Atrial fibrillation screening to prevent stroke in patients with high NT-proBNP - a post-hoc analysis of the randomized LOOP study

Abstract

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): The Innovation Fund Denmark Background and aims Stroke is a leading cause of mortality and disability, and atrial fibrillation (AF) is an important and potentially modifiable risk factor for stroke. AF screening can substantially increase the amount of patients diagnosed and treated, but randomized trials have yet to demonstrate a significant decrease in strokes following screening. N-terminal prohormone of brain natriuretic peptide (proBNP) is an established biomarker for AF and could potentially be used to select patients for screening. We a used randomized trial of AF screening vs usual care to investigated the usefulness of proBNP as a tool to select patients for screening to prevent outcomes. Methods The LOOP Study randomized AF-naïve individuals aged >70 years with additional stroke risk factors in a 1:3 ratio to either continuous AF screening using implantable loop recorder (ILR) with initiation of anticoagulation upon detection of AF, or usual care. In this post-hoc analysis, study participants with a baseline measurement of proBNP were included, and the effect of screening vs usual care was compared in groups according to proBNP tertiles. Results Of 6004 participants randomized, 5819 (97%) had proBNP measured. The tertiles of proBNP were at <11, 11-22, and 22 pmol/L (Figure 1). A total of 1014 participants (17.4%) were diagnosed with AF (ILR 32.1% vs Control 12.5%), and 310 (5.3%) endured a stroke or systemic arterial embolism (SAE) (ILR 4.5% vs Control 5.6%). In the lower two tertiles of proBNP, 13% were diagnosed with AF (ILR 26.6% vs Control 8.3%), and 4.6% endured a stroke or SAE (ILR 4.6% vs Control 4.6%), whereas in the highest tertile of proBNP, 25.9% were diagnosed with AF (ILR 42.9% vs 20.3%), and 6.73% endured a stroke or SAE (ILR 4.4% vs Control 7.5%). In the lower two tertiles of proBNP, there was no protective effect from AF screening as compared with usual care (hazard ratio (HR) 1.00 (95% CI 0.71-1.41), p=0.999), whereas in the highest tertile of proBNP there was a significant effect of screening (HR 0.59 (95% CI 0.37-0.93), p=0.021) (Figure 2). More details including proBNP cutoffs, and the impact on stroke subtypes, disability and mortality will be presented at the Congress. Conclusions In a population at increased risk of stroke, proBNP pose a useful biomarker to select individuals for AF screening to prevent stroke. In persons with increased proBNP, the effect of screening could be significant, whereas there is no signal towards effects from screening in people with normal proBNP levels.