Does Contralateral Suppression at Adrenal Venous Sampling Predict Outcome Following Unilateral Adrenalectomy for Primary Aldosteronism? A Retrospective Study

Context: In primary aldosteronism (PA), adrenal vein sampling (AVS) distinguishes unilateral and bilateral disease by comparison of aldosterone/cortisol (A/F) ratios. There is controversy about the criteria for interpretation, however, and in particular it is not clear whether contralateral suppression (CS) (defined as A/F-adrenal <= A/F-peripheral on the unaffected side) is important. Wetherefore performed a retrospective study to determine whether CS in surgically treated unilateral PA was associated with blood pressure (BP) and biochemical outcomes. Setting and Design: Patients who underwent unilateral adrenalectomy for PA after successful AVS were included if the lateralization index (A/F-dominant: A/F-nondominant) was >= 2. Cases were reviewed at 6 to 24 months follow-up for outcomes with respect to the presence and degree of CS. Results: Sixty-six of 80 patients had CS. Baseline characteristics were similar. At postoperative follow-up, those with CS had lower systolic BP (SBP) (128 mm Hg vs 144 mm Hg, P = 001), a greater proportion with cure or improvement of hypertension (96% vs 64%, P = 0034), a greater proportion with biochemical cure of PA on fludrocortisone suppression testing (43 of 49 [88%] vs 4 of 9 [44%], P = 002) and were taking a lower median number of antihypertensive medications (0 vs 1.5, P = 0032). In a multivariate model, the degree of CS and preoperative SBP were both significantly correlated with postoperative SBP, but the lateralization index, sex, and age were not. Conclusion: In this study, the presence of CS correlated with good BP and biochemical outcomes from surgery. This finding suggests that CS should be a factor in deciding whether to offer surgery for treatment of PA.