In non-rheumatic atrial fibrillation, true is?

Ans. B. The risk of stroke ii less than in atrial fibrillation due to rheumatic valve diseaseNon-rheumatic atrial fibrillation (AF) is associated with a 5-fold risk of embolic stroke compared with a 15-fold risk for rheumatic AF. Excessive alcohol intake is a common causer other causes include hypertension, ischaemic heart disease, thyrotoxicosis and pulmonary embolic disease. Paroxysmal AF carries the same risk of stroke as continuous AF. Cardioversion may be performed without prior anticoagulation in patients with a normal transesophageal echocardiogram. A normal transthoracic echo does not exclude the presence of left atrial thrombus. Anticoagulation is required for up to 4 weeks after cardioversion.