Ivabradine in Postural Orthostatic Tachycardia Syndrome: A Review of the Literature

Postural orthostatic tachycardia syndrome (POTS) is an autonomic disorder characterized by symptoms such as palpitations, dyspnea, chest discomfort, and lightheadedness affecting various systems. The pathophysiology of POTS is not completely understood due to a variety of symptoms showing that the disease is multifactorial. There is no approved uniform management strategy for POTS and hence, no drug has been approved by the United States (US) Food and Drug Administration (FDA) for it. Ivabradine is an FDA-approved drug for stable symptomatic heart failure (HF) and patients with an ejection fraction (EF) of ≤35%. Previous studies have depicted improvement in symptoms of POTS with the use of ivabradine. It is a selective inhibitor of funny sodium channels (I_f) in the sinoatrial (SA) node cells resulting in the prolongation of the slow diastolic depolarization (phase IV) and reduction in the heart rate (HR). Although beta-adrenoceptor blockers are commonly used to lower HR in patients with POTS, they are less ideal due to numerous adverse effects. This review aims to provide a comprehensive and up-to-date picture of all the studies and case reports that utilized ivabradine for the treatment of POTS along with a precise overview of epidemiology, pathophysiology, and types of POTS. To conclude, we recommend further research on the effectiveness of ivabradine in patients who experience symptoms of POTS. Other than stable chronic angina pectoris, its application in this setting has been proven to be effective and safe. Further evaluation by means of randomized control trials is required to encourage use of this HR-lowering agent in common disorders other than HF and stable angina, i.e. POTS.