Patients studied in the ISCHEMIA trial, the largest trial to date to compare revascularisation with a conservative strategy in patients with stable ischaemic heart disease (SIHD), may be unrepresentative of ischaemic heart disease patients entering US cath labs, research presented in a late-breaking trial session at the Society for Cardiovascular Angiography & Interventions 2021 scientific sessions (SCAI 2021, 28 April–1 May, virtual) has concluded.
ISCHEMIA has been described as one of the most important trials in interventional cardiology in recent years. Supported by the US National Heart, Lung, and Blood Institute, the trial looked at whether there is a benefit to adding cardiac catheterisation and, if feasible, revascularisation to optimal medical therapy in stable patients with at least moderate ischaemia on a stress test. Results of the trial were presented at the 2019 American Heart Association Scientific Sessions (AHA 2019; 16–18 November, Philadelphia, USA) by Judith S Hochman (New York University School of Medicine, New York, USA), and concluded that there is no additional benefit to revascularisation in these patients at a median of three years after the procedure.
However, a cross-sectional analysis of the National Cardiovascular Data Registry (NCDR) CathPCI Registry, findings of which were presented at SCAI 2021 by Saurav Chatterjee (Northshore and Long Island Jewish Hospitals of the Northwell Health System, New York, USA), has found that only a minority of SIHD patients referred for coronary intervention in contemporary practice clearly resemble those enrolled in the ISCHEMIA trial.
“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 study senior author Jay Giri (Penn Medicine, Philadelphia, USA).
Patients excluded from ISCHEMIA included those with acute coronary syndrome (ACS), cardiac arrest, cardiogenic shock, ejection fraction <35%, significant left main disease, cardiomyopathy, cardiac transplant, those non-adherent to medication, at high bleeding risk and those having anatomy unsuitable for revascularisation, Chatterjee told SCAI attendees during his virtual presentation.
“That made us hypothesise that potentially, this would lead to a significant proportion of patients who are routinely considered for revascularisation in current US practice,” he said. “Additionally, there are patients, who for various reasons were enrolled over a decade for the ISCHEMIA trial, which may not be representative of the most current form of practice in the USA.”
The study team also assessed variability among different centres in the proportion of ISCHEMIA-like versus patients who did not represent ISCHEMIA in the population of patients who underwent PCI for SIHD.
Analysis was conducted on data collected from the CathPCI Registry between October 2017‒June 2019, which included 388,212 patients from more than 1,600 hospitals. Participants included patients undergoing percutaneous coronary intervention (PCI) for SIHD in routine clinical practice. This SIHD population represented 42.9% of all performed PCI over the examined time period, the analysis showed, with the majority of US PCI performed in patients with ACS, cardiac arrest, or cardiogenic shock. Patients who met ISCHEMIA trial inclusion criteria—moderate to severe ischemia on functional testing, lack of high-risk anatomic or clinical features—and those who did not, were identified.
Among US patients undergoing PCI for SIHD between October 2017–June 2019, 32.3% met ISCHEMIA trial enrolment criteria. Among SIHD patients that did not meet criteria, 18.5% had SIHD with high-risk features (35.2% left main disease, 43.7% left ventricular systolic dysfunction, 16.8% end-stage renal disease), 17.3% had SIHD with negative or low-risk functional testing, and 31.9% either had no stress testing or did not have ischemic burden reported. Compared with the other SIHD cohorts, the ISCHEMIA-like cohort had the lowest in-hospital mortality rate (0.1%), and comparable in-hospital bleeding (0.6%), and acute kidney injury requiring haemodialysis (0.04%).
The findings led Chatterjee, Giri and colleagues to draw the conclusion that a large proportion of contemporary patients undergoing PCI for SIHD in the USA would not have met criteria for inclusion in the ISCHEMIA trial, adding that there was evidence of significant variability in patient selection among SIHD PCI centres.
“Our study reveals that most patients who have intervention are not reflected in the ISCHEMIA trial,” said Chatterjee. “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.”
Following his presentation, Chatterjee was asked by session moderator David Cox (Brookwood Baptist Health, Birmingham, USA) to summarise the “bottom line” from the group’s research. Chatterjee responded: “One of the things that we would like to highlight is that while ISCHEMIA guides a certain component of our clinical decision making, it does not represent all patients who undergo PCI in the USA. There is a large proportion of patients who do not meet these criteria, and future research needs to identify the appropriate patient cohort who will derive the most benefit, especially among patients with SIHD with a need for revascularisation.”