Context: Adrenal venous sampling (AVS) is the key test for subtyping primary aldosteronism(PA), but its interpretation varies widely across referral centers and this can adversely affect themanagement of PA patients.Objectives: To investigate in a real-life study the rate of bilateral success and identification ofunilateral aldosteronism and their impact on blood pressure outcomes in PA subtyped by AVS.Design and settings: In a retrospective analysis of the largest international registry of individual AVS data (AVIS-2 study), we investigated how different cut-off values of the selectivity index(SI) and lateralization index (LI) affected rate of bilateral success, identification of unilateralaldosteronism, and blood pressure outcomes.Results: AVIS-2 recruited 1625 individual AVS studies performed between 2000 and 2015 in 19tertiary referral centers. Under unstimulated conditions, the rate of biochemically confirmedbilateral AVS success progressively decreased with increasing SI cut-offs; furthermore, withcurrently used LI cut-offs, the rate of identified unilateral PA leading to adrenalectomy wasas low as <25%. A within-patient pairwise comparison of 402 AVS performed both underunstimulated and cosyntropin-stimulated conditions showed that cosyntropin increased theconfirmed rate of bilateral selectivity for SI cut-offs = 2.0, but reduced lateralization rates(P < 0.001). Post-adrenalectomy outcomes were not improved by use of cosyntropin or morerestrictive diagnostic criteria.Conclusion: Commonly used SI and LI cut-offs are associated with disappointingly low ratesof biochemically defined AVS success and identified unilateral PA. Evidence-based protocolsentailing less restrictive interpretative cut-offs might optimize the clinical use of this costly andinvasive test.
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