First-Of-Its-Kind Medtronic Study Finds Genetic Markers Of Sudden Cardiac Death Using ICDs

By Jof Enriquez,
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Medtronic has announced findings from two independent clinical trials which identified a specific gene that triggers fatal arrhythmias and sudden cardiac death (SCD). The first-of-their-kind studies could help clinicians determine who is most at risk for SCD and recommend implantable cardioverter defibrillators, or ICDs.

The initial trial, sponsored by Medtronic, found a gene that was associated with SCD in patients implanted with ICDs, Reuters reports. A second study, called the Oregon Sudden Unexpected Death Study, confirmed the findings of the initial trial in the general population.

Medtronic's DISCOVERY trial, a prospective, multi-center study of 1,145 patients, used abnormal heart rhythms recorded in ICDs to establish "positive predictive value of single nucleotide polymorphisms (SNPs) in the genes GNB3, GNAS and GNAQ as predictors of ventricular arrhythmia."

DISCOVERY trial data identified the gene GNAS holds two SNPs that were linked to an increased risk for ventricular tachyarrhythmias (VT) as identified by the ICDs, according to a company statement of the findings presented during the 2015 European Society of Cardiology (ESC) Congress in London.

"This is the first time a gene has been identified using ICD monitoring and then confirmed to be associated with sudden cardiac death in the general population," says Professor Heiner Wieneke, principal investigator of the DISCOVERY trial and chief physician in the Department of Cardiology, Contilia Heart and Vessel Centre, St. Marien-Hospital Mulheim, Germany, in the statement. "These findings are a first step to learning more about how to determine better ways to prevent and treat this condition."

The SNPs identified in the DISCOVERY trial were validated in the Oregon Sudden Unexpected Death Study (SUDS), a community-based study involving 1,335 patients that identified causes of sudden cardiac arrest using blood samples to investigate genetic and biochemical markers of risk, according to the statement. The Oregon-SUDS trial confirmed that the gene identified in the earlier DISCOVER trial was associated with a 50 percent increased risk of SCD.

"This research is vital to helping us better understand why some patients are at higher risk of sudden cardiac death, one of the leading causes of death globally," says Sumeet Chugh, M.D., associate director of the Cedars Sinai Heart Institute and lead investigator for Oregon-SUDS, in the statement. "These findings put us one step closer to understanding the complexities of sudden cardiac death and may, someday, help us identify which patients are at risk."

According to the Oregon-SUDS website, sudden cardiac deaths (SCD) number between 300,000 and 350,000 each year in the United States alone, and "most patients who suffer SCA are not currently classified as high-risk," because of certain diagnostic limitations. The study aims to pinpoint genetic markers which can better identify those at high-risk for fatal arrhythmias and who need heart rhythm devices.

"The results presented today are part of Medtronic's efforts to better identify people at risk of SCD and to get them the right life-saving therapy," says Marshall Stanton, M.D., VP and GM of Tachycardia in the Cardiac Rhythm and Heart Failure Business at Medtronic. "Medtronic looks forward to partnering with the larger clinical research community to further our shared understanding of the risk for sudden cardiac death and how to prevent it."