The Cedars-Sinai Heart Institute has been awarded a $1.66 million, four-year grant from the National Heart, Lung and Blood Institute of the National Institutes of Health to develop a measurement system that could help doctors predict which patients could be struck by sudden cardiac arrest, a heart rhythm disturbance that causes instant death in more than 95 percent of cases.
"Less than five percent of the people who have a sudden cardiac arrest survive, so we have to find a way to predict who is susceptible," said Sumeet S. Chugh, M.D., the study's principal investigator and an internationally renowned expert in sudden cardiac arrest.. "If we can predict, we can prevent."
Although "sudden cardiac arrest" and "heart attack" are often used interchangeably, the terms are not synonymous. Unlike heart attacks (myocardial infarction), which are typically caused by clogged coronary arteries reducing blood flow to the heart muscle, sudden cardiac arrest is the result of defective electrical activity of the heart. Patients may have little or no warning, and the disorder usually causes instantaneous death. Sudden cardiac arrest has been blamed for the deaths of journalist Tim Russert and filmmaker John Hughes.
Chugh, an associate director of the Cedars-Sinai Heart Institute and the Pauline and Harold Price Chair in Cardiac Electrophysiology Research, said the work is based on a key finding from patients' electrocardiograms, also known as ECGs or EKGs. In a normal heart, an electrical impulse travelling through the ventricles of a beating heart takes less than 120 milliseconds to make the journey. Chugh said his preliminary research shows that the journey may be slightly longer in patients who later experience sudden cardiac arrest.
The new grant will enable Chugh and his team to dissect specific relationships between the delayed impulse measurement (called a prolonged QRS duration), other heart and non-heart related conditions, as well as specific abnormalities in the human genome, with the ultimate goal of enhancing the ability of cardiologists to identify the individual at highest risk of sudden cardiac arrest.
"You can have a normally-pumping heart muscle and still have variations in certain measurements," Chugh said. "We need to find out if these variations could signify a predisposition to sudden cardiac arrest."
In addition to his leadership role at the Cedars-Sinai Heart Institute, Chugh heads the Oregon Sudden Unexpected Death Study, a comprehensive, 16-hospital, multi-year assessment of cardiac deaths in the 1 million population Portland, Ore. metropolitan area now ongoing for close to a decade. The data collected in that study provides Chugh and his team with unique, community-based information to mine for answers to what causes sudden cardiac arrest. Chugh's Sudden Death Genomics Laboratory at the Heart institute is funded by two previous grants from the National Heart, Lung and Blood Institute that also enable ongoing work on solving mechanisms of sudden cardiac arrest.
"Sudden cardiac arrest is one of the great mysteries in medicine," said Eduardo Marb-n, M.D., Ph.D., director of the Cedars-Sinai Heart Institute. "This grant is an important weapon that will help us eventually succeed in the fight against the nation's number-one killer, heart disease."
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