In a new study by the University of California School of Medicine in San Diego, the researchers found that a drug used for heart failure improves symptoms associated with postural orthostatic tachycardia syndrome, also known as POTS. This complex and debilitating disorder affects the body’s autonomic nervous system, causing a high heart rate, usually when standing.
Written in the February 15, 2021 online edition of Journal of the American College of Cardiology, the study authors investigated the drug ivabradine and its effects on heart rate, quality of life and plasma norepinephrine levels in people living with POTS. Norepinephrine is a stress hormone and neurotransmitter. In blood plasma, it is used as a measure of sympathetic nervous system activity. Trial participants experienced a reduction in heart rate, improvement in symptoms and overall quality of life one month after taking the drug.
“Ivabradine is a new FDA approved agent for heart failure, but based on its mechanism, we think it could be useful for patients with POTS as it reduces heart rate without affecting blood pressure,” said Pam Taub, MD, cardiologist Cardiovascular Institute of Health, UC San Diego and associate professor of medicine, UC San Diego School of Medicine. “When we can reduce the heart rate, we are providing these patients with the ability to get up, something they could not do without difficulty due to the diagnosis of POTS before.”
The study involved 22 individuals with an average age of 32 years. Each participant was selected and recruited at the UC San Diego Health cardiology clinics from 2018 to 2020.
The study used a randomized, double-blind, placebo-controlled crossover design in which patients started taking ivabradine or placebo for one month. At the end of the month, all participants went through a washout period, in which neither the drug nor the placebo was taken for a week. After the washout period, participants who had previously received ivabradine switched to placebo and vice versa for a month.
Over the two months, patients also met with researchers at seven different clinical visits, in which plasma norepinephrine levels were measured and the head-up tilt test was performed to observe the patient’s heart rate when sitting, lying down or standing.
“Before the study, these patients lived with a high heart rate, ranging from 100 to 115 beats per minute when standing,” said Taub. “After taking ivabradine twice a day for a month, the standing heart rate decreased significantly to around 77 beats per minute compared to the placebo group. Participants also reported improvements in quality of life measures when taking the medication ”.
The researchers also noted that ivabradine was well tolerated without significant side effects, while other drugs used to lower heart rates, such as beta-blockers, can cause fatigue and lower blood pressure.
Taub said the study was the first randomized controlled trial using ivabradine to treat POTS.
POTS is usually caused by a viral infection, trauma, surgery or forced bed rest and most commonly affects young women who are athletes or highly active. Currently, there is no FDA approved treatment for POTS and the condition can severely affect quality of life. Other symptoms of POTS include “brain fog”, dizziness, palpitations, tremors, weakness, blurred vision and fatigue.
Recently, POTS has been identified as a potential “long distance” symptom of COVID-19.
“In our contemporary practice, we are seeing patients who were previously infected with COVID-19 showing symptoms consistent with POTS,” said Jonathan Hsu, MD, cardiologist at UC San Diego Health. “Given the similarities, this study raises the question of whether ivabradine therapy can help patients who experience similar symptoms after a COVID-19 infection and also provides an important area for future studies.”
The authors said they expected ivabradine to be considered as a possible treatment option for those with a confirmed diagnosis of POTS. Currently, the drug is not approved by the FDA for the disease and, when used clinically, it would be “off-label” use.
“Similar to patients with COVID-19, patients with POTS need to be monitored carefully,” said Taub. “The treatment for POTS needs to be personalized for each individual and with this medication, combined with lifestyle therapy, including specific exercises for POTS, we hope to see more people overcome this unfortunate condition.”
Reference: February 15, 2021, Journal of the American College of Cardiology.
DOI: 10.1016 / j.jacc.2020.12.029
Co-authors include: Adena Zadourian, Hannah C. Lo, Cameron K. Ormiston and Shahrokh Golshan, all from UC San Diego.
Disclosure: Pam Taub served as a consultant for Amgen, Bayer, Esperion, Boehringer Ingelheim, Novo Nordisk and Sanofi, and is a co-founder of Empirium Bio. Jonathan Hsu was a consultant for Medtronic, Abbott, Boston Scientific, Biotronik, Biosense Webster, Zoll Medical, Pfizer, Bristol Myers Squibb and Janssen Pharmaceuticals.