Study Calls into Question Reliability of Special Pediatric Heart Tests
July 17, 2001
A study appearing in this week's issue of Circulation: The Journal of the American Heart Association questions the reliability of locally measured echocardiographic data and calls for more standardized testing.
An echocardiograph painlessly and non-invasively measures structural and functional abnormalities of the heart. Physicians often use measurements of the structure and function of the left ventricle - the heart's main pumping chamber - when devising a course of treatment for children who have heart disease.
Physicians wanted to assess the reliability of pediatric echocardiographic measurements, so they compared local measurements with those made at a central facility. The comparison was based on echocardiographic recordings obtained from 735 children at 10 clinical sites throughout the United States.
"Despite the importance placed on pediatric echocardiographic measurements, little has been published about the reliability of these measurements. There is a need to know how good our tests are," says the study's lead author, Steven Lipshultz, M.D., chief of pediatric cardiology at Children's Hospital at Strong. "We determined that locally measured echocardiographic reliability is poor in pediatric, multi-center studies. Our review suggests a need for central re-measurement."
The study may have implications for the planning and conduct of research studies, as well as for the medical treatment of individual patients. "The importance of reliable and accurate left-ventricular measurements can't be overstated," Lipshultz says. "The implications are major. Expert-panel standards of cardiology practice have recommended withholding potentially lifesaving chemotherapy in some asymptomatic children who have cancer when their heart function is below a certain value. Similarly, for asymptomatic children who have leaky heart valves, recommendations exist for open-heart surgery to repair or replace the defective heart valve once heart function is below a certain value. We found that measured values differ widely between medical centers."
The study showed that echocardiographic measures of left-ventricular structure and function calculated locally are subject to very different methods of data acquisition and assessment. Measurements differed so much, Lipshultz says, that a central echocardiograph facility is needed to provide consistent and reliable data for research studies, and repeat measurements for individual children are recommended to provide clinically meaningful results.
"We recommend standardizing how images are acquired and analyzed," Lipshultz says. "Although core laboratories increase the labor and expense of clinical trials, they reduce the variability in measurements. Future pediatric clinical trials should arrange for independent evaluations of this data."
As a result of these findings, the National Institutes of Health supports central re-measurement of thousands of echocardiograms at Children's Hospital at Strong. They are referred here from more than 400 locations around the world. The measurements made at Children's Hospital at Strong have been proven to be more reliable than locally made measurements.
The National Heart Lung and Blood Institute, part of the National Institutes of Health, funded the study.