(RxWiki News) People at risk of dying from heart failure often get an implantable defibrillator to keep their hearts ticking. Current heart assessments, however, are not always on the mark.
To determine the likelihood of sudden cardiac death, doctors currently take a measure of the fraction of blood ejected from the heart in any one heartbeat. Because these “ejection fraction” tests may not give an accurate picture of heart health, many implantable cardiac defibrillator (ICD) operations may be unnecessary.
A new study shows that a simple blood test may give a faster, more precise evaluation of sudden cardiac death risk, and reduce the number of defibrillator procedures.
"Ask a doctor about blood tests to evaluate heart failure risk."
Samuel C. Dudley, MD, chief of cardiology at the Lifespan Cardiovascular Institute in Providence, Rhode Island, and his colleagues have found that a simple laboratory test can identify changes in the gene message (mRNA) for the SCN5A gene, which is known to be related to sudden death in heart failure patients.
About 5 million individuals in the US have heart failure, a condition where the heart is unable to adequately pump blood. More than half a million people are diagnosed annually. Heart failure is the single most common reason for admission to hospitals in the US.
In this investigation, scientists conducted the blood test on 63 heart failure patients who had defibrillators inserted, 43 patients who had heart failure but no record of having an ICD, and 28 participants without heart failure or implanted defibrillators. A total of 21 patients with ICDs had cardiac events.
Heart failure patients who had abnormal heartbeats that would normally cause sudden death had significantly higher levels of the gene variants compared to patients who did not have abnormal heartbeats, according to the research.
"This is the first test of its kind; never before have clinicians been able to accurately assess a patient's risk of sudden cardiac death by performing a blood test," Dr. Dudley said in a press release.
With the commonly used ejection fraction method for assessing cardiac death risk, patients are often advised to get an ICD if the fraction falls below 35 percent. About 60 percent of these patients may not actually need an ICD, however, according to Dr. Dudley and his fellow scientists.
"It's sort of a double-edged sword,” he added in a statement. “With current mechanisms in place, we can't be sure that a patient needs an ICD, but if we believe the risk to be present, it would be irresponsible not to implant an ICD that could save the patient's life.”
Dr. Dudley hopes this new blood test will help curb the widespread overuse of ICDs throughout the U.S. and abroad. To follow up on this pilot program, investigators are planning a large, multi-site trial.
"With this blood test, we can refine the need for such a device, and instead implant the cardiac defibrillators only in the most severe cases of sudden cardiac death risk," said Dr. Dudley in a press release.
The study was published online in April in advance of print in the Journal of the American College of Cardiology. Research was supported by funding from the National Institutes of Health, the Veterans Administration, and the National Center for Research Resources/National Center for Advancing Translational Sciences.