To assess the long-term course of regression of left ventricular hypertrophy (LVH) and haemodynamic changes during spirapril treatment, 11 male hypertensive patients with a left ventricular mass (LVM) > 240 g and a mean age of 48 (range 41-60) years were followed-up with echo-Doppler examinations for 36 months. The initial spirapril dose was 6 or 12 mg once daily, which was titrated to a minimum of 3 mg and a maximum of 24 mg to keep diastolic blood pressure (DBP) < or = to 95 mmHg. Patient compliance based on tablet counts was 98% (range 95-100%). The mean spirapril dose was 9 +/- 6 mg at 3 months, 9 +/- 6 mg at 12 months, and 15 +/- 9 mg at 36 months. Blood pressure was reduced from 161 +/- 20/107 +/- 6 mmHg at baseline to 137 +/- 11/89 +/- 6 mmHg at 3 months (p < 0.001), 141 +/- 20/89 +/- 4 mmHg at 12 months and 135 +/- 11/87 +/- 6 mmHg at 36 months. The respective values for LVM at baseline and at 3, 12 and 36 months were 340 +/- 71 g, 305 +/- 61 g (p < 0.05 vs baseline), 303 +/- 88 g and 298 +/- 94 g. Cardiac output did not change whereas systemic arteriolar resistance (SAR) was significantly reduced after 3 and 36 months (p < 0.01). Thus, the regression of LVH with spirapril was 10% of LVM at 3 months, 11% at 12 months, and 12% at 36 months. These changes were mainly related to a reduction of LV posterior wall thickness and SAR.