Long-term sustained BP reductions with baroreflex activation therapy
Sustained Reduction of Blood Pressure With Baroreceptor Activation Therapy Results of the 6-Year Open Follow-Up
Baroreflex activation therapy (BAT), through electric stimulation of the carotid sinus, leads to significant and sustained reductions of BP in patients with resistant hypertension [1-4]. This therapeutic method has, however, not been introduced into clinical practice, since it is invasive, and there is uncertainty about the long-term sustained efficacy.
In this analysis, the follow-up results of the 3 studies that evaluated BAT are described. The 3 Studies were the US Rheos Feasibility Trial, the DEBuT-HT Trial, and the Rheos Pivotal Trial. Data of 383 patients were available for analysis, of whom 143 had completed 5-years of follow-up, and 48 of 6 years (median follow-up: 5 years). In all 3 trials, the first-generation Rheos system was used, consisting of an implantable pulse generator and leads that were tunnelled subcutaneously and attached to each carotid sinus. Patients were seen at regular intervals, and stimulation parameters were individually adjusted to optimize treatment. Patients were either stimulated at one side (left or right) or bilaterally, depending on which produced the greatest response.
- Patients who discontinued therapy during the first year, had a significantly higher BP at baseline compared with those who continued for a longer time (SBP: 190±24 mmHg vs. 178±23 mm g; DBP: 110±13 mmHg vs. 103±16 mmHg; both P<0.01).
- Over the 6-year period, SBP decreased from 179±24 mmHg to 144±28 mmHg (P<0.0001), and DBP decreased from 103±16 mmHg to 85±18 mmHg (P<0.0001).
- Heart rate was reduced from 74±15 beats/min to 71±13 beats/min (P<0.02).
- Pulse pressure was reduced from 76±19 to 59±17 mmHg (P<0.0001).
- The greatest effect on BP was evident in the early phase after implantation of the device.
- BP reduction did not correlate with age, BMI, or the number of medications taken before BAT. Race, smoking status, the presence or absence of DM, CAD, or a previous stroke, or the use of a MRA or any other type of antihypertensive drug had no effect on the response to BAT.
- The greatest BP reductions were observed in patients with congestive HF, who had significantly higher pre-treatment pressures. In HFpEF patients, the BP reduction was 46/24 mmHg, compared with the overall mean of 32/16 mmHg (P<0.05).
- Patients with isolated systolic hypertension (ISH) showed less pronounced reductions in SBP (−23±7 mmHg), DBP (−8±2 mmHg), and HR (0±1 beats/min), compared with those without ISH.
- 42% of patients had normalised their BP (SBP <140 mmHg and DBP <90 mmHg) at the end of the first year of follow-up.
- The proportion of patients on target varied between 49% and 54% over the entire follow-up period.
- There were 26 non-responders (SBP reduction <10 mmHg).
- In 27% of patients the number of medications fell from a median of 6 to a median of 3, in 34% of patients (34%) medication use remained stable at a median of 5, and in 39% of patients it increased from a median of 5 to a median of 7.
- Except for 1 stroke, all complications resolved without residual effects.
In treatment-resistant hypertensive patients, baroreflex activation therapy lowers BP in the long-term, particularly in those with HF and preserved ejection fraction. These data suggest that BAT may become an alternative therapeutic option for resistant hypertension in clinical practice.