About one-third of U.S. patients undergoing PCI for stable ischemic heart disease (SIHD) meet enrollment criteria for the ISCHEMIA trial, with variation among individual sites in the proportion of patients meeting ISCHEMIA trial criteria, according to a study published Nov. 1 in JACC: Cardiovascular Interventions. The study is part of ACC's Research to Practice (R2P) initiative, which identifies impactful cardiovascular research and analyzes its implications for contemporary clinical practice using ACC's NCDR clinical registries.

Saurav Chatterjee, MD, FACC, et al., used data from ACC’s CathPCI Registry to determine the proportion of U.S. SIHD patients who meet ISCHEMIA trial criteria, and assess variations among sites. The researchers also looked at short-term adverse event rates among SIHD patients who did or did not have similar characteristics as patients in the ISCHEMIA trial.

The study included 388,212 patients enrolled in CathPCI Registry who received PCI for SIHD at 1,662 sites between October 2017 and June 2019. SIHD patients were classified into one of four groups based on whether they met criteria for inclusion in the ISCHEMIA trial. There were 125,302 patients (32.2%) who met inclusion criteria who had a moderate- or high-risk stress test without high-risk anatomic or clinical features. In addition, two groups would have been excluded from the trial: 71,852 (18.51%) for high-risk criteria and 67,159 (17.29%) for low-risk criteria. Finally, 123,899 patients (31.92%) were not classifiable because stress test results or the extent of ischemic burden were not reported. 

Patients who were unclassifiable were more likely than those who met trial criteria to have a history of myocardial infarction (31.8% vs. 25.8%) and heart failure (18.13% vs. 14.79%). In addition, patients who met criteria for the ISCHEMIA trial had the lowest in-hospital mortality rate among all PCI patients (0.11%; p<0.001). There was significant variability in the proportion of patients who met criteria inclusion criteria across PCI centers, with 32.1% (interquartile range: 23.5%-40.6%) of patients undergoing PCI for SIHD meeting criteria at the median hospital.

The researchers note “significant variability in patient selection” among PCI centers, adding that variations may “indicate an opportunity to select SIHD patients more consistently for PCI with greater scrutiny of patients with absent or negative functional testing.” They conclude that the study demonstrates that “a large proportion of patients undergoing PCI for SIHD” would not meet criteria for enrollment in the ISCHEMIA trial.

“The value of an analysis such as this is to assess to what extent clinical trial findings can be translated into clinical practice,” David J. Maron, MD, FACC, et al., write in an accompanying editorial comment, adding that the proportion of patients who would be excluded from the ISCHEMIA trial in the study is “slightly exaggerated.” There is “a large percentage of patients for whom the ISCHEMIA trial is highly relevant; exactly what percentage on the basis of NCDR data is hard to say,” they conclude.

Clinical Topics: Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Acute Heart Failure

Keywords: National Cardiovascular Data Registries, CathPCI Registry, Heart Failure, Registries, Myocardial Infarction, Myocardial Ischemia, Hospital Mortality, Percutaneous Coronary Intervention, Patient Selection, Exercise Test

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