AF Association News & Events
First randomised study of ivabradine for PoTs shows benefit
Dr Pam Taub (Cardiovascular Institute, UC San Diego Health, San Diego, USA) and colleagues report in Journal of the American College of Cardiology that the drug ivabradine may be effective in treating the symptoms of postural tachycardia syndrome (PoTS). Dr Taub notes the study was the first randomised clinical trial using ivabradine to treat PoTS. Additionally, given the similarity between the symptoms of PoTS and those of long COVID, ivabradine may also be valuable for managing long COVID.
According to a UC San Diego press release, Taub et al investigated the drug ivabradine and its effects on heart rate, quality of life and plasma norepinephrine levels in people with PoTS. Norepinephrine is a stress hormone and neurotransmitter. In blood plasma, it is used as a measure of sympathetic nervous system activity.
The study involved 22 individuals (average age 32) who had been screened and recruited from cardiology clinics at UC San Diego Health from 2018 to 2020. Using a randomised, double-blinded, placebo-controlled crossover design in which patients received either ivabradine or a placebo for one month. At the end of the month, all participants underwent a washout period where neither drug nor placebo was taken for one week. After the washout period, the participants who had previously received ivabradine switched to placebo and vice versa for one month.
Over the course of the two months, patients also met with researchers for seven different clinic visits in which plasma norepinephrine levels were measured and head-up tilt testing conducted to observe the patient’s heart rate when sitting, lying down, or standing up.
Dr Taub reports: “Before the study, these patients would be living with elevated heart rates ranging between 100 to 115 beats per minute (bpm) when standing. After taking ivabradine twice a day for one month, the standing heart rate decreased significantly to around 77bpm compared to the placebo group. Participants also reported improvement in quality-of-life measures when on the drug.”
Taub et al also noted ivabradine was well-tolerated with no significant side effects while other drugs used to lower heart rate, such as beta blockers, can cause fatigue and decreased blood pressure. “Ivabradine is a novel agent that is FDA-approved for heart failure but based on its mechanism we thought it could be helpful for patients with PoTS as it reduces heart rate without impacting blood pressure. When we can lower the heart rate, we are providing these patients with the ability to stand up, something they could not do without difficulty before because of their PoTS diagnosis,” Dr Taub observes.
The authors said they hope ivabradine will be considered as a possible treatment option for those with a confirmed diagnosed of PoTS. Currently, the drug is not FDA-approved for the disease and when used clinically it would be “off-label” use in the USA.
Furthermore, the press release observes, PoTs has been identified as a potential “long-hauler” symptom of COVID-19. Dr Jonathan Hsu (UC San Diego Health, San Diego, USA), comments: “In our contemporary practice, we are seeing patients who have previously been infected with COVID-19 present with symptoms consistent with PoTS. Given the similarities, this study leads to the question whether therapy with ivabradine may help patients who experience similar symptoms after a COVID-19 infection and provide an important area for future study as well.”
Dr Taub states: “Similar to patients with COVID-19, patients with PoTS need to be followed carefully. Treatment for PoTS needs to be personalised for each individual and with this drug, paired with lifestyle therapy, including exercises specific for PoTS, we hope we will see more individuals overcome this unfortunate condition.”
The press release states that PoTS is typically caused by a viral infection, trauma, surgery or enforced bedrest, and most commonly affects young women who are either athletes or highly active. Currently, there is no FDA-approved treatment for PoTS and the condition can severely impact quality of life. For more information about the condition, see the STARS PoTS page.