Original title: Impaired Cardiac Baroreflex Sensitivity Predicts Response to Renal Sympathetic Denervation in Patients with Resistant Hypertension. Reference: Christine S. Zuern et al. J Am Coll Cardiol, article in press.
Renal denervation is a new treatment option for patients with resistant arterial hypertension and it is assumed to reduce efferent renal and central sympathetic activity.
Given the multifactorial nature of arterial hypertension pathophysiology (sympathetic system, genetics, lifestyle, diet and metabolic factors), renal denervation will hardly affect all patients in a similar way. Up to now, only baseline values are known to predict the effect (the higher baseline pressure, the more reduced). Therefore, patients with more sympathetic activity should see more benefits; however, it is very difficult to measure this benefit directly through norepinephrine secretion in the daily practice. The association between spontaneous fluctuation of arterial pressure and heart beat, known as cardiac baroreflex, can inform us about sympathetic activity in a non invasive way. Reduced sensibility to this reflex is well associated to hypertension and other pathologies with increased sympathetic activity.
The study included 50 consecutive patients with resistant arterial hypertension (≥ 160 mmHg despite at least 3 drugs) and sinus rhythm (essential to calculate reflex sensitivity). Denervation was performed with the Flex catheter (Ardian/Medtronic Inc., Mountain View, USA) with up to 6 2 minute ablations for each renal artery.
Reflex sensitivity was measured before denervation using a finger photoplethysmograph (Finapres; TNO-TPD Biomedical Instrumentation, Amsterdam, The Netherlands) and a high-resolution ECG. Six months after denervation, mean systolic BP on ABPM was significantly reduced to 149±20mmHg, p=0.003; and diastolic to 4±12; p=0.022).
Twenty-six of the 50 patients (52.0%) saw reduced systolic pressure ≥10 mmHg and were classified as responders. Patients with cardiac barorelfex sensitivity in the lower tertile (more inhibited sensitivity) showed greater reduction of systolic pressure (17±20 mmHg).
In the multivariable analysis, cardiac baroreflex resulted the best predictor of response to denervation, while baseline pressure and BMI had borderline significance.
Conclusion:
Cardiac baroreflex helps identify those patients that will benefit more from renal denervation and, equally importantly, those that will not benefit. Candidate selection should take into account baroreflex prior to denervation.
Editorial comment:
Although this method is more practical than direct measurement of sympathetic activity, it requires software and equipment that are not spread or validated worldwide.
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