Taking dronedarone hydrochloride tablets, chest tightness, shortness of breath and chest pain may be caused by drug-induced bradycardia or tachycardia. 1. Bradycardia: dronedarone is a drug that prolongs cardiac repolarization to achieve antiarrhythmic effects, this type of drug is mainly used for tachyarrhythmia or premature heartbeat, but the drug itself may cause bradycardia arrhythmia occurs when the heartbeat slows down the situation, some patients will have chest tightness and shortness of breath. 2. cause tachycardia: for example, a very small number of patients may have ventricular tachycardia adverse reactions, serious and even tip-twisting ventricular tachycardia leading to syncopal episodes. Therefore, the symptoms of chest tightness and shortness of breath after taking dronedarone, we should consult a doctor in time, by the doctor to determine what is the cause and whether it is necessary to timely treatment.