For patients with postural tachycardia syndrome (POTS), dietary sodium intake can be increased with more confidence, suggests the first study that provides solid evidence to support this treatment strategy.
The results showed that a high dietary intake of sodium can reduce plasma norepinephrine levels and improve orthostatic and stationary tachycardia in patients with POTS.
“These results suggest that increasing dietary salt is a good reason for treating this condition, and this study assures us that we are doing the right thing for patients with POTS by increasing their sodium intake,” he said. ‘author, MD, Satish R. Raj. Medscape Medical News.
The study, with lead author Emily M. Garland, Ph.D., was published online April 26 al Journal of the American College of Cardiology.
Raj, who is a professor of heart science at Cumming School of Medicine at the University of Calgary, Alberta, Canada, explained that POTS includes a spectrum of disorders that affect the automatic nervous system, which regulates heart rate and blood pressure.
“It is a disorder of orthostatic intolerance – Patients feel better when they lie down. It’s different from orthostatic hypotension because a patient with POTS gets up, blood pressure doesn’t necessarily go down, but heart rate goes up excessively. “
While it is normal for heart rate to increase slightly when standing, among patients with POTS, heart rate increases excessively. The condition is defined as an increase in orthostatic heart rate of at least 30 beats / min (or 40 beats / min among individuals 12 to 19 years of age) in the absence of orthostatic hypotension.
The disorder is characterized by a number of symptoms, including dizziness, shortness of breath, palpitations, and exercise intolerance, which are worse when standing upright. Patients also experience chronic fatigue and perceived cognitive impairment, Raj noted.
The typical demographic type of POTS are young women; the condition often begins during adolescence.
Patients usually have a low blood volume, so one approach to treatment is to increase salt and water intake to increase blood volume.
“This is one of the fundamental pillars of treatment, but it has never been properly studied,” Raj commented. The increase in salt intake “is an unusual message from a cardiologist and there have been concerns that we are making recommendations against traditional advice, so we urgently need evidence to support that recommendation.”
The current cross-sectional study included 14 patients with POTS and 13 healthy control people who for a period of 6 days were treated with a low-sodium diet (10 mEq of sodium per day) or a high-sodium diet (300 mEq sodium per day).
Resting and resting heart rate, blood pressure, serum aldosterone level, renin plasma activity, blood volume and plasma norepinephrine and epinephrine levels were measured.
The results showed that among patients with POTS, the high-sodium diet reduced vertical heart rate and the change in heart rate on standing compared to the low-sodium diet.
Heart rate increased by 46 beats / min with the high-sodium diet, compared with 60 beats / min with the low-sodium diet.
Total blood volume and plasma volume increased and standing norepinephrine levels decreased with the high sodium diet compared to the low sodium diet.
However, vertical heart rate, change in heart rate, and vertical norepinephrine levels remained higher among patients with POTS than among control individuals receiving a high-sodium diet.
There was a nonsignificant trend for a lower symptom load score among patients with POTS who received a high-sodium diet compared to those on a low-sodium diet. Mental confusion scores, palpitations, dizziness and headache downward trend in the high sodium diet.
“We found that high levels of dietary salt did what we expected, with an increase in blood volume and a reduction in standing norepinephrine levels and an excessive increase in heart rate. Although it did not completely normalize heart rate, this it was significantly reduced, ”Raj said. .
Another observation of the study was that increasing salt intake appeared to be beneficial across the spectrum of patients.
“There are some patients who have very high levels of sympathetic activation and there have been anecdotal reports that increased salt may not work as well in this group,” he said. “In this study, we did not differentiate, but mean norepinephrine levels were very high and many patients would be considered hyperadrenergic. Our results suggest that this treatment will also help these patients.”
He noted that sodium intake increased in this study only through diet. “We had a special metabolic kitchen. In clinical practice, we advise patients to add regular table salt to their foods and we only use salt tablets when they can’t tolerate so much salt in their diet.”
Recognizing that there may be concerns hypertension with long-term use of this treatment, Raj said there were no signs of an increase in blood pressure in this study. “But for now, it should be considered short-term therapy and patients need to be reviewed every few years as their physiology changes,” he said.
The authors estimate that POTS affects up to 1% of the population. Because there is currently no diagnostic code for the condition, all incidence data are estimates.
Raj points out that there are potentially many people affected, but there is little recognition of the disease among patients and doctors.
“Many GPs are unaware of the POTS,” he noted. “Patients often have to investigate their symptoms themselves and inform their doctor about the disease. Many patients wait years and usually see many different doctors before receiving a correct diagnosis.”
He explained that patients with POTS are often diagnosed with a psychiatric illness. “They are mostly young women with palpitations, heartbeat, tremor, which is often labeled as anxiety,” she said.
Raj urges doctors to consider POTS if patients present with symptoms that are worse when standing up. The diagnosis is confirmed if blood pressure does not drop when standing, but the heart rate increases by at least 30 beats / min.
He points out that there are not enough specialists in this disease, so family doctors need to be able to diagnose and start treatment. If more aggressive treatment is required, patients may be referred to a specialist.
“One of the problems is that this condition is found in different medical specialties. No field has it, so it tends to be ignored. But there are doctors who are interested in POTS and the key is to find one.
“We have finally established that this sodium-rich diet works as a treatment for POTS,” he concluded. “We’ve been using it for a long time, but we now have evidence of its use across the spectrum of patients.”
In a accompanying editorial, Blair P. Grubb, MD, University of Toledo Medical Center, Toledo, Ohio, says that this “magnificent study by Garland et al helps us better establish our understanding of the pathophysiological process that takes place in POTS, while providing a good evidence of the increase in dietary sodium as one of the fundamental pillars of treatment “.
He adds that the field needs more studies of this kind “in our research to better understand POTS and develop therapeutic modalities to help those suffering from this debilitating disease.”
The study was supported in part by the National Heart, Lung and Blood Institute, the National Center for the Advancement of Translation Sciences, and Vanderbilt’s core hormone and analytical services. Raj has been a consultant for Lundbeck NA Ltd and Theravance; he has been chairman of the data monitoring and security board of Arena Pharmaceuticals and as a researcher in the Canadian Cardiac Arrhythmia Network; and has been a member of the medical advisory board of Dysautonomia International and PoTS UK, both without financial compensation.