[Rhythm and conduction disorders in familial myocardiopathy].

Families of eight patients with the diagnosis of familiar cardiomyopathy were reviewed. It was possible to study 121 persons, 64 examined in the Instituto Nacional de Cardiología, and 57 through indirect questioning. It was found that in each of the families some disturbance in rhythm or conduction predominated. The evolution among the members of each family was similar, but was different in comparison with the other families. Those patients which presented complete A-V block died before 30 years of age, the majority of sudden death. The disturbances in rhythm or conduction most frequently observed were: complete A-V block, premature ventricular beats, lengthening of the Q-T, incomplete left bundle branch block, atrial fibrillation, Lown-Ganong-Levine syndrome, Wolff-Parkinson-White syndrome, premature supraventricular beats, incomplete right bundle branch block, ventricular fibrillation, and ventricular tachycardia. It can be concluded that: 1) familiar cardiomyopathy is, in reality, a group of distinct illnesses, with a genetic base; 2) the variability of the clinical findings, electrocardiography, and the evolution, depends on the particular type to which a given case corresponds; 3) it is possible that other varieties of familiar cardiomyopathy exist.