Low-dose aspirin for prevention of stroke in low-risk patients with atrial fibrillation: Japan Atrial Fibrillation Stroke Trial.

BACKGROUND AND PURPOSE: Although the efficacy of anticoagulant therapy for primary prevention of stroke in patients with nonvalvular atrial fibrillation (NVAF) has been established, efficacy of antiplatelet therapy for low-risk patients is disputable in Japanese patients because of the frequent hemorrhagic complications. We examined the efficacy and safety of aspirin therapy in Japanese patients with NVAF in a prospective randomized multicenter trial. METHODS: Patients with NVAF were randomized to an aspirin group (aspirin at 150 to 200 mg per day) or a control group without antiplatelet or anticoagulant therapy. Primary end points included cardiovascular death, symptomatic brain infarction, or transient ischemic attack. RESULTS: A total of 426 patients were randomized to aspirin group and 445 to no treatment. The trial was stopped earlier because there were 27 primary end point events (3.1% per year; 95% CI, 2.1% to 4.6% per year) in the aspirin group versus 23 (2.4% per year; 95% CI, 1.5% to 3.5% per year) in the control group, suggesting a low possibility of superiority of the aspirin treatment for prevention of the primary end point. In addition, treatment with aspirin caused a marginally increased risk of major bleeding (7 patients; 1.6%) compared with the control group (2 patients; 0.4%; Fisher exact test P=0.101). CONCLUSIONS: For prevention of stroke in patients with NVAF, aspirin at 150 to 200 mg per day does not seem to be either effective or safe. Further prospective studies are needed to determine the best preventive therapy for cerebrovascular events in Japanese patients with NVAF.

Echocardiographic assessment of right ventricular obstruction in hypertrophic cardiomyopathy.

Echocardiography was used to evaluate the incidence, flow dynamics and morphological characteristics of right ventricular obstruction in 91 patients with hypertrophic cardiomyopathy. Color flow mapping was used to define the sites of obstruction in the left and right ventricles. Ventricular obstruction was considered to be present if the flow velocity was less than 2.0 m/s as measured by continuous wave Doppler. The thickness of both the right ventricular free wall and anterior ventricular septum was measured to assess the magnitude and extent of hypertrophy. Right ventricular obstruction was present in 14 patients of whom 6 (43%) had left ventricular obstruction also. The right ventricular obstructions were found in the outflow tract (9 patients), mid-base septal bulge (2 patients) and apical trabecular region (3 patients). Doppler waveform was confined to systole in all patients with obstruction in the outflow tract and in one of the patients with mid-base septal bulge. Moreover, the flow wave persisted into early diastole in 4 patients, including 2 with apical trabecular obstruction. The thickness of both the right ventricular free wall and anterior ventricular septum suggested that these hypertrophied regions were the sites of right ventricular obstruction. Thus, echocardiography was useful in evaluating right ventricular obstruction in hypertrophic cardiomyopathy.