Study Title: ABC-AF study - a randomised controlled study of personalised treatment to reduce stroke or death in atrial fibrillation

Presented at: ESC Congress 2025

Link: https://esc365.escardio.org/presentation/312185

Prapared by: Dr. Emre Kipritçi

Introduction
Atrial fibrillation (AF) is one of the leading causes of stroke, heart failure, cognitive decline, and reduced life expectancy among the aging population in developed countries. Oral anticoagulant therapy (OAC) reduces stroke risk by nearly two-thirds in patients with atrial fibrillation (AF), but it is also associated with an increased risk of bleeding. OAC therapies for stroke prevention have varying risk-benefit profiles with respect to bleeding complications and other adverse effects. In patients with atrial fibrillation, the decision to initiate oral anticoagulant therapy is guided by the CHA2DS2-VA score or alternative risk assessment algorithms. These scores have limited evaluative capacity as they are based solely on clinical variables.

Objective
The aim of the randomized controlled ABC-AF (Age, Biomarkers, Clinical history) trial is to prospectively evaluate whether treatment recommendations guided by the ABC-AF risk score improve clinical outcomes.

Methods
This multicenter randomized controlled trial included adult patients with a new or prior diagnosis of atrial fibrillation, regardless of whether they were currently receiving oral anticoagulant therapy. Patients meeting the inclusion and exclusion criteria were randomized in a 1:1 ratio to either the ABC-AF risk score–guided treatment group or the standard care group. The primary endpoint of the study is a composite of stroke or death, while the secondary endpoint is a composite of stroke, death, and major bleeding.

Results
A total of 3,933 patients were enrolled in the study. Of the participants, 33.6% were female, and the mean age was 73.9 years. Paroxysmal atrial fibrillation was present in 51.3% of the patients, and 11.2% had a history of prior stroke or transient ischemic attack. At baseline, treatment distributions were similar between the two randomized groups, with over 85% of participants receiving oral anticoagulant therapy. After randomization, the proportion of patients receiving any oral anticoagulant therapy increased to 97.8% in the active group and 92.6% in the control group (p<0.0001). There was no significant difference between the two groups in the primary endpoint. (p=0.12) Major bleeding occurred in 293 patients, with 152 cases in the active group and 141 cases in the control group (p=0.50). No significant difference was observed between the groups in terms of stroke, death, hospitalization due to myocardial infarction, or heart failure in the secondary endpoint.

Conclusions
The personalized, risk-based treatment strategy guided by the biomarker-based ABC-AF risk score did not improve clinical outcomes compared to standard guideline-based care.

Commentary     
The early termination of patient enrollment due to safety concerns, the inclusion of patients with a lower-than-expected risk profile (lower than COMBINE AF study population), and the fact that a significant proportion of patients were already on oral anticoagulant therapy with high adherence prior to the study led to insufficient statistical power to adequately evaluate the primary objective.