Revascularization May Benefit Stable CAD Patients With Unclassifiable Appropriateness Scores


Older patients with stable CAD who are referred for catheterization but cannot be assigned an appropriateness score are at particularly high risk for cardiovascular events, according to a Canadian study published online October 2, 2015, ahead of print in the American Journal of Cardiology. Moreover, this population has improved outcomes when treated with revascularization—whether PCI or CABG—rather than medical therapy alone.

Take Home: Revascularization May Benefit Stable CAD Patients With Unclassifiable Appropriateness Scores

However, “the proper management for patients who cannot be assigned an appropriateness score is still unknown,” study author Dennis T. Ko, MD, MSc, of Sunnybrook Health Sciences Center (Toronto, Canada), told TCTMD in an email.

“We should not automatically equate patients who had a missing appropriateness score as having an inappropriate indication for coronary revascularization,” he stressed. “It is possible that the absence of noninvasive ischemic testing may mean that clinicians should use alternative ways such as FFR in order to confirm ischemia prior to revascularization.”

Dr. Ko and colleagues looked at data from the Cardiac Care Network registry on 19,227 patients aged 66 years or older who underwent cardiac catheterization in Ontario, Canada, between October 2008 and July 2011. About 1 in every 9 patients (11.2%) could not be assigned an appropriateness score for reasons including lack of an ischemic evaluation (73.9%) and uninterpretable results (24.8%).

Compared with patients with an appropriateness score, unclassified patients were slightly older and had higher rates of severe angina and various comorbidities. Despite their higher risk level, patients who lacked scores were less likely to undergo LVEF assessment before catheterization and to receive recommended therapies including ACE inhibitors or angiotensin receptor blockers, beta-blockers, and statins.

Revascularization Tied to Lower Mortality

Among unclassified patients, the 2-year rate of all-cause death or MI was lower for those who received PCI or CABG within 60 days after the index catheterization than those who were treated with medical therapy—a difference driven by a reduction in mortality. The findings remained after inverse probability weighted propensity adjustment (table 1).

Table 1. Outcomes at 2 Years in Unclassified Patients

In subgroup analyses, the lower risk of death or MI associated with revascularization was seen both in patients who underwent CABG (HR 0.64; 95% CI 0.55-0.75) and in those treated with PCI (HR 0.85; 95% CI 0.74-0.98).

Pre-Cath Ischemic Evaluation Remains Important

The authors point out that the results of the COURAGE trial, which showed that stable CAD patients did not have improved outcomes with PCI vs medical therapy, are discordant with those of the current analysis.

However, they add, the patient populations differ between the 2 studies. Those in the Canadian registry have a higher level of risk, as indicated by the fact that the mortality rate observed in the medical therapy arm at 6 months exceeded that seen at the end of nearly 5 years of follow-up in COURAGE, the authors explain. Also, CABG was used in 40% of revascularization cases in the registry, whereas COURAGE involved mostly PCI.

They acknowledge that the current study, like all observational studies, is subject to unmeasured confounding and may be influenced by survivorship bias. In addition, it remains unclear why ischemic evaluations were skipped in some patients. The cause of their omission “is likely multifactorial, including clinical status with severe ischemic symptoms, comorbidities precluding the use of routine stress test, and inadequate access to noninvasive tests,” the investigators write.

Dr. Ko stressed that “evaluation of ischemia is highly important in the management of patients with stable coronary disease. Therefore, our findings should not be used by clinicians to forgo the use of ischemic evaluation prior to coronary revascularization. Rather, our study addresses a gap in knowledge regarding the application of appropriateness use criteria.”

Manesh R. Patel, MD, of Duke University Medical Center (Durham, NC), who is chair of the American College of Cardiology Task Force for Appropriate Use Criteria (AUC) for Cardiovascular Procedures, agreed.

“I don’t think that these findings mean ischemic evaluation is not needed in most of the stable patients,” he told TCTMD in an email. “Rather, they say that we likely need to address this scenario in the AUC, and hopefully with the upcoming document you will see this. We believe patients with high pretest probability of CAD should go to the cath lab but likely need FFR or other adjunctive technologies for evaluation… to ensure the ischemia-producing lesions are treated.” 


Source: 
Shuvy M, Guo H, Wijeysundera HC, et al. Medical therapy and coronary revascularization for patients with stable coronary artery disease and unclassified appropriateness score. Am J Cardiol. 2015;Epub ahead of print.

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Disclosures
  • The study was supported by a Canadian Institutes of Health Research operating grant.
  • Dr. Ko reports receiving support through a Clinician Investigator Award from the Heart and Stroke Foundation of Ontario.

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