Prevention strategies of cardioembolic ischemic stroke in Chagas' disease.

BACKGROUND The cardioembolic (CE) ischemic stroke is an important clinical manifestation of chronic chagasic cardiopathy; however, its incidence and the risk factors associated to this event have yet to be defined. OBJECTIVE To determine prevention strategies for a common and devastating complication of Chagas' disease, the cardioembolic (CE) ischemic stroke. METHODS 1,043 patients with Chagas' disease were prospectively evaluated from 03/1990 to 03/2002 and followed up to 03/2003. Cox regression was performed to create the CE risk score that was related with the annual incidence of this event: 4-5 points-->4%; 3 points--2-4%; 2 points--1-2%; 0-1 points--<1%. We evaluated the efficacy and safety of two treatment cohorts: (1) 52 patients who used warfarin (INR 2-3) for 14+/-14 months; (2) 104 patients who used acetylsalicylic acid (ASA) (200 mg/d) for 22+/-21 months. RESULTS In group (1), the risk of a major bleeding that needed blood transfusion was 1.9% a year, without CE. Cox regression was used to identify 4 independent variables associated to the event (systolic dysfunction, apical aneurysm, primary alteration of ventricular repolarization and age > 48 years) and an CE risk score was developed, which was associated with the annual incidence of this event. In group (2) there were no bleeding complications and the annual incidence of CE was 3.2%, all of them in patients with 4-5 points. CONCLUSION Based on the risk-benefit analysis, warfarin prophylaxis for cardioembolic stroke in Chagas' disease is recommended for patients with a score of 4-5 points, in whom the risk of CE overweighs the risk of a major bleeding. With a 3-point score, the risks of bleeding and CE are the same, so the medical decision of using either warfarin or ASA has to be an individual one. In patients with a low risk of CE (2-point score) either ASA or no therapy can be chosen. The prophylaxis is not necessary in patients with 0-1 point scores, in whom the stroke incidence is near zero.