Abstract 4850: Improved Myocardial Energetics Following Chronic Treatment Using an Implantable Device in Resistant Hypertension: Results From European and United States Trials of the Rheos® System
Background: The Rheos System provides Baroreflex Activation Therapy (BAT™) and has been shown to chronically reduce blood pressure and improve left ventricular (LV) structure and function in patients with resistant hypertension (HTN). The effect of BAT on myocardial energetics and mechanical efficiency is unknown.
Methods: Resistant HTN (stage II) patients (systolic BP ≥160 mmHg) taking ≥3 anti-HTN drugs were implanted with the Rheos System which was activated 1 month after implant. Baseline data were acquired before implant. Follow-up echocardiograms were performed after 3 and 12 months of BAT. Echocardiograms were reviewed at a blinded core lab. Stroke work was calculated as systolic BP × stroke volume × 0.0144 and eMVO2 was defined as heart rate × systolic BP. Myocardial mechanical efficiency was defined as the ratio of stroke work/eMVO2. Changes at follow-up vs. pre-implant were analyzed with paired t-tests. Data are presented as mean ± SEM.
Results: 34 subjects (19 M/15 F, Age 52.5±1.8 yr) were implanted at 8 centers. Pre-implant myocardial mechanical efficiency was normal. A 15% reduction in stroke work was observed at 3 months and was sustained after 12 months of BAT despite a reduction in anti-HTN medications (table⇓). eMVO2 was significantly reduced with BAT. Myocardial mechanical efficiency was preserved. Cardiac structure, as indexed by LV mass index and left atrial dimension, was abnormal at pre-implant but was significantly improved after BAT.
Conclusions: In addition to previously documented blood pressure reduction, chronic BAT improves myocardial energetics, as indicated by reduced stroke work and eMVO2, while maintaining normal myocardial efficiency in resistant hypertensive patients. Concomitant improvements in cardiac structure were also observed. These data suggest that BAT provide benefits beyond blood pressure reduction and are under further investigation in a large placebo-controlled clinical trial.