The aim of this study was to establish the existence of primary acromegalic cardiomyopathy different from the cardiovascular complications often associated with acromegaly. Thirty-four acromegalic patients, referred to our non-invasive laboratory and divided into two groups on the basis of the presence of hypertension, underwent echocardiographic studies. A control group of 34 subjects individually matched with the patients for age, sex, and blood pressure values was also studied. To evaluate cardiac function during exercise, the normotensive acromegalics, the control group, and a group of 9 athletes with left ventricular mass comparable to that of the acromegalic subjects underwent a handgrip test. Cardiac mass was increased in all patients; hypertensive patients had a greater increase than normotensive patients (144.9 +/- 38 vs 120.9 +/- 20.8 g/m, p < 0.02). Systolic wall stress and percent fractional shortening, although similar to the values confirmed in controls, were modified in the hypertensive patients (wall stress 77.5 +/- 9.3 vs 60.8 +/- 9.4 dyne/cm2, p < 0.01). In all patients, diastolic function at rest was similar to that in controls, although the hypertensive patients had deteriorated diastolic function (E peak 56.9 +/- 12.4 vs 71 +/- 15 cm/s, p < 0.01; A peak 70.4 +/- 21.1 vs 52.3 +/- 16.4 cm/s, p < 0.03; E/A ratio 0.89 +/- 0.37 vs 1.38 +/- 0.35, p < 0.02). During handgrip testing, wall stress in both the normotensive acromegalics and the control subjects increased but remained unchanged in the athlete group; percent fractional shortening decreased in all patients and controls but increased slightly in the athlete group. In conclusion, cardiac hypertrophy caused by GH hyperincretion does not improve acromegalic heart activity: diastolic function, although normal at rest, appears deficient during isometric exercise.