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2015 ACC/AHA/HRS SVT Guidelines

Clinical Quick Reference — Management of Supraventricular Tachycardia

Published: Journal of the American College of Cardiology (2015)
Societies: American College of Cardiology, American Heart Association, Heart Rhythm Society
DOI: 10.1016/j.jacc.2015.09.019
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What's New in 2015

This updated guideline incorporates new evidence on SVT management and provides a comprehensive, mechanism-based approach to diagnosis and treatment:

SVT Classification & Mechanism-Based Approach

Supraventricular tachycardia is defined as tachycardia with atrial rates ≥100 bpm involving tissue above the bifurcation of the His bundle. Classification requires understanding the underlying mechanism:

Junctional Tachycardias (AV Nodal Dependent)

Atrioventricular Nodal Reentrant Tachycardia (AVNRT) — 50-60% of all SVTs. Two distinct AV nodal pathways (fast and slow) create a reentrant circuit. Most commonly fast-slow AVNRT (typical).

Atrioventricular Reentrant Tachycardia (AVRT) — 30-40% of all SVTs. Requires an accessory pathway connecting atrium to ventricle (e.g., Wolff-Parkinson-White syndrome). Orthodromic (antegrade through AV node) vs. antidromic (antegrade through accessory pathway).

Permanent Junctional Reciprocating Tachycardia (PJRT) — Rare (<1%). Concealed slow retrograde accessory pathway with long VA interval and decremental properties.

Atrial Tachycardias (Atrial Mechanism)

Focal Atrial Tachycardia (AT) — Automatic or triggered activity from a single atrial site, characterized by discrete P-wave morphology and 1:1 AV conduction.

Multifocal Atrial Tachycardia (MAT) — ≥3 distinct atrial activation sites with variable AV conduction. Associated with COPD, hypoxia, and acute illness. Irregular ventricular response.

Atrial Flutter — Cavotricuspid isthmus-dependent (typical, ~90%) or non-isthmus-dependent (atypical). Regular atrial rate 240-320 bpm with variable AV conduction.

Sinus Node Dysfunction

Physiologic Sinus Tachycardia: Appropriate heart rate response to exercise, fever, hyperthyroidism, anemia, or heart failure.

Inappropriate Sinus Tachycardia (IST): Unexplained sinus rate >100 bpm at rest or disproportionate elevation with minimal exertion. Diagnosis of exclusion.

Postural Orthostatic Tachycardia Syndrome (POTS): Heart rate increase ≥20 bpm within 10 minutes of standing or ≥30 bpm if supine baseline HR <90 bpm. Associated with syncope and autonomic dysfunction.

Acute Management Algorithm

The approach to acute SVT requires rapid assessment of hemodynamic stability and response to stepwise interventions:

Step 1: Assess Hemodynamic Status

Hemodynamically Stable? Patient alert, SBP adequate, no acute heart failure or angina
If YES → Proceed to vagal maneuvers. If NO → Consider immediate synchronized cardioversion.

Step 2: Vagal Maneuvers (Class I, LOE B-R)

First-line therapy for regular SVT. Patient in supine position; perform maneuver 5-10 seconds:
  • Valsalva maneuver (strain against closed glottis 15-30 seconds)
  • Carotid sinus massage (5-10 seconds, unilateral)
  • Ice water immersion on face (trigger dive reflex)
Success rate: 20-40% termination. If ineffective → proceed to adenosine.

Step 3: Adenosine (Class I, LOE B-R)

IV Adenosine Protocol
Dosing: Rapid IV push with saline flush
  • First dose: 6 mg IV rapid push
  • Second dose: 12 mg IV rapid push (if 6 mg ineffective)
  • Third dose: 12 mg IV rapid push (if 12 mg ineffective)
Success rate: 78-96% for AVNRT/AVRT. Onset within seconds.

