SVT encompasses tachyarrhythmias originating from or conducting through the atria or AV node, typically presenting as a regular narrow-complex tachycardia (QRS ≤120 ms) at rates of 150–250 bpm. The three major subtypes of paroxysmal SVT (PSVT) are AVNRT (~60%), AVRT (~30%), and focal atrial tachycardia (~10%). [1] Prevalence is approximately 2.29 per 1,000 persons, with ~89,000 new cases per year in the US. [2] It is generally a benign condition, but untreated PSVT can cause significant symptom burden and rarely tachycardia-mediated cardiomyopathy (~1%). [1]
1. History
- Onset/offset: Abrupt onset and termination is the hallmark of PSVT — ask about sudden "flip-switch" start/stop [1]
- Palpitations (86%), chest discomfort (47%), dyspnea (38%), lightheadedness (19%) [1]
- Duration of episodes, frequency, and whether self-terminating or requiring ED visits
- Triggers: caffeine, alcohol, stimulants, exercise, emotional stress, sleep deprivation [3]
- Prior episodes, prior ED visits, prior adenosine use, prior ablation
- Polyuria during or after episodes (atrial natriuretic peptide release — classic for SVT)
- Syncope is rare and more likely vagally mediated than directly from SVT [1]
2. Alarm Features
- Hemodynamic instability: hypotension, altered mental status, signs of shock, acute heart failure, ischemic chest pain → immediate synchronized cardioversion [2][4]
- Wide-complex tachycardia (QRS >120 ms) — must distinguish SVT with aberrancy from ventricular tachycardia [2]
- Pre-excited atrial fibrillation (irregular wide-complex tachycardia in WPW) — avoid AV nodal blockers (adenosine, verapamil, diltiazem) as these can precipitate VF [1]
- Persistent tachycardia with signs of heart failure → concern for tachycardia-mediated cardiomyopathy [1]
- New SVT in the setting of structural heart disease, prior MI, or reduced EF
3. Medications
Acute treatment (in order):
- Vagal maneuvers (first-line): Modified Valsalva (43% effective), carotid sinus massage (~10–19%) [1][4]
- Adenosine IV: 6 mg rapid push → 12 mg if no response (half-life ~10 sec; ~90% effective) [1][5]
- IV diltiazem (20 mg) or verapamil (5 mg) over 2 min — 64–98% conversion rate [2][4]
- IV β-blockers (esmolol, metoprolol) — alternative if adenosine ineffective [1]
- Etripamil (intranasal calcium channel blocker) — FDA-approved for PSVT; 64% vs 31% placebo at 30 min [1][6]
Contraindicated/caution:
- Adenosine contraindicated in pre-excited AF (WPW with AF), severe asthma, and use caution in heart transplant recipients [1][4]
- Verapamil/diltiazem contraindicated in HFrEF, wide-complex tachycardia of uncertain origin, and pre-excited AF [2][4]
- Avoid combining multiple antiarrhythmics — risk of proarrhythmia and hemodynamic collapse [7]
Long-term prevention:
- β-blockers or nondihydropyridine CCBs as first-line pharmacotherapy [1]
- Flecainide or propafenone (pill-in-the-pocket) for infrequent episodes in patients without structural heart disease [1]
Medication triggers: Sympathomimetics, theophylline, digoxin toxicity, recreational stimulants (cocaine, amphetamines) [3]
4. Diet
- Caffeine and alcohol are common triggers — counsel moderation [3]
- Energy drinks (high caffeine + stimulant content) — avoid
- Adequate hydration — dehydration can lower the threshold for SVT
- No specific long-term dietary restrictions beyond trigger avoidance
5. Review of Systems
- Cardiovascular: Palpitations, chest pain, dyspnea, presyncope/syncope, exercise intolerance
- Endocrine: Heat intolerance, weight loss, tremor (hyperthyroidism as trigger) [3]
- Psychiatric: Anxiety, panic attacks (commonly confused with SVT and vice versa)
- Pulmonary: Wheezing, cough (relevant for adenosine safety in asthma)
- GI: Nausea during episodes
- Genitourinary: Polyuria during/after episodes (classic for SVT)
6. Collateral History and Family History
- Family history of sudden cardiac death, WPW syndrome, cardiomyopathy, or long QT syndrome [3]
- Familial preexcitation syndrome (rare autosomal dominant)
- Social history: stimulant use (cocaine, methamphetamine, MDMA), alcohol binge drinking, supplement use
- Occupational relevance: pilots, commercial drivers — SVT may affect fitness-for-duty
7. Risk Factors
- Female sex — 2× risk compared to males [2]
- Age >65 — >5× risk compared to younger individuals [2]
