Risk of Life-threatening Heart Rhythm Disturbances in Siblings

Greater than 400,000 persons die suddenly each year in the US. The implantable cardioverter-defibrillator (ICD) has revolutionized the primary prevention of sudden cardiac death (SCD) following myocardial infarction (MI), however, risk stratification remains limited and rests solely on the identification of left ventricular dysfunction. The goal of this study is to determine if genetic factors influence the risk of ventricular arrhythmia remotely after myocardial infarction.

In order to determine if ventricular tachycardia or ventricular fibrillation remotely after MI is a heritable trait, we will conduct a family based case-control sibling study of patients who have received an ICD for ischemic cardiomyopathy. As a first step, we will utilize the GENECARD registry, an existing family linkage study of premature cardiovascular disease, to determine the prevalence of sibling concordance for ICD implantation following MI. Probands and siblings in the GENECARD study will be surveyed regarding their ICD history. The sibling recurrence risk ratio for ICD implantation following MI and subsequent ICD therapies will be used to estimate the sample size required to validate heritability, in a larger patient population. In the validation phase of this protocol, we will use a (1) single healthcare system database (Duke Cardiovascular Databank) and a (2) regional population-based registry, in order to determine concordance for ICD therapies. Patients who agree to participate and provide informed consent will be surveyed regarding their personal ICD history and that of their siblings. The prevalence of ICD therapies will be ascertained in the probands, siblings, and the overall cohort. Sibling concordance for ICD implantation and sibling concordance for subsequent appropriate ICD therapies will be used to determine the sibling recurrence risk ratio for appropriate ICD therapies remotely after MI.

Inclusion criteria

• patients must be alive
• have a history of coronary artery disease / myocardial infarction
• left ventricular ejection fraction ≤ 35%
• received an implantable cardioverter- defibrillator

Exclusion criteria

• nonischemic cardiomyopathy
• Pre-identified hereditary arrhythmia syndrome (e.g. long QT syndrome, Brugada syndrome, etc)
• left ventricular ejection fraction >35%
• no implantable cardioverter-defibrillator