Night-time SBP predicts renal denervation response
Twenty-Four-Hour Blood Pressure Monitoring to Predict and Assess Impact of Renal Denervation. The DENERHTN Study (Renal Denervation for Hypertension)
Background
Renal denervation on top of a standardized stepped-care antihypertensive treatment (SSAHT), significantly reduced daytime, night-time, and 24-hour ambulatory systolic blood pressure (SBP), compared with SSAHT alone, in patients with well-defined resistant hypertension (RH). This finding of the DENERHTN trial (Renal Denervation for Hypertension trial) was confirmed by ambulatory blood pressure monitoring (ABPM) [1]. The use of ABPM for the evaluation of the blood pressure effect by renal denervation contributes to the elimination of observer bias and placebo effect, and allows investigating the effects of renal denervationon a 24-hours basis, and on indices of blood pressure variability [2].
In this predefined analysis, the ABPM results were evaluated in detail, especially those of blood pressure and heart rate (HR) variability, and it was assessed whether ABPM can help predicting blood pressure response to renal denervation.
Main results
- From baseline to 6 months, the mean decreases in daytime, night-time and 24-hour ambulatory SBP were significantly greater in the renal denervation group compared with the control group, with a mean baseline-adjusted difference of approximately −6.0 mmHg.
- The smoothness index was significantly greater in the renal denervation group (1.4±1.2) compared with the control group (0.9±0.6, P=0.02), whereas there were no significant differences in regard to the standard deviations of SBP, diastolic blood pressure and HR, ambulatory arterial stiffness index or the proportion of non-dipper patients.
- The number of responders was significantly higher in the renal denervation group (44.5%) than in the control group (20.8%, P=0.01).
- In univariate analysis, 5 baseline variables were significantly different between responders and non-responders: treatment group, average 24-hour-, daytime-, and night-time SBP and night-time standard deviation of SBP (SDSBP) calculated on wide or narrow periods.
- The number of patients with isolated systolic hypertension did not differ significantly between responders (25%) and non-responders (37%).
- In the stepwise discriminant analysis, baseline average night-time SBP, night-time SDSBP and the treatment group remained significant predictors of daytime SBP response. When analysis was restricted to the renal denervation group, only average night-time SBP and night-time SDSBP remained significantly associated to responders (P=0.005).
- In the receiver operating characteristic (ROC) curves to predict responders according to baseline night-time SBP, night-time SDSBP values and L score in the renal denervationgroup, the area under the curve (AUC) was 0.65 (95% CI: 0.486–0.816; P=0.07) for baseline average night-time SBP and 0.72 (95% CI: 0.565–0.874; P=0.005) for baseline night-time SDSBP.
- For baseline average night-time SBP, a cut-off of 136 mmHg offers the best compromise between sensitivity (75%) and specificity (54%) to predict responders.
- For night-time SDSBP, a cut-off of 12 mmHg offers the best compromise between sensitivity (55%) and specificity (83%) to predict responders.
- When combined together, the 2 cut-off points allow adequate classification of 70% of patients who underwent renal denervationin responder and non-responder groups. The AUC for the L score was 0.76 (95% CI: 0.615–0.900; P<0.001).
Conclusion
Renal denervation in addition to standard antihypertensive treatment results in lower blood pressure in patients with resistant hypertension, with a homogenous effect over 24 hours. Night-time SBP and its variability were the best ABPM-derived predictors for renal denervation responders. These findings confirm the guidelines recommendation, according to which, 24-hour ABPM should systematically precede any decision of renal denervation.
Editorial comment
In the editorial article [3], Hering discusses the treatment of resistant hypertension with renal denervation and comments on the DENERHTN trial as follows: ‘..., the investigators of the DENERHTN trial should be commended on their efforts in performing a rigorously designed multicenter randomized clinical trial and for considering limitations encountered in previous renal denervation studies, including standardized medication therapy, comprehensive independent and blinded assessment of ambulatory blood pressure monitoring, medication adherence assessment and ensuring renal denervationwas supervised by an experienced interventionalist across the Hypertension Excellence Centres.’ The author also highlights the importance of being able to predict good response to this procedure that shows a high variability between patients and concludes: ‘While the improvement of patient adherence to medication can considerably decrease the prevalence of renal denervation, there is still a portion of patients who remain drug-resistant despite all available antihypertensive drug classes as indicated in the DENERHTN study. Renal denervation has the potential to substantially improve blood pressure control on top of medication and should be indicated for difficult to treat hypertension provided that it is performed in properly selected patients and experienced centers. Baseline night-time blood pressure may serve as a marker in predicting response to renal denervation and should be further explored in appropriately designed clinical trials with particular consideration given to validated ambulatory blood pressure devices with defined and adjusted diurnal and nocturnal times.’
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