SCAI 2021: ISCHEMIA Represents a Fraction of Patients with SIHD Undergoing PCI

Jay Giri, MD, MPH

While the ISCHEMIA trial was widely accepted as one of the most important studies in recent years when presented at AHA 2019 , a new analysis suggests patients within the trial might only represent a small fraction of patients undergoing coronary intervention.

Conducted as part of the Research to Practice (R2P) Initiative and presentedat the Society of Coronary Angiography and Interventions (SCAI) 2021 Scientific Sessions, the study compared patients from the trial to those within a real-world PCI registry suggests fewer than 1-in-3 patients undergoing PCI for stable ischemic heart disease (SIHD) in the US met ISCHEMIA eligibility criteria.

"The ISCHEMIA trial is one of the most important studies in interventional cardiology over the last decade. While the findings are very valuable in informing our decision-making in many patients—the population enrolled does not appear representative of the broad range of patients that modern US coronary interventionists encounter," said senior investigator Jay Giri, MD, MPH, assistant professor of medicine at Penn Medicine, in a statement.

Highly anticipated and met with acclaim, the ISCEHMIA trial provides insight into the risk-benefit relationship with use of invasive or conservative strategies in patients with SIHD. Ultimately, the trial concluded an initial invasive strategy was linked to lower levels of angina but did not demonstrate significant reductions risk of death or events at 3 years.

To learn more about the real-world application of study results, a team from institutions across the US sought to determine the proportion of patients undergoing PCI for SIHD meeting inclusion criteria for the landmark trial. Two do so, they designed their study as a cross-sectional analysis of data from the National Cardiovascular Data Registry (NCDR) CatchPCI Registry.

After performing a search from October 2017-June 2019, investigators identified 388,212 patients undergoing PCI for SIHD at 1662 hospitals in the US. Of note, the 388,212-patient cohort represents 42.9% of patients who underwent PCI during the study period. Of note, inclusion criteria for ISCHEMIA included presence of SIHD, moderate to severe ischemia on functional testing, and lack of high-risk anatomic or clinical features.

Upon analysis, just 32.3% of the 388,212 patients, which represents 13.5% of all PCI patients, met criteria for inclusion in the ISCHEMIA trial. Among the patients who did not meet ISCHEMIA criteria, 18.5% had SIHD with high-risk features and 17.3% had SIHD with negative to low-risk functional trusting.Investigators pointed out they were unable to classify 123,899 patients because they had no stress testing or did not have ischemic burden reported.

Among the 71,852 patients with SIHD and high-risk features, 35.2%had left main disease, 43.7% had left ventricular systolic dysfunction, and 16.8% had end-stage renal disease.

In assessments examining the impact of geographic variation, investigators found the median number of PCI patients with SIHD meeting ISCHEMIA criteria was 32.1% (IQR, 23.5-40.6) and noted less than 1% of institutions had greater than 69% of SIHD PCI considered eligible for enrollment. When comparing outcomes among the study groups, investigators noted patients in the ISCHEMIA eligible cohort had the lowest in-hospital mortality rate. Additionally, investigators observed this group also had comparable rates of in-hospital bleeding and need for new dialysis.

"Our study reveals that most patients who have intervention are not reflected in the ISCHEMIA trial," said Saurav Chatterjee, MD, principal investigator and a cardiologist at Northwell Health, in the aforementioned statement. "These results help shine a light into what is truly happening in Cath labs across the country, and the kinds of patients who are being referred for intervention."

This study, “Comparison of the ISCHEMIA trial population to Patients undergoing Percutaneous Coronary Intervention in US Practice: a CathPCI National Cardiovascular Data Registry (NCDR) Research to Practice (R2P) Initiative,” was presented at SCAI 2021.