The increased risk of stroke/transient ischemic attack in women with a cardiac implantable electronic device is not associated with a higher atrial fibrillation burden

Abstract

In patients with atrial fibrillation (AF), risk stratification for stroke is the cornerstone of clinical decision making.1 In patients with AF female gender has emerged as a stroke risk factor in many studies and metaanalyses2 and has been included in the CHA2DS2-VASc score, which is the stroke risk stratification scheme recommended in most guidelines.1,2 However, there is an age dependency to stroke risk in females, and there is no significant increase in the overall risk of stroke in female patients age<65 years with lone AF.2 The precise reasons why female gender increases the thromboembolic risk are not completely known.3,4 The relationship between stroke and AF burden has recently been the object of growing interest, since AF burden provides an overall assessment of the amount of time spent in AF, and has been associated with an increased risk of stroke.5-9 Even if clinical risk stratification is based on clinical factors, data from patients implanted with a cardiac implantable electrical device (CIED) providing continuous monitoring of the atrial rhythm showed that the maximum daily AF burden is associated with an increased risk of ischaemic stroke or transient ischemic attack (TIA), even after adjustment for oral anticoagulants use and the CHADS2 score.10,11 This suggests that measuring daily AF burden may have important clinical relevance8 and supports the search for specific thresholds of AF burden associated with a substantial increase in the risk of ischaemic stroke.6,7,11 Indeed, AF burden can improve the predictive value of clinical risk scores, such as CHADS2, for stroke and thromboembolism.7 In this analysis, based on data collected in a prospective observational research of patient with a CIED we tested the hypothesis that the increased thromboembolic risk in female patients may be related to a higher burden of AF, by comparing the maximum AF daily burden inmen and women during long-term follow-up. Methods Project design and patient population Patients participating to the Italian ClinicalServiceVR Project [ClinicalTrials.gov Identifier: NCT01007474],12 a national medical care project aiming to improve the quality of diagnostic and therapeutic strategies through the use of implantable cardiac devices in clinical practice, were considered for the present analysis. The project consists of a shared environment for prospective collection, management, analysis and reporting of data from patients in whomMedtronic devices have been implanted. In the Italian ClinicalServiceVR Project, patients are prospectively followed by participating centres according to clinical practice and guidelines through standard in-hospital visits. An independent scientific committee of physicians prospectively identifies key clinical questions on a yearly basis for analysis and publication. A charter assigns the ownership of data to the centres and governs the conduct and relationship of the scientific committee and Medtronic. The project was approved by each site's Medical Ethics Committee orMedical Director and conforms to the principles outlined in the Declaration of Helsinki. Each patient provided informed consent for data collection and analysis. For the present analysis, patients were included if they had a CIED with an atrial lead, had not permanent atrial tachyarrhythmia/atrial fibrillation (AT/AF), had a clinical follow-up duration of at least 183 days or more, and had device data continuously stored during the observation period.