IS IT TIME TO RETHINK OUR MODEL OF ATRIAL FIBRILLATION AND STROKE?
T. Jared Bunch, M.D., Intermountain Medical Center Heart Institute, Murray, UT, USA
Atrial fibrillation is the most common sustained arrhythmia in clinical practice and the leading cause of disabling strokes in developed countries. The CHADS2 and CHA2DS2VASc scores are intended for patients with atrial fibrillation (AF) as a tool for assessing stroke risk. These scores summate risk factors of an advancing disease state. These scores also predict dementia risk, cardiac and total mortality and have similar utility in patients without AF. AF is an additive risk factor when applied to score models of all people. Critical to current treatment strategies to reduce stroke in AF patient is the mechanistic role of the arrhythmia for the genesis of thromboembolism. Traditionally the prevalent mechanism considered is that of atrial fibrillation onset, local stasis, hypercoagulability, and inflammation in the left atrium and left atrial appendage, followed by formation of thrombus. If this mechanism is a dominant causes of stroke then local therapies such as left atrial appendage occlusion or ligation, durable rhythm control approaches, and pill-in-the-pocket anticoagulation strategies should lower risk. Recent data from implantable cardiac devices have raised significant questions regarding this mechanism as a dominant cause of stroke. In light of these emerging data, we must ask the question of if it is time to rethink our model of AF and stroke? Critical to these data is understanding the degree to which AF is a risk factor of stroke and if it is modifiable versus a risk marker of systemic disease severity. In addition, when AF is considered in the setting of a systemic disease state that evolves, what temporal and dynamic tools can offer benefit to give insight into the disease severity and risk?