The population represented in the ISCHEMIA trial for stable ischemic heart disease (SIHD) – which commonly informs contemporary decision-making – does not appear to reflect the majority of patients encountered by U.S. coronary interventionalists today, according to a large, new registry study.
The findings from 388,212 patients in the National Cardiovascular Data Registry (NCDR) CathPCI Registry who underwent percutaneous coronary intervention (PCI) for SIHD were presented in a late-breaking presentation on Thursday at the Society for Cardiovascular Angiography and Interventions (SCAI) 2021 Virtual Scientific Sessions.
ISCHEMIA is “one of the most important studies in interventional cardiology over the last decade,” informing physician decisions for many patients, the current study’s senior author, Jay Giri, MD, MPH, of Penn Medicine said in an accompanying press statement.
The trial – presented in 2019 – found that PCI did not decrease the risk of major adverse ischemic events compared with optimal medical therapy among stable patients with moderate ischemia over a follow-up period of 3.3 years, calling the practice of coronary intervention and revascularization into question, the press statement noted.
ISCHEMIA did show improvement of angina symptoms with revascularization, but “overall the mortality and heart endpoints were not superior,” according to the lead author on the current study, Saurav Chatterjee, MD, Northshore and Long Island Jewish Hospitals of the Northwell Health System, during the SCAI presentation.
However, the proportion of patients undergoing PCI for SIHD in current U.S. interventional practice who meet ISCHEMIA inclusion criteria was unknown.
The current study, therefore, set out to run cross-sectional analyses of the NCDR CathPCI Registry between October 2017 and June 2019, including 388,212 patients undergoing PCI for SIHD in routine clinical practice across 1,662 hospitals. They comprised 42.9% of all patients undergoing PCI during the study period.
The researchers then identified the patients within the cohort who met ISCHEMIA trial inclusion criteria, which included having SIHD, moderate to severe ischemia on functional testing and lack of high-risk anatomic or clinical features including left ventricular systolic dysfunction, end-stage renal disease and left main coronary artery disease.
They found that 125,302 patients met the criteria (32.3%; 13.5% of all patients undergoing PCI). At the median hospital, 32.1% (interquartile range: 23.5% to 40.6%) of SIHD patients met the criteria.
The data also show the potential for at least short-term improvement in outcomes for those meeting the criteria of the ISCHEMIA trial population, Chatterjee added during his presentation.
The ISCHEMIA-like cohort had the lowest in-hospital mortality rate at 0.1% (p < 0.01), but had comparable in-hospital bleeding rates (0.6%) and acute kidney injury requiring hemodialysis (0.04%) with other SIHD cohorts.
Of the SIHD patients who did not meet ISCHEMIA criteria, 71,852 (18.5%) had SIHD with high-risk features, of whom 35.2% had left main disease, 43.7% left ventricular systolic dysfunction and 16.8% end-stage renal disease.
SIHD with negative or low-risk functional testing was identified in 67,159 (17.3%), while 123,899 (31.9%) either had no stress testing or did not have ischemic burden reported. These patients also represented “possibly a higher risk profile population,” Chatterjee explained during a press conference, with significant percentages of comorbidities such as previous myocardial infarctions.
The researchers are still running analyses “on better classifying this unclassifiable population,” he said, “but our impression is that this most likely represents an opportunity to document and select patients more optimally”.
As a whole, the current study population “does not appear representative of the broad range of patients that modern U.S. coronary interventionists encounter,” Giri concluded.