Finding new treatments for drug-resistant hypertension

While there are many effective drugs to treat high blood pressure (also known as hypertension), they don’t work for everyone. Professor Morris Brown, previously at the University of Cambridge and now at Queen Mary University of London, has a long-standing interest in an underlying cause of drug-resistant hypertension, called primary hyperaldosteronism, or Conn’s syndrome. In this condition, a small non-cancerous tumour (adenoma) on one or both adrenal glands (just above the kidneys), pumps out too much of a hormone called aldosterone, raising blood pressure. It’s increasingly recognised that Conn’s syndrome is a far more common cause of hypertension than previously thought, being present in at least 10% of all people with hypertension, and up to 20% of people with resistant hypertension.

If Conn’s syndrome is caused by a tumour in a single adrenal gland, some patients are cured of their high blood pressure by removing the gland with surgery. But even though this treatment is available, very few people get tested for Conn’s syndrome, and they are often diagnosed too late for the damaging effects of high blood pressure to be reversed. This is because making the diagnosis requires an invasive procedure called adrenal vein sampling. Doctors can feel reluctant to put patients through this invasive test for Conn’s syndrome if they think it’s unlikely to be the cause of their symptoms anyway.

Developing a non-invasive test to diagnose Conn’s syndrome

In 2007, the BHF funded Professor Brown to develop a new imaging technique to simplify the diagnosis of Conn’s syndrome. Building on work originally done by Swedish researchers, Professor Brown and his team developed a simple, non-invasive PET-CT scan using a radiotracer that lights up the tiny tumours which are responsible. The PET-CT scan has the potential to transform the diagnosis of Conn’s syndrome. The scan has been used in some 200 patients and is currently being tested against adrenal vein sampling (the standard diagnostic test) in the MATCH clinical trial to find out if it is as effective for diagnosing Conn’s syndrome.

Towards a targeted treatment for Conn’s syndrome

Currently the usual treatment for an adrenal gland tumour (adenoma) is the removal of the whole adrenal gland by keyhole surgery (called laparoscopic adrenalectomy). But doctors are often reluctant to remove the whole gland to get rid of what they regard as a tiny, non-cancerous tumour. A potential exciting solution is to use an electric current to remove the nodule without affecting the rest of the adrenal gland, avoiding the need for surgery. The BHF is currently funding a clinical trial led by Professor Brown (the WAVE trial) designed to compare the effectiveness of this approach with keyhole surgery. The results of this study could transform the treatment of people with Conn’s syndrome, and reduce their risk of complications from high blood pressure, such as heart attacks and strokes.

First published 1st June 2021