Apical hypertrophic cardiomyopathy (AHCM) is characterized by primary hypertrophy localized exclusively in the apex of the left ventricle. Previous studies have indicated that AHCM results in a unique combination of cross-sectional echocardiographic (CSE) and ECG findings ('giant' T wave inversion and high R wave voltage in the precordial leads). The aims of this study were: (1) to assess the degree of AHCM in a quantitative fashion (2) to evaluate the possible relationship between apical hypertrophy, quantitatively determined, and ECG findings in patients with AHCM (3) to verify the changes in echocardiographic and ECG parameters over time (4) to define the relationship between the severity of AHCM and the clinical course of such patients. Eleven selected patients with AHCM were studied for an average 6 year follow-up period; there were seven men and four women (age from 18 to 62 years, mean 49). Apical hypertrophy was assessed quantitatively by determining the muscle cross-sectional area in the apical region, which was considered an index of myocardial mass. From the end-diastolic apical four chamber view, endocardial and epicardial contours were digitized in order to obtain the total muscle cross-sectional area of the left ventricle. The walls of the left ventricle were then divided into three regions (basal, intermediate, apical). The final value of each cross-sectional muscle area was obtained from the mean measurements of four independent and blinded observers. In AHCM the apical muscle cross-sectional area (AMA) ranged from 10.3 to 17.9 cm2, mean 13.2 +/- 2.6 cm2.(ABSTRACT TRUNCATED AT 250 WORDS)