Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 54-year-old man is evaluated for elevated blood pressure noted recently at a local health fair. He has no other medical history and takes no medications.

On this visit and on two subsequent nurse visits, the patient’s blood pressure measurements are less than 140/90 mm Hg. BMI is 34. Cardiac examination reveals an S₄ gallop. The remainder of the examination is normal.

Laboratory studies show a normal chemistry panel, and a urine dipstick demonstrates no blood or protein.

Electrocardiogram demonstrates evidence of left ventricular hypertrophy.

Which of the following is the most appropriate next step in management?

A. Ambulatory blood pressure monitoring
B. Lisinopril
C. Plasma aldosterone-plasma renin ratio
D. Repeat blood pressure measurement in 6 months

MKSAP Answer and Critique

The correct answer is A.

Ambulatory blood pressure monitoring (ABPM) is appropriate for this patient who likely has masked hypertension. He has evidence of end-organ manifestations (left ventricular hypertrophy) that is potentially related to hypertension, yet has not presented with blood pressure measurements consistent with hypertension (≥140/90 mm Hg). This raises the possibility of masked hypertension, which is defined as normal office blood pressure measurements but elevated blood pressure (>135/85 mm Hg) in the ambulatory setting. Prior to initiating medical therapy, a more detailed assessment of this patient’s blood pressure should be pursued, with ABPM as an appropriate next step. Although ABPM does not carry a formal indication for the diagnosis of masked hypertension, it may be useful in establishing this blood pressure pattern. ABPM-ascertained hypertension is associated with a higher risk of cardiovascular death compared with office or home blood pressure–determined hypertension.

The left ventricular hypertrophy identified by electrocardiogram in this case may be secondary to hypertension but also may be due to other (such as genetic) causes and requires formal echocardiography to further evaluate and guide therapy. Initiating a blood pressure–lowering agent is not appropriate until both blood pressure and the electrocardiogram findings are clarified further with ABPM and echocardiography.

A plasma renin-plasma aldosterone ratio is used to evaluate for hyperaldosteronism as a secondary cause of hypertension and is typically indicated in patients with difficult-to-treat blood pressure elevations and hypokalemia. This patient has not been diagnosed with hypertension and has no electrolyte abnormalities.

Because this patient has evidence of end-organ damage possibly due to hypertension, follow-up assessment of his blood pressures in 6 months might further delay diagnosis and is not appropriate.

Key Point

• Ambulatory blood pressure monitoring may be helpful in diagnosing masked hypertension in patients with end-organ manifestations but normal office blood pressure measurements.

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