Background:
Primary aldosteronism (PA) is a common cause of secondary hypertension found in 5 to 10% of the hypertensive patients. The diagnostic of PA is important because it is associated with adverse cardiovascular outcomes and may be cured with surgery. The principal forms of PA are the adrenal adenoma (unilateral) and the hyperplasia of adrenal glands (bilateral). Adrenal vein sampling (AVS) is considered the gold standard to distinguish the unilateral from the bilateral form of PA. Compared to computed tomography scanners (CT-scan), AVS is often discordant. This discordance could be secondary to a lack of sensitivity of cortisol, the marker used to assess lateralization. Free metanephrines (fMN), which are continuously released by the adrenal gland could be a potential alternative. We hypothesized that the discordance with CT-scans would be lower when fMN were used as marker of lateralization.
Objective:
To compare the concordance of adrenal angio-CT with AVS using cortisol (control marker) and free metanephrine (new marker) as AVS lateralization markers.
Methods:
This study was prospective and monocentric. Patients with PA who had both a CT-scan and a bilaterally selective AVS and were included in the analysis. A Fisher exact test was used to compare the two methods (AVS and CT-san) with each marker. A Cohen’s kappa coefficient was then used to compare the level of agreement.
Results:
A total of 101 participants (42 women/49 men) were included in the Study. Using a cut-off level of 3 for lateralization, the levels of agreement of CT-scan with AVS using fMN was 0.3010.072 compared to 0.2720.070 with AVS using cortisol. Using a cut-off level of 5 for lateralization, the levels of agreement of CT-scan with AVS using fMN was 0.2470.066 compared to 0.1950.064 with AVS using cortisol. The best agreement between AVS using PCC and PFMC is when the less stringent lateralization index is used (3 vs 5).
Conclusion:
The use of plasma free metanephrine concentration as a maker for lateralization only marginally improved the concordance of AVS compard to CT-scan. It confirms that the decision to surgically or pharmacologically treat patient with hypertension should no rely solely on imagery. More studies are needed to determine the utility of fMN in the interpretation of AVS lateralization.