RESISTANT HYPERTENSION AND METABOLIC SYNDROME –A TWO-WAY RELATIONSHIP

Abstract

Objective: Resistant hypertension is often accompanied by sympathetic hyperactivity, arterial stiffness and metabolic syndrome. Moreover, the idea of metabolic syndrome increasing the effect of resistant hypertension in sympathetic nervous system and vascular wall is under examination. The aim of this study was to appraise the effect of the metabolic syndrome on sympathetic drive, as it was assessed by MSNA estimations, and arterial stiffness in patients with resistant hypertension. Design and method: We studied 34 patients with resistant hypertension (age: 57 ± 11 years, 22 males, office blood pressure (BP): 157/93 ± 13/11 mmHg, 24-hour BP: 138/83 ± 14/10 mmHg, under 3.2 ± 0.5 antihypertensive drugs) who underwent anthropometric measurements, blood examinations and transthoracic echocardiographic study, for assessment of the metabolic profile. In all participants, MSNA was evaluated based on established methodology (microneurography) and arterial stiffness on the basis of carotid to femoral pulse wave velocity (PWV). Metabolic syndrome was defined according to the Adult Treatment Panel III criteria. Results: Patients with resistant hypertension and metabolic syndrome (n = 14), compared to those without metabolic syndrome (n = 20) were characterized by higher levels of office systolic BP (166 ± 15 vs 151 ± 15 mmHg, p < 0.001), fasting glucose (132.7 ± 2.7 vs 94.7 ± 2.2 mg/dl, p < 0.05), waist circumference (109.1 ± 5.3 vs 94.8 ± 9.3 cm, p = 0.002), as well as left ventricular mass index (124.2 ± 16.2 vs 114.4 ± 16.2 g/m2, p = 0.001). Furthermore, metabolic syndrome patients exhibited greater levels of MSNA (84.8 ± 2.5 vs 74.2 ± 2.4 bursts per 100 heart beats, p < 0.001) and greater levels of carotid to femoral PWV (11.5 ± 0.8 vs 9.1 ± 1.3m/sec, p < 0.001). In all participants, sympathetic nerve traffic as assessed by resting MSNA was related to office systolic BP (r = 0.38, p < 0.05) and waist circumference (r = 0.33, p = 0.002), but there was no association with PWV values (p = NS). Conclusions: In patients with resistant hypertension, metabolic syndrome is associated with high MSNA and PWV levels. These results suggest thatthe presence of metabolic syndrome can exacerbate the setting of resistant hypertension, through sympathetic overdrive and vascular abnormalities, conditions that can be the subject of therapeutic interventions.