A vacuum-cleaner-like device that sucks blood clots out of the arteries of heart attack victims before angioplasty reduces the death rate in the following year by nearly half, researchers reported today.
By physically removing clots, the device prevents loose fragments from breaking off, flowing through the bloodstream and blocking other vessels.
Based on preliminary results from this study and others, cardiovascular surgeons in many large centers are already using the technique to improve outcomes for their patients.
These results "will encourage other physicians to use it," said Dr. Ravi Dave, a staff cardiologist at Santa Monica-UCLA and Orthopaedic Hospital, who was not involved in the study but has been using the technique for a year and a half.
There have been several smaller studies previously looking at various ways to break down and remove clots, and the results have been mixed, said Dr. Spencer King of St. Joseph's Heart and Vascular Institute in Atlanta.
With these new results, "perhaps other technologies will be encouraged to do it even more effectively," said King, a former president of the American College of Cardiology who was also not involved in the study.
With the device developed by Medtronic Inc. of Minneapolis, the cardiac surgeon threads a thin wire guide into the body through the groin and all the way to the clot. This is also the first step in angioplasty, in which a balloon is inserted and inflated to compress the blockage. But before inserting the balloon, the surgeon inserts a thin tube and, using a syringe, sucks up as much of the clot as possible.
In the new study, Dr. Felix Zijlstra and his colleagues at the University Medical Centre Groningen in the Netherlands studied 1,071 heart attack victims who were randomly assigned to receive either conventional angioplasty or clot removal -- technically called thrombus aspiration -- followed by angioplasty. Most patients also received a stent to keep the artery open.
In February, the team reported in the New England Journal of Medicine that patients receiving aspiration had a much brisker blood flow following the surgery, a trait that is usually associated with increased survival.
The researchers reported a trend toward lower mortality in the first month after surgery -- 2% mortality in patients undergoing aspiration compared with 4% in those receiving only angioplasty -- but the results were not considered statistically significant.
In the first full year after the intervention, 19 of the 535 patients (3.6%) who underwent aspiration died, compared with 36 of the 536 (6.7%) who had angioplasty alone, the team reported in the international medical journal Lancet.
About 5.6% of patients in the aspiration group either died or suffered a second heart attack in the first year, compared with 9.9% of the patients receiving angioplasty alone.
"We are the first to demonstrate the efficacy of thrombus aspiration in terms of improved clinical outcome," Zijlstra said.
Dave noted that removing the clot did not significantly delay angioplasty and that the procedure was relatively easy to perform. "It's a very quick step . . . and it is a very user-friendly device," he said.
Subgroup analysis of the patients suggests that the technique is most valuable for larger clots, which are more likely to have pieces break off, said Dr. George W. Vetrovec of Virginia Commonwealth University, who was not involved in the study.
"That's been my own personal experience," he said.
The technique might also be very useful in patients who did not receive angioplasty within the recommended window of 90 minutes after their initial symptoms.
The longer the delay before angioplasty, he said, the more time the clot has to grow, rendering the angioplasty alone more problematic.
The study was partly funded by Medtronic. The authors reported that they had no financial conflicts of interest.