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Keywords:

  • atrial fibrillation;
  • low-dose warfarin and aspirin;
  • stroke prevention

Abstract. Edvardsson N, Juul-Möller S, Ömblus R, Pehrsson K (Sahlgrenska University Hospital, Malmö University Hospital, Bristol-Myers Squibb Bromma; and Karolinska University Hospital; Stockholm, Sweden). Effects of low-dose warfarin and aspirin versus no treatment on stroke in a medium-risk patient population with atrial fibrillation. J Intern Med 2003; 254: 95–101.

Objectives. To assess the optimal stroke prevention treatment for patients with atrial fibrillation (AF) and a low–medium risk (≤4%) of stroke.

Design. A total of 668 patients with persistent or permanent AF, without an indication for full dose and with adequate rate control on sotalol, were randomized to warfarin 1.25 mg + aspirin 75 mg daily (W/A, 334 patients) or no anticoagulation (C, 334 patients). The mean follow-up period was 33 months. The protocol intended to verify a 37% relative risk reduction provided a 4% stroke incidence in the C group.

Results. The stroke incidence was less in the W/A group, although the reduction was not statistically significant (W/A 9.6% versus C 12.3%). Four haemorrhagic strokes were identified, two in each group. Secondary end-points were transient ischaemic attacks (TIA) (W/A 3.3% versus C 4.5%), all cause mortality (W/A 9.3% versus C 10.8%), cardiovascular morbidity (W/A 17.7% versus C 22.2%) and the combination of stroke + TIA (W/A 11.7% versus C 16.5%). Bleedings were documented in 19 versus four patients (W/A 5.7% versus C 1.2%) (P = 0.003), although none fatal. Sinus rhythm (SR) was recorded occasionally in 68 patients (W/A 9.6% versus C 10.8%). The stroke incidence tended to be higher in those with SR than without, 16.2% versus 10.4%.

Conclusions. Our results were inconclusive, but consistent with a small beneficial effect of W/A for reduction of stroke and major vascular events in AF patients at moderate risk. The low-dose regiment produced, however, a significantly increased risk of bleedings. Documented SR occasionally recorded may represent a subpopulation that warrants full dose warfarin.