RÉSUMÉ
Adrenal vein sampling (AVS) is the standard procedure for distinguishing unilateral primary aldosteronism (PA) from bilateral PA. In cases where only one adrenal vein is successfully cannulated, it has been suggested that subtype classification can be determined based on the ratio of the concentration of aldosterone between the adrenal vein and the inferior vena cava (AV/IVC index). However, diagnostic performance of the ipsilateral versus contralateral AV/IVC index in predicting lateralization has not been directly compared. In a retrospective cohort of 133 patients with confirmed PA who underwent successful AVS, the performance of the AV/IVC index to predict laterality was evaluated and the area under the receiver operating characteristic (AUROC) curves was calculated. In detecting left unilateral PA (n = 47), the AUROC of the right AV/IVC index (RAV/IVC) was significantly higher than the AUROC of the left AV/IVC (LAV/IVC) index (0.967 vs. 0.871, p = 0.008). In detecting right unilateral PA (n = 30), the AUROC of the LAV/IVC index tended to be higher than that of the RAV/IVC index, but the difference did not reach statistical significance (0.966 vs. 0.906, p = 0.08). In detecting left unilateral PA, the sensitivities of the RAV/IVC and LAV/IVC indices were 83% and 46%, respectively, while the specificities of both were above 90%. In detecting right unilateral PA, the sensitivities of the LAV/IVC and RAV/IVC indices were 80% and 43%, respectively, while the specificities of both were above 90%. The AV/IVC index has superior diagnostic performance in detecting contralateral unilateral PA compared to ipsilateral unilateral PA.