STEMI: Immediate vs. Deferred PCI of Nonculprit Lesions – 3-Year Outcomes

The approach to revascularizing all coronary artery lesions during a heart attack—specifically, whether to address blockages beyond the one causing the immediate crisis—has been a subject of ongoing debate. New research published in The New England Journal of Medicine suggests that immediately addressing these additional blockages doesn’t offer a significant advantage over a more delayed approach, guided by further testing. The international iMODERN trial, initially presented at TCT 2025, found similar rates of death, recurrent heart attack, and heart failure hospitalization at three years between patients undergoing immediate versus deferred percutaneous coronary intervention (PCI) for non-culprit lesions during treatment for a STEMI (ST-elevation myocardial infarction).

Understanding the Current Approach to STEMI and Multivessel Disease

A STEMI occurs when a coronary artery is completely blocked, cutting off blood supply to the heart muscle. Primary PCI—using a catheter to open the blocked artery—is the standard treatment. However, many patients experiencing a STEMI as well have blockages in other coronary arteries, known as non-culprit lesions. The question has been whether these additional blockages should be addressed immediately during the initial procedure, or if a more cautious, delayed approach is preferable. Current guidelines recommend revascularization of these non-culprit lesions in certain cases, but the optimal timing has remained unclear.

Previous trials suggested that immediate PCI of non-culprit lesions could improve survival and reduce the risk of future heart attacks. However, these trials often used endpoints that were open to interpretation, such as unplanned revascularization. The iMODERN trial aimed to address these uncertainties with a more rigorous design and a focus on clinically significant outcomes.

The iMODERN Trial: Design and Findings

The iMODERN trial involved 1,146 patients with STEMI and multivessel disease from multiple international centers. Participants were randomly assigned to either an immediate PCI strategy, guided by the instantaneous wave-free ratio (iFR), or a deferred PCI strategy, guided by cardiac stress MRI. The primary endpoint—a composite of all-cause death, recurrent heart attack, or heart failure hospitalization—was assessed at three years.

Researchers found no significant difference in the primary endpoint between the two groups: 9.3% in the immediate PCI group versus 9.8% in the deferred PCI group (HR = 0.95. 95% CI, 0.65-1.4; P = .81). This indicates that immediate PCI did not demonstrably reduce the risk of adverse cardiovascular events compared to the delayed approach.

Specifically, rates of all-cause death (4.1% vs. 3.9%), recurrent heart attack (5.4% vs. 5.5%), and heart failure hospitalization (0.6% vs. 2.3%) were similar between the groups. There was a trend toward fewer stroke or transient ischemic attack events in the immediate PCI group (1.3% vs. 3.7%), though the clinical significance of this finding requires further investigation.

What Does This Mean for Patients?

The iMODERN trial’s findings suggest that a more individualized approach to revascularization in STEMI patients with multivessel disease may be warranted. The study does not definitively rule out a potential benefit from immediate PCI, but it does demonstrate that it is not superior to a deferred strategy guided by MRI. Which means that clinicians can consider a range of factors—including the patient’s overall health, the severity of the non-culprit lesions, and the availability of advanced imaging techniques—when making treatment decisions.

It’s significant to understand that the trial’s results reach with some limitations. The confidence intervals around the primary endpoint were relatively wide, meaning that a little benefit or harm from immediate PCI cannot be entirely excluded. The study population was carefully selected, and the findings may not be generalizable to all STEMI patients with multivessel disease. Primary PCI remains a crucial intervention for STEMI, and this study focuses specifically on the *additional* question of how to manage other blockages present at the time.

Understanding iFR and MRI Guidance

The iMODERN trial utilized two different methods for guiding revascularization decisions. IFR (instantaneous wave-free ratio) is a physiological assessment of coronary artery blood flow, used during PCI to determine whether a lesion is truly causing a significant blockage. Cardiac stress MRI, assesses heart muscle function and blood flow at rest and during stress, providing information about the severity of ischemia (reduced blood flow) in different areas of the heart. Using these tools allows clinicians to make more informed decisions about which lesions require intervention.

The Role of Cardiac MRI in Deferred PCI

The deferred PCI strategy in the iMODERN trial relied heavily on cardiac stress MRI to identify patients who would benefit from further intervention. MRI allows for detailed visualization of heart muscle damage and blood flow, helping to pinpoint areas of significant ischemia. This approach avoids unnecessary PCI procedures in patients whose non-culprit lesions are not causing significant problems. Best practices emphasize a careful assessment of risk and benefit before proceeding with any invasive procedure.

What Comes Next: Refining Revascularization Strategies

The iMODERN trial adds to the growing body of evidence suggesting that a one-size-fits-all approach to revascularization in STEMI patients is not optimal. Future research will likely focus on identifying specific patient subgroups who may benefit most from immediate versus deferred PCI. This could involve incorporating genetic information, advanced imaging biomarkers, and more detailed assessments of coronary artery physiology. Ongoing surveillance and data collection will also be crucial for refining treatment guidelines and improving outcomes for patients experiencing STEMI.

The findings underscore the importance of a collaborative approach to care, involving cardiologists, radiologists, and other healthcare professionals to develop individualized treatment plans based on the best available evidence. Patients should discuss the risks and benefits of different revascularization strategies with their doctors to make informed decisions about their care.