Key result
ILR screening cuts stroke or systemic embolism ~40% vs. usual care in elevated NT-proBNP.
Why the study?
NT-proBNP is a strong predictor of incident AF and stroke, but its utility in AF screening remains unknown.
Does implantable loop recorder screening reduce stroke or systemic embolism in older adults with stroke risk factors stratified by NT-proBNP levels?
RCT (n=5,819)
Open-label with blinded outcome adjudication
1:3
Yes
Does implantable loop recorder screening reduce stroke or systemic embolism in older adults with stroke risk factors stratified by NT-proBNP levels?
Hazard Ratio: 0.6 (95% CI 0.4–0.9)
Absolute Event Rate: 4.28% vs 7.51%
Absolute Risk Reduction: 3.23%
Number Needed to Treat: 31
p-value: P interaction = 0.029
NT-proBNP levels may help identify older patients with stroke risk factors who are most likely to benefit from implantable loop recorder screening for atrial fibrillation.
Supports NT-proBNP-stratified ILR screening for stroke prevention in older adults; extends AF detection trials to biomarker-enriched populations.
Background: Research suggests NT-proBNP (N-terminal pro-B-type natriuretic peptide) to be a strong predictor of incident atrial fibrillation (AF) and stroke. However, its utility in AF screening remains unknown. The aim of this study was to investigate NT-proBNP as a potential marker for screening efficacy with respect to AF yield and stroke prevention. Methods: In the LOOP Study (Atrial Fibrillation Detected by Continuous ECG Monitoring Using Implantable Loop Recorder to Prevent Stroke in High-Risk Individuals), 6004 AF-naïve individuals at least 70 years old and with additional stroke risk factors were randomized 1:3 to either screening with an implantable loop recorder (ILR) and initiation of anticoagulation upon detection of AF episodes lasting ≥6 minutes or usual care (control). This post hoc analysis included study participants with available NT-proBNP measurement at baseline. Results: A total of 5819 participants (96.9% of the trial population) were included. The mean age was 74.7 years (SD, 4.1 years) and 47.5% were female. The median NT-proBNP level was 15 pmol/L (interquartile range, 9–28 pmol/L) corresponding to 125 pg/mL (interquartile range, 76–233 pg/mL). NT-proBNP above median was associated with an increased risk of AF diagnosis both in the ILR group (hazard ratio, 1.84 [95% CI, 1.51–2.25]) and the control group (hazard ratio, 2.79 [95% CI, 2.30–3.40]). Participants with NT-proBNP above the median were also at higher risk of clinical events compared with those having lower levels (hazard ratio, 1.21 [95% CI, 0.96–1.54] for stroke or systemic embolism [SE], 1.60 [95% CI, 1.32–1.95] for stroke/SE/cardiovascular death, and 1.91 [95% CI, 1.61–2.26] for all-cause death). Compared with usual care, ILR screening was associated with significant reductions in stroke/SE and stroke/SE/cardiovascular death among participants with NT-proBNP above median (hazard ratio, 0.60 [95% CI, 0.40–0.90] and 0.70 [95% CI, 0.53–0.94], respectively) but not among those with lower levels ( P interaction =0.029 for stroke/SE and 0.045 for stroke/SE/cardiovascular death). No risk reduction in all-cause death was observed in either NT-proBNP subgroup for ILR versus control ( P interaction =0.68). Analyzing NT-proBNP as a continuous variable yielded similar findings. Conclusions: In an older population with additional stroke risk factors, ILR screening for AF was associated with a significant reduction in stroke risk among individuals with higher NT-proBNP levels but not among those with lower levels. These findings should be considered hypothesis generating and warrant further study before clinical implementation. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02036450.
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Xing et al. (2023) conducted an RCT in Atrial fibrillation-naïve with additional stroke risk factors (n=5,819). Implantable loop recorder (ILR) screening vs. Usual care was evaluated on Composite of stroke or systemic embolism (SE) among participants with NT-proBNP >15 pmol/L (HR 0.60, 95% CI 0.40-0.90, p=P interaction = 0.029). In older adults with stroke risk factors, ILR screening for atrial fibrillation significantly reduced the risk of stroke or systemic embolism by 40% (HR 0.60) compared to usual care among those with NT-proBNP >15 pmol/L.
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