Step 4: IV Antiarrhythmics or Cardioversion

If adenosine ineffective or contraindicated:
  • Beta-blockers: IV metoprolol 5 mg q5min or IV esmolol infusion
  • Calcium channel blockers: IV verapamil 5-10 mg or diltiazem 0.25 mg/kg
  • For regular SVT only: IV procainamide 10-15 mg/kg
Synchronized Cardioversion: 50-100 J biphasic for hemodynamic instability or failure of drugs

Adenosine Administration: Detailed Protocol

Dosing Regimen

Dose Sequence Amount Route Timing Notes
Initial dose 6 mg IV rapid push + saline flush Seconds onset; effective in ~60% Preferred starting dose; fewer side effects
Second dose 12 mg IV rapid push + saline flush Wait 1-2 minutes if first fails Effective in additional 20-30%
Third dose 12 mg IV rapid push + saline flush Wait 1-2 minutes if second fails Rarely needed; reassess diagnosis

Administration Technique

Proper Administration

  • Use large-bore peripheral IV or central line (>20 gauge preferred)
  • Have saline-primed flush ready before injection
  • Administer bolus as rapidly as possible over 1-2 seconds
  • Follow immediately with 20 mL saline flush and raise arm
  • Continuous cardiac monitoring; have resuscitation equipment available
  • Patient may experience transient asystole, chest pain, dyspnea, flushing

Contraindications & Cautions

Absolute/Relative Contraindications

  • Severe asthma or COPD: Risk of bronchospasm; consider alternative
  • Decompensated heart failure: May worsen hemodynamics
  • Severe hypotension: Avoid; use synchronized cardioversion
  • Recent dipyridamole use: Markedly potentiates adenosine; reduce dose by 50%
  • Pre-excited atrial fibrillation: AVOID — increases AP conduction and VF risk
Pearl: Adenosine's rapid metabolism and short half-life make it ideal for emergency SVT conversion. The transient asystole/bradycardia is expected and usually self-limited. Failure of rapid saline flush is a common reason for treatment failure — ensure rapid administration and vigorous flushing into central circulation.

Atrioventricular Nodal Reentrant Tachycardia (AVNRT)

AVNRT accounts for 50-60% of all SVTs and is the most common SVT mechanism. It involves reentry within the AV node using two distinct pathways.

Acute Treatment (Class I, LOE B-R)

First-Line Approach

  • 1 Vagal maneuvers followed by IV adenosine 6 mg → 12 mg → 12 mg
  • Success rate: 78-96% termination within seconds
  • If adenosine contraindicated: IV verapamil 5-10 mg or diltiazem 0.25 mg/kg
  • If hemodynamically unstable: Synchronized cardioversion at 50-100 J

Chronic Management Recommendations

COR LOE Strategy Details
1 B-NR Catheter ablation Indicated for recurrent symptomatic AVNRT. Success rate 90-98%; recurrence 1-3%. AV block risk <0.5%.
IIa B-R Beta-blockers or CCB For mild/infrequent AVNRT or patients deferring ablation. Beta-blockers: metoprolol, atenolol. CCB: verapamil, diltiazem.
IIb B-R Flecainide/propafenone For frequent episodes despite beta-blockers/CCB and no structural heart disease.
Pearl: AVNRT has an excellent prognosis. Ablation is definitive (>95% long-term success) with low complication risk. For infrequent, well-tolerated episodes, beta-blockers or CCB is reasonable. Frequent symptomatic episodes favor ablation.

Atrioventricular Reentrant Tachycardia (AVRT) & Wolff-Parkinson-White Syndrome

AVRT accounts for 30-40% of SVTs and requires an accessory pathway connecting atrium to ventricle. Management differs based on SVT type and whether pre-excited AF is present.

Acute Treatment: Orthodromic SVT (Class I, LOE B-R)

Standard Approach

  • 1 Vagal maneuvers → IV adenosine 6 mg → 12 mg → 12 mg
  • Success rate: 85-95% termination
  • If adenosine contraindicated: IV verapamil or diltiazem
  • If hemodynamically unstable: Synchronized cardioversion

Acute Treatment: Pre-Excited Atrial Fibrillation (Class I, LOE C-LD)

Critical Management Point

  • AVOID: AV nodal blocking agents (adenosine, verapamil, diltiazem, beta-blockers) in pre-excited AF
  • WHY: These block AV node, increasing AP conduction → faster ventricular rate → VF risk
  • USE INSTEAD: IV procainamide 10-15 mg/kg at 20-50 mg/min (slows AP refractory period)
  • ALTERNATIVE: IV ibutilide or flecainide if available
  • IF UNSTABLE: Immediate synchronized cardioversion (preferred)

Chronic Management: Ablation Indications

Class I (Indicated):

  • Recurrent symptomatic orthodromic AVRT (>1 episode)
  • Any patient with pre-excited AF (high SCD risk)
  • Accessory pathway with very short refractory period (<250 ms) and occupational concerns (pilots, drivers)
  • Patient preference after informed counseling

Success Rates: 95-98% success with <1% recurrence. Ablation is definitive.

