WASHINGTON – On the heels the recently published final report from the SYMPLICITY HTN-3 renal denervation trial, a new analysis showed that Black patients, like non-Blacks, had sustained blood pressure control.
Contrary to a signal from earlier results, “there is nothing race specific about renal denervation,” said presenter Deepak L. Bhatt, MD, at the Cardiovascular Research Technologies conference, sponsored by MedStar Heart & Vascular Institute.
Dr. Deepak L. Bhatt
Black patients are well represented among patients with treatment-resistant hypertension and considered an important subgroup to target, according to Dr. Bhatt, director of Mount Sinai Heart, New York. This is the reason that they were not only a prespecified subgroup in SYMPLICITY HTN-3, but race was one of two stratification factors at enrollment. At the time of the study design, there was an expectation that Black patients would benefit more than non-Blacks.
This did not prove to be the case during the 6-month controlled phase of the trial. When patients randomized to renal denervation or the sham procedure were stratified by race, the primary endpoint of reduction in office systolic blood pressure (SBP) reached significance in the experimental arm among non-Black patients (–6.63 mm Hg; P = .01), but not among Black patients (–2.25 mm Hg; P = .09).
Blacks comprised 26% of SYMPLICITY HTN-3 trial
In the initial controlled analysis, published in the New England Journal of Medicine, the lack of benefit in the substantial Black enrollment – representing 26% of the study total – weighed against the ability of the trial to demonstrate a benefit, but Dr. Bhatt pointed out that BP reductions were unexpectedly high in the sham group regardless of race. Patients randomized to the sham group were encouraged to adhere to antihypertensive therapy, and based on response, this was particularly effective in the Black sham subgroup.
In SYMPLICITY HTN-3, patients with treatment-resistant hypertension were randomized to renal denervation or a sham procedure in a 2:1 ratio. While the controlled phase lasted just 6 months, the follow-up after the study was unblinded has continued out to 3 years. Safety and efficacy were assessed at 12, 24, and 36 months.
Unlike the disappointing results at 6 months, renal denervation has been consistently associated with significantly lower BP over long-term follow-up, even though those randomized to the sham procedure were permitted to cross over. About two-thirds of the sham group did so.
In the recently published final report of SYMPLICITY, the overall median change in office SBP at 3 years regardless of race was –26.4 mm Hg in the group initially randomized to renal denervation versus –5.7 mm Hg (P < .0001) among those randomized to the sham procedure.
In the subgroup analysis presented by Dr. Bhatt, the relative control of office SBP, as well as other measures of blood pressure, were similarly and significantly reduced in both Black and non-Black patients. In general, the relative control offered by being randomized initially to renal denervation increased over time in both groups.
For example, the relative reduction in office SBP favoring renal denervation climbed from –12.0 mm Hg at 12 months (P = .0066) to –21.0 at 18 months (P = .0002) and then to –24.9 mm Hg (P < .0001) at 36 months in the Black subgroup. In non-Blacks, the same type of relative reductions were seen at each time point, climbing from –13.5 (P < .0001) to –20.5 (P < .0001) and then to –21.0 (P < .0001).
The comparisons for other measures of BP control, including office diastolic BP, 24-hour SBP, and BP control during morning, day, and night periods were also statistically and similarly improved for those initially randomized to renal denervation rather than a sham procedure among both Blacks and non-Blacks.