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A research team at the UA Sarver Heart Center is spearheading a clinical study to predict who is at risk from sudden cardiac death and who is not. Non-invasive imaging technology is key to this effort and could save health-care industry millions.

By Daniel Stolte, AHSC Office of Public Affairs
October 15, 2008

On a February morning in 2005, Steven Mark Gootter began his day like any other. He got up early, rounded up the family dog and headed out for a morning jog. That was the last time his wife, their two young children and the rest of his family and friends would see him alive. Steven never came home again – sudden cardiac death had claimed the life of this vibrant, athletic, seemingly healthy 42-year-old man.

Before today is over, almost 1,000 people in the United States alone will share Steven's fate and die suddenly from heart disease. Dr. Vincent L. Sorrell, a physician and researcher at The University of Arizona Sarver Heart Center, has assembled an interdisciplinary team to spearhead an effort to fight sudden cardiac death and save millions of dollars in health-care costs. This groundbreaking research is made possible through a research grant awarded to Sorrell from the Steven M. Gootter Foundation, a Tucson initiative to fight sudden cardiac death.

Implantable cardiac defibrillator devices, dubbed "the emergency room in your chest," have proven to be lifesavers because they detect heart rhythm abnormalities and shock the heart back into a normal rhythm. However, doctors struggle to accurately predict who is at risk from sudden cardiac arrest.

"In certain patient subgroups, only 5 percent of implanted defibrillators ever fire," Sorrell said. "In other words, 95 percent of these individuals with ICDs may not need them."

Over the course of a lifetime, the costs of the device, the implant procedure and follow-up care easily can exceed $150,000. Add to that the medical risks associated with any surgical procedure and it becomes obvious that ICDs are a blessing for a few patients that really need them – but pose an immense burden on the health-care system when implanted in someone whose heart never triggers the device. The numbers also make it clear that the current tests used in determining who is a candidate for an ICD are less than perfect.

Sorrell's team has launched a study to investigate new ways of identifying the patients who most likely would benefit from an ICD. At the heart of the new approach lies a sophisticated, non-invasive imaging technology called cardiac magnetic resonance imaging, or CMR. Cardiac MRI uses a powerful magnetic field and computer software to construct high-resolution, three-dimensional images of the heart.

"With CMR, there are no unwanted risks or side effects, unlike those associated with other imaging techniques like CT scans or nuclear stress tests, which involve radiation or contrast agents that are toxic to the kidneys," Sorrell said. "The patient goes into the tube, and within 30-60 minutes we have an image that allows us to make a pretty accurate assessment of the size and location of scarring in the heart muscle. It is this feature of CMR that we think will predict the cardiac arrest risk this patient faces."

More importantly, the UA researchers believe that conventional imaging tests systematically miss patients who are at severe risk for sudden cardiac death, while at the same time flagging "false positives" – singling out patients for ICD implantation who do not face any substantial risk.

"Under the current parameters, a patient with extensive scarring in the heart (for example, due to a previous heart attack) likely would be considered a candidate for an ICD," said Sorrell. "At the same time, another patient, whose heart shows no scarring, would receive a pat on the back and be told, ‘You're in great shape,'" he adds.

"With our high-resolution CMR imaging tests, we sometimes find patients who may be previously cleared but actually have unsuspected scarring in their heart, while others, whose hearts are riddled with scar tissue, may actually face an extremely low risk of sudden cardiac death," Sorrell said. "Based on preliminary data, we believe it is the intermediate-sized scar that predicts the risk for fatal heart rhythm disturbances, and that large, major scars alter heart function, but pose less of a risk."

Sorrell's team has started a one-of-a-kind registry to systematically identify patients at risk, based predominantly on non-invasive CMR imaging. The results obtained so far look promising and could open the path to a "paradigm shift," ultimately saving the lives of individuals who otherwise would die from sudden cardiac death and potentially saving millions in health-care costs.

The Sarver Heart Center is a Center of Excellence at the UA engaging in basic and clinical research, patient care, training of health-care professionals and public education. The center's more than 120 physicians and scientists are working toward a future free of heart disease and stroke.

The mission of the Steven M. Gootter Foundation is to save lives by defeating sudden cardiac death through increased awareness, education and scientific research. The Foundation works to increase awareness of sudden cardiac death among those who may be at risk, fosters education among the public and health-care professionals, and funds scientific research into the causes of and treatments for sudden cardiac death.