Pearl on Asymptomatic Pre-Excitation: Not all pre-excited patients need ablation. Those with low-risk pathways (slow AP conduction) generally have benign prognosis. Risk stratification via EP study is recommended for occupational/athletic concerns or pre-excited AF development. Shortest RR interval <250 ms during AF indicates high risk.

Focal Atrial Tachycardia

Focal AT represents 10-15% of SVTs and results from automatic or triggered activity from a discrete atrial site, characterized by a single P-wave morphology.

Acute Treatment (Class IIa-IIb, LOE B-R)

Initial approach: Vagal maneuvers and adenosine are less effective (30-50% success) because mechanism is automaticity/triggered activity, not reentry. Adenosine may transiently slow AV conduction, aiding diagnosis.

If hemodynamically stable:

  • IIa IV beta-blockers (metoprolol 5 mg q5min) or CCB (verapamil 5-10 mg, diltiazem 0.25 mg/kg)
  • IIb IV propafenone or amiodarone

If hemodynamically unstable: Synchronized cardioversion at 50-100 J.

Chronic Management

COR Strategy Details
1 Ablation (symptomatic) Success rate 70-90% depending on location. Recurrence 5-15%.
IIa Beta-blockers or CCB First-line drug therapy; moderate efficacy (~50-60% reduce episodes)
IIb Antiarrhythmics (flecainide, propafenone) For refractory AT despite beta-blockers/CCB; check LV function first

Multifocal Atrial Tachycardia (MAT)

MAT is characterized by ≥3 distinct P-wave morphologies with variable AV conduction and irregular ventricular rate. Usually associated with acute illness (COPD exacerbation, hypoxia, CHF, infection).

Acute Management

Treatment Approach

  • 1 Treat underlying condition (hypoxia, infection, heart failure, thyroid disease)
  • Vagal maneuvers and adenosine are ineffective in MAT (atrial mechanism, not reentry)
  • IIa IV beta-blockers or CCB if hemodynamically stable
  • IIb IV magnesium sulfate 1-2 g
  • Goal: Rate control, not conversion (usually resolves with underlying disease treatment)

Chronic Management

Key principle: MAT is primarily a manifestation of underlying disease. Arrhythmia usually resolves when underlying condition is treated.

  • Beta-blockers or CCB for rate control (first-line)
  • Avoid class IC antiarrhythmics (limited efficacy)
  • Amiodarone reserved for refractory cases
  • Ablation generally ineffective (multiple foci)

Inappropriate Sinus Tachycardia & Postural Orthostatic Tachycardia Syndrome

Inappropriate Sinus Tachycardia (IST)

Definition: Persistent sinus tachycardia (>100 bpm at rest) or inappropriate heart rate response to minimal exertion with no identifiable cause. Diagnosis of exclusion.

Management:

  • IIa Beta-blockers (atenolol, metoprolol) or non-DHP CCB (verapamil, diltiazem) for rate control
  • IIb Ablation of SANRT or sinus node modification
  • Prognosis: Usually benign; physical conditioning often helpful

Postural Orthostatic Tachycardia Syndrome (POTS)

Definition: Orthostatic HR increase ≥20 bpm (or ≥30 bpm if supine HR <90 bpm) within 10 minutes of standing, with syncope or autonomic symptoms.

Management:

  • 1 Conservative measures: Increased salt/fluid intake, compression stockings, lower extremity exercises
  • IIa Beta-blockers (propranolol, atenolol) or midodrine for refractory cases
  • IIb Fludrocortisone or ivabradine in selected patients
  • Prognosis: Highly variable; some spontaneous remission, others chronic

Antiarrhythmic Drugs for SVT

Comprehensive drug reference with dosing, monitoring requirements, and key contraindications:

