IMR Press / RCM / Volume 22 / Issue 4 / DOI: 10.31083/j.rcm2204139
Open Access Review
Inappropriate sinus tachycardia: a review
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1 Department of Cardiology, Khyber Medical Institute Srinagar, 190010 Jammu and Kashmir, India
2 Department of Cardiology, Walter Reed Medical Center, Bethesda, MD 20814, USA
3 Department of Internal Medicine, Central Michigan University, Mt Pleasant, MI 48859, USA
4 Division of Cardiology, University of Toledo, Toledo, OH 43606, USA
5 Section of Electrophysiology, McLaren Greater Lansing Hospital, Lansing, MI 48910, USA
*Correspondence: (Khalil Kanjwal)
Academic Editor: Yoshiaki Kaneko
Rev. Cardiovasc. Med. 2021, 22(4), 1331–1339;
Submitted: 25 September 2021 | Revised: 14 October 2021 | Accepted: 15 October 2021 | Published: 22 December 2021
(This article belongs to the Special Issue Clinical Electrophysiology: Diagnosis and Treatment)
Copyright: © 2021 The Author(s). Published by IMR Press.
This is an open access article under the CC BY 4.0 license (

Inappropriate sinus tachycardia (IST) has been defined as a resting heart rate of >100 beats per minute and an average 24-hour heart rate >90 bpm with distressing symptoms resulting from the persistent tachycardia. IST is prevalent in 1% of the middle-aged population, mostly females. Rarely can elderly patients also present with IST. Possible mechanisms of IST include intrinsic sinus node abnormality, beta-adrenergic receptor stimulating autoantibody, beta-adrenergic receptor supersensitivity, muscarinic receptor autoantibody, or hyposensitivity, impaired baroreflex control, depressed efferent parasympathetic/vagal function, nociceptive stimulation, central autonomic overactivity, aberrant neurohumoral modulation, etc. Symptoms associated with IST are palpitations, chest pain, fatigue, shortness of breath, presyncope, and syncope. Despite these distressing symptoms, IST has not been associated with tachycardia-associated cardiomyopathy or increased major cardiovascular events. Various treatment options for patients with IST are ivabradine, beta-adrenergic blockers, calcium channel blockers, psychiatric evaluation, and exercise training. Although, endocardial radiofrequency ablation targeting the sinus node has been used as a treatment modality for otherwise treatment-refractory IST, the results have been dismal. The other modalities used for refractory IST treatment are endocardial modification of the sinus node using radiofrequency energy, combined endo and epicardial ablation of the sinus node, thoracoscopic epicardial ablation of the sinus node, sinus node sparing thoracoscopic and endocardial hybrid ablation. The goal of this review is to provide the readership with the pathophysiological basis of IST and its management options.

Autonomic dysfunction
Inappropriate sinus tachycardia
Fig. 1.
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