Outcomes in the ISCHEMIA Trial Based on CAD and Ischemia Severity

This pre-specified secondary analysis of the ISCHEMIA trial examined whether CAD severity (assessed by CCTA at enrollment) or ischemia severity (assessed by stress testing) predicted outcomes and modified the benefit of invasive versus conservative management in 5,179 patients with stable coronary disease.

CAD anatomical severity — measured by CCTA — predicted mortality and MI independently of ischemia severity. Ischemia severity did not independently predict outcomes once CAD severity was accounted for. Among patients with the most severe anatomical disease (multivessel and left main involvement), the invasive strategy showed a numerical reduction in MI that was not significant at the 4-year follow-up but suggested possible longer-term benefit.

The headline finding — that CAD severity, not ischemia severity, drives outcomes in stable coronary disease — is one of the most clinically important results from the ISCHEMIA dataset. It challenges the conceptual foundation of ischemia-guided revascularization: the idea that the severity of ischemia on stress testing indicates which patients will benefit from PCI or CABG. If ischemic burden on nuclear imaging or stress echo does not independently predict events once anatomy is known, then obtaining anatomical information (via CCTA) may be more strategically valuable than ischemia quantification.

This analysis reinforces CCTA’s role as the primary diagnostic tool for stable chest pain, rather than functional testing.

We rate the evidence strong. A rigorous pre-specified ISCHEMIA subgroup analysis establishing CAD anatomy as the primary outcome predictor — reframing the diagnostic strategy for stable coronary disease.