Documenting Ischemia Prior to Elective Percutaneous Coronary Intervention

To the Editor: In their observational cohort study of Medicare fee-for-service beneficiaries aged 65 years or older, Dr Lin and colleagues¹ reported that the majority of patients with stable coronary artery disease did not undergo stress testing to document ischemia within 90 days prior to elective percutaneous coronary intervention (PCI). The authors state that for patients with stable angina, any vessels to be dilated must be shown to be “associated with a moderate to severe degree of ischemia on noninvasive testing” (referring to the class IIa recommendation in section 5.1 on page e205 of the guidelines from the American College of Cardiology, the American Heart Association, and the Society for Cardiovascular Angiography and Intervention [ACC/AHA/SCAI]² ).

The authors apparently did not have access to data on intracoronary physiologic measurements such as fractional flow reserve (FFR), an important measure of the hemodynamic significance of intermediate (40%-70% diameter luminal narrowing) coronary arterial stenoses.³ Fractional flow reserve, the ratio of distal coronary pressure to aortic root pressure measured during maximal hyperemia, is easily obtained during cardiac catheterization before PCI. A low FFR (<0.75) correlates with ischemia on noninvasive testing while a normal FFR (>0.75) is associated with an extremely low future event rate, implying that PCI can be safely deferred.^{3 - 5} The ACC/AHA/SCAI guidelines quoted by Lin et al actually include intracoronary physiologic measurements (also as a class IIa recommendation) as an alternative to performing noninvasive functional testing in determining whether an intervention is warranted (section 5.6.2, page e224).

In the last paragraph of their article, the authors imply that their findings highlight an opportunity for improvement in the care of patients and that improved adherence to guidelines would improve the safety and delivery of health care to Medicare beneficiaries while decreasing expenditure on costly and inappropriate procedures. These statements would be justified if the authors had data on evaluation of coronary stenoses by intracoronary hemodynamic measurements. In some instances, it may be less costly and equally safe and effective to use these measurements during diagnostic cardiac catheterization instead of having both a cardiac catheterization and a stress test (usually a nuclear study) to decide on whether PCI is indicated.