Researchers used a marker of heart function called an ST-segment score to determine whether the X-sizer suction device could benefit heart patients. ST-segment score is calculated during an electrocardiogram. A high ST-segment score indicates a heart attack. The faster the ST-segment score decreases, or resolves, after a heart attack, the better the blood flow in coronary vessels and the better the patient will fare overall.
ST-segment resolution was observed immediately after treatment in 83 percent of patients treated with suction plus angioplasty, compared with 52 percent of those who had angioplasty alone.
Angioplasty, in which a balloon-tipped catheter is inflated to open blocked arteries, and stenting, the insertion of a wire-mesh tube to keep an artery open, are life-saving procedures when blood clots in coronary arteries cause a heart attack or unstable angina (chest pain). However, the procedures carry a risk of moving the blood clot, or fragments of it, further downstream, which could cause another heart attack or stroke.
In a trial that investigated ways to avoid the danger of these traveling blood clots, Austrian scientists used a pretreatment system that removes the clot, or thrombus, from the body. This experimental procedure is called a thrombectomy.
The X-sizer thrombectomy device is threaded through the blood vessels to the area of blockage, similar to the way a balloon-tipped catheter is positioned in angioplasty. However, the X-sizer is a two-channeled catheter. When it reaches the clot, a tiny device with a spinning helical tip in the first channel fragments the blood clot while a miniature vacuum system in the second channel sucks up the clot pieces.
“Thrombectomy with the X-sizer before angioplasty and/or the placement of a stent improves blood flow in the large vessels of the heart, as well as circulation in the tiny microvessels,” says study author Peter Siostrzonek, M.D., associate professor of medicine at the General Hospital of Vienna/Department of Cardiology at the Univeristy of Vienna. The two-step treatment takes only 10 to 20 minutes longer than angioplasty alone, he adds.
This is the largest randomized trial of the X-sizer system. Other thrombectomy systems are under study, including one that uses ultrasound; but most of the studies on the other thrombectomy treatments were not randomized, says co-investigator Gilbert Beran, M.D. He adds that this study is also unique for its emphasis on the heart’s microcirculatory function, the system of tiny vessels that is crucial to good heart function. The X-sizer system is used clinically in several countries but is still considered experimental in the United States.
In the study, 66 people with heart attack or unstable angina were randomly assigned to get X-sizer therapy plus angioplasty or angioplasty alone. Various aspects of blood flow around the heart and in the microvessels were studied, including ST-segment resolution.
ST-segment resolution was significantly better both immediately after treatment and six hours later in X-sizer treated patients, compared with people who received only angioplasty, Beran says. He also notes that X-sizer treatment seemed particularly effective when used in arteries that were larger than 3 millimeters in diameter.
“It appears that more X-sizer patients regained circulation that was closer to normal,” Siostrzonek says. “We believe that faster return of blood flow is associated with greater protection of the affected heart muscle and therefore better clinical outcome since more heart muscle may be saved.”
He cautions that the results are preliminary and must be confirmed. One limitation of the study was the relatively small number of patients. “Larger trials are needed to determine whether the X-sizer treatment will result in a better clinical outcome,” he says.
Co-authors include Irene Lang, M.D.; Wolfgang Schreiber, M.D.; Stefan Denk, M.D.; Thomas Stefenelli, M.D.; Bonni Syeda, M.D.; Gerald Maurer, M.D.; and Dietmar Glogar, M.D., F.E.S.C.
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