Sudden cardiac death (SCD) is a well known complication of non ST segment elevation myocardial infarction (NSTEMI). Arrhythmogenic right ventricular dysplasia (ARVD) is an inherited cardiomyopathy which is frequently associated with ventricular arrhythmias incluidng SCD. We present a case of ARVD presenting as SCD in the setting of non ST elevation myocardial infarction.CASE PRESENTATIONS: A 51 year-old African-American man with new complaints of chest pain of several hours duration called 911 after an episode of near-syncope. He had a past medical history of hypertension and gastritis as well as a family history including myocardial infarction. He was on nifedipine XR and cimetidine. He had no known drug allergies. He had a forty pack-year history of tobacco use. En route to the ER, he had an episode of pulseless ventricular tachycardia (VT) in the ambulance and was successfully cardioverted with 360 Joules.. In the ER, his vital signs were BP 150/95, HR 59, RR 18, T 37.3. Physical exam was normal. His electrocardiogram (EKG) showed sinus bradycardia with voltage criteria for left ventricular hypertrophy (LVH) and T wave inversion in leads V1-V3. Routine labs were within normal limits. He was admitted to the ICU and placed on aspirin, nitropaste, intravenous heparin, beta-blockers and intravenous lidocaine. Serial cardiac enzymes were consistent with a NSTEMI. 2D echocardiography revealed four-chamber enlargement with a left ventricular ejection fraction of 50% without regional wall motion abnormalities. A signal average EKG was performed and was negative. A cardiac catheterization (LHC) revealed a 70% distal left anterior descending artery stenosis with mild LV dysfunction. Medical treatment was continued including aspirin, beta-blockers and an ACE inhibitor. Overnight in the ICU, the patient had an episode of non-sustained monomorphic VT with documented left bundle branch morphology. An electrophysiologic study (EPS) was obtained and revealed a right ventricular outflow tract (RVOT) VT, an uncommon and ablatable cause of VT. Other focuses of VT were not ellicited with programed stimulation. The patient subsequently underwent successful radio-frequency ablation of his RVOT VT but had an episode of sustained monomorphic VT post-procedure treated with cardioversion. A 2D echocardiogram was repeated to evaluate for right ventricular dysplasia. This was inconclusive. The patient was sent for a cardiac MRI which revealed right ventricular free wall and septal fat deposits consistent with right ventricular dysplasia. An automatic implanted cardioverter defibrillator (AICD) was then placed and the patient was later discharged home on aspirin, metoprolol, benazepril, and simvastatin. He was symptom free at his one year visit.DISCUSSION: Arrhythmogenic right ventricular dysplasia is an inherited cardiomyopathy with a genetic abnormality on chromosome 14. There is fatty infiltration of the right ventricular free and/or septal walls. There is associated ventricular tachycardia and SCD. ARVD presents more frequently in children and young adults. EKG findings include ventricular tachycardia with left bundle branch morphology, right axis deviation and T wave inversion over the precordial leads. Epsilon waves can also be seen in the right precordial leads. Most patients show an abnormal right ventricle by echocardiography, computed tomography, magnetic resonance imaging or right ventricular angiography. MRI is the non-invasive test of choice. Endomyocardial biopsy is definitive but usually not performed. There is no definitive medical treatment of the associated arrhythmias. AICD’s are now indicated after an episode of SCD or VT associated with ARVD. Cardiac transplantation is the only definitive treatment currently.
The case above displays the diagnostic challenges of SCD. Despite potential multiple mechanisms of VT including ischemia and RVOT VT, a third mechanism was ultimately uncovered. A thorough search for all possible mechanisms of VT including ARVD must always be considered and sought.
L.M. Arcement, None.