Hypertension has become a public health crisis in the United States and around the world. While most hypertension specialists come from the disciplines of nephrology, cardiology or internal medicine, Naomi D. L. Fisher, MD, believes endocrinologists should play a role, too.
“As endocrinologists, hypertension can and should fall within our domain, even though other doctors don’t typically consult with us in these cases,” said Dr. Fisher, director of the Brigham’s Hypertension Service and Hypertension Specialty Clinic.
Brigham investigators have done extensive clinical and research work in the physiology and epidemiology of high blood pressure. Dr. Fisher has also been active in raising awareness of the dangers of hypertension, including co-authoring a November 2018 editorial in JAMA, which outlines the global scope of this problem.
Dr. Fisher finds it striking that in 2010, high blood pressure for the first time became the leading risk factor for the overall global burden of disease. “When you think about what has caused most deaths around the world, it’s typically infantile diarrhea, communicable diseases and other infectious diseases,” she said. “But now high blood pressure has surpassed all of them.”
The situation in the United States is equally troubling, and perhaps distorted by the controversy over revised clinical guidelines published by the American College of Cardiology/American Heart Association (ACC/AHA) in November 2017.
The ACC/AHA report lowered the threshold for stage 1 hypertension from 140/90 mm Hg to 130/80 mm Hg, thus increasing the prevalence of hypertension in the United States by almost 43 percent, according to one estimate. As a result of the revised U.S. guidelines, young Americans have experienced the greatest increases in hypertension prevalence. Furthermore, the control rate of hypertension in this country continues to hover around 50 percent (and that’s when applying the higher 140/90 mm Hg threshold).
“It’s imperative that we find more inventive, innovative ways to care for patients with high blood pressure and to treat hypertension on a population level,” Dr. Fisher said.
To that end, Dr. Fisher is engaged in a variety of efforts to improve control of hypertension. For example, she led the Brigham Protocol-based Hypertension Optimization Program, the results of which were presented to the American College of Cardiology last March.
Program participants were given a Bluetooth-enabled blood pressure cuff, which linked to the EMR. They measured their blood pressure in duplicate twice a day, and titrations were based on 28 readings collected over the course of a week. Dr. Fisher said the results showed that a home-based program run by non-physicians can provide efficient, effective and rapid control.
“How are we going to care for the 100 million patients in this country with high blood pressure? We can’t keep bringing them all into the office every two weeks, which is what we really need to get the best titration.” Dr. Fisher explained. “The traditional office-based method has failed us, so we’re trying to figure out how to do that more effectively and at a much, much lower cost to provide even better control.”
Dr. Fisher is also the Brigham principal investigator on the Radiance-HTN project, which is examining whether ultrasound-based renal denervation reduces blood pressure in patients with hypertension. The group’s first paper demonstrated positive results and was published in The Lancet last June.
Renal denervation is a minimally invasive procedure that delivers ultrasound energy to thermally ablate and disrupt renal sympathetic nerves that are believed to play a central role in blood pressure regulation. After producing encouraging results in initial trials, renal denervation showed disappointing efficacy in the SYMPLICITY HTN-3 study. “Many people thought that signaled its death knell,” Dr. Fisher noted.
New technology, better training of clinicians and more rigorous study protocols are starting to cast renal denervation in a more favorable light. The Lancet paper is one of several recent papers highlighting randomized control trials that show its efficacy.
Dr. Fisher is involved in more studies to be published in the next few years, including one focusing on patients with resistant hypertension.
“It’s well-recognized that the risk of complications like heart attack, stroke, heart failure and dementia all rise as blood pressure goes up,” Dr. Fisher concluded. “So those of us in the medical profession need to be more responsible about monitoring and treating blood pressure. We have to do better, and endocrinologists should be part of the solution.”