- ~50% of patients are aged 45–64 years [1]
- Associated comorbidities: chronic pulmonary disease (15.7%), diabetes (12.5%), heart failure (8.4%), cerebrovascular disease (7.8%) [1]
- Lone PSVT (no cardiovascular disease) accounts for ~39% of cases — younger patients (mean age 37) with faster rates (mean 186 bpm) [1]
- WPW pattern on ECG: prevalence 0.1–0.3% in general population [2]
- Triggers: caffeine, alcohol, stimulants, hyperthyroidism, electrolyte disturbances [3]
8. Differential Diagnosis
The following algorithm from the 2015 ACC/AHA/HRS Guidelines illustrates the systematic approach to narrow-complex tachycardia:
- Sinus tachycardia — gradual onset/offset, identifiable P waves, rate usually <150 bpm; treat underlying cause
- Atrial flutter — sawtooth flutter waves (especially leads II, III, aVF); rate ~150 bpm with 2:1 block is classic; adenosine unmasks flutter waves without terminating [9]
- Atrial fibrillation — irregularly irregular; no discrete P waves
- Multifocal atrial tachycardia (MAT) — irregular, ≥3 P-wave morphologies; associated with COPD, hypoxia
- Ventricular tachycardia — wide complex; must be excluded when QRS >120 ms; AV dissociation, fusion/capture beats favor VT [2]
- Junctional ectopic tachycardia — rare; may show AV dissociation
- Anxiety/panic disorder — sinus tachycardia, no abrupt onset/offset; diagnosis of exclusion
9. Past Medical History
- Prior SVT episodes, prior adenosine use, prior cardioversion
- Prior catheter ablation (recurrence rates vary by substrate)
- Known WPW syndrome or pre-excitation on prior ECGs
- Structural heart disease: valvular disease, cardiomyopathy, congenital heart disease
- Thyroid disease (hyperthyroidism)
- Chronic lung disease (relevant for adenosine safety)
- Surgical history: prior cardiac surgery (atrial scarring → atrial tachycardia)
10. Physical Exam
- Vital signs: Heart rate (typically 150–250 bpm), blood pressure (assess for hemodynamic stability), SpO₂
- Cardiovascular: Regular rapid rhythm, assess for murmurs (valvular disease), JVD (heart failure), "frog sign" (cannon A waves in JVP during AVNRT)
- Pulmonary: Crackles (pulmonary edema/heart failure)
- Neck: Thyroid enlargement/tenderness, carotid bruits (before carotid massage)
- Neurologic: Mental status (altered = hemodynamic instability)
- Extremities: Peripheral perfusion, edema
11. Lab Studies
Recommended initial labs: [1][3]
- CBC — evaluate for anemia, infection
- BMP — electrolytes (K⁺, Mg²⁺, Ca²⁺), renal function
- TSH — rule out hyperthyroidism
- Troponin — if chest pain or concern for ischemia (note: mild troponin elevations in young patients with low CAD risk during SVT generally do not indicate coronary disease) [1]
- BNP — if concern for heart failure
- Magnesium level — hypomagnesemia can lower arrhythmia threshold
12. Imaging
- Chest X-ray — if concern for heart failure (cardiomegaly, pulmonary edema) [3]
- Transthoracic echocardiography — recommended to evaluate for structural heart disease, especially in new-onset SVT, older patients, or those with cardiac comorbidities [1][3]
- Coronary CTA or stress testing — only if clinical risk factors for CAD and anginal symptoms [1]
- Imaging is generally unnecessary in young, otherwise healthy patients with typical PSVT and normal exam
13. Special Tests
- Modified Valsalva maneuver — both diagnostic and therapeutic; 43% conversion rate (REVERT trial) [1]
- Adenosine challenge — diagnostic value: response to adenosine helps differentiate SVT subtypes (termination = AVNRT/AVRT; unmasking of flutter waves = atrial flutter; no effect = consider VT or inadequate dose) [1][9]
- Ambulatory monitoring: Holter (24–48 hr), event monitors, patch monitors (2 weeks), implantable loop recorders for infrequent episodes [1]
- Electrophysiology study (EPS) — gold standard for definitive diagnosis and mapping prior to ablation [1]
- Consumer wearable devices: sensitivity poor for short episodes (<15 sec) but improves for episodes >60 sec [1]
14. ECG
ECG examples of PSVT at various rates and in WPW are shown below:
Key ECG findings:
- Regular narrow-complex tachycardia (QRS ≤120 ms), rate 150–250 bpm
- No visible P waves or P waves buried in QRS → most likely AVNRT (pseudo-R' in V1, pseudo-S in inferior leads) [11-12]
