Blood pressure profile, sympathetic nervous system activity, and subclinical target organ damage in patients with polycythemia vera

Introduction Polycythemia vera (PV) is a rare myeloproliferative disease associated with an increased prevalence of hypertension and increased risk of cardiovascular complications. However, the precise mechanisms leading to the elevation of blood pressure (BP) and secondary target organ damage remain poorly understood. Objectives The study aimed to evaluate BP profile, assess the activity of the sympathetic nervous system and the renin‑angiotensin system, and provide a comprehensive assessment of subclinical target organ damage in patients with PV. Patients and methods Twenty consecutive patients with newly diagnosed PV and 20 control subjects were included. The following were assessed: BP, levels of catecholamines, urinary and plasma O‑methylated catecholamine metabolites, concentrations of aldosterone and renin. We also assessed microneurography sympathetic nervous system activity (MSNA) and baroreflex control of heart rate as well as subclinical target organ damage. Results At similar levels of BP, BP variability was decreased in the PV group (mean [SD] 24‑hour systolic BP, 9 [3] vs 12 [3] mm Hg; P = 0.003). Patients with PV had lower norepinephrine excretion (mean [SD], 16.54 [6.32] vs 25.46 [12.88] μg/d; P = 0.03) as well as decreased MSNA as assessed by microneurography compared with controls (mean [SD] MSNA, 30.7 [8.7] bursts/min vs 38.7 [5.4] bursts/min; P = 0.007 and MSNA 51.8 [11] bursts/100 beats vs 61.1 [11.3] bursts/100 heart beats; P = 0.04). Baroreflex control of HR was unaltered in the PV group. Increased hemoglobin levels and red blood cell count correlated with decreased retinal capillary flow in patients with PV. Conclusions Patients with PV, characterized by high hemoglobin concentrations and hematocrit levels had lower sympathetic nervous activity and decreased BP variability as compared with controls. There was no relationship between hemoglobin plasma concentration, hematocrit level, and target organ damage.