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Renal denervation reduced BP, LV mass index in resistant hypertension
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Results of a multicenter study have concluded that renal denervation reduced BP and left ventricular mass index, while improving ejection fraction in a cohort of individuals with resistant hypertension. The beneficial effects were partly BP independent, according to the researchers.
Felix Mahfoud, MD, of the Klinik für Innere Medizin III at the Universitätsklinikum des Saarlandes in Homburg/Saar, Germany, and fellow researchers noted in the study that sympathetic stimulation has been known to induce LV hypertrophy and may increase CV risk. They added that sympathetic outflow and BP may be reduced by catheter-based renal denervation.
The current study was a multicenter investigation that included 72 patients with resistant hypertension — 55 who underwent renal denervation and 17 controls. The aim was to investigate whether renal denervation impacted anatomic and functional myocardial parameters as assessed by cardiac MRI.
Felix Mahfoud
The patient population had a mean age of 66 ± 10 years. Participants were evaluated at baseline and 6 months.
A significant reduction in systolic and diastolic BP of 22/8 mm Hg was observed in the renal denervation group. The intervention also significantly reduced LV mass index by 7.1% (46.3 ± 13.6 g/m1.7 vs. 43 ± 12.6 g/m1.7; P<.001). No changes in LV mass index were reported among controls (41.9 ± 10.8 g/m1.7 vs. 42 ± 9.7 g/m1.7; P=.653).
Renal denervation was associated with a significant increase in LV ejection fraction (43% vs. 50%; P<.001) among patients with impaired LV ejection fraction at baseline (defined as <50%).
The analysis included a subgroup of patients with reduced LV circumferential strain at baseline; LV circumferential strain increased by 21% in those patients who received renal denervation (−14.8 vs. −17.9; P=.001). No such increase occurred among controls (−15.5 vs. −16.4; P=.508).
“Interestingly, the structural and functional cardiac changes occurred partly BP independent, pointing towards a direct role of modulating sympathetic nervous system activity,” Mahfoud and colleagues wrote.
Disclosure: The researchers report financial disclosures with Boston Scientific, Cordis, Medtronic/Ardian and St. Jude Medical.
Perspective
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Paul D. Williams, MD
The field of renal denervation (RDN) is currently in flux given the preliminary announcement of the SYMPLICITY HTN-3 trial results in January, which failed to meet its primary efficacy endpoint of office BP reduction. This small study by Mahfoud and colleagues investigating the effect of RDN on cardiac mass and function, as assessed by blinded CMR, is therefore of great interest. In 55 patients treated with the first generation Symplicity device (Medtronic), there was a significant reduction in LV hypertrophy, even in those 'nonresponders' who did not experience a substantial reduction in BP. This raises the intriguing possibility that RDN may have beneficial effects in addition to BP reduction. There was also an improvement in ejection fraction seen in the 19 patients with pre-existing LV systolic dysfunction.
Major limitations of this study include its nonrandomized design, and the possibility that the small number of control patients may not have been adequately matched — for instance, the control group had significantly lower baseline systolic BP. Therefore the results can only be considered hypothesis generating. It is possible that the improvements in BP and LV hypertrophy seen following RDN were simply due to improved compliance with antihypertensive medications, a factor which was not adequately assessed in this study.
The full results of HTN-3, to be presented imminently at ACC, are eagerly awaited, will be hotly debated and will guide future development of this therapy. Even if enthusiasm has been dampened, there are certainly enough signals from studies such as this one that RDN does have clinically relevant effects to warrant further well designed randomized controlled trials.
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