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More Is Better, At Least In Angioplasty

August 19, 2005
University of Michigan Health System
Before patients get their clogged heart arteries re-opened, they may want to ask their doctor just how many such procedures he or she has done, a new study finds. The answer may make a big difference in a patient's risk of suffering a major setback before leaving the hospital.

ANN ARBOR, Mich. -- Before patients get their clogged heart arteriesre-opened, they may want to ask their doctor just how many suchprocedures he or she has done, a new study finds. The answer may make abig difference in each patient's risk of suffering a major setbackbefore leaving the hospital.

In the most up-to-date analysis yet of this contentious issue,researchers from the University of Michigan Cardiovascular Center andthe Blue Cross Blue Shield of Michigan Cardiovascular Consortium findthat the risk of major complications from angioplasty and relatedprocedures is much lower among patients whose doctors perform a largenumber of those procedures each year. The paper is published in theJournal of the American College of Cardiology.

In fact, the risk of major cardiovascular problems was 63percent higher among patients treated by doctors who performed lessthan 90 procedures each year, compared with those who did more than 90.

However, the study found no difference in the risk of deathbefore leaving the hospital among patients treated by low- andhigh-volume doctors. And, it found that a few doctors who performedfewer angioplasties each year still had very good patient outcomes,suggesting that "practice makes perfect" isn't the whole story for theminimally invasive procedures known as percutaneous coronaryinterventions (PCI).

The researchers say their data, from 18,504 artery-openingprocedures done in 14 Michigan hospitals by 165 physicians during 2002,reflects current angioplasty care, including advanced clot-preventingdrugs and devices called stents that hold arteries open after they'recleared. Both advances, and better technology for deploying stentswithin an artery, have helped make PCI procedures safer.

While previous studies using older data have shown majordifferences in rates of complications and death depending on how manyartery-clearing procedures doctors have done, the new study suggeststhat the playing field is leveling.

But, says lead author Mauro Moscucci, M.D., the bottom line isstill that more is better, for the most part. Moscucci, who directs thecardiac catheterization laboratory at the U-M where angioplasties andstenting procedures are performed, leads the multi-hospital projectfunded by BCBSM that provided the new data. He is an associateprofessor of cardiovascular medicine at the U-M Medical School.

"The relationship between physician volumes and patientoutcomes is not as strong as it used to be, but it's still present,"says Moscucci. "While a cutoff number may not be enough by itself topredict how well a patient will do, it's still a useful tool."

In fact, the new study suggests that 90 procedures a year maybe a better threshold than 75, the current standard used by nationalheart groups.

The study grouped doctors into five quintiles by number ofprocedures a year: 1 to 33, 34 to 89, 90 to 139, 140 to 206 and 207 to582. It documented how many patients had had emergency bypass surgery,a second angioplasty, a heart attack, a stroke or mini-stroke, or haddied, before leaving the hospital -- a combined measure ofcomplications known as MACE for major adverse cardiovascular events.Bypass surgery is often performed when a problem occurs during a PCIprocedure or the physician can't adequately restore blood flow usingminimally invasive techniques, and repeat angioplasty during the samehospital stay indicates incomplete treatment the first time.

The analysis of current data was made possible by theBCBSM-funded project, the BCBSM Cardiovascular Consortium, which forthe last eight years has pooled data from Michigan hospitals in aneffort to assess and improve PCI care.

David Share, M.D., clinical director for the Blues' Center forHealth Care Quality and Evaluative Studies, says, "The study tells ustwo things. In general, experience does lead to proficiency in currentpractice in cardiac procedures, and also that volume is not an absoluteindicator of quality. The real test of quality is risk-adjustedanalysis of each individual physician's outcomes."

The doctors in the two lower quintiles, called "low-volume"for the purpose of the study, accounted for nearly 2,500 (13.6 percent)of the procedures. They tended to use more of the new clot-preventingdrugs, called glycoprotein IIb/IIIa inhibitors, than the higher-volumedoctors, and also used more of the dye that helps doctors see blockagesand artery walls during PCI procedures. They also treated more patientswho had had a heart attack in the last 24 hours, a measure of emergencyangioplasty used to restore blood flow when a heart artery needs urgentre-opening.

The researchers made statistical adjustments to the data inorder to compare the low- and higher-volume physicians more accurately,but still there was a significant difference in MACE rates.

When the researchers used the 75-procedure cutoff instead,they didn't find that significant difference after adjusting forpatient characteristics -- at least at first. But then they looked atPCI procedure performed on weekends, when only emergency procedures aretypically done. The difference was striking: low-volume (less than75/year) doctors had nearly twice the rate of MACE on weekends ashigh-volume doctors.

The new data come at a time when some cardiologists haveargued that improvements in PCI technology have made annual experiencelevels less important, and have made angioplasty more available toAmericans in smaller communities.

More research on PCI volume, MACE and mortality rates in otherstates will be needed, says Moscucci, who is a member of the AmericanCollege of Cardiology committee that is currently examining andrevising the ACC's credentialing criteria for PCI providers.

In the meantime, he says, patients who have been told they needan angioplasty or stent on a non-emergency basis should consider askingthe doctor how many procedures he or she does in a year, or how wellhis or her patients do. Those who live in states such as New York,California and New Jersey, where PCI data are made available to thepublic can look their doctor's records up, he adds.

In addition to Moscucci and Share, the papers authors includeU-M Cardiovascular Center co-director Kim Eagle, M.D., FACC, U-Mresearcher Eva Kline-Rogers, RN, M.S., and physician leaders fromseveral of the participating hospitals across Michigan.

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