Herz
-
The decision to anticoagulate patients with atrial fibrillation (AF) involves weighting the risk of an embolic event without therapy versus the risk of a hemorrhagic event on therapy. Improved methods of monitoring anticoagulation with the International Normalized Ratio (INR), and recent evidence of the efficacy and safety of low-dose warfarin (INR range 2.0 to 3.0) have clarified the role of anticoagulation in AF. Over the past four years, five large prospective randomized trials in patients with nonvalvular atrial fibrillation (NVAF) have reported substantial reductions in stroke in patients treated with low-dose warfarin therapy. ⋯ The role of aspirin in AF is less clear as only two of the five prospective trials randomized patients to aspirin therapy and only one documented aspirin benefit. Therefore, aspirin appears to offer less benefit but is a satisfactory alternative to warfarin therapy. Aspirin is currently recommend for patients who are poor candidates for anticoagulation or individuals with AF who are considered to be at low risk for stroke.
-
In patients with Wolff-Parkinson-White syndrome the accessory pathway may participate in various tachyarrhythmias thereby influencing symptoms and prognosis. Atrial fibrillation occurs in 10 to 32% of patients and may have life-threatening consequences by precipitating ventricular fibrillation in patients with rapid conduction due to an accessory pathway with short anterograde refractory period (< 250 ms). Pathogenesis of atrial fibrillation in the WPW syndrome and therapeutic options are reviewed in this presentation. ⋯ Anterograde conduction properties of the pathway appear to be more important than retrograde properties. High incidence of atrial fibrillation is related to short anterograde refractory periods, and of note, this arrhythmia is rare (3%) in patients with concealed pathways. With intracardiac recordings, Jackman et al. could demonstrate atrial fibrillation due to micro-reentry originating in accessory pathway networks.(ABSTRACT TRUNCATED AT 250 WORDS)