Treatment-resistant hypertension (TRH) is defined as blood pressure (BP) that remains above goal despite adhering to the maximally tolerated doses of three antihypertensive drugs with the complementary mechanism of action, and including one diuretic agent. Hypertension is usually asymptomatic, and treatment adherence is one major obstacle to the successful control of BP.
Baroreceptor activation therapy (BAT) is a treatment option proposed for patients with TRH. The BAT aims to reduce BP by electrically stimulating the carotid baroreflex, which acts on the sympathetic and parasympathetic nervous system. The Barostim neo™, a second-generation device for BAT, is currently the only available CE-marketed device that activates the baroreceptor reflex by electric impulses. The first generation device, the Rheos® system, is not marketed anymore. The two generations of devices feature significant differences: the Barostim neo™ consists of a smaller electrode, and a smaller pulse generator with longer battery life, the electrode is placed unilaterally on only one carotid sinus, and thus the surgical procedure is more straightforward and shorter, requiring less recovery time. Due to these substantial differences, pooling of efficacy and safety data of both devices would not make sense.
The authors wanted to assess the effectiveness and safety of the BAT to decrease BP and reduce the number of cardiovascular events as compared to standard therapy. They have searched four databases: Medline, Embase, Cochrane Library and CRD, including publications dating 2008 – 2017 that were written in English or German. A search in three clinical trials registries (ClinicalTrials.gov; WHO-ICTRP; EU Clinical Trials) was conducted in order to identify ongoing and unpublished studies, resulting in 31 potential hits. Eventually, two (2) RCTs and five (5) case-series were identified. However, the RCTs and one case-series were only describing the Rheos® system and thus were not considered for recommendation.
Regarding clinical effectiveness, no studies were identified that compare BAT to standard therapy for the second-generation device. One case-series reports that the second-generation device demonstrated an average decrease in SBP by 8 mmHg. A reduction of at least 5 mmHg was not achieved in 20 of 44 patients (45%). Furthermore, the evidence did not demonstrate significant BP differences after 6 months follow-up of the patients treated with the first-generation device. The quality of effectiveness evidence was meagre.
Regarding safety, again no studies were identified that compare BAT to standard therapy. However, observing the case-series, the second-generation device had less adverse events reported and, within the six months follow-up, none of the second-generation devices needed to be explanted, compared to the first-generation device. This evidence was of very poor quality, too.
The authors remind that BAT is currently not reimbursed in Austria and state that the estimated treatment costs for the implantation are at EUR 3,500, the Barostim neo™ system costs EUR 21,000, and the battery costs are EUR 15,000 if replacement is needed.
The authors hence conclude that there is no sufficient evidence to conclude on effectiveness or safety of BAT and thus they do not recommend its inclusion into the Austrian benefit catalogue. There are currently three (3) RCTs going on, and their results may bring new evidence.
See the full report in English (with summary in German) here.
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