A 44-year-old patient with postinfarction cardiosclerosis presents with frequent heart rate disorders and lower extremity edema. Objectively: Ps- 95/min., irregular, 10- 12 extrasystoles per minute. BP- 135/90 mm Hg. The 1st heart sound at the apex is weakened. Pulmonary respiration is rough. The liver is enlarged 2 cm. ECG: irregular sinus rhythm, heart rate – 95/min., frequent polytopic ventricular extrasystoles. What antiarrhythmic drug is advisable in this case for treatment and prevention of extrasystole?