The effects of baroreflex activation therapy on blood pressure and sympathetic function in patients with refractory hypertension: the rationale and design of the Nordic BAT study

Objective: To explore the effects of baroreflex activation therapy (BAT) on hypertension in patients with treatment resistant or refractory hypertension.Methods: This investigator-initiated randomized, double-blind, 1:1 parallel-design clinical trial will include 100 patients with refractory hypertension from 6 tertiary referral hypertension centers in the Nordic countries. A Barostim Neo System will be implanted and after 1 month patients will be randomized to either BAT for 16 months or continuous pharmacotherapy (BAT off) for 8 months followed by BAT for 8 months. A second randomization will take place after 16 months to BAT or BAT off for 3 months. Eligible patients have a daytime systolic ambulatory blood pressure (ABPM) of 145mm Hg, and/or a daytime diastolic ABPM of 95mm Hg after witnessed drug intake (including 3 antihypertensive drugs, preferably including a diuretic).Results: The primary end point is the reduction in 24-hour systolic ABPM by BAT at 8 months, as compared to pharmacotherapy. Secondary and tertiary endpoints are effects of BAT on home and office blood pressures, measures of indices of cardiac and vascular structure and function during follow-up, and safety.Conclusions: This academic initiative will increase the understanding of mechanisms and role of BAT in the refractory hypertension.