A noticeable change in the heartbeat including irregular beats, stronger beats, or faster heart rate caused by drugs. Sympathomimetic medications, anticholinergic medications (atropine), and vasodilators can lead to a pounding heartbeat or racing of the heart. Stimulants, caffeine, amphetamines, nicotine, cocaine, alcohol, some decongestants, and some dietary and herbal supplements can contribute to chest palpitations in the absence of extreme stress or heart abnormalities.