[Arrhythmogenic right ventricle: dysplasia or cardiomyopathy? Value of left ventricle ejection fraction].

The left ventricular ejection fraction (LVEF) of 76 patients suffering from arrhythmogenic dysplasia or cardiomyopathy of the right ventricle (ventricular tachycardia associated with structural abnormalities of the right ventricle) demonstrated two subgroups situated above and below 45%. Values of LVEF less than 45% were similar to those of a control population of 6 cases of idiopathic dilated cardiomyopathy with ventricular tachycardia of left ventricular origin (p = 0.2). These patients also have the same unfavourable long-term prognosis. Histological data obtained from four cases belonging to the group of patients with dysplasia or cardiomyopathy of the right ventricle with a low ejection fraction demonstrated the presence of signs of myocarditis involving both ventricles. This suggests that these patients may suffer from an infectious phenomenon superimposed on a specific histological substrate, which may lead to deterioration of their myocardial function. These results are in line with those of the literature. The term arrhythmogenic cardiomyopathy of the right ventricle should therefore be reserved to the subgroup of patients with an LVEF less than 45%. Finally, arrhythmogenic cardiomyopathy of the right ventricle appears to be a complication of dysplasia following the development of a myocarditic phenomenon. This may explain the wide range of clinical forms observed in patients with ventricular tachycardia of right ventricular origin associated with structural abnormalities of the right ventricle.