Drug Class IV Acute Dose Oral Chronic Dose Key Monitoring
Metoprolol Beta-blocker 5 mg IV q5min × 3 50-200 mg/day div HR, BP; avoid in asthma/COPD, decompensated HF
Atenolol Beta-blocker 5 mg IV q5min 25-100 mg daily Renal dosing; HR, BP
Esmolol Beta-blocker (IV only) 0.5 mg/kg loading, then 0.05-0.2 mg/kg/min infusion N/A Continuous monitoring; rapid offset if stopped
Verapamil Non-DHP CCB 5-10 mg IV over 2 min 120-360 mg/day (IR or ER) HR, BP, AV block; avoid in HF, hypotension
Diltiazem Non-DHP CCB 0.25 mg/kg IV; repeat 0.35 mg/kg in 15 min 120-360 mg/day (div or ER) HR, BP, AV block; caution in HF
Adenosine Purine nucleoside 6 mg IV push, then 12 mg × 1-2 Not used chronically Transient asystole expected; caution in asthma
Flecainide Ic antiarrhythmic N/A 150-300 mg/day div (50-100 mg TID) ECG (QRS, PR); avoid structural HD/CAD; renal dosing
Propafenone Ic antiarrhythmic N/A 450-900 mg/day div (150-300 mg TID) ECG, liver function; avoid structural HD; beta-blocker effects
Procainamide Ia antiarrhythmic 10-15 mg/kg IV at 20-50 mg/min 3-4 g/day div ANA, CBC, ECG; drug-induced lupus risk; renal/hepatic function
Amiodarone III antiarrhythmic 150 mg IV over 10 min; repeat 150 mg in 10-15 min 200-400 mg daily (long half-life; taper over weeks) TSH, LFTs, CXR (pulmonary toxicity); eye exams; photosensitivity
Sotalol III + beta-blocker N/A 80-160 mg BID (CrCl-adjusted) ECG (QTc), renal function; QTc >500 ms contraindicated; torsades risk
Dofetilide III antiarrhythmic N/A 250-500 mcg BID (CrCl, QTc-adjusted) QTc (must be <440 ms); renal function; inpatient initiation required

Drug Selection by SVT Type

AVNRT/Orthodromic AVRT: Beta-blockers or CCB first-line. If inadequate, add flecainide or propafenone (check LV function).

Focal AT/MAT: Beta-blockers or CCB. Antiarrhythmics less effective. Amiodarone for refractory.

Pre-excited AF (emergency): Procainamide IV ONLY (never adenosine, verapamil, or beta-blockers).

Catheter Ablation for SVT

Radiofrequency catheter ablation is the definitive treatment for SVT, with high success rates and low recurrence across all SVT types.

Indications by SVT Type

SVT Type COR Success Rate Recurrence Key Risks
AVNRT (recurrent) 1 90-98% 1-3% AV block (<0.5%); modern technique minimizes risk
AVRT/WPW (symptomatic) 1 95-99% <1% AV block with septal pathway (1-2%); coronary injury rare
Focal AT (refractory) 1 70-90% 5-15% Location-dependent; structural damage rare
MAT No Benefit N/A N/A Multiple foci; ablation ineffective

Procedural Approach

Electrophysiology Study (EP): Baseline intracardiac electrograms document mechanism. Programmed stimulation confirms diagnosis and guides ablation target.

Mapping Techniques:

  • Conventional mapping: Multipolar catheters; activation/entrainment techniques
  • 3-D electroanatomic mapping (CARTO, NavX): Spatial reconstruction of anatomy and electrical activity; improved accuracy, reduced fluoroscopy

Energy sources: Radiofrequency (standard), cryoablation (lower pain, reversible), laser/ultrasound (investigational).

Complication Risk

Major Complications: 1-3%
  • Atrioventricular block (highest with septal pathways; use cryoablation for safety)
  • Coronary artery injury (rare; posteroseptal/right coronary sinus targets have higher risk)
  • Cardiac perforation/tamponade (<1%)
  • Thromboembolic stroke (<1%)
  • Vascular access complication
Pearl: Modern SVT ablation with 3-D mapping is one of the safest procedures in interventional cardiology. High-volume centers achieve >95% success with <1% major complications. Refer complex cases (CHD, septal pathways) to specialized centers.

Special Populations

Pregnancy

Incidence: SVT incidence increases 2-3 fold during pregnancy (AVNRT and AVRT most common).

First Trimester Acute Treatment:

  • 1 Vagal maneuvers
  • 1 IV adenosine (rapidly metabolized; extremely low teratogenicity)
  • 1 IV verapamil or diltiazem
  • Avoid: ACE inhibitors, warfarin (teratogenic), class IC antiarrhythmics

Chronic Management: Beta-blockers preferred (labetalol safest). Verapamil/diltiazem reasonable alternative. IIa Ablation if frequent symptomatic SVT refractory to drugs.

Elderly Patients

Considerations: Increased structural heart disease, slower metabolism, increased drug sensitivity, polypharmacy.

