To the Editor:

Thank you to Dr. Quencer and colleagues for an excellent article on primary aldosteronism.¹ I have two questions about testing for primary aldosteronism in patients with atrial fibrillation (AF):

• The authors recommend testing for primary aldosteronism in all patients with AF. Is this true even when blood pressure is normal? If so, can we expect the AF to resolve if the underlying aldosterone concerns are addressed and there are no other contributing causes?

• If a patient is normotensive, can we assume that they do not have primary aldosteronism, even with AF or other risk factors?

In Reply

We thank Dr. Dudley for these questions on case detection testing for primary aldosteronism in patients with AF. Our article states that patients with AF and hypertension should undergo case detection with measurement of the aldosterone-renin ratio.

Although the most recent Endocrine Society guidelines do not include unexplained AF as an indication for case detection, they acknowledge that some institutions measure aldosterone-renin ratio for patients with new-onset AF.¹ A prospective study published in 2020 found that 42% of patients with nonvalvular AF had primary aldosteronism.² A meta-analysis found that AF was 3.5 times more common in patients with primary aldosteronism than in those with essential hypertension.³

The rate of primary aldosteronism in patients with unexplained AF is nearly 4 times higher than the rate in patients with well-established reasons to screen for primary aldosteronism (e.g., resistant hypertension).

Proposed causal mechanisms for development of AF in patients with primary aldosteronism include cardiac fibrosis, electrical remodeling, ventricular diastolic dysfunction, and hypokalemia.⁴ With targeted medical or surgical treatment for primary aldosteronism, the prevalence of AF decreases to that seen in patients with essential hypertension.⁵ Therefore, primary aldosteronism case detection should be considered in hypertensive patients with otherwise unexplained AF.

Normotensive primary aldosteronism exists but is rare.⁶ It is typically discovered on workup for hypokalemia or an incidental adrenal nodule, and many of these patients develop hypertension. For practical purposes, patients with normal blood pressure do not need testing for primary aldosteronism, even with risk factors such as unexplained AF.