- P waves in ST segment (short RP) → likely AVRT [12]
- Long RP tachycardia → atypical AVNRT, PJRT, or atrial tachycardia [12]
- Delta wave on baseline ECG (pre-excitation) → WPW syndrome [13]
- Rate of exactly ~150 bpm → always consider atrial flutter with 2:1 block [9]
- ST depressions during SVT are common rate-related changes and do not necessarily indicate ischemia in low-risk patients [1]
Dangerous patterns:
- Wide-complex tachycardia — must rule out VT (use Brugada criteria)
- Pre-excited AF (irregular wide-complex) — emergent cardioversion, avoid AV nodal blockers
Always obtain:
- 12-lead ECG during tachycardia AND after conversion to sinus rhythm (look for delta waves, pre-excitation) [2]
- Continuous ECG recording during adenosine administration [1]
15. Assessment
- PSVT is generally benign with excellent prognosis in structurally normal hearts [1]
- Severity stratification: Hemodynamically stable vs. unstable dictates the treatment algorithm
- Typical presentation: young to middle-aged female with sudden-onset regular palpitations, no structural heart disease
- Atypical presentations: syncope (rare, vagally mediated), chest pain mimicking ACS, heart failure exacerbation in patients with reduced EF
- Complications: Tachycardia-mediated cardiomyopathy (~1%), rarely cardiac arrest (primarily in WPW with pre-excited AF) [1]
16. Treatment Plan
Hemodynamically unstable → Immediate synchronized cardioversion (50–100 J) with sedation if possible [1-2]
Hemodynamically stable → Stepwise approach:
- Vagal maneuvers (modified Valsalva preferred): Strain at 40 mmHg × 15 sec → supine with passive leg raise × 15 sec → return to semirecumbent [1]
- Adenosine 6 mg rapid IV push with saline flush → if no response, 12 mg × 1–2 doses [5]
- Always run continuous ECG strip during administration
- Have defibrillator pads in place [1]
- IV diltiazem (20 mg) or verapamil (5 mg) if adenosine fails [1-2]
- IV β-blocker (esmolol, metoprolol) as alternative [4]
- Synchronized cardioversion if refractory to pharmacotherapy [2]
Long-term management:
- Catheter ablation — first-line for recurrent symptomatic PSVT; single-procedure success rates: AVNRT 94.3%, AVRT 98.5%, focal AT 77% [1]
- Pharmacotherapy (β-blockers, CCBs) for patients who decline or are not candidates for ablation [1]
- Pill-in-the-pocket (flecainide/propafenone) for infrequent episodes without structural heart disease [1]
- Teach patients vagal maneuvers for self-termination at home [1]
17. Disposition
Discharge criteria:
- Converted to sinus rhythm and hemodynamically stable
- No evidence of pre-excitation (WPW) on post-conversion ECG
- No structural heart disease or heart failure
- Reliable follow-up arranged
- First episode or known recurrent PSVT with established management plan
Admission/observation criteria:
- Hemodynamic instability or required cardioversion
- Refractory SVT not responding to standard therapy
- New heart failure or troponin elevation with CAD risk factors
- Wide-complex tachycardia of uncertain etiology
- Concern for WPW with rapid pre-excited conduction
Specialist consultation triggers:
- All patients with recurrent PSVT should be referred to cardiology/electrophysiology for consideration of ablation [1][3]
- Pre-excitation on ECG → urgent EP referral (risk stratification for sudden death) [1]
- Refractory SVT in the ED → cardiology consultation
18. Follow Up / Return Precautions
- Follow-up: Cardiology/EP referral within 1–4 weeks for recurrent PSVT; sooner if pre-excitation identified [3]
- Return precautions: Return immediately for recurrent palpitations with chest pain, syncope, severe dyspnea, or prolonged episodes not terminating with vagal maneuvers
- Patient counseling:
- Teach modified Valsalva and bearing-down techniques for home use [1]
- Avoid known triggers (caffeine, alcohol, stimulants)
- SVT is generally benign — reassurance is important
- Discuss ablation as a curative option (>94% success for AVNRT/AVRT) [1]
- Expected course: Episodes may recur unpredictably; without ablation, long-term recurrence on medical therapy is ~68% over 5 years vs. 0% with ablation in one RCT [1]
References
1. Diagnosis and Management of Paroxysmal Supraventricular Tachycardia. — Peng G, Zei PC. The Journal of the American Medical Association. 2024.
