by Robert Fay

The American Heart Association (AHA) has published the first scientific statement regarding the diagnosis, evaluation, and treatment of resistant hypertension. The statement, published on April 7, 2008 on the Hypertension website, addresses resistant hypertension prevalence, patient characteristics, prognosis, and treatment recommendations.

Resistant hypertension is defined as blood pressure that remains above goal even after treatment with 3 antihypertensive medications or blood pressure that is controlled but requires 4 or more medications. Although the prevalence is unknown, resistant hypertension is a common clinical problem, and evidence from clinical trials suggests that 20 to 30 percent of trial participants have the condition. The definition is useful for identifying patients at high risk of having reversible causes of hypertension and/or patients who, because of persistently high blood pressure levels, may benefit from special diagnostic and therapeutic considerations. As defined, resistant hypertension includes patients whose blood pressure is controlled with more than 3 medications. That is, patients whose blood pressure is controlled but require 4 or more medications to do so should be considered resistant to treatment.

Although not well known, the authors say that the prognosis of patients with resistant hypertension compared with patients with more easily controlled hypertension is "presumably impaired," because patients with resistant hypertension typically have associated cardiovascular risk factors, such as diabetes, obstructive sleep apnea (OSA), left ventricular hypertrophy (LVH), and/or chronic kidney disease (CKD). Patient characteristics associated with resistant hypertension include older age, high baseline blood pressure, obesity, female sex, African American ethnicity, and residency in the southeastern United States.

Evaluation should be directed toward confirming true resistant hypertension, excluding pseudoresistance, which can result from inaccurate blood pressure measurement, poor patient adherence to treatment regimens, and white-coat hypertension. In addition, physicians should identify reversible causes, which include lifestyle factors such as obesity, excess dietary salt intake and alcohol consumption, and medications that can increase blood pressure, such as non-steroidal anti-inflammatories (NSAIDs), sympathomemetic agents, stimulants, oral contraceptives, cyclosporine, erythropoietin, natural licorice, and herbal compounds like ephedra.

Physicians should also screen for secondary causes, such as OSA, primary aldosteronism, which occurs in approximately 20 percent of patients with resistant hypertension, renal artery stenosis, as well as less common secondary causes, such as pheochromaocytoma, Cushing's syndrome, hyperparathyroidism, aortic coarctation, and intracranial tumor.

Resistant hypertension is almost always multifactorial, according to the statement. Its treatment is based on identification and reversal of lifestyle factors, such as weight loss, dietary salt and fat restrictions, alcohol moderation, and increased physical activity and fiber intake. In addition, secondary causes of the condition should be treated.

Medical therapy should include withdrawal of medications that may interfere with blood pressure. Diuretics are often underused in people with resistant hypertension, according to the statement. Patients with primary aldosteronism may benefit from adding mineralcorticoid receptor antagonists (MRAs) to their treatment regimen. In addition, the statement points out that some research has shown that patients taking at least one of their hypertensive agents at bedtime had better 24-hour mean blood pressure control, especially lower nighttime systolic and diastolic blood pressure. Finally, the statement recommends a hypertension specialist for patients whose blood pressure remains resistant after 6 months of treatment.

"The recent scientific statement by the AHA emphasizes that controlling blood pressure is not always easily achieved," said E. Magnus Ohman, MD, FRCPI, FACC, Professor of Medicine and Director of the Program for Advanced Coronary Disease at Duke University Medical Center. "The AHA recommends that in some cases many different type of medications are needed and that physicians should work closely with their patients to identify the barriers to achieving optimal blood pressure with its associated better outcomes."

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Source: Calhoun DA, Jones D, Textor S, et al. 2008. Resistant Hypertension: diagnosis, evaluation, and treatment. Hypertension Published on April 7, 2008 on the Hypertension website.

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