Causes of PVCs in Young Sick Patients
In young patients with underlying medical conditions, the primary objective is to exclude structural or functional heart disease, as PVCs in this context may have prognostic significance, unlike isolated PVCs in otherwise healthy young individuals which are typically benign. 1
High-Risk Underlying Conditions
Young patients with certain underlying conditions are at increased risk for clinically significant PVCs and sudden cardiac death:
Structural Heart Disease
- Congenital heart disease is a major cause of PVCs with prognostic significance in young sick patients 1
- Cardiomyopathies (dilated, hypertrophic, or arrhythmogenic) can present initially with symptomatic ventricular arrhythmias 1
- Myocardial tumors (particularly in infants) can cause incessant ventricular tachycardia and PVCs 1
- Coronary artery anomalies represent an important structural cause in young patients 1
Primary Arrhythmic Disorders
- Long QT syndrome (LQTS) and other ion channel defects are critical causes, particularly forms with AV block or digital syndactyly 1
- Wolff-Parkinson-White (WPW) syndrome with short refractory periods (≤240 ms) can cause PVCs and carries SCD risk 1
- Short-coupled torsade de pointes predominantly affects young patients, with PVCs having extremely short coupling intervals (<300 ms) initiating polymorphic VT 1
Inflammatory/Infectious Causes
- Myocarditis from viral infections (Coxsackie B, adenovirus, parvovirus B19, HHV-6) causes active inflammatory destruction of myocytes with resultant PVCs 1
- HIV-related cardiotoxicity and opportunistic infections can cause myocarditis and PVCs 1
Metabolic and Toxic Causes
Electrolyte Abnormalities
- Hyperkalemia is a specific cause of sustained VT and PVCs in infants and young patients 1
- Hypokalemia and hypomagnesemia contribute to PVC development through altered cellular electrophysiology 2
Drug-Induced Causes
- Digoxin toxicity can cause ventricular arrhythmias, particularly dangerous when misdiagnosed as SVT in infants 1
- Verapamil administration in infants with unrecognized VT (presumed SVT) can precipitate VF and sudden death 1
Age-Specific Considerations
Infants
- Accelerated idioventricular rhythm is the most common sustained ventricular arrhythmia, typically benign and self-resolving within the first year 1, 2
- Incessant VT from myocardial tumors or cardiomyopathy represents a high-risk scenario requiring urgent evaluation 1
Children and Adolescents
- PVC prevalence increases from <5% in children to 10% by age 10 and 25% during late adolescence 1
- Catecholaminergic polymorphic VT is an exception to the generally benign prognosis of hemodynamically tolerated VT in young patients with structurally normal hearts, carrying significant SCD risk 1
Critical Diagnostic Approach
The essential first step is excluding structural and functional heart disease through:
- Echocardiography to assess cardiac structure and function 3, 4
- Exercise stress testing to determine if PVCs suppress with exercise (benign) or increase (concerning for underlying pathology) 3
- 24-hour Holter monitoring to quantify PVC burden and identify non-sustained VT 3
- Cardiac MRI when subtle structural abnormalities are suspected 3
Risk Stratification by PVC Burden
- <100 PVCs/24h: 0% risk of structural heart disease 3
- <2,000 PVCs/24h: 3% risk of structural heart disease 3
- ≥2,000 PVCs/24h: Up to 30% risk of structural heart disease 3
Important Clinical Pitfalls
Never administer digoxin or verapamil for presumed SVT in infants without excluding VT, as this can precipitate ventricular fibrillation and sudden death. 1
- PVCs with QRS duration >160ms from the right ventricular outflow tract may indicate early arrhythmogenic right ventricular cardiomyopathy rather than benign outflow tract ectopy 3
- Symptomatic ventricular arrhythmias may be the initial presentation of previously undiagnosed cardiomyopathy 1
- Family history of sudden cardiac death warrants genetic testing and comprehensive evaluation 3