Management of Tachyarrhythmias: Evidence-Based Guidelines
Immediate Assessment and Classification
The first critical step is to assess hemodynamic stability—any tachyarrhythmia causing hypotension, altered mental status, chest pain, or acute heart failure requires immediate synchronized cardioversion without delay for pharmacologic therapy. 1, 2
- Classify the tachyarrhythmia by QRS width: narrow (<120 ms) indicates supraventricular origin, while wide (≥120 ms) should be presumed ventricular tachycardia until proven otherwise 1, 2
- Assess rhythm regularity on a 12-lead ECG during the tachycardia episode to guide diagnosis and treatment 2
- Document hemodynamic parameters including blood pressure, mental status, presence of chest pain, and signs of heart failure 1, 2
Hemodynamically Unstable Tachyarrhythmias
Immediate synchronized cardioversion is the definitive treatment for any tachyarrhythmia causing hemodynamic compromise—do not wait for intravenous access or pharmacologic agents. 1, 2, 3
- Deliver synchronized cardioversion starting at 100-200 J biphasic for organized rhythms 2
- Use unsynchronized defibrillation at maximum output for pulseless ventricular tachycardia or ventricular fibrillation 2
- For pre-excited atrial fibrillation (irregular wide-complex tachycardia in Wolff-Parkinson-White syndrome), proceed directly to DC cardioversion as AV nodal blocking agents may precipitate ventricular fibrillation 1, 2
Hemodynamically Stable Narrow QRS Tachycardias (SVT)
Initial Non-Pharmacologic Intervention
Begin with vagal maneuvers (Valsalva or carotid sinus massage) in the supine position while recording a 12-lead ECG to capture the response. 1, 2
- Perform carotid sinus massage only after auscultating for carotid bruits; avoid if bruits are present 2
- Document the ECG during vagal maneuvers as the response pattern aids in diagnosing the specific mechanism 2
Pharmacologic Management
If vagal maneuvers fail, administer adenosine 6 mg rapid IV push followed by 20 mL saline flush; if ineffective after 1-2 minutes, give 12 mg, repeatable once. 1, 2
- Adenosine terminates AVNRT and AVRT by transiently blocking the AV node 2
- Critical contraindication: Never use adenosine, beta-blockers, calcium-channel blockers, or digoxin in pre-excited atrial fibrillation (WPW syndrome) as these agents may accelerate ventricular response and precipitate ventricular fibrillation 1, 2
- Adenosine should be used cautiously in patients with severe coronary artery disease as it may provoke ischemia 4
Alternative Agents When Adenosine Fails or Is Contraindicated
- Intravenous metoprolol or esmolol (beta-blockers) for rate control or rhythm conversion 2
- Intravenous diltiazem or verapamil (non-dihydropyridine calcium-channel blockers) as alternatives 2, 3
- Avoid combining IV calcium-channel blockers with IV beta-blockers due to potentiation of hypotensive and bradycardic effects 1
Hemodynamically Stable Wide QRS Tachycardias
Treat all wide-complex tachycardias as ventricular tachycardia unless proven otherwise—misdiagnosing VT as SVT and treating with AV nodal blockers can be fatal. 1, 2
Pharmacologic Termination
For stable monomorphic VT without severe heart failure or acute MI, intravenous procainamide 10-17 mg/kg at 20-50 mg/min is the preferred first-line agent. 1, 2
- Sotalol may be used if procainamide is unavailable and there is no structural heart disease 1, 2
- For patients with left ventricular dysfunction, severe heart failure, or acute MI, intravenous amiodarone 150 mg over 10 minutes is preferred due to superior hemodynamic tolerance 1, 2
- Amiodarone can be repeated (150 mg every 10 minutes) and continued as an infusion (1 mg/min for 6 hours, then 0.5 mg/min) 2
Polymorphic VT and Torsades de Pointes
- Assess the QT interval first: normal QT polymorphic VT suggests acute coronary syndrome requiring urgent revascularization 2
- For prolonged QT (torsades de pointes), give magnesium sulfate 2 g IV, correct electrolytes (potassium >4.0 mEq/L, magnesium >2.0 mg/dL), stop all QT-prolonging drugs, and consider temporary overdrive pacing 2
Post-Stabilization Management and Referral
All patients with documented wide-complex tachycardia require ICU/CCU admission and immediate cardiology/electrophysiology consultation regardless of successful termination. 2
- Refer to an arrhythmia specialist for: wide-complex tachycardia of unknown origin, Wolff-Parkinson-White syndrome, narrow-complex tachycardias resistant or intolerant to drugs, severe symptoms during palpitations, or recurrent SVT 2
- Catheter ablation has >95% success rates for AVNRT and AVRT and should be offered to patients with recurrent symptomatic episodes 2
- Consider coronary revascularization if VT is associated with ischemic heart disease 1
Long-Term Management of Ventricular Arrhythmias
Implantable cardioverter-defibrillator (ICD) is indicated for secondary prevention in survivors of cardiac arrest or sustained VT, and for primary prevention in patients with LVEF ≤35%, NYHA class II-III, on optimal medical therapy, with expected survival >1 year. 2
- When ICD is not feasible, amiodarone, sotalol, or beta-blockers may be used, though they are less effective for mortality reduction 2
- Asymptomatic nonsustained VT in heart failure patients should not be treated with antiarrhythmic drugs as suppression does not improve prognosis 2
Critical Safety Principles
- Never use AV nodal blocking agents (adenosine, beta-blockers, calcium-channel blockers, digoxin) in suspected pre-excitation syndromes 1, 2
- Correct electrolyte abnormalities (potassium, magnesium, calcium) promptly in all patients with tachyarrhythmias 2
- Initiation of class I or class III antiarrhythmics without documented arrhythmia is discouraged due to pro-arrhythmic risk 2
Accessing Guidelines
The most comprehensive and recent guidelines for tachyarrhythmia management are the 2014 AHA/ACC/HRS Guideline for the Management of Patients with Atrial Fibrillation 4 and the 2003 ACC/AHA/ESC Guidelines for the Management of Patients with Supraventricular Arrhythmias 4. These are published in Circulation and the Journal of the American College of Cardiology and are available through the American College of Cardiology (www.acc.org) and American Heart Association (www.heart.org) websites. The 2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients with Syncope 4 provides additional guidance on arrhythmia-related syncope evaluation.