What is the treatment for supraventricular tachycardia (SVT)?

Treatment of Supraventricular Tachycardia (SVT)

For hemodynamically stable SVT patients, begin with vagal maneuvers (particularly the modified Valsalva maneuver), followed immediately by intravenous adenosine if vagal maneuvers fail; for hemodynamically unstable patients showing hypotension, altered mental status, shock, chest pain, or acute heart failure, perform immediate synchronized cardioversion. 1

Acute Management Algorithm

Step 1: Assess Hemodynamic Stability

Determine if the patient shows signs of instability including hypotension, altered mental status, signs of shock, chest pain, or acute heart failure. 1

If Hemodynamically Unstable:

• Perform immediate synchronized cardioversion, which is highly effective for terminating SVT and should be done promptly without delay. 1

If Hemodynamically Stable, proceed to Step 2:

Step 2: Vagal Maneuvers (First-Line)

• The modified Valsalva maneuver is the most effective vagal technique with an overall success rate of approximately 27.7% for converting SVT to sinus rhythm. 1, 2
• The modified Valsalva maneuver is significantly more effective than carotid sinus massage and should be your first choice. 2

Step 3: Adenosine (If Vagal Maneuvers Fail)

• Administer intravenous adenosine, which has a 90-95% success rate for terminating AVNRT and orthodromic AVRT. 1, 3
• Adenosine is remarkably safe with a half-life of only a few seconds, though approximately 30% of patients experience brief side effects including chest discomfort, dyspnea, and flushing. 1, 3
• Adenosine is preferred over verapamil as first-line pharmacotherapy due to its superior safety profile and rapid metabolism. 3

Step 4: Alternative Pharmacologic Agents (If Adenosine Fails)

• Use intravenous calcium channel blockers (diltiazem or verapamil) or beta blockers, which have success rates of 80-98% for conversion to sinus rhythm. 1
• Critical caveat: Avoid these agents in patients with suspected ventricular tachycardia, pre-excited atrial fibrillation, or systolic heart failure. 1

Special Populations

Pre-Excited Atrial Fibrillation (Wolff-Parkinson-White)

• Use ibutilide or intravenous procainamide for stable patients with pre-excited AF. 1
• Never use AV nodal blocking agents (adenosine, calcium channel blockers, beta blockers, or digoxin) as they may enhance conduction over the accessory pathway and precipitate ventricular fibrillation. 1

Long-Term Management

First-Line: Catheter Ablation

Catheter ablation is the most effective therapy to prevent recurrent SVT and should be offered to all patients as first-line long-term management. 1, 4

• Success rates range from 94.3-98.5% with a single procedure. 1, 4
• All patients treated for SVT should be referred for a heart rhythm specialist opinion. 5

Alternative: Pharmacologic Prevention

For patients who decline ablation or are not candidates:

• Oral beta blockers, diltiazem, or verapamil are reasonable options. 1
• In patients without structural heart disease only: Flecainide or propafenone can be used for prevention of paroxysmal SVT. 1, 6
• Critical warning: Flecainide should never be used in patients with recent myocardial infarction, structural heart disease, or chronic atrial fibrillation due to significant proarrhythmic risk (4% in SVT patients, with potential for fatal ventricular arrhythmias). 6