Nocturnal Hypertension, Nondipping Phenomenon and Target Organ Damage in Obstructive Sleep Apnea Patients - The Bad and the Worse

Background: Nocturnal blood pressure (NBP) abnormalities are often encountered in obstructive sleep apnea (OSA) patients. Both phenomena are associated with increased cardiovascular morbidity and mortality in general hypertensives. The aim of the study was to determine the prevalence of target organ damage (TOD) in different nighttime blood pressure patterns of newly diagnosed OSA patients with early hypertension. Materials and Methods: Seventy-four patients participated in the study. OSA was verified by a polysomnography. All patients had controlled hypertension. 24-hour BP monitoring divided participants into: 39 (NH) - nocturnal hypertensives; 18 NND - nocturnal normotensive dippers, (NBP fall>10%, NBP<120/70mmHg); 17 (NNN) - nocturnal normotensive non-dippers (NBP fall<10%, NBP<120/70mmHg). Anthropological glucometabolic and sleep study characteristics were collected. Cardiac damage (left ventricular mass index - LVMI, relative wall thickness - RWT) was assessed by a standard echocardiography; renal damage by microalbuminuria and vascular damage by ultrasonography of the carotid vessels. Results: Left ventricular hypertrophy (LVH) was met in 33% of the dippers, 64.7% of NNN and in 62.6% of NH. LVMI in non-dippers was higher when compared to dippers (127.71± 8.71 vs 109.1± 4.9g/m2, p=0.03) and nearly identical to those in patients with NH (127.71± 8.71 vs 124.18 ± 5.92g/m2, p=0.42). Microalbuminuria was present in 3% and 6% of dippers/non-dippers and in 51% of NH. IMT and RWT were within the same range in the three groups. Multivariate regression analysis showed that: LVMI correlated positively to age and sleep time at SaO2<90%; RWT correlated positively to BMI, age and AHI. IMT and microalbuminuria correlated to none of the parameters. Conclusion: In newly diagnosed OSA patients with early hypertension (duration <3 years) TOD was detected mostly at cardiac level. It was presented by an increased LVMI, that was associated with the age and the sleep time at SaO2<90%.