Management:

  • Vagal maneuvers and adenosine still first-line; similar efficacy to younger patients
  • Lower IV drug doses often needed
  • Beta-blockers may worsen fatigue; CCB often preferred
  • 1 Ablation is safe and recommended for recurrent symptomatic SVT; similar outcomes to younger patients
  • Assess for HF, renal dysfunction, and CAD before initiating antiarrhythmics

Congenital Heart Disease (CHD)

Unique Features: Atrial reentry (Fontan, TOF repair), accessory pathways, sinus node dysfunction, scar-related tachycardias.

Management:

  • Acute treatment similar (vagal, adenosine, IV drugs, cardioversion)
  • 1 Ablation indicated for recurrent SVT; often uses 3-D mapping given complex anatomy
  • Cryoablation preferred for some substrates
  • Close long-term follow-up with CHD-experienced cardiologist

Athletes & Highly Symptomatic Patients

Considerations: SVT during exercise compromises cardiac output and athletic performance. Recurrent episodes may severely impair quality of life.

Management:

  • 1 Ablation preferred over long-term drug therapy to preserve exercise capacity
  • For WPW with rapid AP: Ablation recommended even if minimally symptomatic (safety concern)
  • Beta-blockers may impair exercise tolerance
  • Clearance for competitive sports depends on SVT type, treatment success, and LV function

Key Do's and Don'ts in SVT Management

DO: Essential Actions

  • Obtain 12-lead ECG during SVT (if safe; helps identify mechanism)
  • Perform vagal maneuvers in HEMODYNAMICALLY STABLE patients with regular SVT
  • Administer adenosine 6 mg IV rapid push with saline flush as first-line drug
  • Assess for pre-excitation (short PR + delta wave) before AV nodal blockers
  • Use IV procainamide (not adenosine/verapamil) in pre-excited atrial fibrillation
  • Consider EP study and ablation for recurrent symptomatic SVT (Class I for most)
  • Risk-stratify asymptomatic pre-excitation with EP testing if occupational concerns
  • Refer to high-volume ablation centers for complex anatomies (CHD, septal pathways)

DON'T: Common Pitfalls

  • DO NOT use adenosine in pre-excited atrial fibrillation (increases AP conduction → VF)
  • DO NOT use verapamil/diltiazem in hemodynamically unstable SVT (hypotension risk)
  • DO NOT use verapamil/diltiazem in pre-excited AF (AP blocking risk)
  • DO NOT delay cardioversion in hemodynamically unstable patients awaiting drug response
  • DO NOT assume adenosine failure = non-SVT (may be focal AT, adenosine-resistant AVNRT, or procedural error)
  • DO NOT initiate flecainide/propafenone without ruling out structural HD or CAD
  • DO NOT omit saline flush after adenosine (poor delivery = treatment failure)
  • DO NOT dismiss palpitations as anxiety without ECG documentation
  • DO NOT use sotalol/dofetilide in patients with electrolyte abnormalities (torsades risk)

ECG Interpretation Tips

Diagnostic Clues

Regular vs. Irregular?
  • Regular: AVNRT, AVRT, focal AT, atrial flutter with fixed AV block
  • Irregular: MAT, AF, atrial flutter with variable AV block
QRS duration?
  • Narrow (<120 ms): Supraventricular (except pre-excitation or aberrancy)
  • Wide (≥120 ms): Aberrancy, pre-excitation, or VT (distinguish carefully)
RP interval (R to P)?
  • Short RP (<70 ms): Typical AVNRT (P buried in QRS)
  • Long RP (>70 ms): Atypical AVNRT, PJRT, or focal AT

Related Clinical Calculators & Resources

Access integrated tools to aid in SVT risk stratification, drug safety, and patient counseling:

SVT Differential Diagnosis

Interactive tool to differentiate AVNRT, AVRT, focal AT, and other SVTs based on clinical and ECG features.

EASY-WPW Score

Risk stratification for asymptomatic pre-excitation; predicts accessory pathway refractory period and SCD risk.

Atrial Tachycardia Localization

P-wave morphology analysis and activation map interpretation to localize focal atrial tachycardia origin.

QTc Drug Safety Checker

Identify drug interactions and QTc prolongation risk before antiarrhythmic therapy (sotalol, dofetilide, amiodarone).

Corrected QT (QTc) Calculator

Bazett's and Fridericia formulas for QTc calculation; assess baseline QTc before antiarrhythmic initiation.

CHA₂DS₂-VASc Score

Stroke risk stratification in patients with atrial fibrillation or atrial flutter (for anticoagulation guidance).