A Cedars-Sinai Heart Institute physician researcher has received a $2.5 million grant from the National Heart, Lung, and Blood Institute to develop a risk assessment tool that could identify patients susceptible to sudden cardiac arrest, a usually fatal heart rhythm malfunction.
Approximately 350,000 people in the U.S. die each year from sudden cardiac arrest, accounting for 50 percent of all cardiovascular deaths nationally.
"Fewer than five percent of patients survive, making it absolutely essential that we develop a way to predict who will have a sudden cardiac arrest," said Sumeet S. Chugh, MD, an associate director of the Cedars-Sinai Heart Institute and an internationally recognized expert in the condition. "However, our current methods of making these important clinical predictions are falling short of expectations."
Although 'heart attack' and 'sudden cardiac arrest' are often used interchangeably, the terms are not synonymous. A heart attack -- myocardial infarction -- is typically caused by clogged coronary arteries that reduce 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.
The main clinical method for predicting risk of the condition is measurement of the left ventricular ejection fraction (pumping function of the heart muscle), generally by a test known as the echocardiogram. If patients are deemed at high risk based on a low value of the ejection fraction, they may receive a surgically implanted live-saving defibrillator. However, healthcare providers and researchers are now realizing that many who receive this defibrillator may never actually use it.
A decade ago, Chugh, the Pauline and Harold Price Chair in Cardiac Electrophysiology Research, and his team of researchers pointed out that more than two-thirds of all who suffer sudden cardiac arrest do not have a low ejection fraction. In fact, they suffer sudden cardiac arrest despite having a preserved ejection fraction, with a normal pumping muscle of the heart.
"This gap in our knowledge of sudden cardiac arrest prediction is now well-recognized as a 'black box' that needs to be solved if we are to tackle the difficult, global problem of sudden cardiac arrest," Chugh said.
Chugh and colleagues have been the first to identify several risk factors for sudden cardiac arrest, including genetic markers, electrical and structural abnormalities of the heart as well as biomarkers in the blood. The new grant from the National Heart, Lung, and Blood Institute will support research for discovery of novel risk predictors of sudden cardiac arrest in patients with preserved left ventricular ejection fraction or pumping ability of the heart muscle. This is going to be a team effort involving important collaborations with investigators at the Framingham Heart Study in Massachusetts and CV Path Inc. in Maryland.
"If we can develop an accurate assessment tool for sudden cardiac arrest , it will be a huge step toward solving one of medicine's great mysteries," said Eduardo Marbán, director of the Cedars-Sinai Heart Institute. "The best way to treat a medical condition is to be able to prevent it from happening in the first place. "
In addition to his leadership role at the Cedars-Sinai Heart Institute, Chugh heads the Oregon Sudden Unexpected Death Study, a comprehensive, 16-hospital, multiyear assessment of cardiac deaths in the Portland metropolitan area, home to 1 million people. The study has been underway for more than a decade. Data collected from it provides Chugh and his team with unique, community-based information to mine for answers to what causes sudden cardiac arrest.
Cedars-Sinai Medical Center