Mechanisms of Ventricular Arrhythmias
Sudden cardiac arrest due to ventricular arrhythmias, with an estimated annual incidence of 300,000-350,000 events, is a condition with significant implications for public health, accounting for 50 percent of all cardiovascular deaths in the United States. A cornerstone of this program is the Oregon Sudden Unexpected Death Study (Oregon SUDS), the largest community-based (population approximately one million residents) comprehensive evaluation of its kind. Established in 2002 and currently funded by the National Heart, Lung, and Blood Institute and the American Heart Association, this ongoing multidisciplinary study uses a population-based case-control design. The Oregon SUDS continues to yield information about novel clinical, genetic and biochemical pathways involved in the genesis of ventricular arrhythmias, with the goals of enhancing the methods of preventing and managing sudden cardiac arrest and of advancing the understanding of the mechanisms of pulseless electrical activity and ventricular fibrillation. As of 2015, the Oregon SUDS has been expanded to include Ventura County, CA (pop. 850,000) under the umbrella of the PRESTO Network.
Selected findings from this study:
- Compared to men, women have fewer cardiac structural abnormalities and lower levels of clinically recognized coronary disease prior to cardiac arrest.
- Less than a third of cases of sudden cardiac arrest would have been identified as high risk prior to their arrest, based on their left ventricular function.
- Markers on the EKG, including prolonged ventricular repolarization (QTc interval), prolonged depolarization (QRS duration), and increased transmural dispersion of repolarization (T-peak to T-end interval) increase risk of sudden cardiac death in the general population.
- Increased left ventricular mass predicts future SCD risk, independent of left ventricular function.
- Specific clinical features distinguish individuals whose cardiac arrest was precipitated by ventricular fibrillation from those that presented with pulseless electrical activity (PEA), a rhythm with a much lower survival rate. Identifying factors that predict PEA may improve prevention and survival.
- We are involved in large-scale analyses across multiple studies for the discovery of novel genes associated with SCD and have identified several novel genetic loci that influence risk of sudden cardiac arrest.