Emergency Department Management of Symptomatic Tachycardia

Immediate Assessment and Stabilization

• Determine hemodynamic instability (altered mental status, ischemic chest pain, acute heart failure, hypotension or shock) and proceed immediately to synchronized cardioversion with sedation if the patient is conscious. American Heart Association recommendation. 1, 2
• In hemodynamically stable patients, obtain a 12‑lead ECG before any further intervention and follow an algorithmic evaluation. American Heart Association guidance. 1

Differential Diagnosis

Narrow‑Complex Tachycardia (QRS < 0.12 s)

• Sinus tachycardia is the most common narrow‑complex tachyarrhythmia in the emergency department and usually reflects physiologic responses to fever, dehydration, anemia, hypotension, pain, or anxiety. American Heart Association data. 1
• Atrial fibrillation with rapid ventricular response should be considered as a narrow‑complex rhythm. American Heart Association evidence. 3
• Atrial flutter is another possible narrow‑complex tachyarrhythmia. American Heart Association evidence. 3
• When the heart rate is < 150 bpm, the tachycardia itself is unlikely to be the primary cause of symptoms unless there is underlying ventricular dysfunction; clinicians should search for other etiologies. American Heart Association recommendation. 1

Wide‑Complex Tachycardia (QRS ≥ 0.12 s)

• Ventricular tachycardia (VT) is the most frequent cause of wide‑complex tachycardia and should be assumed until proven otherwise. American Heart Association guidance. 3, 4, 5
• SVT with aberrancy, pre‑excited tachycardia (e.g., Wolff‑Parkinson‑White), and ventricular paced rhythms are additional differentials. American Heart Association evidence. 3, 4
• A regular wide‑complex rhythm favors VT or SVT with aberrancy; an irregular wide‑complex rhythm suggests atrial fibrillation with aberrancy, pre‑excited atrial fibrillation, or polymorphic VT/torsades de pointes. American Heart Association classification. 3

Initial Investigations

• Perform a 12‑lead ECG promptly to define rhythm, QRS width, regularity, and P‑wave relationship. American Heart Association protocol. 1
• Initiate continuous cardiac monitoring for all patients with symptomatic tachycardia. American Heart Association and American College of Cardiology recommendation. 1, 6
• Record vital signs, including blood pressure, and obtain pulse‑oximetry to assess for hypoxemia. American Heart Association standard. 1
• Order a complete blood count to evaluate for anemia as a potential driver of sinus tachycardia. American Heart Association guidance. 1
• Obtain a toxicology screen when a drug‑induced arrhythmia is suspected. American College of Cardiology recommendation. 6, 7

Management of Specific Tachyarrhythmias

Sinus Tachycardia

• No antiarrhythmic therapy is required; treat the underlying cause (e.g., fever, dehydration, anemia, pain, sepsis, pulmonary embolism, hyperthyroidism). American Heart Association recommendation. 1
• Avoid “normalizing” the heart rate in patients with poor cardiac function where tachycardia is compensatory, as this may be detrimental. American Heart Association caution. 1

Stable Narrow‑Complex SVT

• First‑line therapy: vagal maneuvers, with the Valsalva maneuver preferred for safety and efficacy, especially in older adults. American Heart Association guideline. 8, 9
• Second‑line: adenosine 6 mg rapid IV bolus; if ineffective, repeat with 12 mg (may repeat once). Adenosine has minimal transient side effects. American Heart Association protocol. 8, 9
• Third‑line: AV‑nodal blocking agents (beta‑blockers such as metoprolol or esmolol; calcium‑channel blockers such as diltiazem or verapamil) for rate control, with caution in obstructive pulmonary disease or heart failure. American Heart Association guidance. 4, 2
• Contraindication: AV‑nodal blockers (adenosine, calcium‑channel blockers, beta‑blockers, digoxin) must not be used in pre‑excited atrial fibrillation/flutter (WPW) because they can precipitate rapid ventricular response and hemodynamic collapse. American Heart Association warning. 4

Stable Wide‑Complex Tachycardia (Assumed VT)

• First‑line pharmacologic therapy: procainamide 15 mg/kg IV infused over 30–60 min for stable monomorphic VT when severe heart failure or acute myocardial infarction is absent. American Heart Association recommendation. 3, 2
• If severe heart failure, acute MI, or impaired left‑ventricular function is present, amiodarone 150 mg IV over 10 min is preferred. American Heart Association recommendation. 3, 5, 2
• Adenosine may be administered in undifferentiated regular stable wide‑complex tachycardia to aid diagnosis; termination of the rhythm suggests SVT with aberrancy rather than VT. American Heart Association guidance. 3, 4, 5, 2
• Adenosine must not be used for unstable, irregular, or polymorphic wide‑complex tachycardia. American Heart Association contraindication. 3, 2
• Calcium‑channel blockers (verapamil, diltiazem) are absolutely contraindicated for wide‑complex tachycardia of unknown origin because they can cause hemodynamic collapse if the rhythm is VT. American Heart Association warning. 4

Ischemic Polymorphic VT (Normal QT)

• Treat as monomorphic VT with amiodarone. American Heart Association recommendation. 2

Unstable Tachycardia (Any Rhythm)

• Immediate synchronized cardioversion without delay for pharmacologic therapy; provide sedation if the patient is conscious and time permits. American Heart Association protocol. 1, 4, 5
• Do not postpone cardioversion to obtain additional diagnostic studies. American Heart Association principle.

Disposition and Follow‑up

• Patients who are hemodynamically unstable require urgent cardioversion and should be admitted to an intensive or coronary care unit for continued monitoring and cardiology/electrophysiology consultation. American College of Cardiology data. 6, 7
• Initiation of antiarrhythmic drug therapy also mandates admission for monitoring. American College of Cardiology recommendation. 6, 7

Initial Approach to Tachycardia Workup

Immediate Stabilization

• The American Heart Association recommends assessing for hemodynamic instability by looking for acute altered mental status, ischemic chest discomfort, acute heart failure signs, hypotension, or shock 10, 11
• The American College of Cardiology suggests simultaneously performing actions such as attaching a cardiac monitor, obtaining vital signs, establishing IV access, and checking oxygen saturation via pulse oximetry 10, 12
• Providing supplemental oxygen if hypoxemia or respiratory distress is present, as hypoxemia commonly drives tachycardia 10, 11

Critical Decision Point: Stable vs. Unstable

• If unstable, perform immediate synchronized cardioversion, and sedate if conscious and time permits 10, 11
• If stable, obtain a 12-lead ECG to define the rhythm, and determine if heart rate >150 bpm 10, 12

Algorithmic Classification Based on ECG

• Assess QRS width, and determine if regular or irregular narrow-complex tachycardia 10, 12
• For regular narrow-complex tachycardia, consider sinus tachycardia, atrial flutter, AV nodal reentry, accessory pathway-mediated tachycardia, or atrial tachycardia 12
• For wide-complex tachycardia, most are ventricular in origin, and differential includes ventricular tachycardia, SVT with aberrancy, pre-excited tachycardias, and ventricular paced rhythms 11, 12

Post-Stabilization Management

• Even if VT self-terminates, urgent cardiology consultation is required as this represents a potentially life-threatening condition 11, 13
• Obtain echocardiography to evaluate for structural heart disease in patients with VT 13
• Refer to electrophysiology for wide-complex tachycardia of unknown origin, clear history of paroxysmal regular palpitations, drug-resistant or drug-intolerant narrow-complex tachycardia, and patients desiring freedom from long-term drug therapy 11