TY - JOUR
T1 - Effects of Atrial Fibrillation Screening According to Echocardiographic Measures of Cardiac Structure and Function
T2 - A Post Hoc Analysis of the LOOP Randomized Clinical Trial
AU - Olsen, Flemming Javier
AU - Diederichsen, Søren Zöga
AU - Jørgensen, Peter Godsk
AU - Jensen, Magnus T
AU - Dahl, Anders
AU - Landler, Nino Emanuel
AU - Bertelsen, Litten
AU - Olesen, Morten Salling
AU - Graff, Claus
AU - Brandes, Axel
AU - Krieger, Derk
AU - Haugan, Ketil
AU - Højberg, Søren
AU - Køber, Lars
AU - Svendsen, Jesper Hastrup
AU - Biering-Sørensen, Tor
PY - 2026/1/6
Y1 - 2026/1/6
N2 - BACKGROUND: Subclinical atrial fibrillation (SCAF) poses an increased stroke risk, but whether oral anticoagulation for SCAF prevents stroke is unclear. We sought to investigate the treatment effect of SCAF screening according to measures of cardiac structure and function.METHODS: This was an echocardiographic substudy of the LOOP (Atrial Fibrillation Detected by Continuous ECG Monitoring) study, which randomized older people at risk of stroke to usual care or an implantable loop recorder (ILR) with monitoring for SCAF and subsequent oral anticoagulation. A subset (24% of trial population) underwent echocardiography to measure left ventricular size and function, left atrial volume and strain, and valvular pathology. The primary outcome was a composite of stroke or systemic embolism.RESULTS: The study included 1422 participants (ILR: n=1001; control: n=421; mean age: 74 years; men: 54%). During follow-up, 354 (25%) were diagnosed with AF (ILR versus control: 30% versus 12%). During a median follow-up of 5.5 years (interquartile range, 4.9-5.9 years), 55 (4%) developed the primary outcome (ILR versus control: 3.9% versus 3.8%). No conventional measure of cardiac structure and function modified the treatment effect from randomization. However, left atrial contraction strain significantly modified the treatment effect (Pinteraction=0.003), such that a lower risk of the primary outcome was noted from ILR with lower left atrial contraction strain values (hazard ratio [HR], 0.38 [95% CI, 0.16-0.87], for participants with contraction strain<16.5%).CONCLUSION: In a post hoc analysis of the LOOP study, conventional echocardiographic measures did not modify the effect of SCAF screening for stroke prevention. However, a significant stroke risk reduction was observed from ILR randomization among participants with reduced left atrial contraction strain.
AB - BACKGROUND: Subclinical atrial fibrillation (SCAF) poses an increased stroke risk, but whether oral anticoagulation for SCAF prevents stroke is unclear. We sought to investigate the treatment effect of SCAF screening according to measures of cardiac structure and function.METHODS: This was an echocardiographic substudy of the LOOP (Atrial Fibrillation Detected by Continuous ECG Monitoring) study, which randomized older people at risk of stroke to usual care or an implantable loop recorder (ILR) with monitoring for SCAF and subsequent oral anticoagulation. A subset (24% of trial population) underwent echocardiography to measure left ventricular size and function, left atrial volume and strain, and valvular pathology. The primary outcome was a composite of stroke or systemic embolism.RESULTS: The study included 1422 participants (ILR: n=1001; control: n=421; mean age: 74 years; men: 54%). During follow-up, 354 (25%) were diagnosed with AF (ILR versus control: 30% versus 12%). During a median follow-up of 5.5 years (interquartile range, 4.9-5.9 years), 55 (4%) developed the primary outcome (ILR versus control: 3.9% versus 3.8%). No conventional measure of cardiac structure and function modified the treatment effect from randomization. However, left atrial contraction strain significantly modified the treatment effect (Pinteraction=0.003), such that a lower risk of the primary outcome was noted from ILR with lower left atrial contraction strain values (hazard ratio [HR], 0.38 [95% CI, 0.16-0.87], for participants with contraction strain<16.5%).CONCLUSION: In a post hoc analysis of the LOOP study, conventional echocardiographic measures did not modify the effect of SCAF screening for stroke prevention. However, a significant stroke risk reduction was observed from ILR randomization among participants with reduced left atrial contraction strain.
KW - Humans
KW - Atrial Fibrillation/physiopathology
KW - Male
KW - Female
KW - Aged
KW - Echocardiography/methods
KW - Stroke/prevention & control
KW - Anticoagulants/administration & dosage
KW - Electrocardiography, Ambulatory
KW - Ventricular Function, Left
KW - Risk Factors
KW - Loop
KW - Stroke
KW - Atrial fibrillation
KW - Left atrium
KW - Strain
KW - Treatment
U2 - 10.1161/JAHA.125.041184
DO - 10.1161/JAHA.125.041184
M3 - Article
C2 - 41467399
SN - 2047-9980
VL - 15
JO - Journal of the American Heart Association
JF - Journal of the American Heart Association
IS - 1
M1 - e041184
ER -