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Evaluation of Rhythm Monitoring Strategies in Atrial Fibrillation Screening
Study Questions:
What are the performance characteristics for different screening strategies to detect atrial fibrillation (AF)?
Methods:
The current study population comprised 590 individuals randomized to and receiving implantable loop recorder before June 2015 and continuously monitored during 40 (38-42) months thereafter. Eligible subjects were recruited from the general population, were ≥70 years of age, and had ≥1 of the following stroke risk factors: hypertension, diabetes, heart failure, or previous stroke. Exclusion criteria included any history of AF or cardiac electronic implantable device. Monitoring was grouped by specific monitoring time periods from 10 seconds to 30 days using the implantable loop monitor. The primary outcome of interest was new-onset AF lasting ≥6 minutes detected initially through the implantable loop monitor, and then adjudicated by senior cardiologists. After continuous monitoring for >3 years, complete day-to-day heart rhythm datasets were reconstructed for every participant, including exact time of onset and termination of all AF episodes. The yield across strategies and population subgroups was compared using nonparametric tests.
Results:
Data from the 590 participants, which included 659,758 days of continuous monitoring, were included in the present analysis. A total of 20,110 AF episodes were detected. Among participants with AF, the number of episodes ranged from 5 to 84 (average 22), lasting a mean of 1.0 hour (hr) (0.3- 2.6), median 0.4 (0.2-1.6) hr, while the longest continuous episode per participant lasted 4.1 (1.6-12) hrs. Daily AF duration lasting ≥5.5 hrs was detected in 118 participants (20.0% of all participants), and episodes lasting ≥24 hrs were detected in 33 participants (5.6% of all). AF episodes lasting ≥7 days were detected in nine participants. A single 10-second electrocardiogram (ECG) yielded a sensitivity (and negative predictive value) of 1.5% (66%) for AF detection. Sensitivity increased to 8.3% (67%) for twice-daily 30-second ECGs during 14 days, and to 11% (68%), 13% (68%), 15% (69%), 21% (70%), and 34% (74%) for a single 24-hr, 48-hr, 72-hr, 7-day, or 30-day continuous monitoring, respectively. AF detection further improved when subsequent screenings were performed, or when the same monitoring duration was spread over several periods as compared to a single period (e.g., three 24-hr monitoring vs. one 72-hr monitoring), p < 0.0001 for all comparisons. The sensitivity was consistently higher among participants with age ≥75 years, male sex, CHADS2 score >2, or B-type natriuretic peptide (NT-proBNP) ≥40 pmol/L, and among participants with underlying ≥24-hr AF episodes compared to shorter AF, p < 0.0001 for all screening strategies.
Conclusions:
The investigators concluded that in screening for AF among participants with stroke risk factors, the diagnostic yield increased with duration, dispersion, and number of screenings, although all strategies had low yield compared to implantable loop recorders. The sensitivity was higher among participants who were older, males, or had higher NT-proBNP.
Perspective:
This study suggests that monitoring to screen for AF has the highest diagnostic yield among patients with specific characteristics defined in part by age, sex, and CHADS2 risk factors. Importantly, shorter periods of monitoring, even 30-day monitoring, can miss some episodes. These results require confirmation with additional studies in other populations before long-term monitoring should be used for patients suspected of AF.
Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Cardiovascular Care Team, Geriatric Cardiology, Heart Failure and Cardiomyopathies, Prevention, Anticoagulation Management and Atrial Fibrillation, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Heart Failure and Cardiac Biomarkers, Hypertension
Keywords: Arrhythmias, Cardiac, Atrial Fibrillation, Defibrillators, Implantable, Diabetes Mellitus, Electrocardiography, Electrocardiography, Ambulatory, Geriatrics, Heart Failure, Hypertension, Monitoring, Physiologic, Natriuretic Peptide, Brain, Peptide Fragments, Risk Factors, Secondary Prevention, Stroke, Vascular Diseases
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