A 33-year-old African American man presented to the emergency department (ED) with the complaint of chest pain along with shortness of breath while taking a shower at home. He didn't have any past medical or surgical history and worked as a schoolteacher. He had no known family history of any heart disease. He had played basketball and football during high school with no issues.
In the ED, he was noted to be tachycardic with heart rate 119/min. The rest of his vital signs were blood pressure 123/87 mmHg and respiratory rate 18/min. Laboratory investigations were within normal limits with a normal renal and liver function tests and a complete blood count was within normal limits. A urine drug screen was positive for opiates, benzodiazepines and cannabinoids.
He developed palpitations in the ED, during which an electrocardiogram (ECG) showed a wide complex tachycardia with heart rate of 240/minute (Fig. 1). He was administered 6mg adenosine which was followed by second dose of 12mg adenosine which did not terminate the arrhythmia. He received 150mg of Amiodarone with no response. This was followed by another 150mg after which his ECG revealed a normal sinus rhythm. He was maintained on an Amiodarone drip and admitted to the cardiac critical care unit (CCU) for closer monitoring.
On hospital day 1, he developed bradycardia with ECG revealing sinus bradycardia with heart rate 44/minute (Fig. 2). Amiodarone drip was discontinued. An echocardiogram showed normal left ventricular (LV) function with normal ejection fraction. He underwent cardiac catheterization which did not reveal any coronary abnormalities or obstruction. A cardiac magnetic resonance imaging (MRI) was done which showed multiple patchy areas of midwall late gadolinium enhancement particularly prominent as transmural enhancement in the inferolateral mid myocardium (Fig. 3). He was started on pindolol and was evaluated by electrophysiological cardiologist for implantable cardiac defibrillator (ICD). A high-resolution computerized tomography (CT) of chest done with contrast did not show any reticular opacities in lung parenchyma or hilar adenopathy. An endomyocardial biopsy was done which was negative for myocarditis or any granulomatous disease, and Congo Red stain was negative for amyloidosis. Serum angiotensinogen converting enzyme (ACE) level was 35 U/L (within normal limits). He underwent an ICD placement for secondary prevention of ventricular arrhythmias and was discharged from the hospital with a plan to pursue a positron emission tomography (PET) scan as an outpatient and discuss further treatment options.
As an outpatient, he underwent a PET scan which did not show any tracer activity in the myocardium or any evidence of cardiac sarcoidosis. He was also evaluated by Ophthalmologist and was not found to have any manifestations of ocular sarcoidosis. He was referred for genetic testing which revealed heterozygous mutation in LMNA gene. Interrogation of his ICD did not show any further VT in subsequent office visit and his family members including children were recommended to get genetic testing for screening.
In the absence of other identifiable etiology and a known association of LMNA gene mutation with ventricular arrhythmia, we think the VT in this young patient is due to LMNA gene mutation.