Trial Report Heart Rate Lowering with Ivabradine and Burden of Symptoms in Patients with Postural Orthostatic Tachycardia Syndrome, 2025, Marchetta et al

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Heart Rate Lowering with Ivabradine and Burden of Symptoms in Patients with Postural Orthostatic Tachycardia Syndrome

Marchetta, Michele; Lopez, Rocio I.; Hogwood, Austin C.; Thomas, Georgia; Abbate, Gerardina; Markley, Roshanak; Canada, Justin M.; Abbate, Antonio

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Abstract
Postural Orthostatic Tachycardia Syndrome (POTS) is a clinical syndrome of tachycardia upon standing leading to palpitations, dizziness, chest pain and/or fatigue. An exaggerated norepinephrine response with standing is often present in POTS, but it remains unclear whether the tachycardia is compensatory for a reduced stroke volume or whether the tachycardia is itself causing the symptoms of POTS.

We herein report the effects of heart rate lowering with ivabradine, a selective If channel blocker, on symptom burden in patients with POTS. Following ivabradine treatment, there was a significant reduction in the change in heart rate with standing (ΔHR) in all patients from 40 (30-70) to 15 (8-19) bpm (p=0.011), without significant changes in blood pressure. The Malmö score was significantly reduced in all patients from 86 (74-92) to 39 (32-66) (p=0.005). A correlation between ΔHR and the change in Malmö score (R=+0.828; R2 quadratic= 0.635; p<0.001) was present.

The parallel improvement in heart rate response and symptoms with ivabradine suggests that the tachycardia response in POTS may not be considered compensatory but rather central to the pathophysiology of POTS symptoms.

Link (Journal of Cardiovascular Pharmacology) [Paywall]
 
I've been on Ivabradine for about 2 months now. I haven't noticed a huge improvement in my ability to function, but I definitely have improved more in the last 2 months than the previous 2 years. Which may be mostly coincidence, or also getting acid reflux somewhat under control. I don't know which has helped the most. Probably both. The acid reflux makes a huge difference on my energy levels.

I do notice a lot fewer palpitations, less tachy, though it's still there. If I do too much I still can see it reflected in my resting pulse and HRV, but it's less pronounced.

I'm still dizzy and light-headed most of the time, especially after effort. But it's less pronounced, and improves faster.

I'm on a minimal dose, only once per day, in the morning, since my evening and night resting pulse was already excellent.

I've been slowly improving over the last 2 years, so it may just be that. But I can now take short walks every day. Which I have to, to walk the dog, since my dad slipped and fell on ice 3 weeks ago and can't do it temporarily. So that's been a lot of help.

One change I noticed is that my breathing fastens on effort, as my pulse rises, whereas it only used to do that if I reached anaerobic threshold. I'm pretty much always slightly out of breath, but it's like the breathing faster reflex only kicked in at a higher level.

When I saw a cardio about 6 months ago, I didn't say anything about ME/CFS or past anything, I only framed it in terms of the heart symptoms and being unable to exercise, and the time I spent mostly bedbound because my pulse would jump madly on the slightest exertion. He immediately went to POTS, didn't fuss around. Only had to do a stress test.
 
Cerebral flow is probably the core issue in POTS and without measuring that you're measuring compensatory effects. Arguably the HR boost is the body trying to get blood to the head.
 
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