The Intra-Procedural Cortisol Assay During Adrenal Vein Sampling: Rationale and Design of a Randomized Study (I-Padua).

INTRODUCTION: Adrenal vein sampling (AVS) is the gold standard test for the subtyping of primary aldosteronism (PA). This procedure is hampered by unsuccessful bilateral cannulation of adrenal veins in up to two thirds of the cases depending on the cutoff of the selectivity index used. The rapid intra-procedural cortisol assay (IRCA) can increase the rate of bilateral success of AVS. This hypothesis needs to be proven using a randomized prospective study approach.

AIM: We will therefore evaluate if an IRCA guiding adrenal vein sampling can increase the rate of selectivity and success of adrenal vein catheterization.

METHODS: Consecutive patients with a biochemical diagnosis of PA and seeking surgical cure will be randomized to undergo AVS according to the usual practice with or without IRCA. The primary endpoint of the study will be the rate of bilaterally selective AVS studies, as defined by a value of the selective index >2.00 under baseline (unstimulated) conditions. With a total of 200 patients submitted to AVS, e.g. 100 patients in each arm, the study has 82% power to detect a 18% difference between arms at a two-sided α level =0.05.

EXPECTED RESULTS: Given this power the study should allow to conclusively determine if IRCA is useful or not for improving the success rate of AVS. From the clinical standpoint this will be a major accomplishment in the field of the subtyping of PA considering the current disastrous situation regarding the clinical use of AVS.