2. Diagnosis and Management of Paroxysmal Supraventricular Tachycardia. — Peng G, Zei PC. The Journal of the American Medical Association. 2024.
3. Diagnosis and Management of Paroxysmal Supraventricular Tachycardia. — Peng G, Zei PC. The Journal of the American Medical Association. 2024.
4. 2015 ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. — Page RL, Joglar JA, Caldwell MA, et al. Journal of the American College of Cardiology. 2016.
5. 2015 ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. — Page RL, Joglar JA, Caldwell MA, et al. Journal of the American College of Cardiology. 2016.
6. Common Types of Supraventricular Tachycardia: Diagnosis and Management. — Nasir M, Sturts A, Sturts A. American Family Physician. 2023.
7. Common Types of Supraventricular Tachycardia: Diagnosis and Management. — Nasir M, Sturts A, Sturts A. American Family Physician. 2023.
8. Part 9: Adult Advanced Life Support: 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. — Wigginton JG, Agarwal S, Bartos JA, et al. Circulation. 2025.
9. Part 9: Adult Advanced Life Support: 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. — Wigginton JG, Agarwal S, Bartos JA, et al. Circulation. 2025.
10. FDA Drug Label. — Updated date: 2018-12-04. Food and Drug Administration.
11. FDA Drug Label. — Updated date: 2018-12-04. Food and Drug Administration.
12. FDA Orange Book. — FDA Orange Book. 2026.
13. FDA Orange Book. — FDA Orange Book. 2026.
14. Part 8: Pediatric Advanced Life Support: 2025 American Heart Association and American Academy of Pediatrics Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. — Lasa JJ, Dhillon GS, Duff JP, et al. Pediatrics. 2026.
15. Part 8: Pediatric Advanced Life Support: 2025 American Heart Association and American Academy of Pediatrics Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. — Lasa JJ, Dhillon GS, Duff JP, et al. Pediatrics. 2026.
16. 2015 ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. — Page RL, Joglar JA, Caldwell MA, et al. Journal of the American College of Cardiology. 2016.
17. 2015 ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. — Page RL, Joglar JA, Caldwell MA, et al. Journal of the American College of Cardiology. 2016.
18. Evaluation and Initial Treatment of Supraventricular Tachycardia. — Link MS. The New England Journal of Medicine. 2012.
19. Evaluation and Initial Treatment of Supraventricular Tachycardia. — Link MS. The New England Journal of Medicine. 2012.
20. Electrocardiographic Differential Diagnosis of Narrow Complex Tachycardia. — Megan Starling, William J. Brady The Electrocardiagram in Emergency and Acute Care. 2023.
21. Electrocardiographic Differential Diagnosis of Narrow Complex Tachycardia. — Megan Starling, William J. Brady The Electrocardiagram in Emergency and Acute Care. 2023.
22. ACC/AHA/ESC Guidelines for the Management of Patients With Supraventricular Arrhythmias--Executive Summary. A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Supraventricular Arrhythmias) Developed in Collaboration With NASPE-Heart Rhythm Society. — Blomström-Lundqvist C, Scheinman MM, Aliot EM, et al. Journal of the American College of Cardiology. 2003.
23. ACC/AHA/ESC Guidelines for the Management of Patients With Supraventricular Arrhythmias--Executive Summary. A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Supraventricular Arrhythmias) Developed in Collaboration With NASPE-Heart Rhythm Society. — Blomström-Lundqvist C, Scheinman MM, Aliot EM, et al. Journal of the American College of Cardiology. 2003.
24. 2015 ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. — Page RL, Joglar JA, Caldwell MA, et al. Heart Rhythm. 2016.
25. 2015 ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. — Page RL, Joglar JA, Caldwell MA, et al. Heart Rhythm. 2016.
26. Eligibility and Disqualification Recommendations for Competitive Athletes With Cardiovascular Abnormalities: Task Force 9: Arrhythmias and Conduction Defects: A Scientific Statement From the American Heart Association and American College of Cardiology. — Zipes DP, Link MS, Ackerman MJ, et al. Circulation. 2015.
27. Eligibility and Disqualification Recommendations for Competitive Athletes With Cardiovascular Abnormalities: Task Force 9: Arrhythmias and Conduction Defects: A Scientific Statement From the American Heart Association and American College of Cardiology. — Zipes DP, Link MS, Ackerman MJ, et al. Circulation. 2015.