Tachycardia-mediated cardiomyopathy is a form of dilated cardiomyopathy and heart failure induced by a persistent/chronic supraventricular or ventricular tachyarythmia. The incidence and the patho-physiology remain unspecified. Sometimes related to a previous cardiomyopathy, the diagnosis is always retrospective, but important because of the clinical and the significant haemodynamic improvement following the control of heart rate.