Uncontrolled hypertension is not the same as resistant hypertension. Experts at the third UK Symposium on Renal Denervation (16 October, London, UK) urged physicians to universally apply ambulatory blood pressure monitoring in order to help distinguish between the two and work within a multidisciplinary team to suitably select patients before offering the minimally invasive catheter-based procedure.
True resistant hypertension is a fraction of uncontrolled hypertensions as the latter includes patients with pseudohypertension, ie those with white coat effect and those who do not take their medication as prescribed. Appropriate patient selection is crucial for renal denervation treatment success and requires close cooperation between hypertension specialists and interventionists, the experts noted.
In the SYMPLICITY HTN-2 trial, patients with office systolic blood pressure of ≥160mmHg (≥150mmHg if they had type II diabetes mellitus), and a stable regimen of three or more antihypertensive medicines, were offered renal denervation as long as they did not have any of the exclusion criteria.
Mark Caulfield, William Harvey research Institute and Barts NIHR Cardiovascular Biomedical Research Unit, Queen Mary University of London, UK, told delegates that confirmation of sustained raised blood pressure using ambulatory blood pressure monitoring is essential. “This will allow the detection of ‘white coat’ or alerting response which may be the cause of apparently resistant hypertension,” he said.
Caulfield also said that most national and international guidelines recommend that selection, treatment and follow-up of patients for this intervention requires a multidisciplinary team which must include hypertension specialists who can demonstrate active involvement in the routine investigation and care of patients with resistant hypertension.
Murray Esler, senior director, Baker IDI Heart and Diabetes Institute, Melbourne, Australia, made the point that renal denervation is a field in evolution, with many unanswered questions. “It is important to use ambulatory 24-hour blood pressure measurements that will screen out white coat hypertension, and allow comparison between office and ambulatory blood pressure reduction after the procedure,” he said.
Esler also said that it was imperative to identify patients who are drug-resistance confounders. Based on data adapted from Calhoun DA et al (Circulation 2008), Esler noted that “It is important to eliminate pseudoresistance which could be attributable to imperfect drug choices by the doctor, poor patient concordance to prescribed drugs and the white coat effect.”
Physicians must identify and treat contributing lifestyle factors such as obesity, physical inactivity, excessive alcohol ingestion and salt intake. “Non-steroidal anti-inflammatory agents, sympathomimetics such as diet pills and decongestants, stimulants, oral contraceptives, licorice and psychotropic drugs should be discontinued or minimised as they are interfering substances,” he said.
Esler also noted that physicians need to screen for the secondary causes of hypertension and that pharmacological treatment has to be maximised. “Maximise diuretic therapy, combine agents with different mechanisms of action and use aldosterone antagonists such as spironolactone, if required,” he said.
With around 81 companies developing renal denervation devices and 60 trials about renal denervation listed on clinicaltrials.gov, there is a clear and evident interest in the procedure. Experts have noted that the endovascular nerve ablation procedure is at an “end of the beginning” stage with many questions currently unanswered.
Melvin Lobo, consultant physician, NIHR Barts Cardiovascular Biomedical research Unit, speaking at the UK Symposium on Renal Denervation told delegates that a UK registry had been created in view of the paucity of data to support the widespread adoption of renal denervation as standard of care treatment for resistant hypertension. Data on all patients undergoing this procedure in the UK must be submitted to inform practice, generate research opportunities and permit audit of clinical effectiveness and outcomes, delegates were told.