Pearls help diagnose, manage drug-resistant hypertension

A few diagnostic pearls can help internists suss out when a patient truly has drug-resistant hypertension and what to do about those cases.

In a way, treating drug-resistant hypertension is easy. Double-check the diagnosis. Don't rush the readings. Cut the salt. In another way, managing it is hard. White-coat hypertension confounds the diagnosis. Patients are rushed, and so are clinicians. And lifestyle modifications are tough to enforce.

So what's an internist to do?

Dr Townsend Photo by Kevin Berne
Dr. Townsend. Photo by Kevin Berne

Raymond R. Townsend, MD, a professor of medicine and associate director of the Clinical and Translational Research Center at the University of Pennsylvania in Philadelphia and the director of the Penn hypertension program, offered pearls about “Best Strategies for the Work-up and Management of Resistant Hypertension” at Internal Medicine 2014 in Orlando, Fla., in April.

Drug-resistant hypertension is present when the patient takes 3 or more drugs, one of which is a diuretic, at reasonable or maximum-tolerated doses, yet still has a systolic blood pressure of 140 mm Hg or more or a diastolic blood pressure of 90 mm Hg or more, Dr. Townsend said.

He assessed the prevalence of this disorder by presenting a study published online Feb. 29, 2012, by Circulation in which researchers from Kaiser Permanente Colorado and Kaiser Permanente Northern California looked at 200,000 newly diagnosed hypertension patients and found that 1.9% progressed to taking more than 3 drugs at 1.5 years.

Resistant hypertension is associated with a 1.5-fold prevalence of chronic kidney disease and twice the risk of cardiovascular complications, Dr. Townsend pointed out. “There's something not just about the treatment of blood pressure but the response to the treatment of blood pressure that determines some of the outcomes that we see,” he said.

Diagnostic pearls

The first step in treatment is to ensure that a patient truly has drug-resistant hypertension, Dr. Townsend advised. Make sure it's not a white-coat effect by conducting ambulatory blood pressure monitoring. As shown by a 2001 study in the American Journal of Hypertension, 28% of patients with resistant hypertension had blood pressure readings of less than 135/85 mm Hg on follow-up ambulatory blood pressure monitoring.

“When a patient in your office is on 5 drugs and they've got hypertension, you've got about a 30% chance that blood pressures are lower outside the office,” he said.

If the ambulatory results don't make sense to you, double-check the monitors and how patients use them. “This is not one of those ‘the evidence says' kind of things,” he said. “This is one of those more common-sense sort of things.”

Ask patients if an instruction manual came with the monitor and whether they read it, he said. Patients may try to emulate the way the medical assistant used the in-office equipment, rather than follow written directions specific to the equipment they use at home. Have patients bring in the monitor and watch them use it. “Training people and watching their technique is absolutely paramount,” Dr. Townsend stressed.

Don't rush the readings in the office, either, he cautioned. In his office, mornings are a busy, rushed time with patients and staff, which can throw off the readings. Try not to artificially raise a patient's blood pressure by moving them too quickly through the visit.

Also, ensure the in-office technique used to measure blood pressure is correct, he said. “You want to make sure that you're using a cuff appropriate to the size of the arm or the taper of the arm,” he noted. He polled the audience and found that, out of necessity, about half reported sometimes measuring blood pressure by putting a thigh cuff on an arm.

Lifestyle changes

Identify and tackle lifestyle factors to help combat resistant hypertension, Dr. Townsend emphasized. Reducing salt is the main issue, because salt is in everything, he said. Exercise will always help lower blood pressure a little bit, but “It is still worth preaching the gospel of low salt,” he noted.

Alternative medicines, supplements, and over-the-counter medications can all interfere with hypertension medications, Dr. Townsend said. He encourages patients who bring in their prescription medications for exams to bring in their over-the-counter meds as well. “The biggest offenders here: the nonsteroidals, occasionally cough and cold preparations, and sometimes over-the-counter or Internet-based appetite suppressants,” he said.

His clinic conducts a renin assay and aldosterone test on every patient, unless they are clearly not needed, for example when people come with an already diagnosed secondary form of hypertension like a pheochromocytoma or a paraganglioma. Dr. Townsend explained that in some U.S. and European populations, about 1 person in 5 with drug-resistant hypertension has a relatively high aldosterone concentration.

For patients with sleep apnea, a dental device or a continuous positive airway pressure (CPAP) device may lower blood pressure by about 3 mm Hg, Dr. Townsend said, “But you're not going to cure hypertension with it. You might make them less tired during the day. I'm still waiting for the blockbuster study that says there's a huge blood pressure benefit to CPAP.” If a patient or spouse reports apnea symptoms, however, there's no question that CPAP should be offered, he noted.

Dr. Townsend said if a patient hasn't achieved hypertension control after a year, it's time for a new set of eyes: a partner in the practice, a hypertension specialist, or a subspecialist physician who does hypertension care. Patients gets tired of coming back for adjustments. He added, “And every once in a while, people have screwy symptoms, so it helps as a reality check for you (or me) as well.”