What is Barostim (Baroreflex Activation Therapy)?
Barostim is an implantable device-based therapy that electronically stimulates baroreceptors in the carotid sinus to reduce sympathetic nervous system activity and enhance vagal tone, primarily used to treat resistant hypertension and heart failure with reduced ejection fraction when conventional medical therapy fails. 1
Device Components and Mechanism
The Barostim system consists of three key components: baroreflex activation leads placed adjacent to the carotid sinus, an implantable pulse generator (similar to a pacemaker), and an external programming system that allows individualized titration of therapy parameters. 1
Physiological Effects
The device works by mimicking the body's natural baroreflex mechanism. When blood pressure rises, baroreceptors in the carotid sinus normally detect this change and trigger compensatory responses. 2 Barostim artificially activates these baroreceptors, producing several beneficial effects: 1
- Heart rate reduction through enhanced vagal activity
- Arterial vasodilation from decreased sympathetic tone
- Improved renal blood flow with enhanced sodium excretion (natriuresis)
- Decreased levels of angiotensin II, vasopressin, and atrial natriuretic peptide
- Improved baroreflex sensitivity, which is often impaired in hypertensive patients 2
Clinical Indications
Resistant Hypertension
The American College of Cardiology and American Heart Association recommend Barostim for patients with resistant hypertension who remain uncontrolled despite taking three or more antihypertensive medications (including a diuretic) at maximally tolerated doses. 1 This aligns with the definition of true resistant hypertension requiring confirmation after excluding pseudo-resistance and medication non-adherence. 2, 1
Heart Failure
Barostim is also indicated for patients with heart failure with reduced ejection fraction (HFrEF) who have inadequate response to optimal medical therapy. 1, 3
Clinical Efficacy
Blood pressure reductions are substantial and sustained: Studies show average systolic blood pressure decreases of 38 mmHg at 1 year, 36 mmHg at 2 years, 40 mmHg at 3 years, and 53 mmHg at 4 years in patients with resistant hypertension. 4 In one prospective study, systolic blood pressure decreased from 169 mmHg to 148 mmHg at 6 months and 145 mmHg at 1 year, while the number of required antihypertensive medication classes decreased from 6.6 to 5.6. 5
Additional cardiac benefits include: reduced left ventricular mass, decreased posterior wall thickness (cardiac remodeling), and improved quality of life in heart failure patients. 4, 3
Evolution of the Technology
The current Barostim neo system represents a significant advancement over the first-generation Rheos device. 6, 4 The key improvement is that Barostim neo operates via unilateral (single-sided) carotid stimulation rather than bilateral stimulation, using a completely different electrode design. 6 This achieves comparable efficacy with a simpler, less invasive procedure. 6
Safety Profile and Adverse Events
Common Side Effects (Grade I - Mild)
Nearly all patients (97.6%) experience mild adverse events, predominantly within the first 6 months after device activation. 5 These are typically:
- Local discomfort at the implant site
- Device-related sensations that can be resolved by optimizing stimulation parameters
- Procedure-related issues directly related to the surgical incision or anesthesia 5
Moderate Adverse Events (Grade II)
Approximately 28.6% of patients experience medically significant events including hypertensive crises, syncope, or arrhythmias, though patients' elevated individual cardiovascular risk profiles may contribute to these occurrences. 5
Management of Side Effects
Most adverse events resolve without sequelae through individualized adjustment of the pulse generator settings. 5 Because blood pressure response and side effect profiles vary considerably between patients, no standardized parameter settings exist—each patient requires individualized programming. 5 Regular follow-up visits are mandatory to monitor and adjust device parameters. 1, 5
Patient Selection Criteria
Appropriate Candidates
- True resistant hypertension confirmed after excluding pseudo-resistance (white coat effect) and medication non-adherence 2
- Uncontrolled blood pressure on three or more antihypertensive medications including a diuretic
- Multidisciplinary assessment and shared risk-benefit discussion completed
Contraindications
The European Society of Cardiology specifically excludes: 1, 7
- Patients with moderate to severe renal impairment (eGFR <40 mL/min/1.73 m²)
- Patients with secondary hypertension (where an underlying cause should be addressed instead)
Implementation Considerations
The procedure should be performed in medium to high-volume centers to ensure procedural quality and safety. 1, 7 The implantation procedure carries risks comparable to other active implantable devices like pacemakers. 4
Current Evidence Limitations
Important caveats exist: While the first-generation Rheos device was studied in the double-blind, randomized Rheos Pivotal Trial, the currently used Barostim neo system lacks data from large randomized controlled trials. 3 Additionally, not all patients respond to therapy—the reasons for non-response remain unclear and require further investigation. 6 Large randomized trials demonstrating reduction in cardiovascular events (not just blood pressure) are still lacking. 3
Role in Treatment Algorithm
According to the American Heart Association, device-based therapies like Barostim await full clarification of their role pending results from rigorous, double-blind, sham-controlled studies. 2 However, if independent benefit is confirmed, incorporation into treatment algorithms alongside lifestyle and pharmacological therapies would be appropriate. 2 The therapy represents an option when conventional approaches have been exhausted in true resistant hypertension. 2, 1