Tachycardia Workup and Management

Heart Rate Thresholds and Clinical Instability

The American Heart Association recommends initiating immediate workup when heart rate is ≥150 beats per minute or when any patient shows signs of hemodynamic instability, regardless of heart rate 1
Heart rate ≥150 bpm indicates a likely primary arrhythmia requiring immediate evaluation, as this threshold distinguishes true tachyarrhythmias from physiologic responses 1
The American College of Cardiology suggests lowering the threshold for workup (<150 bpm) in patients with known ventricular dysfunction, as these patients are more vulnerable to hemodynamic compromise from tachycardia 1
Proceed directly to workup and treatment without delay when signs of acute altered mental status, ischemic chest discomfort or pain, acute heart failure, hypotension, or shock are present 2, 3, 1

Attach cardiac monitor and obtain vital signs, and establish IV access when tachycardia workup is indicated 3, 1
Assess oxygen saturation and respiratory status, as hypoxemia is a common reversible cause of tachycardia 1
Obtain 12-lead ECG to define rhythm characteristics, but only after stabilization in unstable patients 1

Any suspected ventricular tachycardia requires urgent cardiology consultation and echocardiography even if self-terminated 3, 1
If pre-excitation is present on resting ECG with history of paroxysmal regular palpitations, presume AVRT and refer to electrophysiology without needing to capture the arrhythmia 3
In hypertensive patients, assess for occult heart failure symptoms if resting heart rate >80-85 bpm by clinical examination, biomarkers, or echocardiogram 4

Refer to cardiology or electrophysiology when wide-complex tachycardia of unknown origin, clear history of paroxysmal regular palpitations, drug-resistant or drug-intolerant narrow-complex tachycardia, or patients desiring freedom from long-term drug therapy are present 3
Any suspected ventricular tachycardia, even if self-terminated, requires referral to cardiology or electrophysiology 3

Never delay cardioversion in unstable patients while obtaining 12-lead ECG 3
Never use AV nodal blocking agents in pre-excited atrial fibrillation, as this accelerates ventricular response and can be lethal 3
Never give adenosine for irregular or polymorphic wide-complex tachycardia, as it may cause degeneration to ventricular fibrillation 5, 3

In the first week of life, the upper normal limit (98th percentile) is 166 beats/min; in the first month it is 179 beats/min 6
After six months, the upper normal limit declines to approximately 160 beats/min 6
Work up sinus tachycardia in neonates when associated with fever, infection, anemia, pain, dehydration, hyperthyroidism, or myocarditis 6