Inappropriate sinus tachycardia
Inappropriate sinus tachycardia is a persistently elevated resting sinus rate, or an exaggerated rate response to minimal exertion, without an identifiable secondary cause. It is a diagnosis of exclusion in young women, and treatment centers on beta-blockade or ivabradine after ruling out reversible drivers.
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What this article covers
- Overview
Definition: inappropriate sinus tachycardia (IST) is a persistently elevated resting sinus rate (typically over 100 per minute, or a mean above 90 over 24 hours) or an exaggerated rate response to…
- Epidemiology
Predominantly affects young women, often in healthcare occupations.
- Risk factors
Female sex and young adulthood. Prior viral illness or autonomic dysfunction.
- Pathophysiology
Enhanced sinoatrial automaticity: an intrinsically faster sinus node.
- Clinical features
Palpitations at rest and with minimal exertion.
- Differential diagnosis
Physiologic (secondary) sinus tachycardia: an identifiable cause such as fever, anemia, or hyperthyroidism, distinguished by resolution once that driver is corrected rather than a persistent unprovoked rate (sinus tachycardia).
- Diagnosis
Establish as a diagnosis of exclusion: persistent sinus tachycardia with normal P-wave morphology and no secondary cause: the diagnostic basis is documenting an elevated resting or minimally provoked…
- Management
First-line, exclude and treat reversible contributors and reassure: address deconditioning with graded exercise, correct anemia, remove stimulants, and manage anxiety.
- Complications
Symptom burden and reduced quality of life.
- Prognosis
Benign, without excess mortality. Often fluctuating, with periods of improvement.
- Prevention
Maintain aerobic conditioning and hydration, with generous fluid and a sodium intake of about 8 to 10 g per day.
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