What are the common causes of ventricular tachycardia (VT) in a 30-year-old white female?

Causes of Ventricular Tachycardia in a 30-Year-Old White Female

In a 30-year-old white female, VT most commonly occurs in the absence of structural heart disease and is often related to elevated catecholamines, though congenital long QT syndrome, pregnancy-related cardiomyopathy, and idiopathic VT are critical considerations. 1

Primary Etiologies by Category

Structurally Normal Heart (Most Common in This Age Group)

Idiopathic VT related to catecholamine excess is the predominant cause when structural heart disease is absent. 1

• Catecholamine-mediated VT occurs frequently in young women without overt structural disease and is typically beta-blocker sensitive 1
• Idiopathic right ventricular outflow tract (RVOT) VT represents the most benign form of VT in patients without structural heart disease 2
• Idiopathic left ventricular VT can occur in structurally normal hearts 2

Congenital Long QT Syndrome (Critical Sex-Specific Risk)

Women have significantly higher risk of long QT-related VT and torsades de pointes compared to men, with 70% of Long QT Registry subjects being female. 1

• Post-pubertal females experience predominant incidence of cardiac arrests and syncope from long QT syndrome, whereas males are at higher risk before puberty 1
• Drug-induced torsades de pointes is substantially more common in women due to longer baseline QT intervals and pharmacodynamic differences 1
• Women typically have longer QT intervals than men, particularly at slower heart rates, increasing arrhythmia susceptibility 1

Pregnancy and Postpartum-Related Causes

New-onset VT during the last 6 weeks of pregnancy or early postpartum period mandates evaluation for peripartum cardiomyopathy. 1

• Peripartum cardiomyopathy must be ruled out in women presenting with VT during late pregnancy or postpartum 1
• The postpartum period carries greater risk for cardiac arrest in women with congenital long QT syndrome compared to during pregnancy 1
• Elevated catecholamine states during pregnancy can trigger VT even without structural disease 1

Structural Heart Disease (Less Common in This Age Group)

While structural heart disease is the most common cause of VT overall, it is less prevalent in 30-year-old patients without known cardiac history. 2

• Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death in young people, including young adults, with complex ventricular arrhythmias occurring in 90% of adults with HCM 1
• Prior myocardial infarction scar is the most common substrate for sustained monomorphic VT in structural heart disease, though uncommon at age 30 2
• Dilated cardiomyopathy can present with ventricular arrhythmias 1
• Arrhythmogenic right ventricular cardiomyopathy should be considered in young patients with VT 2

Metabolic and Endocrine Causes

Endocrine disorders cause VT through electrolyte disturbances, hormone effects on myocardial receptors, or acceleration of underlying structural disease. 1

• Thyroid disorders: Hypothyroidism causes QT prolongation and VT risk, while thyrotoxicosis rarely causes VT except with electrolyte disturbances 1
• Pheochromocytoma may present with VT due to catecholamine excess and can cause reversible cardiomyopathy 1
• Electrolyte imbalances from primary aldosteronism, Addison disease, or parathyroid disorders cause arrhythmogenesis through QRS and QTc prolongation 1
• Diabetes is a more pronounced predictor of coronary disease and VT in women compared to men 1

Other Considerations

• Hemochromatosis with cardiac involvement can cause ventricular arrhythmias, though incidence is unknown 1
• Acromegaly is associated with complex ventricular arrhythmias in up to 50% of patients, correlating with left ventricular mass and disease duration 1

Critical Clinical Pitfalls

Do not assume VT in a young woman is benign without excluding long QT syndrome, structural heart disease, and pregnancy-related cardiomyopathy. 1

• Failure to obtain a baseline ECG during sinus rhythm may miss pre-excitation or QT prolongation 3
• Women with hyperglycemia, elevated hematocrit, and decreased vital capacity have higher risk for coronary disease and VT compared to traditional male risk factors 1
• Even brief episodes of VT (≥3 beats) in patients with structural heart disease indicate increased sudden death risk 4

Diagnostic Algorithm

1. Obtain 12-lead ECG during sinus rhythm to identify QT prolongation, pre-excitation, or structural abnormalities 3
2. Assess pregnancy status and timing relative to symptom onset 1
3. Echocardiography to evaluate for structural heart disease, including HCM, cardiomyopathy, and valvular disease 1, 3
4. Laboratory evaluation including electrolytes, thyroid function, and consideration of catecholamine levels if pheochromocytoma suspected 1, 3
5. Family history of sudden cardiac death or long QT syndrome 1
6. Ambulatory monitoring if episodes are intermittent 3