Drug-resistant hypertension draws attention of AHA

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Drug-resistant hypertension is a common clinical problem faced by both primary care clinicians and specialists, according to a scientific statement from the American Heart Association, which appeared in the June issue of Hypertension.

While the exact prevalence of resistant hypertension is unknown, clinical trials suggest that it is not rare, involving perhaps 20 to 30 percent of study participants, according to the statement’s authors. As older age and obesity are two of the strongest risk factors for uncontrolled hypertension, the incidences of resistant hypertension will likely increase as the population becomes more elderly and heavier, the authors wrote.

David A. Calhoun, MD, chair of the guideline writing committee, and colleagues said the prognosis of resistant hypertension is unknown, but cardiovascular risk is undoubtedly increased as patients often have a history of long-standing, severe hypertension complicated by multiple other cardiovascular risk factors such as obesity, sleep apnea, diabetes and chronic kidney disease.

Calhoun, a hypertension specialist at the University of Alabama at Birmingham, told the New York Times that it is “becoming more difficult to treat and it’s requiring more and more medications to do so.”

The diagnosis of resistant hypertension requires use of good blood pressure technique to confirm persistently elevated blood pressure levels, according to the authors. Resistant hypertension is almost always multi-factorial in etiology.

If patients need that many drugs, they are likely to be at greater risk for illness even if they lower their blood pressure to normal, the authors wrote. These patients have usually had high blood pressure for some time and, as a result, have more organ damage.

They recommended that the treatment requires identification and reversal of lifestyle factors contributing to treatment resistance; diagnosis and appropriate treatment of secondary causes of hypertension; and use of effective multidrug regimens.

The researchers also noted that as a subgroup, patients with resistant hypertension have not been widely studied. Observational assessments have allowed for identification of demographic and lifestyle characteristics associated with resistant hypertension, and the role of secondary causes of hypertension in promoting treatment resistance is well documented; however, identification of broader mechanisms of treatment resistance is lacking. In particular, attempts to elucidate potential genetic causes of resistant hypertension have been limited.

Calhoun and colleagues wrote that recommendations for the pharmacological treatment of resistant hypertension remain largely empiric due to the lack of systematic assessments of three or four drug combinations.

They said that studies of resistant hypertension are limited by the high cardiovascular risk of patients within this subgroup, which generally precludes safe withdrawal of medications; the presence of multiple disease processes (e.g. sleep apnea, diabetes, atherosclerotic disease) and their associated medical therapies, which confound interpretation of study results; and the difficulty in enrolling large numbers of study participants.