AIM: Despite guidelines, PCI still used in MI patients with occluded arteries

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Previous research has found that PCI did not significantly reduce clinical events in patients with totally occluded infarct-related arteries (IRA) that were identified a minimum of 24 hours after MI. Despite the fact that these results triggered guideline updates to discourage the use of PCI in this patient population, still a large number of practices may not be adhering to these guidelines and continue to use PCI in these patients, according to a study published online July 11 in the Archives of Internal Medicine.

The previous 2006 Occluded Artery Trial (OAT) found no benefit of PCI for persistent totally occluded IRA, identifed a minimum of 24 hours after MI. After OAT results showed that PCI did not reduce clinical events and that the procedure also had a small impact on angina and quality of life, changes were made to American College of Cardiology (ACC) and American Heart Association (AHA) guidelines. The guidelines now include late reperfusion (>24 hours) with PCI of the infarct artery in asymptomatic patients who are hemodynamically and electrically stable as a Class III indication.

In the current study, Marc W. Deyell, MD, of the University of British Columbia in Vancouver, Canada, and colleagues evaluated the monthly PCI trends for occlusions after the OAT results were published and ACC/AHA guidelines were published.

Deyell and colleagues identified 28,780 patients enrolled in the CathPCI Registry from 2005 to 2008 who underwent catheterization more than 24 hours (on calendar days three to 28) after MI with a totally occluded native coronary artery and no major OAT exclusion criteria. The researchers looked at PCI trends at hospitals within the highest quartile for reporting diagnostic procedures.

Of the study cohort, 90.7 percent of patients presented with non-STEMI, 43.9 percent of patients had one-vessel disease and 49.9 percent had two-vessel disease. The mean age of patients ranged from 61.5 years to 61.7 years.

The authors reported that cardiac catheterization was performed in 11,083 patients prior to OAT results; 7,838 patients after publication of OAT but before guideline revisions; and in 9,859 patients after guideline revisions took place. The authors reported that multivessel PCI was performed in 12.5 percent of patients and 53 percent of patients with coronary occlusions underwent PCI that targeted a total occlusion that was identified after MI. The rate of PCI for non-occluded targets did not change.

In an accompanying editorial, Mauro Moscucci, MD, MBA, of the University of Miami Miller School of Medicine in Florida, wrote, "Clinical trials have shown the importance of time to reperfusion. However, while the 'early' open artery hypothesis has been consistently confirmed, the 'late' open artery hypothesis (i.e., reperfusion of an occluded infarct-related artery at a time too late for myocardial salvage and in patients without continuous symptoms) has been controversial for years."

While Deyell et al noted that the crude rate of PCI for total occlusions was “slightly but significantly lower” after OAT results were published and after guidelines were revised, there was a spike in the rate of PCI for occlusions in March 2006, prior to the publication of the OAT results.

“This peak substantially accounted for the observed decline in the crude rate of PCI in subsequent time periods,” the authors wrote. While there was a significant decline in PCI for occlusions from the spike in March 2006 to OAT publication, there was no further decline after publication of the OAT or after guidelines were revised.

The authors also found no difference in the monthly trends of occluded PCI between the time period after OAT was published and after guideline revisions.

During a secondary analysis, the authors identified 5,542 patients with qualifying occlusions who were treated at the highest quartile of hospitals reporting diagnostic catheterizations. The researchers reported that 41.9 percent of these patients did not receive PCI, 17.7 percent underwent PCI of a non-occluded target only and 40.4 percent underwent PCI of an occlusion.

Of these patients, the authors found that the crude rate of PCI for total occlusions declined from 42.4 percent prior to the publication of OAT to 39.9 percent after OAT results were published but before guidelines were revised. After guidelines were revised, this number dropped to 38.5 percent.

“Overall, we found no change in the adjusted rate of PCI for total occlusions identified at least 24 hours after MI following the publication of the OAT or the revision of the major guidelines,” the authors wrote.

“These findings suggest that the evidence provided by the OAT and other small studies and the resultant Class III guideline recommendations ('should not be performed') for PCI in clinically stable patients with persistently occluded IRAs more than 24 hours after STEMI or non-STEMI have not, to date, been widely incorporated into clinical practice in a large cross-section of hospitals in the U.S.”

The study authors speculated that one reason the updated guidelines were not undertaken may be due to the fact that while the OAT trial was negative, the results did not portray excessive harm from PCI apart from increased reinfarction. Moscucci, on the other hand, speculated that "physicians' barriers to the applications of new guidelines include lack of awareness, lack of familiarity and lack of agreement with the evidence supporting the guidelines." Moscucci also noted that guidelines aimed to eliminate a certain behavior may be more difficult to implement than guidelines aimed at the introduction of a new behavior.

“To our knowledge, the impact of a negative trial demonstrating lack of efficacy and excess cost of a procedure and subsequent guideline revisions has not been previously assessed," Deyell and colleagues wrote. Additionally, they wrote that “physicians may be less likely to alter their practice based on negative results, especially when there are important competing factors.

“In conclusion, among this large cross section of hospitals in the U.S., we found only modest evidence that the results of the OAT and its incorporation into major guideline revisions have influenced cardiology and interventional cardiology practice over the subsequent one to two years,” the authors noted.

Additionally, Deyell et al said that the results are cause for concern due to the fact that they imply many stable patients with recent MI and occlusion still undergo costly PCI procedures, a rather ineffective procedure in this setting. Secondly, the researchers said that “a large public, scientific and human patient investment in the generation of robust clinical evidence has yet to broadly influence U.S. practice.”

Moscucci concluded that these results should place attention on procedures that increase healthcare costs without a clear benefit for patients. "We must heed the call to professional responsibility aimed at the elimination of tests and treatments that do not result in any benefit for our patients, and for which the net effects will be added costs, waste and possible harm," he added.