Isolated ambulatory hypertension and changes in target organ damage in treated hypertensive patients

Isolated ambulatory hypertension is a condition characterized by elevated ambulatory but normal clinic blood pressure (BP), and has been reported to be associated with increased cardiovascular risk in untreated subjects. However, little is known about the relationship between this condition and intermediate end points such as target organ damage (TOD) in treated hypertensives. We investigated the impact of isolated ambulatory hypertension on left ventricular hypertrophy (LVH) and microalbuminuria (MA) in a selected sample of treated nondiabetic hypertensives with effective and prolonged clinic BP control (BP<140/90 mmHg). Clinic BP measurements, routine diagnostic procedures, echocardiography and 24-h urine collection for MA, were undertaken in 80 patients (mean age 53±8 years) with essential hypertension attending our hospital outpatient centre at baseline and after an average follow-up of 30 months. At follow-up evaluation BP status was assessed by self-measurement of BP and ambulatory BP monitoring (ABPM). At the follow-up visit, 51 out of 80 patients (63.7%) reached a BP control according to ABP (average daytime BP<132/85 mmHg) criteria (group I) whereas the remaining 29 did not (group II); home BP was controlled (BP<135/85 mmHg) in all members of group I and in 86% of group II. In the overall study population, mean Sokolow voltage, LV mass index (LVMI) and urinary albumin excretion (UAE) decreased compared to baseline from 24.1±5.0 to 18.9±5.1 mm (P<0.05), 115.6±24.1 to 97.7±21.6 g/m2 (P<0.01), 11.8±23.7 to 5.8±14.9 mg/24 h (P<0.05), respectively. The prevalence of ECG LVH, altered LV patterns and MA fell from 7.5 to 2.5% (P=NS), from 45 to 25 (P<0.01) and from 13.7 to 5.1% (P<0.05), respectively. However, when data were analysed separately for the two groups a significant decrease of echo LVH and MA was found only in patients with controlled ABP. LVMI and MA decreased from 117.1±23.1 to 95.9±22.1 g/m2 (P<0.01) and 12.8±24.7 to 4.1±5.7 mg/24 h (P<0.05) in group I, and from 114.1±24.8 to 102.3±20.3 (P=NS) and 11.9±22.1 to 6.3±18.1 mg/24 h (P=NS) in group II. In conclusion, in the present study isolated ambulatory hypertension in treated patients is associated with a lack of regression in cardiac and extracardiac TOD, suggesting that a tight BP control throughout the 24 h plays a key role in lowering hypertension-induced structural and functional alterations at cardiac and renal level.