Effect of High Dietary Sodium Intake in POTS Patients

Apr 27, 2021
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Authors:
Garland EM, Gamboa A, Nwazue VC, et al.
Citation:
Effect of High Dietary Sodium Intake in Patients With Postural Tachycardia Syndrome. J Am Coll Cardiol 2021;77:2174-2184.
Summary By:
Melvyn Rubenfire, MD, FACC

Quick Takes

  • A very high sodium load (6.9 g) over 5 full days improves the parameters associated with postural orthostatic tachycardia syndrome (POTS).
  • However, despite the high sodium intake, POTS subjects still met the criteria for POTS of a Δ heart rate of ≥30 bpm when going from lying to standing position.
  • Volume depletion does not fully explain POTS, but pooling of blood in the central and peripheral veins may decrease venous return, resulting in decreased stroke volume and systolic blood pressure.

Study Questions:

Does a high sodium (HSod) diet reduce orthostatic tachycardia (Δ heart rate) and upright heart rate compared with a low sodium (LSod) diet in the postural orthostatic tachycardia syndrome (POTS), and what is the effect on plasma volume (PV) and plasma norepinephrine?

Methods:

A total of 14 women with POTS and 13 healthy control subjects (HC), ages 23-49 years, were enrolled in a crossover study with 6 days of LSod (10 mEq sodium/day) or HSod (300 mEq sodium/day) diet. Supine and standing heart rate, blood pressure, serum aldosterone, plasma renin activity, blood volume, and plasma norepinephrine and epinephrine were measured. The 6-day diet was conducted in a similar phase of menstrual cycle in each group.

Results:

POTS patients and HC did not differ in age (mean 35 years), height, weight, or body mass index. POTS had marginally higher serum sodium. In POTS, the HSod diet reduced upright heart rate and Δ heart rate compared with the LSod diet. Total blood volume and PV increased, and standing norepinephrine decreased with the HSod compared with the LSod diet. However, upright heart rate, Δ heart rate, and upright norepinephrine remained higher in POTS than in HC on the HSod diet (median 117 bpm, 46 bpm, and 753 pg/ml in POTS vs. 85 bpm, 19 bpm, and 387 pg/ml in HC, respectively), despite no difference in the measured PV.

Conclusions:

In POTS patients, high dietary sodium intake compared with low dietary sodium intake increases plasma volume, lowers standing plasma norepinephrine, and decreases Δ heart rate.

Perspective:

300 mEq sodium/day is about 6.9 g of sodium and 10 mEq of sodium is 230 mg, each of which is a very difficult diet over 5 days. The challenge is not a useful tool for diagnosis nor testing the value of very high sodium intake.

Clinical Topics: Arrhythmias and Clinical EP, Cardiovascular Care Team, Diabetes and Cardiometabolic Disease, Dyslipidemia, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Lipid Metabolism, Novel Agents, Diet

Keywords: Aldosterone, Arrhythmias, Cardiac, Blood Pressure, Diet, Sodium-Restricted, Epinephrine, Heart Rate, Hypovolemia, Menstrual Cycle, Norepinephrine, Plasma, Plasma Volume, Postural Orthostatic Tachycardia Syndrome, Renin, Sodium, Sodium, Dietary, Secondary Prevention, Stroke Volume, Tachycardia


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