Non-rheumatic atrial fibrillation and stroke.

The risk of systemic embolism and stroke in patients with non-rheumatic atrial fibrillation (NRAF) should not be underestimated. The annual embolic rate is approximately 5% and in those with left atrial enlargement and/or left ventricular (LV) dysfunction, or who have already had systemic embolism, this rate may be as high as 20%. Decisions on patient management and the prophylaxis of stroke must always be individualised. The risk of bleeding related to warfarin is almost certainly greater than that encountered in the previous randomised trials. Also, clinical and echocardiographic features can further define absolute risk in an individual patient with NRAF. Clinical markers of increased risk of embolism in patients with NRAF include older age, previous cerebral embolism, recent congestive heart failure, hypertension and diabetes mellitus. Transthoracic echocardiography improves risk stratification and should be performed in the vast majority of patients. Embolic risk is greatest in those with increasing left atrial dilation, atrial dysfunction and LV dysfunction. Transoesophageal echocardiography sharpens the risk profile in selected patients. Overall randomised trials show greater benefit with warfarin than aspirin. In general, increasing age is associated with a greater incidence of structural heart disease and probably implies greater potential benefit with warfarin. Increasing age per se may not increase the risk of warfarin-related bleeding. When the decision is made to warfarinise patients, at the present time data suggest that the target INR should be in the range of 2.0–3.0.