Framework for Sudden Cardiac Death in a Young Patient
Helpful to think about these patients in 2 broad categories: 1) Structural Heart Disease; and 2) No Structural Heart Disease.
- Structural Heart Disease
o Hypertrophic Cardiomyopathy
o Dilated Cardiomyopathy
o Other causes of Cardiomyopathy (such as infiltrative)
o Valvular heart disease
o Congenital Heart Disease (Tetralogy of Fallot, VSD, Eisenmenger’s, etc)
o Scar-mediated structural abnormalities & arrhythmias
o Ischemic heart disease secondary to nonatherogenic coronary artery disease (arteritis, dissection, congenital artery anomalies)
- No Structural Heart Disease
o Ischemic heart disease: CAD with MI
Coronary artery embolism
Coronary artery spasm
o Channelopathies: Long QT, Short QT, Brugada
o Familial sudden cardiac death
o Pre-excitation syndrome
o Idiopathic ventricular fibrillation
o Aortic Dissection
** Also, do not forget non-cardiac causes of sudden cardiac death (pulmonary embolism, intracranial hemorrhage, central airway obstruction, drug-induced)
What is Arrhythmogenic Right Ventricular Dysplasia (ARVD)?
- Also known as Arrhythmogenic right ventricular cardiomyopathy (ARVC)
o 1/2000 to 1/5000 in the general adult population. It is an important cause of sudden cardiac death in young adults!
o Although rarely diagnosed in the United States, it has accounted for ~11% of overall cases of SCD in young adults in certain parts of Europe.
o Affects men more frequently than woman, with an approximate ratio of 3:1.
o Familial background has been demonstrated in >50% of cases (make sure to perform genetic testing in all 1st degree relatives).
o RV myocardial atrophy with fibrofatty replacement, leading to ventricular electric instability.
o Now believed to be a genetic defect in desmosomes (flashback to Step1 studying), resulting from defective cell adhesion proteins such as plakoglobin, desmoplakin, plakophilin-2 (PKP2 gene), and desmoglein-2.
o Mainly an autosomal dominant pattern of inheritance, although an autosomal recessive variant has been seen.
- Clinical Manifestations:
o Symptoms: palpitations (67%), syncope (32%), atypical chest pain (27%), dyspnea (11%), RV failure (6%)
o Ventricular arrhythmias
o Supraventricular tachyarrythmias: may be present in up to 25% of patients with ARVC.
o In patients with autosomal recessive disease, there have been associations with palmoplantar keratosis and wooly hair!
- EKG Findings:
o QRS prolongation: due to delayed RV activation
o Incomplete or complete RBBB: due to conduction delay in the terminal Purkinje system
o Epsilon wave: due to low amplitude potentials caused by delayed activation of some portion of RV
o Inversion of T waves in the right precordial leads
- Diagnostic Criteria: Complicated diagnostic criteria is available for us to reference online via the 2010 revised Task Force Criteria
o Activity restriction: there is an association between exercise and induction of VTs.
o Beta blockers: No firm evidence on benefit of beta blockers
o ICD: primary prevention for high risk patients or secondary prevention in those with prior sustained ventricular arrhythmia
o Antiarrhythmic drugs: may reduce frequency of sustained and nonsustained ventricular arrhythmias, but have not been shown to reduce the risk of SCD.
o Cardiac transplantation: rarely for patients who develop heart failure symptoms or ventricular arrhythmias that are progressive despite use of meds and ICD.