Initial Approach to Sinus Tachycardia

Definition and Diagnosis

Sinus tachycardia is defined as a heart rate greater than 100 beats per minute with positive P waves in leads I, II, and aVF and negative in aVR, according to the American College of Cardiology 1, 4
It is non-paroxysmal, distinguishing it from re-entry tachycardias, as noted by the American Heart Association 1
A 12-lead ECG shows P waves of normal axis (between 0° and 90° in the frontal plane), which can be wider and more pointed, as described by the Journal of the American College of Cardiology 5, 1

Physiological sinus tachycardia: an appropriate response to physical, emotional, pathological, or pharmacological stress, as defined by the American College of Cardiology 2
Inappropriate sinus tachycardia: a persistent increase in heart rate at rest without an identifiable cause or disproportionate to the level of stress, according to the American Heart Association 1, 6

Physiological causes: physical exertion, emotional stress, anxiety, as noted by the Journal of the American College of Cardiology 4
Pathological causes: fever, hypovolemia, anemia, hypotension, pain, heart failure, hyperthyroidism, as described by the American College of Cardiology 4, 3, 6
Medication-related causes: caffeine, alcohol, nicotine, salbutamol, aminophylline, atropine, catecholamines, as listed by the Journal of the American College of Cardiology 4, 2

Beta-blockers: first-line treatment for symptomatic sinus tachycardia, particularly effective for stress-related and anxiety-related tachycardia, as recommended by the American College of Cardiology 1, 2, 3
Non-dihydropyridine calcium channel blockers (diltiazem, verapamil): alternative to beta-blockers, especially useful in hyperthyroidism if beta-blockers are contraindicated, as noted by the American Heart Association 1, 3, 6

Inappropriate sinus tachycardia primarily affects women (90%) with a mean presentation age of approximately 38 years, as described by the American College of Cardiology 1, 6
Distinguishing inappropriate sinus tachycardia from postural orthostatic tachycardia syndrome is crucial, as suppressive treatment of the sinus rhythm can lead to severe orthostatic hypotension in the latter case, as warned by the American Autonomic Society 6