Single intravenous injection of drugs arrests 1/3 of atrial fibrillation paroxysms and only 1/7 of atrial flutter paroxysms. According to the frequency of the arresting effect in paroxysms of atrial fibrillation, isoptin, a combination of procaine hydrochloride with strophanthin, and giluritmal take first place. In paroxysms of atrial flutter, isoptin produces the best effect. Combined antiarrhythmic therapy with several drugs results in the arrest of about 50% of tachyarrhythmia paroxysms in a few hours to 10 days. Emergency indications for the application of electric-pulse therapy are noted among 7.9% of patients with fibrillation and among 6.6% of those with flutter of the atria.