Feasibility Study of RadioFrequency Endoscopic ABlation, With ULtrasound Guidance, as a Non-surgical, Adrenal Sparing Treatment for Aldosterone-producing Adenomas

Primary hyperaldosteronism (PA) is one of the commonest causes of hypertension. It is estimated to be the root cause in 10% of all patients with hypertension and 20% of all patients with resistant hypertension. Conventionally, patients with PA are divided 50:50 into those with a curable, unilateral aldosterone-producing adenoma (APA), and those with bilateral idiopathic adrenal hyperplasia (IAH).

Individual clinicians may reasonably consider it unnecessary to diagnose a benign condition whose work-up for surgery can be arduous, and the benefits uncertain. Public health doctors could reasonably despair at a large increase in demand for scarce surgical resources, when long term comparison of medical and surgical approaches have not been undertaken. Yet PA is regarded as a high-risk subset of hypertension, with an estimated 4-12 fold excess rate of cardiovascular complications compared to otherwise comparable patients with Hypertension. The American Endocrine Society Guidance recommends that where resources permit, a unilateral APA should be removed in order to protect patients from the long-term consequences of excess aldosterone. At present, most APAs are removed by key-hole surgery, with a 2% conversion rate to open surgery.

While such surgery is justified by the serious cardiovascular risk of PA, the high level of proof (of unilateral disease) before surgical referral has the paradoxical outcome of reducing take-up of a procedure that can be life-prolonging. A further paradox is that the rigid division of PA into unilateral adenoma vs bilateral hyperplasia is probably incorrect and that an intervention which does not require the distinction may, in stages, come to be regarded as the more logical approach to cure of PA, with reduction/prevention of cardiovascular risk. The obvious alternative intervention is selective ablation of APA(s), sparing most of the adjacent adrenal gland. Several publications report anecdotal success using this technique. The eligibility criteria for ablation were variable, but generally the patients were medically unfit or declined to undergo surgery. Success rates, measured as reversal of the biochemical abnormalities of PA, and radiological resolution, were high. However, there were few major adverse events. Most patients were monitored in hospital after the procedures, with shorter stays than the 2-3 days typical of most centres following laparoscopic surgery.

The investigators wish to progress from the experience with percutaneous and retroperitoneoscopic ablation to an approach which should maximise the ease and applicability of ablation whilst reducing the risk of adverse events. The primary outcome of the study will be safety. However, by the end of the study the investigators also need to have sufficient evidence of efficacy to justify, and guide design of, a subsequent multi-centre comparison trial.

Population Patients over the age of 18 diagnosed with left adrenal aldosterone producing adenoma meeting criteria from Endocrine Society clinical practice guidelines for primary hyperaldosteronism. The intervention (ultrasound guided endoscopic radiofrequency ablation) will be offered to those unsuitable for left adrenalectomy, who do not want surgery, or those who meet the criteria for surgery but wish to consent to radiofrequency ablation.