The effectiveness of renal denervation in treating high blood pressure could be much less than observed in clinical trials, according to a Belgian study of ambulatory blood-pressure monitoring in patients with resistant hypertension treated using renal denervation instead of drugs.
The reduction in blood pressure could be as little as a third of that observed in the office when measured using ABPM technology, heartwire reported.
The average blood pressure reduction from office-cuff measurement was 17.6 mm Hg after 6 months, but only 5.9 mm Hg when measured with 24-hour ABPM, according to the website. Results from the 109-patient trial were presented at the European Society of Hypertension meeting in Milan.
That’s less than reported in Medtronic‘s (NYSE:MDT) Symplicity HTN-2 trial last March at the American College of Cardiology’s annual meeting. Two-year data from that trial showed that 40 patients who received the Symplicity treatment "sustained a significant drop in blood pressure," with no device-related serious adverse events, no late vascular complications and no significant decline in kidney function.
"Our results on the office measurement are less than what was observed in the Symplicity HTN-2 trial but still in the same range," lead investigator Dr. Alexandre Persu of the Cliniques Universitaires Saint-Luc in Brussels told heartwire. "But in Symplicity, there are only few ABPM results, and even in those that were done, the reduction was also just ⅓ [of the office measurements]. Our study is the largest collection of ambulatory blood-pressure measurements, and the results on ABPM are not impressive. That’s why we are skeptical. We are not sure if this modest reduction would translate into a reduction into hard clinical events. It’s possible, but it still remains to be proven.
"We think that renal denervation should be mainly for research right now," Persu added. "It should be reserved only as a last resort for truly resistant hypertensive patients in whom all attempts have been made to lower blood pressure at expert clinical centers."
Persu’s study also showed a wide variation in responses to renal denervation among patients, with "a substantial proportion" experiencing no change in blood pressure – or even higher systolic blood pressure after receiving the treatment, according to the website. Twenty-three percent of patients measured in the office showed unchanged or higher blood pressure after 6 months; measured using ABPM that number rose to 35%, heartwire reported.
"We have found that the results of renal denervation are highly variable in real life, and we wanted to try to have an unbiased look at the procedure and the results achieved in hypertension centers," Persu said. "The final word will come from the new randomized, controlled clinical trials."