increased with longer monitoring durations. Approximately 80 % of diagnoses were made after 2 days of monitoring; the likelihood of capturing recurrent AF was 4 times higher with 14 days of monitoring compared to 2 days.