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Adrenal vein sampling, CT scanning yield similar outcomes in primary aldosteronism screening
ORLANDO, Fla. — As a screening method, adrenal vein sampling is a “brilliant concept” when used to identify primary aldosteronism and its subtypes, but the invasive procedure is not without its faults when compared with adrenal CT scanning, according to a speaker here.
Jaap Deinum, MD, PhD, a specialist in vascular medicine at Radboud University Medical Center in the Netherlands and current president of the Dutch Society of Hypertension, said compared with adrenal CT scans, adrenal vein sampling (AVS) identified the presence of aldosterone-producing adenomas — present in about half of primary aldosteronism cases — at a similar rate and resulted in similar clinical benefits after 1 year of follow-up.
“The distinction [between subtypes] is important because the treatment is different,” Deinum said, speaking during a session on controversies in primary aldosteronism. “We perform adrenalectomy for an [aldosterone-producing adenoma], and we prescribe a mineralocorticoid receptor antagonist, like spironolactone, for [bilateral] hyperplasia.”
CT scans can detect only a difference in size in the adrenal glands, according to Deinum, and the procedure is generally thought to be nonspecific and have limited sensitivity, as it cannot identify small nodules. He said AVS is considered a “gold standard” test, as it can discriminate between the two subtypes.
“But how good is AVS, actually?” Deinum asked. “Physiologically, it’s a brilliant concept, but there are some issues with it, which are mainly practical. It’s a laborious test. It’s patient unfriendly, it’s expensive, it’s invasive, with a slight risk for complications. Radiation exposure can be substantial, and there is limited availability for a growing number of patients.”
In addition, the evidence supporting AVS is based on retrospective studies, which are susceptible to bias, Deinum said.
In the SPARTACUS trial, a diagnostic randomized controlled trial conducted at 13 Dutch and Polish medical centers, Deinum and Tanja Dekkers, MD, of the division of vascular medicine at Radboud University Medical Center, and colleagues analyzed data from 184 adults with confirmed primary aldosteronism assigned at least three antihypertensive drugs or with hypertension accompanied by spontaneous or diuretic-induced hypokalemia. Patients were recruited between July 2010 and May 2013. The researchers randomly assigned patients to undergo adrenal CT scanning (n = 92) or AVS (n = 92). Patients assigned to CT scanning underwent adrenalectomy in cases of a unilaterally enlarged adrenal with a normal contralateral gland; patients with bilaterally enlarged or normal adrenal glands were prescribed mineralocorticoid receptor antagonist therapy. Antihypertensive therapy was initiated and adjusted by treating physicians during follow-up to achieve target blood pressure.
Of the 92 patients assigned to undergo CT scans, 46 underwent adrenalectomy and 46 were prescribed mineralocorticoid receptor antagonist therapy. Of the 92 assigned to AVS, 46 underwent adrenalectomy and 46 were prescribed mineralocorticoid receptor antagonist therapy. There were no differences in the intensity of antihypertensive medications required to control BP between patients with CT-based treatment vs. AVS-based treatment, Deinum said. In the CT scan group, 39 patients (42%) reached target BP vs. 41 patients (45%) in the AVS group. Researchers found no between-group differences in health-related quality of life.
Biochemically, 37 (80%) patients with CT-based adrenalectomy and 41 (89%) of those with AVS-based adrenalectomy had resolved hyperaldosteronism (P = .25). Adverse events were similar between groups.
The findings suggest that both procedures are “imperfect” tests, Deinum said.
“This is a bit contrary to the expectations. ... AVS was not better than CT [scanning],” he said. “Why is that? Well, perhaps AVS and CT scans identify different kinds of aldosterone-producing adenomas. If this is the case, then our concept of adenoma as opposed to hyperplasia as a dichotomy is probably wrong.
“There are similar outcomes after CT- or AVS-based management,” Deinum said. “AVS and CT both are imperfect tests. So, that means that AVS cannot be considered the real ‘gold standard’ test. We have also shown that a prospective, randomized trial in primary aldosteronism is feasible, and we think that this design should be employed more often.” – by Regina Schaffer
Reference:
Deinum J. Is adrenal vein sampling the gold standard? Results from the SPARTACUS trial. Presented at: The Endocrine Society Annual Meeting; April 1-4, 2017; Orlando, Fla.
Disclosure: Deinum reports no relevant financial disclosures.
Perspective
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Jaap Deinum, MD, PhD, is a plausible speaker, and his inclusion in a session on controversies in primary aldosteronism is clearly appropriate given the unexpected outcome of the SPARTACUS trial. It is also appropriate to include in any presentation the particularities of the trial which may have contributed to the failure of the investigators to find a significant difference between AVS and CT:
- Obvious and marked sex and age selection biases: of 184 subjects only 50 were women, and the mean age in both AVS and CT groups was 53.1 years;
- The referred cohort was at the very florid end of primary aldosteronism (resistant hypertension and/or hypokalemia), with only 12% meeting exclusion criteria;
- The lateralization discrepancy (CT right 12, left 38; AVS right 22, left 26);
- The discordance between local and central imaging in 14 patients;
- The unusual medication schedule for non-lateralized patients (mineralocorticoid receptor antagonists progressively up to 200 mg/day spironolactone, 400 mg/day eplerenone), followed by adjunct therapy as required;
- The extraordinary 340 adverse events in 136 patients, 21 serious.
The data are what they are. I have no quarrel with the reporting, but with the interpretation. This is in no way a representative group of patients with primary aldosteronism, and to extrapolate from this group to primary aldosteronism across the board is not justified. Transparency is fundamental to medical research — basic, translational and clinical. Transparency demands that presentations include the various issues that would make generalization hazardous.
The gold standard refers to a currency provision that was abandoned almost a century ago. AVS is not the gold standard, but remains the way to lateralize adrenal hypersecretion in all but a very small fraction of patients with primary aldosteronism. It is expensive, but in expert hands remarkably accurate. It is my hope that it will be increasingly replaced by cheaper, equally accurate means, but this will not be imaging by CT.