What class of antihypertensive agents is contraindicated in patients with bilateral renal artery stenosis due to the risk of acute renal failure?

Angiotensin-converting enzyme (ACE) inhibitors are contraindicated in patients with bilateral renal artery stenosis because they can lead to acute renal failure. In these patients, renal perfusion is already compromised due to the narrowed arteries supplying the kidneys. ACE inhibitors decrease the production of angiotensin II, a hormone that plays a critical role in constricting efferent arterioles of the glomeruli, thus maintaining glomerular filtration rate (GFR). When the efferent arterioles dilate as a result of ACE inhibition, it can lead to reduced renal perfusion pressure and further compromise kidney function, potentially resulting in acute renal failure.

In contrast, thiazide diuretics, calcium channel blockers, and potassium-sparing diuretics do not carry the same risk in this scenario. Thiazide diuretics primarily work on the distal convoluted tubule and do not significantly affect the renal blood flow through alterations in angiotensin II levels. Calcium channel blockers primarily affect vascular smooth muscle and do not directly interfere with renal blood flow in the context of renal artery stenosis. Potassium-sparing diuretics act on the collecting ducts and also do not have the same adverse impact as ACE inhibitors when it