Diagnostic Workup for Ventricular Tachycardia Etiology
The comprehensive workup for determining the etiology of ventricular tachycardia (VT) should include 12-lead ECG, echocardiography, cardiac MRI, ambulatory ECG monitoring, exercise testing, and in some cases electrophysiology studies. 1
Initial Evaluation
- 12-lead ECG: A baseline ECG during sinus rhythm should be obtained to look for evidence of underlying heart disease, and if possible, a 12-lead ECG during tachycardia should be recorded to help differentiate VT from supraventricular tachycardia with aberrancy 1
- Thorough history: Focus on cardiac symptoms, medication use, family history of sudden cardiac death, and potential triggers such as exertion or emotional stress 1
- Physical examination: Assess for signs of structural heart disease including murmurs, jugular venous distention, and peripheral edema 1
Cardiac Imaging
- Echocardiography: Essential first-line imaging to assess ventricular function and detect structural heart disease, including cardiomyopathies, valvular disease, and wall motion abnormalities 1
- Cardiac MRI with contrast: Particularly valuable for detecting arrhythmogenic right ventricular cardiomyopathy (ARVC), infiltrative diseases, myocardial scarring, and other cardiomyopathies that may not be evident on echocardiography 1
Extended Monitoring and Stress Testing
- 24-hour Holter monitoring: To quantify PVC burden and detect non-sustained VT episodes; patients with ≥2,000 PVCs per 24 hours have a higher likelihood of underlying structural heart disease 1
- Exercise stress testing: Particularly important for patients with VT symptoms associated with exertion or suspected ischemic heart disease; can help assess for exercise-induced ventricular arrhythmias and ischemia 1
- Extended ambulatory monitoring: Modern leadless recorders allow for longer monitoring periods, including during physical activity, which is valuable for capturing intermittent arrhythmias 1
Laboratory Testing
- Electrolyte panel: To rule out electrolyte abnormalities (particularly potassium, magnesium, and calcium) that can precipitate VT 1
- Thyroid function tests: Thyroid disorders can contribute to arrhythmias 1
- Toxicology screening: When drug-induced VT is suspected 1
Advanced Testing
- Electrophysiology study (EPS): Indicated in patients with recurrent VT, high PVC burden (≥2,000/24h), or when noninvasive testing is inconclusive; can help determine the mechanism and location of the arrhythmia 1
- Coronary angiography: For patients ≥30 years with risk factors for coronary artery disease, as CAD is the most common cause of VT in older adults 1
- Genetic testing: Consider in patients with suspected inherited arrhythmia syndromes or cardiomyopathies, especially with a family history of sudden cardiac death 1
Special Considerations
- Age-specific approach: In patients ≥30 years, coronary artery disease is the most common cause of sudden cardiac death, warranting appropriate investigation 1
- Family screening: For patients with suspected inherited conditions or unexplained VT, evaluation of first-degree relatives may be valuable 1
- QT interval assessment: Careful measurement of the QT interval during sinus rhythm is important to rule out long QT syndrome 1
Common Pitfalls to Avoid
- Misdiagnosis of wide-complex tachycardias: VT can be misdiagnosed as SVT with aberrancy; when in doubt, treat as VT, especially in patients with structural heart disease 1
- Incomplete evaluation: Failure to perform comprehensive cardiac imaging can miss underlying structural heart disease 1
- Overlooking family history: A family history of sudden cardiac death should prompt consideration of inherited arrhythmia syndromes 1
- Ignoring medication effects: Many medications can cause QT prolongation and predispose to torsades de pointes 1
By following this systematic approach, clinicians can identify the underlying etiology of ventricular tachycardia and guide appropriate management to reduce morbidity and mortality.