Background and Disease Burden
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia globally, affecting millions and significantly increasing the risk of ischemic stroke and mortality. Effective stroke prevention with oral anticoagulation (OAC) is established as the cornerstone in AF management. Yet, balancing stroke risk reduction against bleeding complications remains a clinical challenge. Traditional clinical risk scores, such as CHA2DS2-VASc for stroke and HAS-BLED for bleeding, are widely used but have limitations in individual patient risk discrimination.
Recent advances propose the use of biomarkers combined with clinical variables to create more precise risk stratification models. The ABC-AF (Age, Biomarkers, Clinical history in AF) risk score integrates cardiac biomarkers like N-terminal pro B-type natriuretic peptide (NT-proBNP), cardiac troponins, and growth differentiation factor-15 (GDF-15) alongside clinical factors to better predict stroke, bleeding, and death risks. While these biomarker-based scores show promise in retrospective validations, their prospective utility to guide tailored therapeutic decisions remains insufficiently tested.
This important registry-based, randomized controlled study aimed to evaluate if a multidimensional treatment strategy guided by individual ABC-AF risk scores could improve long-term outcomes in patients with AF compared to usual guideline-directed care.
Study Design
Conducted across multiple centers, this open-label, randomized controlled trial enrolled 3933 adults with AF. Key baseline characteristics included a median age of 73.9 years, 33.6% women, 51.3% with paroxysmal AF, and 11.2% with prior stroke or transient ischemic attack (TIA). The majority (85.7%) were on oral anticoagulation at baseline.
Participants were randomized to two arms:
– Active arm: Investigators received patients’ individual ABC-AF risk scores, highlighting stroke and bleeding risks, used as decision support to tailor treatment. This included individualized OAC choice preferences with direct oral anticoagulants (DOACs).
– Control arm: Management was at the discretion of investigators following standard care without ABC-AF score guidance.
The primary outcome was a composite of stroke or death. Secondary outcomes included individual components of the primary endpoint plus major bleeding and a composite of stroke, death, or major bleeding.
Key Findings
The trial was prematurely terminated due to safety concerns, specifically a trend towards increased mortality in patients with higher baseline stroke risk (CHA2DS2-VASc scores ≥3) in the active arm. Consequently, it was underpowered to definitively test the primary endpoint.
During a median follow-up of 2.6 years, the incidence rates per 100 patient-years (PY) were:
– Primary composite (stroke or death): 3.18 in active vs. 2.67 in control (HR 1.19, 95% CI 0.96–1.48, p=0.12)
– Stroke alone: 0.87 vs. 0.74 (HR 1.18, 0.78–1.79, p=0.44)
– Death alone: 2.44 vs. 2.02 (HR 1.21, 0.94–1.55, p=0.13)
– Major bleeding: 2.82 vs. 2.61 (HR 1.08, 0.86–1.36, p=0.50)
– Composite of stroke, death, or major bleeding: 5.21 vs. 4.55 (HR 1.14, 0.96–1.36, p=0.13)
A significantly higher proportion of patients received OAC in the active arm post-randomization (97.8% vs 92.6%, p<0.0001), suggesting that ABC-AF score reporting influenced prescribing behavior. Yet, this did not translate into outcome improvements.
No heterogeneity was seen in the primary outcome across different ABC-AF risk strata (interaction p=0.98).
Expert Commentary
This landmark trial is among the first to prospectively evaluate biomarker-driven personalized treatment strategies for AF. The findings are notable, as the proposed biomarker-based tailoring did not reduce key adverse outcomes, despite theoretically superior individual risk discrimination. Increased use of OAC in the active arm underscores that ABC-AF scores can alter clinical decision-making, but this alone was insufficient to improve patient prognosis.
Several factors may explain these results. The open-label design and premature termination limit power and may introduce bias. The trend toward increased mortality in higher-risk patients receiving ABC-AF-guided therapy raises safety concerns that warrant further investigation. Possible overtreatment or unmeasured confounders could play a role.
Current guidelines endorse using clinical risk scores for stroke and bleeding assessment, supported by large evidence bases. Incorporating biomarkers is an appealing precision medicine step but requires prospective validation in adequately powered trials before routine clinical integration. This study highlights challenges in translating risk stratification advances into improved hard clinical outcomes.
Conclusion
The ABC-AF biomarker-based risk score-guided treatment strategy did not demonstrate clinical benefit over conventional guideline-based AF management. These data emphasize the importance of rigorous prospective evaluations of personalized medicine tools in diverse populations and clinical contexts. While biomarker incorporation may enhance risk prediction, implementing such approaches to improve clinical outcomes remains elusive.
Future research should focus on refining biomarkers, understanding patient subgroups that may benefit, and optimizing clinical decision support systems. Until then, established guideline-recommended risk assessments and management remain the standard of care in AF stroke prevention.
References
Oldgren J, Hijazi Z, Arheden H, Björkenheim A, Frykman V, Janzon M, Ravn-Fischer A, Renlund H, Själander A, Åkerfeldt T, Wallentin L. Biomarker-based ABC-AF Risk Scores for Personalized Treatment to Reduce Stroke or Death in Atrial Fibrillation – a Registry-based Multicenter Randomized Controlled Study. Circulation. 2025 Aug 30. doi: 10.1161/CIRCULATIONAHA.125.076725. Epub ahead of print. PMID: 40884774.
Lip GYH, Nieuwlaat R, Pisters R, Lane DA, Crijns HJGM. Refining Clinical Risk Stratification for Predicting Stroke and Thromboembolism in Atrial Fibrillation Using a Novel Risk Factor-Based Approach: The Euro Heart Survey on Atrial Fibrillation. Chest. 2010 Feb;137(2):263-72.
January CT, Wann LS, Calkins H, et al. 2019 AHA/ACC/HRS Focused Update of the 2014 Atrial Fibrillation Guideline. Circulation. 2019 Jul 9;140(2):e125-e151.