The patient most likely has renal artery stenosis, which is suggested by the history of coronary artery disease, dyslipidemia, and TIA, and the increased creatinine in response to an ACE inhibitor.
Renal artery stenosis is the most common cause of secondary hypertension in adults. The two major causes of renal artery stenosis are atherosclerosis and fibromuscular dysplasia. Atherosclerosis is most likely in our patient, given his history of vascular problems and dyslipidemia. Fibromuscular dysplasia is caused by an abnormal arterial wall structure and is most commonly found in middle-aged women. Renal artery stenosis should be suspected when treatment with an ACE inhibitor or angiotensin-receptor blocker (ARB) causes an increase in creatinine, as angiotensin-mediated constriction of the efferent arteriole may be the only way that these patients are able to maintain an adequate glomerular filtration rate (GFR).
Vera and Neutze discuss specific findings that should motivate a search for secondary causes of hypertension. These include flushing and sweating (pheochromocytoma), a renal artery bruit (renal artery stenosis), and hypokalemia (hyperaldosteronism). If a renal artery bruit is detected, renal ultrasound may be useful in diagnosis.
Cooper et al. performed a randomized controlled trial to evaluate the benefit of renal artery stenting vs. medical therapy in elderly patients. Subjects all received medical therapy, while some underwent renal artery stenting in addition. The trial found that there was no benefit to renal artery stenting.
Illustration A is an MRI/MRA showing right renal artery stenosis in a patient with hypertension. Illustration B is a chart detailing several different causes of secondary hypertension, including associated signs and symptoms and work-up.
Answer 1: Creatinine should not increase in response to an ACE inhibitor in essential hypertension.
Answer 3: Coarctation of the aorta is associated with an arm to leg systolic blood pressure difference of >20 mmHg.
Answer 4: Pheochromocytoma is associated with periodic flushing and sweating.
Answer 5: Hyperthyroidism, not hypothyroidism, is associated with hypertension.
Viera AJ, Neutze DM. Diagnosis of secondary hypertension: an age-based approach. Am Fam Physician. 2010 Dec 15;82(12):1471-8.
PMID:21166367 (Link to Abstract)
Cooper, CJ, et. al. Stenting and medical therapy for atherosclerotic renal-artery stenosis. N Engl J Med. 2014 Jan 2;370(1):13-22.
PMID:24245566 (Link to Abstract)
USMLE World Step 1 QBank Question #456. Copyright © USMLEWorld, LLC 2012