[Analysis of high frequency and low amplitude late potentials in the body surface electrocardiogram, in acute and chronic stages of ischemic cardiopathy]. / Análisis de los potenciales tardíos de alta frecuencia y baja amplitud del electrocardiograma de superficie, en las fases aguda y crónica de la cardiopatía isquémica.

A study to evaluate late potentials (LP) was carried out in 50 patients diagnosed as suffering from coronary heart disease. All the patients were divided into two groups: Group A, was made of 25 patients in the acute period of myocardial infarction, and group B, was made of other 25 patients in the chronic phase, with more of 3 months of evolution from the acute event. Average age in group A was 54.2 years, and 58.1 years in group B. Twenty normal volunteer subjects (group C) were also studied as a reference group. All the subjects in the 3 groups were in normal sinus rhythm, and no one of them showed bundle branch block in the basal ECG. Analysis of the vector magnitude was made for each point of the averaged wave, as the result of the mean root square of the addition of bipolar leads X, Y and Z, using a LP-3000 Fidelity Medical Inc. equipment, with a four poles Butterworth filter. LP were detected in 32% of the patients in group A, and in 56% of the group B (p less than 0.001). No LP was observed in patients of the group C. Concerning the localization of myocardial infarction, maximum CPK value, or Lown's grade of ventricular arrhythmias observed in coronary care unit, or in the 3rd week Holter monitoring, did not show significant statistical correlationship with the presence of LP in group A.(ABSTRACT TRUNCATED AT 250 WORDS)