Relationship between temporal rhythm-based classification of atrial fibrillation and stroke: real-world vs. clinical trial

Background The risk of stroke according to clinical classification of atrial fibrillation (AF) remains poorly defined. Here, we assessed the impact of AF type on stroke risk in vitamin K antagonist-treated patients with AF in 'real-world' and 'clinical trial' cohorts. Methods Post-hoc analysis of patient-level data from the Murcia AF Project and AMADEUS trial. Clinical classification of AF was based on contemporary recommendations from international guidelines. Study endpoint was the incidence rate of ischaemic stroke. Stroke risk was determined using CHA(2)DS(2)-VASc score and CARS. A modified CHA(2)DS(2)-VAS'c' score that applied one additional point for a 'c' criterion of continuous AF (i.e. non-paroxysmal AF) was calculated. Results We included 5,917 patients: 1,361 (23.0%) real-world and 4,556 (77.0%) clinical trial. Baseline demographics were balanced in the real-world cohort but clinical trial participants with non-pAF (vs. pAF) were older, male-predominant and had more comorbidities. Crude stroke rates were comparable between the groups in real-world patients (IRR 0.72 [95% CI,0.37-1.28], p = 0.259) though clinical trial participants with non-pAF had a significantly higher crude rate of stroke events (IRR 4.66 [95%,CI,2.41-9.48], p < 0.001). Using multivariable analysis, AF type was not independently associated with stroke risk in the real-world (adjusted HR 1.41 [95% CI,0.80-2.50], p = 0.239) and clinical trial (adjusted HR 1.16 [95% CI,0.62-2.20], p = 0.646) cohorts, after accounting for other risk factors. There was no significant improvement in the CHA(2)DS(2)-VAS'c' compared to CHA(2)DS(2)-VASc score in either cohorts (p > 0.05). Conclusions Overall, our results support the need for anticoagulation based on thromboembolic risk profile rather than AF type.