Christian Ott (Department of Nephrology and Hypertension, University of Erlangen-Nuremberg, Erlangen, Germany) and others have reported in the Journal of American College of Cardiology that the use of renal denervation in patients with moderate true treatment-resistant hypertension is associated with substantial reductions in both office and 24-hour ambulatory blood pressure.
Ott et al commented that while studies have shown that catheter-based renal denervation produces “substantial and sustained” reductions in blood pressure in patients with severe treatment-resistant hypertension, only one small retrospective study has assessed the role of renal denervation in patients with moderate hypertension. They added: “We therefore initiated a prospective multicentre open label pilot study, aimed to assess the efficacy of renal denervation in true moderate treatment-resistant hypertension.”
The authors included patients in the study if their office blood pressure was between ≥140/90mmHg and <160/100mmHg, commenting: “True resistant hypertension was confirmed by initial 24-hour ambulatory blood pressure monitoring, thereby excluding white coat- or pseudo-resistant hypertension.” All patients eligible for treatment underwent renal denervation with Medtronic’s Symplicity catheter, and were treated between February 2011 and March 2012.
Of the 54 patients in the study, most were middle-aged, male, and overweight. The mean office blood pressure was 151/83mmHg and mean 24-hour ambulatory blood pressure was ≥130/80mg mmHg. Ott et al reported that no adverse events were observed with the procedure.
Office blood pressure was significantly reduced at three months (p=0.011) with further significant reductions at six months (p<0.001). The authors noted: “In 51% of patients, office blood pressure was controlled after renal denervation—defined as office blood pressure <140/90mmHg. 61.1% of patients had an office systolic blood reduction of ≥10mmHg six months after renal denervation (defined as treatment response).” They added that they also observed significant reductions in 24-hour ambulatory blood pressure at six months (p<0.001), and that renal denervation reduced both day- and night-time ambulatory blood pressure.
Ott et al stated: “The major finding of our prospective, multicentre study is that renal denervation resulted in significant reduction in office systolic and diastolic blood pressure as well as 24-hour ambulatory blood pressure in moderate true treatment-resistant hypertension.” They added that “not surprisingly” the reductions in office blood pressure observed were less than observed in previous reports because “entry blood pressure criteria were lower and pre-treatment blood pressure is the major determinant of the magnitude of blood pressure fall”. However, according to Ott et al, even modest blood pressure reductions are “accompanied by significant attenuation of cardiovascular morbidity and mortality.”
Calling their data “encouraging”, the authors stated that their results potentially indicated “an innovative interventional approach to treat patients with moderate treatment-resistant hypertension.”
Study author Roland E Schmieder, Department of Nephrology and Hypertension, University of Erlangen-Nuremberg, Erlangen, Germany, told Cardiovascular News that more data on this area was needed. He said: “Firstly, a randomized preoperative trial in these patients with moderate treatment-resistant needs to be conducted. Indeed, on 7th March this year, Medtronic submitted an investigational device exemption to the US FDA to assess in a randomised, controlled trial, the safety and efficacy for renal denervation for renal denervation in patients with moderate treatment-resistant hypertension. Second, our results challenge the common practice to up titrate the medication with all available drugs, irrespective how many they are. Renal denervation (depending on the results of the randomized trial) may represent an alternative treatment strategy, with better compliance and fewer side effects.”