Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a kind of inherited cardio-myopathy, which is characterized by fibro-fatty replacement of right ventricular myocardium, leading to ventricular arrhythmia. However, rapid atrial arrhythmias are also common, including atrial fibrillation, atrial flutter and atrial tachycardia. Long term rapid atrial arrhythmia can lead to further deterioration of cardiac function. This case is a 51-year-old male. He was admitted to Department of Cardiology, Peking University Third Hospital with palpitation and fatigue after exercise. Electrocardiogram showed incessant atrial tachycardia. Echocardiography revealed dilation of all his four chambers, especially the right ventricle, with the left ventricular ejection fraction of 40% and the right ventricular hypokinesis. Cardiac magnetic resonance imaging found that the right ventricle was significantly enlarged, and the right ventricular aneurysm had formed; the right ventricular ejection fraction was as low as 8%, and the left ventricular ejection fraction was 35%. The patients met the diagnostic criteria of ARVC, and both left and right ventricles were involved. His physical activities were restricted, and metoprolol, digoxin, spironolactone and ramipril were given. Rivaroxaban was also given because atrial tachycardia could cause left atrial thrombosis and embolism. His atrial tachycardia converted spontaneously to normal sinus rhythm after these treatments. Since the patient had severe right ventricular dysfunction, frequent premature ventricular beats and non-sustained ventricular tachycardia on Holter monitoring, indicating a high risk of sudden death, implantable cardioverter defibrillator (ICD) was implanted. After discharge from hospital, physical activity restriction and the above medicines were continued. As rapid atrial arrhythmia could lead to inappropriate ICD shocks, amiodarone was added to prevent the recurrence of atrial tachycardia, and also control ventricular arrhythmia. After 6 months, echocardiography was repeated and showed that the left ventricle diameter was reduced significantly, and the left ventricular ejection fraction increased to 60%, while the size of right ventricle and right atrium decreased slightly. According to the clinical manifestations and outcomes, he was diagnosed with ARVC associated with arrhythmia induced cardiomyopathy. According to the results of his cardiac magnetic resonance imaging, the patient had left ventricular involvement caused by ARVC, and the persistent atrial tachycardia led to left ventricular systolic dysfunction.