Tachycardia Causes and Diagnosis

Physiological and Pathological Factors

Tachycardia is caused by multiple physiological and pathological factors, including infection with fever, dehydration, anemia, heart failure, hyperthyroidism, and exogenous substances such as caffeine, beta-agonist drugs, and illicit stimulants, according to the American College of Cardiology and American Heart Association 1, 2
Physiological sinus tachycardia occurs in response to appropriate autonomic influences and can be caused by physical activity or exercise, emotional responses or stress, fever and infection, dehydration, anemia, heart failure, hyperthyroidism, and pain, as stated by the American College of Cardiology 1, 2, 3, 4

Caffeine, alcohol, nicotine, beta-agonist medications, aminophylline, atropine, catecholamines, illicit stimulant drugs, and cannabis can trigger tachycardia, as reported by the American College of Cardiology 1, 2, 4
Anticancer treatments, particularly anthracycline compounds, can also cause tachycardia, according to the American College of Cardiology 2, 4

Inappropriate sinus tachycardia is defined as sinus tachycardia unexplained by physiological demands, with resting heart rates >100 bpm and average rates >90 bpm in a 24-hour period, and possible mechanisms include dysautonomia, neurohormonal dysregulation, and intrinsic sinus node hyperactivity, as stated by the American Heart Association 1, 5
Supraventricular tachycardias, including atrioventricular nodal re-entrant tachycardia, atrioventricular re-entrant tachycardia, atrial tachycardia, atrial flutter, and sinus node reentry tachycardia, can cause tachycardia, according to the American College of Cardiology 6, 7

Acid-base disturbances can cause tachycardia, as reported by the American College of Cardiology 2, 4

Cardiomyopathies can cause tachycardia, according to the American Heart Association 1

Anxiety disorders, autonomic dysfunction, and postural orthostatic tachycardia syndrome can precipitate tachyarrhythmias, as stated by the American Heart Association 1, 5

Patients with tachycardia may experience palpitations, lightheadedness or dizziness, weakness and fatigue, and syncope in severe cases, according to the American College of Cardiology 1, 5
When evaluating tachycardia, it's essential to distinguish between supraventricular and ventricular origins, identify if the tachycardia is regular or irregular, determine if the QRS complex is narrow or wide, evaluate for underlying structural heart disease, and rule out secondary causes such as hyperthyroidism, anemia, and dehydration, as recommended by the American Heart Association 1, 5

Atrioventricular nodal reentrant tachycardia (AVNRT) is a common reentry mechanism producing accelerated heart rates, according to the American Heart Association 8
Atrioventricular reentrant tachycardia (AVRT) involves accessory pathways, as noted by the American Heart Association 8
Atrial tachycardia (focal and multifocal) arises from localized atrial sites, as reported by the American Heart Association 8
Atrial flutter represents macroreentrant atrial tachycardia, according to the American Heart Association 8
Sinus node reentry tachycardia causes abrupt onset and termination, as noted by the American Heart Association 8

Ventricular couplets, triplets, and non-sustained ventricular tachycardia always require investigation as markers for underlying cardiac pathology, as recommended by the American College of Cardiology 9
Premature ventricular contractions (PVCs) are present in <1% of athletes but may indicate underlying heart disease, particularly when ≥2 PVCs appear on ECG, according to the American College of Cardiology 9
Among athletes with ≥2,000 PVCs per 24 hours, up to 30% have underlying structural heart disease, as reported by the American College of Cardiology 9

In athletes ≥30 years of age, coronary artery disease (CAD) becomes the most common cause of sudden cardiac death and should be considered when evaluating tachycardia, as noted by the American College of Cardiology 9

Resting sinus tachycardia >120 bpm warrants repeat ECG after rest, as recent exercise or anxiety may be responsible, according to the American College of Cardiology 9

The American College of Cardiology recommends obtaining a 12-lead ECG during tachycardia to distinguish supraventricular from ventricular origins and assess QRS width 10
If resting sinus tachycardia >120 bpm, the American College of Cardiology suggests repeating the ECG after a rest period to exclude recent exercise or anxiety 11

The American Heart Association, as published in Circulation, states that the mainstay of management involves identifying and eliminating or treating the underlying cause 12
The American College of Cardiology recommends beta-blockers as first-line for anxiety-related tachycardia, inappropriate sinus tachycardia, and symptomatic thyrotoxicosis 12
The American College of Cardiology suggests that for anxiety disorders with recurrent tachycardia, cognitive-behavioral therapy demonstrates clear benefit 13

The American College of Cardiology notes that emotional stress and anxiety-related disorders are extremely common non-cardiac causes of tachycardia, often misdiagnosed, leading to extensive unnecessary cardiac testing 13
The American College of Cardiology recommends beta-blockade for physiological symptomatic sinus tachycardia triggered by emotional stress and anxiety disorders 12
Cognitive-behavioral therapy reduces symptom frequency by 32% over 3 months in patients with recurrent chest pain and tachycardia despite negative cardiac workup, according to the American College of Cardiology 13

The American Heart Association, as published in Circulation, suggests that non-dihydropyridine calcium channel blockers (diltiazem, verapamil) serve as alternatives when beta-blockers are contraindicated 12
The American College of Cardiology warns against initiating class I or III antiarrhythmic drugs without documented arrhythmia due to proarrhythmic risk 10
The American College of Cardiology advises against repeatedly ordering cardiac testing in patients with multiple negative evaluations; instead, refer for cognitive-behavioral therapy 13

After all reversible physiological and pathological triggers have been excluded, clinicians should actively consider primary supraventricular and ventricular arrhythmias as possible causes of persistent tachycardia. – American College of Cardiology 14

An echocardiogram is recommended to screen for underlying cardiomyopathy, valvular disease, and impaired ventricular function in patients with unexplained tachycardia. – American College of Cardiology 14

In patients with unexplained syncope or presyncope where non‑invasive investigations (e.g., ECG, Holter, echocardiography) are nondiagnostic, an invasive electrophysiology study (EPS) may be considered to identify occult arrhythmic substrates. – American College of Cardiology 15