1. Continuous intra-arterial ambulatory monitoring of blood pressure was recorded in 46 patients with mild to moderate hypertension under standardized conditions. M-mode echocardiography was performed after recording and left ventricular mass index calculated by standard formulae.
2. Systolic blood pressure from continuous recording was significantly correlated with left ventricular mass index (mean 24 h: r = 0.543, n = 45, P < 0.001). Diastolic blood pressure exhibited a weaker but still significant correlation with left ventricular mass index (mean 24 h: r = 0.318, n = 45, P < 0.05). Casual systolic blood pressure was significantly correlated with left ventricular mass index (r = 0.476, n = 46, P < 0.001) but casual diastolic blood pressure did not correlate with left ventricular mass index (r = 0.245, n = 46). Awake blood pressure variability, age, resting plasma renin activity and resting plasma noradranaline levels did not have a significant correlation with left ventricular mass index.
3. Nine patients were treated for 16 weeks with once-daily timolol and repeat ambulatory monitoring and M-mode echocardiography was performed with the same protocol.
4. Once-daily timolol provided good 24 h control of blood pressure and repeat echocardiography showed a reduction in left ventricular mass index in that group of patients (t = 2.59, P < 0.05).