Removing clot aids heart attack recovery

New research suggests that more people survive major heart attacks with fewer problems if doctors use a mini-vacuum to clear out an artery blockage instead of pushing it aside to restore blood flow.

The Dutch study is the largest to date to show that suctioning out the clot before implanting a stent has big benefits, 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.

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.

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 to 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 to 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.

Vetrovec, who wrote an accompanying editorial in the journal, said that the clot-removing technique is not routinely used in the U.S. It can take a bit longer to clear out the clot, he said, and guidelines recommend fast action on blocked arteries.

He said the study has "the potential to change practice," but noted that the heart attack death rate is already so low that this technique isn't likely to substantially change outcomes.

Removing the clot should have been a major DUH. Leaving it in there seems like it’s merely delaying the inevitable.

They didn't leave it there. Percutaneous coronary intervention (PCI) was also called coronary angioplasty. This is done by docs called interventional cardiologists. Think of this as another variation of endoscopy, in this case intravascular endoscopy. I'm not a cardiologist.

IIRC, this first started as coronary angiography. They would snake this flexible instrument, based on the mechanics that allows flexible endoscopes, into one of the femoral arteries and snake it back into the aorta and finally back into the coronary arteries where a dye would be injected into the coronary arteries so they could visualize the blockage represented by narrowed coronary arteries.

See the blockage near 12 o'clock. The blood clot was also presumed to be there at the narrowing. Initialy the imaging was done prior to coronary artery bypass grafting. Eventually they developed a variety of devices for the end of these intravascular endoscopes that they can perform intravascular ultrasound or "rotorooter" gizmos that mechanically dislodge the clot and/or atherosclerotic plaque as well as place stents in the coronary arteries.

Drug-Eluting Stents, Bare-Metal Stents, and Bypass Surgery

Data from two studies suggest that when considering PCI, the setting matters more than the stent.

Drug-eluting stents (DES) are frequently used in off-label situations. Two new observational studies illuminate the real-world use of DES.

In the first study, investigators used data from the National Heart, Lung, and Blood Institute (NHLBI) Dynamic Registry to compare the safety and efficacy of DES versus bare-metal stents (BMS) for manufacturer-approved versus off-label indications. The off-label group (1312 DES recipients and 2110 BMS recipients) included patients with lesions that were restenotic; in bypass grafts; in long (>30 mm), small, and large vessels; at ostial, left main, and bifurcation locations; and totally occluded. DES recipients had longer and more complex lesions than BMS recipients and also were more likely to be receiving dual antiplatelet therapy at 1 year. In this group, mortality at 1 year was lower in DES recipients (3.7%) than in BMS recipients (6.4%, P<0.001), although no significant difference remained after adjustment for baseline characteristics. The adjusted risk for repeat revascularization was lower with DES than with BMS (hazard ratio, 0.63).

In the second study, a report from the New York State Department of Health, researchers compared outcomes in 7437 patients who underwent coronary artery bypass grafting (CABG) from October 2003 to December 2004 and in 9963 patients who received DES. The mean follow-up period was about 19 months. Adjusted mortality was lower with CABG than with DES, both in patients with 3-vessel disease (HR, 0.80) and in those with 2-vessel disease (HR, 0.71). In patients with 3-vessel disease, the adjusted survival rate was 94.0% at 18 months with CABG versus 92.7% with DES (P=0.03). In DES patients, the rate of target-vessel revascularization was 7.0%, and subsequent CABG was performed in 2.2%. Subsequent percutaneous coronary intervention was performed in 5.1% of CABG patients.

Comment: The NHLBI results suggest that although drug-eluting stents in off-label settings may pose greater risks than in approved settings, the risks are similar to those of bare-metal stents, and the need for repeat revascularization is reduced. The New York State findings of lower mortality with CABG than with DES in patients with multivessel disease, while significant, were slight (about 1%) and limited by incomplete follow-up data (deaths occurring outside of New York State were not recorded) and the need for substantial adjustment for differences in baseline characteristics. As the editorialist notes, unmeasured confounders as well as patient and physician preference may have influenced the results of both studies, and longer follow-up is necessary to confirm the relative safety profile of DES; nonetheless, these reports provide useful data for making better-informed decisions.

— Howard C. Herrmann, MD

Published in Journal Watch Cardiology January 23, 2008 Citation(s):
Marroquin OC et al. A comparision of bare-metal and drug-eluting stents for off-label indications. N Engl J Med 2008 Jan 24; 358:342.

Drug-Eluting Stents vs. Coronary-Artery Bypass Grafting in Multivessel Coronary Disease

Leprosy outbreak causes concerns in Northwest Arkansas

P.S. I'm just a family practice doc. The latest that I heard or read was that blood clots form at the points of rupture in the atherosclerotic plaque of the coronary arteries causing myocardial infarctions(MI), aka acute coronary syndrome(ACS). In the past having a CABG meant that a chest was opened in major surgery. Surgeons has been developing minimally invasive techniques to avoid breaking bones while doing bypass grafting on coronary arteries.

P.P.S. I think I accessed that Journal Watch article just because I'm registered with, not a subscriber to, the New England Journal of Medicine(NEJM).FReepmail me if you want on or off my health and science ping list.

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.