4 Efficacy
This section describes efficacy outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
The following outcomes were reported in patients treated by implantation of a bilateral baroreceptor stimulation device:
4.1
A randomised controlled trial of 265 patients treated by implantation of a bilateral baroreceptor stimulation device that was either turned on 1 month after implantation (immediate stimulation) or turned on after 6 months (deferred stimulation) was carried out. Response rates at 6 months (defined as a 10 mmHg or more drop in systolic blood pressure at month 6 compared with systolic blood pressure obtained 1 month after implantation) were 54% and 46% respectively (p=0.97). Of those patients whose blood pressure responded to active therapy at 6 months, 88% maintained a response at 12 months (p<0.001). The mean decreases in systolic blood pressure at 6 months were 16±29 mmHg for immediate stimulation and 9±29 mmHg for deferred simulation (p=0.08). The proportion of patients with systolic blood pressure of 140 mmHg or less at 6 months was 42% for immediate stimulation and 24% for deferred stimulation (p=0.005).
4.2
A cohort study of 322 patients, which was an open-label follow-up of the randomised controlled trial described in section 4.1 (including all patients who had a device implanted regardless of whether they were subsequently randomised), reported a mean decrease in blood pressure of 35/16 mmHg compared with pre-implantation, after a mean follow-up of 28 months. Among the 244 patients whose blood pressure responded (defined as a 10 mmHg or more drop in systolic blood pressure at month 6 compared with systolic blood pressure obtained 1 month after implantation) 55% reached goal pressures (less than 140 mmHg or less than 130 mmHg in patients with diabetes or kidney disease) throughout follow-up. A case series of 45 patients treated by implantation of a bilateral baroreceptor stimulation device reported that mean blood pressure decreased by 21/12 mmHg in 37 evaluable patients after 3 months of baroreceptor stimulation (p=0.001). The mean reduction after 2 years of follow-up was 33/22 mmHg (n=17, p=0.001 for systolic blood pressure and p=0.002 for diastolic blood pressure).
4.3
The cohort study of 322 patients reported that the mean number of prescribed medications fell significantly between pre-implantation and month 12 in those patients whose blood pressure responded to the device (n=244). These reduced from 5.3±1.9 to 4.7±2.1 and remained lower after a mean follow-up of 28 months (p<0.05).
The following outcomes were reported in patients treated by implantation of a unilateral baroreceptor stimulation device:
4.4
A case series of 30 patients treated by implantation of a unilateral stimulation device reported a mean reduction in systolic blood pressure from the pre-implant baseline of 26±3 mmHg at 3‑month follow-up (p<0.001). The mean reduction was 26±4 mmHg at 6‑month follow-up (p<0.001). The proportion of patients with systolic blood pressure of 140 mmHg or less was 43% at 6‑month follow-up. A case series of 25 patients treated by implantation of a unilateral stimulation device reported that the mean blood pressure decreased from 160/83 mmHg at baseline to 143/74 mmHg at 6‑month follow-up (p<0.01).
4.5
The specialist advisers listed key efficacy outcomes as reduction in blood pressure at 6 and 12 months, reduction in blood pressure variability, reduction in heart rate, and reduction in left ventricular hypertrophy.