EVOLUTION OF THE ELECTROCARDIOGRAPHIC CHANGES IN PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY

In 75 patients with hypertrophic cardiomopathy (HCM) followed for a mean period of 5.5 years (range 2-20 years), evolution of the electrocardiographic (EKG) changes was assessed. Progression of EKG abnormalities occurred in 35 patients (47%). It was manifested by an increase in precordial QRS voltage in 33 patients, development of new P-wave mitral in 11 patients, and development or disappearance of pathologic Q waves in 14 patients. With follow-up times > 5 years, 5-8 years, and > 8 years, EKG progression was present in 27, 41, and 80% of patients, respectively. Age < 30 years at the beginning of study and left ventricular outflow obstruction predisposed to EKG progression within 5-8 years. Patients with progressive EKG changes were more prone to experience clinical deterioration than those without EKG progression (63 vs. 15%, p < 0.001). With chronic verapamil administration, progression of EKG abnormalities occurred insignificantly less often than with propranolol treatment (35 vs. 64%, p = 0.20). It is concluded that with long-term follow-up, HCM tends to progress in a significant proportion of adult patients.