Incidence and risk of short episodes of atrial fibrillation detected with 14 days of continuous electrocardiographic monitoring
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AbstractBackgroundThere is widespread interest in population-based screening for atrial fibrillation (AF). However, there is debate regarding the optimal screening method and duration.ObjectivesTo estimate the incidence of short-duration AF detected by a single continuous 14-day electrocardiographic (ECG) monitor in older individuals without prior AF and to estimate the risk of ischemic stroke or systemic embolism associated with these episodes.MethodsPacemaker and defibrillator electrograms were reviewed from a cohort of individuals ≥65 years old, with a history of hypertension, but no prior AF. For each participant, we simulated a continuous 14-day ECG monitor by randomly selecting a 14-day window in the 6 months following enrolment and measured the total AF burden during that period. We repeated random sampling 1000 times to ensure a robust estimate of the likelihood of capturing AF in a single 14-day period. We used Cox proportional hazards models adjusted for CHA2DS2-VASc score to estimate the risk of ischemic stroke or systemic embolism associated with different burdens of AF.ResultsAmong 2470 participants with at least 6 months of follow-up, the mean CHA2DS2-VASc score was 4.0±1.3. The proportion of participants with an AF burden of >6 min on a single 14-day monitor was estimated as 3.1%, while the proportion with burdens of >15 min and >30 min were 2.9% and 2.6%, respectively.Over a mean follow-up of 2.5 years, 44 participants had an ischemic stroke or systemic embolism; the rate among patients with an AF burden ≤6 mins was 0.70%/year. An AF burden >6 min was associated with an increased risk of stroke or systemic embolism (2.2%/year, HR 3.0; 95% CI 1.3–5.7), as were burdens >15 min (2.4%/year; HR 3.3; 95% CI 1.4–6.4) and >30 min (2.6%/year HR 3.5; 95% CI 1.5–6.7).ConclusionApproximately 3% of individuals aged 65 years and older and with hypertension may have previously undiagnosed asymptomatic AF detected by a single 14-day continuous ECG monitor. As little as 6 minutes of AF may be associated with an increased risk of stroke. Randomized clinical trials are required to definitively assess screening in this population.Funding AcknowledgementType of funding source: None
