Implantable loop recorder monitoring detected subclinical atrial fibrillation in 35% of at-risk older adults, though the median AF burden was low at 0.13% of monitoring time and progression was limited.
Observational (n=590)
Yes
In at-risk older adults, subclinical AF detected by implantable loop recorders is highly prevalent (35%) but typically presents with a very low burden, limited progression, and minimal symptoms.
BACKGROUND As new heart rhythm monitoring technologies emerge, subclinical atrial fibrillation (AF) signifies a future challenge to health care systems. The pathological characteristics of this condition are largely unknown. OBJECTIVES This study sought to characterize the natural history of subclinical AF in at-risk patients from the general population. METHODS The authors studied 590 individuals ≥70 years of age with ≥1 of hypertension, diabetes, previous stroke, or heart failure, without history of AF, undergoing long-term implantable loop recorder monitoring as part of the LOOP (Atrial Fibrillation Detected by Continuous ECG Monitoring Using Implantable Loop Recorder to Prevent Stroke in High-risk Individuals) study. Baseline assessments included N-terminal pro-B-type natriuretic peptide (NT-proBNP). All day-to-day heart rhythm and symptom data were extracted from the device. Endpoints included AF burden, AF progression, symptom reports, and heart rate during AF. RESULTS A total of 685,445 monitoring days were available for analysis. Adjudicated AF episodes lasting ≥6 min were detected in 205 participants (35%). The AF burden was median 0.13% (interquartile range: 0.03% to 1.05%) of the monitoring time and changed by a factor of 1.31 (95% CI: 1.02 to 1.68) per doubling of NT-proBNP. AF episodes were present 2.7% (interquartile range: 1.0% to 15.7%) of monitoring days after debut. Progression to 24-h episodes was seen in 33 of the AF patients (16%), whereas 46 (22%) had no AF episodes in the last 6 months of monitoring or longer. Symptoms were absent in 185 (90%) at debut, and 178 (87%) never reported AF-related symptoms during follow-up. The averaged heart rate during AF was 96 (interquartile range: 83 to 114) beats/min, 24 (interquartile range: 9 to 41) beats/min faster than daytime sinus rates. CONCLUSIONS Although previously unknown AF was highly prevalent, the burden was low, and progression was limited. In addition, symptoms were scarce, and the heart rate was only modestly elevated. (Atrial Fibrillation Detected by Continuous ECG Monitoring Using Implantable Loop Recorder to Prevent Stroke in High-risk Individuals LOOP; NCT02036450).
“More than 30% of patients with risk factors will have AF detected if continuous monitoring is applied, but the AF burden is low and AF progression is limited.”
Diederichsen et al. (Mon,) conducted a observational in Subclinical atrial fibrillation (n=590). Implantable loop recorder monitoring was evaluated on Atrial fibrillation (AF) burden (cumulative duration of AF episodes ≥6 minutes divided by total monitoring time). Implantable loop recorder monitoring detected subclinical atrial fibrillation in 35% of at-risk older adults, though the median AF burden was low at 0.13% of monitoring time and progression was limited.