Stress Imaging Outperforms ECG in Predicting Cardiac Events, ISCHEMIA Trial Finds

The ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) trial enrolled 5,179 patients across 320 global centers, each with moderate-to-severe stable coronary artery disease. Participants underwent different types of stress tests — nuclear imaging (2,567 patients), echocardiography (1,085), cardiac magnetic resonance imaging or CMR (257), and exercise ECG (1,270). Using Cox proportional hazards models, the researchers evaluated the associations between various stress test findings and key cardiovascular events.

The primary endpoint included cardiovascular (CV) death, myocardial infarction (MI), resuscitated cardiac arrest, or hospitalization due to unstable angina or heart failure. Additional endpoints included CV death alone, spontaneous MI, procedural MI, and type 2 MI.

The study led to the following findings:

• A higher number of scarred heart segments was significantly linked to an increased risk of the composite primary endpoint (HR: 1.07).
• Lower left ventricular ejection fraction (LVEF) at rest (HR: 0.88) and during stress (HR: 0.87) were strong predictors of adverse cardiovascular outcomes.
• Echocardiography and nuclear imaging showed predictive value across several cardiovascular endpoints.
• The extent of ischemia identified on stress cardiac magnetic resonance imaging (CMR) was a strong predictor of the composite primary endpoint and spontaneous myocardial infarction.
• Exercise ECG showed limited predictive ability compared to imaging tests.
• The number of ischemic segments was significantly associated with both spontaneous and procedural myocardial infarctions but was only borderline significant for predicting the composite primary endpoint.

The research suggests that while all forms of stress testing provide prognostic information, their predictive accuracy differs based on the modality and the endpoint considered. Stress CMR, in particular, emerged as a valuable tool, potentially warranting broader use in evaluating patients with stable coronary artery disease.

"The ISCHEMIA trial, conducted across 320 centers worldwide, demonstrated that stress imaging and exercise ECG varied in their ability to predict major cardiovascular outcomes, helping to uncover distinct risk patterns associated with ischemia and infarction. Among the different modalities, stress CMR stood out as a strong predictor of multiple clinical endpoints, indicating its value in patient assessment," the researchers wrote.

"These findings emphasize the need for individualized diagnostic strategies and support the growing role of advanced imaging in guiding treatment decisions for patients with chronic coronary syndromes," they concluded.

Reference:

Shaw LJ, Phillips LM, Leipsic J, et al. Comparative prognosis by stress ECG and stress imaging: results from the ISCHEMIA trial. JACC Cardiovasc Imaging. 2025;Epub ahead of print.