Instead, heart patients with aortic-valve stenosis fared better when surgeons relied on echocardiograms, a non-invasive procedure.
"If you do a good echocardiogram and you are confident about the results, I don't see a reason for doing the passage through the valve," says Dr. Heyder Omran, lead author of the study and an associate professor of cardiology at the University of Bonn in Germany. "Those who do will certainly expose the patient to the risk of stroke."
The study appears in the April 12 issue of The Lancet.
Aortic-valve stenosis is a narrowing, or obstruction, of the valve between the left ventricle (lower chamber) of the heart, and the aorta, a large artery that connects to it.
It is one of the most common forms of valvular disease, occurring in approximately five of every 10,000 people, according to the American Heart Association. Its symptoms include shortness of breath after exercise, fainting and angina, or chest pain. To repair the diseased valve, surgeons replace it.
To diagnosis the degree of stenosis, or narrowing, surgeons generally look to two tests:
1. Push a catheter through the diseased valve. The pressure differences between the left ventricle and the aorta reveal the extent of the disease.
2. Echocardiogram, a test that uses sound waves to create a picture of the heart. The picture is more detailed than X-ray image, and there is no radiation exposure.
In most cases, using the echocardiogram alone is the way to go, Omran says, because his study found patients who had catheterization had a much higher rate of stroke.
Omran and his colleagues studied 152 patients with valvular aortic stenosis -- 101 patients received catheterization through the valve, while in 51 patients the catheter was not pushed through the valve. Thirty-two heart patients without valvular disease were used as controls.
About 22 percent of the patients who underwent catheterization of the aortic valve had indications of blood clot in MRI scans after the procedure. Three of the patients had an impairment of neurological function, and indicator of stroke.
Other cardiologists, however, questioned the findings.
Catheterization is used routinely to assess the valvular disease, and complications are rare, says Dr. Stephen Ramee, a cardiologist at the Ochsner Clinic Foundation in New Orleans.
Furthermore, he adds, magnetic resonance imaging (MRIs) are very, very sensitive and whatever lesions they are picking up could be of little or no significance.
But the most important reason for continuing to use catheterization, he says, is that echocardiograms are easily misread. Echocardiograms can make it appear the disease is more or less severe than it really is.
Any added risk of catheterization is far outweighed by the risk of doing unnecessary heart surgery, he says.
The risk of death from heart surgery can range from 2 percent to 25 percent, depending on the person's heart function and health at the time of surgery, he says.
The key, he adds, is "to make the diagnosis correctly and to not send a patient to surgery who doesn't need it."
Ramee says he uses the echocardiogram first. If that shows there's a problem, he uses catheterization. If both confirm the disease is severe enough to require treatment, then, and only then, will he do heart surgery.