Experts debate merits of adrenal vein sampling in primary aldosteronism
CHICAGO — Adrenal vein sampling is often touted as a “gold standard” method to select patients for the surgical management of primary aldosteronism; however, for many reasons, its superiority and accuracy is increasingly being challenged, as two experts highlighted during a debate here.
Cross-sectional imaging via CT or MRI lacks the accuracy to direct surgical therapy, whereas lifelong medical management does not fully address one of the most important concerns among patients — quality of life, William F. Young, MD, MSc, chair of endocrinology and professor of medicine at the Mayo Clinic College of Medicine in Rochester, Minnesota, said during his portion of the debate on the utility of adrenal vein sampling at the Endocrine Society Annual Meeting. The 2016 Endocrine Society guidelines recommend adrenal vein sampling to distinguish between unilateral and bilateral disease, which typically determines whether patients will be managed with surgery or medical therapy.
“The accurate localization of aldosterone-producing adenomas is essential for curative surgical intervention,” Young said. “Simply put, adrenal vein sampling carries high accuracy and cross-sectional imaging with CT or MRI does not.”
But adrenal vein sampling has many downsides, and is not the most practical option when managing most patients, Paul Stewart, MD, FRCP, faculty dean of medicine and health and professor of medicine at the University of Leeds, United Kingdom, said during his counter-argument. Imaging innovation — and not adrenal vein sampling — will likely provide the way forward in managing the disease, Stewart said.
“Adrenal vein sampling is invasive, hard to do, frequently fails, is costly and is without evidence base in terms of improving outcome for patients with primary aldosteronism,” Stewart told Endocrine Today before the debate. “There is no unified agreement over the protocols to be used, nor over its interpretation. So, why do it?”
‘Flipping a coin in the air ’
Using a case study in which a male patient underwent both CT and adrenal vein sampling, Young highlighted the difficulty of identifying which adrenal gland has aldosterone excess — or, whether both sides do —when nodules are observed on both the left and right sides. In studies conducted at the Mayo Clinic in 2004 and at the University of Michigan in 2017, 25% and 12% of patients, respectively, would have been bypassed for curative surgery had they not undergone adrenal vein sampling, Young said. Even more importantly, he said, nearly one-quarter of the patients at Mayo Clinic and one-third of the patients at the University of Michigan would have gone on to surgery and it would not have impacted their primary aldosteronism had they not undergone adrenal vein sampling, as CT imaging indicated the wrong adrenal producing aldosterone excess, Young said.
“The accuracy of CT is about 56%,” Young said. “It’s not much better than flipping a coin in the air.”
A “myth” persists among endocrinologists that adrenal vein sampling is too difficult a procedure to be practical and generalizable, Young said. The key, he said, is for the endocrinologist to develop a partnership with a trusted interventional radiologist with a consistent protocol. Technology has also improved, making the process easier than adrenal vein sampling procedures 15 years ago.
“Adrenal vein sampling is not difficult, but it does require some effort,” Young said. “The endocrinologist needs to identify one interested and engaged interventional radiologist to develop their adrenal vein sampling program together.”
A ‘pragmatic solution’
Endocrinologists must think very hard about the utility of adrenal vein sampling, Stewart said. For most patients with aldosterone producing adenomas, the procedure is not practical nor cost effective, has poor reproducibility, and lacks consensus on both protocol and the interpretation of any data the test generates, he said.
“What might we expect of a ‘gold standard?’ I think we use this term glibly,” Stewart, also an honorary consultant endocrinologist at the Leeds Teaching Hospitals NHS Trust, said here. “Is adrenal vein sampling easy to do? It certainly isn’t. Is it safe or noninvasive? No. There is a complication rate — adrenal hemorrhage, adrenal vein dissection and a nice paper in the journal literature showed that the radiation exposure through fluoroscopy is 6 times that of someone having a coronary angiography.”
Addressing the discordant rate between imaging and adrenal vein sampling, Stewart noted the discordant rate between repeat adrenal vein sampling procedures.
“What do you think the discordant rate is between adrenal vein sampling on day 1, and then repeat adrenal vein sampling on a second time?” Stewart said. “It’s 66%. Adrenal vein sampling is only accurate in 33% of cases, and indeed, in 1 in 6 cases, you see a flip in which side the tumor is located. There is no reproducibility at all for this gold-standard test.”
A “pragmatic solution” for most patients, Stewart said, should include considering surgery in patients aged 35 years and younger, and possibly up to age 50 years, when there is a typical adrenal lesion observed on a fine cut CT scan and the contralateral adrenal gland appears normal. Mineralocorticoid receptor blockade therapy is “highly effective” as an alternative to surgery, Stewart said.
“We don’t need to operate on everybody,” Stewart said. “The challenge is to address the mass population with this disease, insuring that we are treating them appropriately and attacking the wider cardiovascular risk profile. My contention is adrenal vein sampling is rarely indicated.”
Logistics are also an issue when it comes to adrenal vein sampling, Stewart said.
“These patients [with primary aldosteronism] are all over the U.S., not just clustered around a center of excellence,” Stewart said during the rebuttal portion of the debate. “And that’s the real challenge, making sure we can provide the most appropriate therapy and avoid the potential misleading consequences of performing adrenal vein sampling.” – by Regina Schaffer
Stewart PM, Young WF. Debate: This House Believes that Adrenal Vein Sampling has a Major Role to Play in the Management of Patients with Primary Aldosteronism. Presented at: The Endocrine Society Annual Meeting; March 17-20, 2018; Chicago.
Disclosures: Young reports he is a consultant for Nihon Medi-Physics Ltd., a company working on noninvasive imaging techniques to localize the source of aldosterone excess.