Background:
Adrenal vein sampling (AVS) is crucial for differentiating between unilateral and bilateral causes of primary aldosteronism (PA) [1]. However, there is a lack of uniform agreement regarding use of adrenocorticotropic hormone (ACTH) stimulation during AVS [2]. At Monash Health, AVS has been performed both pre- and post-ACTH stimulation since 2010.
Aim:
We reviewed the impact of ACTH stimulation on AVS success rates and outcomes including selectivity index (SI=cortisol adrenal vein : cortisol peripheral vein), lateralization index (LI= aldosterone-cortisol ratio dominant adrenal vein : aldosterone-cortisol ratio non-dominant adrenal vein) and contralateral suppression index (CSI= aldosterone-cortisol ratio non-dominant adrenal vein : aldosterone-cortisol ratio peripheral vein).
Methods:
An audit was conducted on AVS procedures performed at Monash Health between January 2010 and March 2015 inclusive. Clinical information was collected on screening aldosterone and renin concentration, AVS aldosterone and cortisol levels pre- and post-ACTH stimulation, adrenal imaging, blood pressure and antihypertensive medication. Successful cannulation was defined as SI > 2 pre-ACTH and >3 post-ACTH; successful lateralisation was defined as LI >3 pre-ACTH and > 4 post-ACTH, and supported by CSI < 1.
Results:
Out of 28 AVS cases with pre-and post-ACTH data, cannulation success of the left adrenal vein was 81% (22/27) pre-ACTH and 96% (26/27) post-ACTH; and of the right adrenal vein was 60% (17/28) both pre-and post-ACTH. The improved cannulation rate was not associated with the timing of AVS. However, ACTH stimulation significantly lowered the LI and incorrectly obscured lateralization in five cases. These patients were diagnosed with unilateral aldosterone excess based on their pre-ACTH LI and CSI. ACTH did not significantly affect the CSI. Four of these patients have had successful surgery with one awaiting surgery.
Conclusion:
The rate of successful cannulation in AVS increased after ACTH stimulation, but at the cost of masked lateralization.