Ventricular Tachycardia Due to Intramyocardial Metastasis in a Young Adult

Introduction: Ventricular Tachycardia (VT) is overall rare in the pediatric population. When found, it is most commonly associated with congenital and hereditary heart disease. Here, we present a case of VT secondary to an intramyocardial metastasis in a patient with known malignancy.

Case Description: The patient is a 19 year old male with a history of metastatic desmoplastic round blue cell tumor of the femur on chemoradiation therapy who presented to the ER with 3 days of exhaustion and fatigue. He has a history of a large pericardial effusion requiring pericardiocentesis 3 months prior. In the ER, his heart rate was 120 beats per minute. An echocardiogram showed enlargement of his prior pericardial effusion, but no evidence for tamponade. He began having runs of nonsustained and sustained VT with a RBBB morphology. He was begun on an esmolol drip, and due to hypotension and recurrent VT this was transitioned to an infusion of amiodarone (150 mg IVP over 10 minutes, followed by infusion at 1 mg/mL for 6 hours and 0.5 mg/mL for 18 hours) and lidocaine (1 mg/kg IV bolus followed by 1 mg/mL IV infusion). Repeat TTE showed concern for an extracardiac mass with compression of the left ventricular free wall, and cardiac MRI revealed a 2.7x2.7x1.8 cm mass involving the basal anterolateral wall likely involving the mitral annulus. He was stabilized in the PICU without the need for electrical cardioversion. He transitioned to oral amiodarone and oral mexiletine. Due to his long-term prognosis and shared decision making, he did not receive a LifeVest or ICD prior to discharge.

Discussion: In pediatrics, the incidence of VT is often subdivided between “benign” VT in structurally normal hearts (eg: idiopathic left VT and idiopathic right VT) and structurally abnormal hearts (eg: HCM, non-compaction, post-surgical repairs) or known channelopathies (eg: Long QT Syndrome). The rates of VT with symptoms, requiring interventions, and mortality are substantially different between these groups. In a study of a general pediatric population in a single center, only 27 cases were identified over a 10 year period, with just 1 case attributable to a cardiac tumor (Roggen et al, 2008). Metastatic tumors are far more common than primary cardiac tumors; however they are usually silent or mistaken for the patient’s overall health deterioration (Jayaprakesh S, 2018). Our patient represents a confluence of adult and pediatric medicine: a pathologic entity (VT) common to adult patients, requiring antiarrhythmic medications uncommon in pediatrics, but due to a metastatic lesion of a pediatric bone tumor.

Conclusion: Ventricular tachycardia in the young adult population requires a high index of suspicion for both congenital and acquired heart disease. While uncommon, VT can originate due to metastatic intramyocardial tumors in patients with malignancy.