ISCHEMIA results may only apply to subset of real-world PCI population
Click Here to Manage Email Alerts
According to an analysis in JACC: Cardiovascular Interventions, the results of the ISCHEMIA trial of invasive vs. conservative treatment of stable ischemic heart disease may only be applicable to one-third of the real-world PCI population.
“Guidelines recommend revascularization for patients with stable ischemic heart disease (SIHD) in the appropriate clinical context to reduce the risk of subsequent ischemic events and to improve symptomatic angina,” Saurav Chatterjee, MD, cardiologist at Northwell Health, and colleagues wrote. “The large, multinational ISCHEMIA trial was performed to clarify the benefits of revascularization added to optimal medical therapy in patients with moderate or large territory ischemia.”
For the ISCHEMIA trial, the benefits of revascularization were evaluated using an invasive strategy of optimal medical therapy plus diagnostic catheterization. PCI or CABG was subsequently performed, based on results of catheterization.
As Healio previously reported, the ISCHEMIA trial established that there was no difference in long-term CV outcomes (CV death, MI, hospitalization for unstable angina, HF or resuscitated cardiac arrest) among stable patients with moderate or severe ischemia assigned to an invasive strategy compared with a conservative approach of optimal medical therapy only.
According to the present study, experts had previously raised concerns regarding the applicability of the ISCHEMIA findings due to the trial’s exclusion of patients with renal disease, recent ACS or intervention, left main disease and ischemic cardiomyopathy.
Therefore, researchers evaluated proportion of patients with SIHD who met the inclusion criteria for the ISCHEMIA trial using the nationwide National Cardiovascular Data Registry CathPCI Registry. Researchers also evaluated short-term adverse event rates among patients in the registry compared with ISCHEMIA participants.
Real-world registry vs. ISCHEMIA
From October 2017 to June 2019, 388,212 patients in the CathPCI registry underwent PCI for SIHD. This figure represented 41.88% of all patients who had PCI during that time. Of those patients, 32.28% met the criteria for entry into the ISCHEMIA trial.
According to the study, 17.29% of patients had low-risk criteria that would have excluded them from the ISCHEMIA trial, and 31.92% were unclassifiable, owing to lack of stress testing or reporting of the extent of ischemia.
Overall, 13.5% of all patients undergoing PCI in the U.S. were classified as similar to participants in ISCHEMIA trial.
Of those who would have been excluded from the ISCHEMIA trial, 18.51% had high-risk criteria, including 35.2% with left main stenosis, 43.7% with ejection fraction less than 35% and 16.8% with end-stage renal disease.
Moreover, patients in the registry who were most like those included in the ISCHEMIA trial had the lowest rates of in-hospital mortality among all patients undergoing PCI (0.11%; P < .001). The ISCHEMIA-like patients in the registry had an 0.64% rate of in-hospital bleeding and an 0.04% rate of acute kidney injury requiring hemodialysis, figures comparable to all patients in the registry.
Additionally, researchers reported considerable between-hospital variability in the proportion of ISCHEMIA-like patients who underwent PCI. According to study, at the median hospital, 32.1% of patients who underwent PCI for stable ischemia heart disease met ISCHEMIA inclusion criteria (interquartile range, 23.5-40.6).
“The current study demonstrates that a large proportion of patients undergoing PCI for SIHD in the United States would not have met criteria of the ISCHEMIA trial population, with significant variability in patient selection among SIHD PCI centers in the United States,” the researchers wrote.
How to interpret these results
In a related editorial, several ISCHEMIA and ISCHEMIA-CKD study researchers discussed how these findings might impact and inform the general applicability of the results of the ISCHEMIA trial.
“At worst, the ISCHEMIA trial results apply to only 32% of patients undergoing elective PCI in the United States. At best, the trial results apply to a far higher proportion, excluding only those at high risk (18.5%) or with unacceptable symptoms despite maximal medical therapy (percentage unknown), for whom PCI is clearly indicated,” the editorial authors wrote. “The purpose of the analysis by Chatterjee et al is to inform the cardiovascular community of the proportion of patients with SIHD in clinical practice who would have been excluded from ISCHEMIA without regard for the logic of each exclusion criterion. The purpose of this editorial is to provide context for the analysis, admittedly from the perspective of ISCHEMIA investigators, with the hope that this helps readers clearly see the relevance of the trial to patients under their care.”
Reference:
Collapse
Click Here to Manage Email Alerts