Stroke Risk as a Function of Atrial Fibrillation Duration and CHA 2 DS 2 -VASc Score

Abstract

Background: Studies of patients with cardiovascular implantable electronic devices show a relationship between atrial fibrillation (AF) duration and stroke risk, although the interaction with CHA 2 DS 2 -VASc score is poorly defined. The objective of this study is to evaluate rates of stroke and systemic embolism (SSE) in patients with cardiovascular implantable electronic devices as a function of both CHA 2 DS 2 -VASc score and AF duration. Methods: Data from the Optum electronic health record deidentified database (2007–2017) were linked to the Medtronic CareLink database of cardiovascular implantable electronic devices capable of continuous AF monitoring. An index date was assigned as the later of either 6 months after device implantation or 1 year after electronic health record data availability. CHA 2 DS 2 -VASc score was assessed using electronic health record data before the index date. Maximum daily AF burden (no AF, 6 minutes–23.5 hours, and >23.5 hours) was assessed over the 6 months before the index date. SSE rates were computed after the index date. Results: Among 21 768 nonanticoagulated patients with cardiovascular implantable electronic devices (age, 68.6±12.7 years; 63% male), both increasing AF duration ( P <0.001) and increasing CHA 2 DS 2 -VASc score ( P <0.001) were significantly associated with annualized risk of SSE. SSE rates were low in patients with a CHA 2 DS 2 -VASc score of 0 to 1 regardless of device-detected AF duration. However, stroke risk crossed an actionable threshold defined as >1%/y in patients with a CHA 2 DS 2 -VASc score of 2 with >23.5 hours of AF, those with a CHA 2 DS 2 -VASc score of 3 to 4 with >6 minutes of AF, and patients with a CHA 2 DS 2 -VASc score ≥5 even with no AF. Conclusions: There is an interaction between AF duration and CHA 2 DS 2 -VASc score that can further risk-stratify patients with AF for SSE and may be useful in guiding anticoagulation therapy.