Duy Le, MD

Senoo K, Lip GYH, Lane DA, Büller HR, and Kotecha D. Residual Risk of Stroke and Death in Anticoagulated Patients According to the Type of Atrial Fibrillation: AMADEUS Trial. Stroke. 2015 

There is no question that atrial fibrillation is clearly a risk factor for stroke. Prior studies yield mixed results when it comes to duration of atrial fibrillation and risk of embolism. While the debate rages on, Senno et al attempt to answer this question by performing a post-hoc analysis of the AMADEUS trial. The AMADEUS trial evaluated afib patients treated with fixed dose idraparinux vs. oral VKA therapy. Senno et al take this data set and evaluate the permanent afib vs non-permanent afib group with regards to a primary outcome of cardiovascular death or stroke. They hypothesize that patients with permanent afib along with heart failure are at highest risk of the aforementioned outcome.

2072 patients (46%) had non-permanent AF with 16% having pre-existing heart failure. 2484 patients (54%) had permanent afib, with 29% of those patients having heart failure. With regards to the primary end point: sixty eight patients (3 per 100 patient years) in the permanent afib group and 31 patients (1.7 per 100 patient years) in the non-permanent group exhibited a stroke or cardiac event. Due to a low overall event rate however, there was not enough power to detect a difference between subgroups of those with and without heart failure.

Weaknesses of the study include the inherent fact that this study is a post hoc analysis. Additionally, a low outcome rate makes it difficult to perform a logistic regression analysis to rule out confounding factors affecting the outcome. Nonetheless, it does show a correlation between permanent afib leading to a higher risk of stroke. In the big picture, we should potentially be more wary of patients in permanent afib, as they have been shown here to still have an increased risk of stroke despite being anticoagulated. Although this may suggest that sinus conversion of afib may reduce future stroke in conjunction with anticoagulation, more studies would have to be done to validate such an idea.