Doctors should preferably suction out the clot instead of pushing it aside in order to implant the stent, Dutch researchers say.
Those treated that way would have better prospects of surviving major heart attacks.
The Dutch study is the largest to date to prove the efficacy of vacuuming the heart and could lead to wider use in heart attack treatment. Previous smaller studies of various devices had mixed results.
"This study suggests that it is worth doing," said Dr. George Vetrovec, a heart disease expert at Virginia Commonwealth University in Richmond.
Most heart attacks occur when a buildup of plaque in a coronary artery ruptures, and a blood clot forms, blocking the flow of oxygen-rich blood to the heart. The preferred treatment is an angioplasty to quickly reopen the artery, reports CNN.
Doctors snake a tube through a blood vessel to the blocked artery and use a small balloon to compress the blockage and restore blood flow. A tiny metal-mesh stent is put in place to keep the artery open.
But sometimes the procedure causes bits of the clot or plaque to break off and plug the tinier vessels, restricting blood flow to the heart, said Dr. Felix Zijlstra, who led the study at University Medical Center Groningen in the Netherlands.
The artery is open "but still the blood doesn't go where you want it to go," he said.
They tried a different approach, suctioning the clot out before inserting the stent, and found that reduced debris and improved blood flow. The results are published in Thursday's New England Journal of Medicine.
For the study, doctors enrolled 1,071 patients who came to the hospital in 2005 or 2006 with a major heart attack and needed emergency angioplasty. Half received the conventional procedure; the other half had the blood clot suctioned out. Doctors threaded a small tube to the blockage and sucked out the clot with a syringe before putting in a stent.
"In daily practice, we say that we use the vacuum cleaner," said Zijlstra.
The heart attack was stopped in its tracks in 57 percent of the vacuum group and 44 percent of those getting regular care.
Using a dye, the researchers measured how much blood from the opened artery was saturating the heart tissue. In the conventional group, 26 percent of the patients had little or no blood reaching the heart tissue, compared with 17 percent of the patients who had the blockage removed.
Over the next 30 days, those with the poorest blood flow had higher death rates -- 5 percent compared with 1 percent for the best flow group -- and more serious complications.
Zijlstra said they are continuing to follow those patients, and the technique has been adopted at his hospital.
"I think there will be definitely others who will follow us very quickly. It's not very difficult to apply," he said.
The study was paid for by the Dutch medical center and Medtronic Inc., which makes the device used in the study. Other similar devices are available around the world.