Stroke prevention in atrial fibrillation : from atrial fibrillation screening to anticoagulation

Abstract

Atrial fibrillation (AF) is the commonest sustained arrhythmia encountered in clinical practice and it confers a 5-fold increased risk of ischemic stroke. Thus stroke prevention forms the cornerstone of management in AF. The thesis investigated the various aspects of stroke prevention in AF and how they can change the contemporary management of AF. This thesis comprises of 14 original studies involving 5,969 patients in the primary care setting as well as 9,727 patients in the hospital-based setting.

The thesis analyzed the contemporary management of stroke prevention in atrial fibrillation, from the diagnosis of asymptomatic AF utilizing various new tools to evaluation and comparison of efficacy and clinical benefits of different oral anticoagulants.

The first part of this thesis includes four studies evaluating the benefit of anticoagulation with warfarin in various subsets of AF patients. Contrary to the common belief, warfarin was shown to be associated with better clinical outcomes in patients with underlying coronary artery disease and AF, and less gastrointestinal bleeding when compared to aspirin. In AF patients with end-stage renal failure requiring peritoneal dialysis and in those with hyperthyroidism, warfarin was shown to be beneficial in preventing ischemic stroke.

The second part of the thesis includes four studies evaluating the use of non-vitamin K antagonist oral anticoagulants (NOAC) in ischemic stroke prevention in AF patients. The results showed that NOAC was superior to warfarin in both ischemic stroke prevention as well as reduction in intracranial haemorrhage in anticoagulated AF patients.

The third part of the thesis includes three studies evaluating the ischemic stroke risk stratification in AF patients. Results demonstrated that Chinese AF patients were associated with higher ischemic stroke risk than Caucasian counterparts. In addition, Chinese AF patients on warfarin were associated with worse quality of anticoagulation, echoing the aforementioned benefit of NOAC over warfarin.

The final part of this thesis, which includes three prospective studies, assesses and compares the diagnostic accuracy of various newly developed tools including AliveCor Heart Monitor, Microlife home blood pressure monitoring machine with automated AF detection and Cardiio smartphone-based photoplethysmographic application for large-scale community based screening for AF in at-risk group.

This series of studies illustrated the importance of ischemic stroke prevention in Chinese AF patients and AF screening with advanced technology will play a pivotal role in identifying patients with asymptomatic AF so that appropriate anticoagulation, preferably NOAC, can benefit the at-risk patients.