Simple two-in-one test signals high risk after a heart attack

Dec 04, 2007

Everyone loves a two-fer, but a two-in-one heart test that has the potential to save lives is the real deal. According to new research, pairing two findings from one simple test makes it significantly more likely that doctors will identify patients who face the greatest risk after a heart attack.

The research, which appears in the December 11, 2007, issue of the Journal of the American College of Cardiology, found that by examining both the nervous system and the heart’s electrical system, cardiologists could better identify which patients were at highest risk of cardiac arrest or death, even years after a heart attack.

“This is important because past studies, focusing on a single test, failed to identify most people at risk,” said Derek V. Exner, M.D., M.P.H., a heart rhythm specialist and an associate professor at the University of Calgary’s Libin Cardiovascular Institute of Alberta, in Canada. “We developed a simple method of identifying approximately twice as many people at risk. That means we can potentially save more lives.”

The REFINE study—formally named the Risk Estimation Following Infarction, Noninvasive Evaluation—assessed two factors critical to the development of serious cardiac arrhythmias. An electrical system that has been damaged by a heart attack sets the stage for serious disturbances in the heart’s rhythm. At the same time, a nervous system that’s on high alert, even without a patient realizing it, makes it more likely that a serious arrhythmia will take hold and progress to cardiac arrest and death.

For the study, Dr. Exner and his colleagues enrolled 322 patients who had suffered a heart attack and had at least a mild abnormality in the heart’s pumping ability. Within 2 to 4 weeks of the heart attack, and again at 10 to 14 weeks, they performed a variety of tests to measure the status of both the nervous system and the heart’s electrical system. They then tracked patients for an average of nearly four years.

Having patients wear a heart monitor for 18 to 24 hours as they went about their daily activities turned out to be both a simple and effective way to identify high-risk patients. Using the all-day electrocardiogram, researchers analyzed the heart’s electrical system by looking for T-wave alternans (TWA), an abnormality in the heart’s rhythm so subtle it must be detected by a computer. Researchers also analyzed the electrocardiogram for evidence that the nervous system was on high alert by looking for abnormalities in “heart rate turbulence” (HRT), a measure of the heart’s ability to adapt to change.

Early after a heart attack, TWA and impaired HRT were not accurate warning signs of future risk. At the 10- to 14-week mark, however, TWA and impaired HRT clearly identified patients at increased risk—and they were particularly powerful when used in combination. The 20 percent of patients who had both TWA and impaired HRT on the all-day heart monitor and, in addition, had a persistent abnormality in the heart’s pumping ability, faced more than six times the risk of cardiac arrest or death during follow-up when compared to other patients in the study.

Using an exercise test to detect TWA was also effective, but not as simple and efficient as using the all-day heart monitor to look for both impaired HRT and TWA at the same time.

Studies that are expected to begin in 2008 will evaluate whether an implantable cardioverter-defibrillator (ICD) can save the lives of patients with abnormalities in both the nervous system and the heart’s electrical system. Until then, those at highest risk should receive intensive follow-up, Dr. Exner said.

“The outlook is good for most heart attack survivors. However, the one in five patients in our study who had abnormal tests were at high risk of serious problems,” he said. “Close follow-up with a physician and the use of medications known to be beneficial after a heart attack—aspirin, beta blockers, ACE inhibitors, and statins—are very strongly recommended.”

Source: American College of Cardiology

Explore further: Were clinical trial practices in East Germany questionable?

add to favorites email to friend print save as pdf

Related Stories

Should the Japanese give nuclear power another chance?

Oct 24, 2014

On September 9, 2014, the Japan Times reported an increasing number of suicides coming from the survivors of the March 2011 disaster. In Minami Soma Hospital, which is located 23 km away from the power plant, ...

Remote healthcare for an aging population

Sep 30, 2014

An aging population and an increased incidence of debilitating illnesses such as Parkinson's and Alzheimer's disease means there is pressure on technology to offer assistance with healthcare - monitoring and treatment. Research ...

Recommended for you

Were clinical trial practices in East Germany questionable?

Oct 23, 2014

Clinical trials carried out in the former East Germany in the second half of the 20th century were not always with the full knowledge or understanding of participants with some questionable practices taking place, according ...

Schumacher's doctor sees progress after injury

Oct 23, 2014

A French physician who treated Michael Schumacher for nearly six months after the Formula One champion struck his head in a ski accident says he is no longer in a coma and predicted a possible recovery within three years.

User comments : 0