Association of Metabolic Syndrome and Blood Pressure Nondipping Profile in Untreated Hypertension

Abstract

There is a marked association between metabolic syndrome (MS) and increased cardiovascular risk. Moreover, nondipping (patients with <10% decline in the asleep relative to the awake blood pressure (BP) mean) has also been associated with increased cardiovascular morbidity and mortality. We investigated the association between MS and impaired nocturnal BP decline in 1,770 nondiabetic, untreated hypertensive patients (824 men and 946 women), 48.7 +/- 13.2 years of age. BP was measured by ambulatory monitoring for 48 h to increase reproducibility of the dipping pattern. Physical activity was simultaneously monitored every minute by wrist actigraphy. MS was present in 42.4% of the patients. The prevalence of a nondipper BP profile was significantly higher in patients with MS (46.1% vs. 37.5% in patients without MS, P < 0.001). Patients with MS were characterized by significant elevations in uric acid (5.9 mg/dl vs. 5.2 mg/dl, P < 0.001), fibrinogen (314 mg/dl vs. 304 mg/dl, P = 0.021), and globular sedimentation rate (13.8 mm vs. 11.6 mm, P < 0.001). Nondipping was significantly associated to the presence of MS in a multiple logistic regression model adjusted by other significant confounding factors, including age, serum creatinine, and cigarette smoking. The single most relevant factor in the definition of MS associated to nondipping was elevated waist perimeter. This study documents a significant increase of a blunted nocturnal BP decline in patients with MS. Patients with MS were also characterized by elevated values of relevant markers of cardiovascular risk, including fibrinogen and globular sedimentation rate.