Screening for Left Main Coronary Artery Disease via CTA in Patients With Ischemia

Hand holding a pen point Computed Tomography Angiography Coronay (CTA coronary) with blur background.
A post hoc analysis of the ISCHEMIA study evaluated the markers of left main CAD via clinical and noninvasive functional parameters.

In patients with moderate to severe inducible ischemia, the use of clinical and stress testing parameters have been shown to be only weakly predictive of left main coronary artery disease (LMD) on computed tomography angiography (CTA), with anatomical imaging required to rule out LMD in most cases. The findings were published in the Journal of the American College of Cardiology.

A post hoc analysis of the International Study of Comparative Health Effectiveness With Medical and Invasive Approaches (ISCHEMIA; identifier: NCT01471522) was conducted. Recognizing that detection of 50% or wider diameter stenosis LMD has therapeutic and prognostic implications, the investigators sought to identify markers of LMD as detected on CTA, with the use of clinical and stress testing parameters. The analysis included randomized and nonrandomized participants from ISCHEMIA. Enrolled patients also had locally determined moderate or severe ischemia diagnosed via a nonimaging exercise tolerance test (ETT), stress nuclear myocardial perfusion imaging, or stress echocardiography, followed by CTA to rule out LMD.

Following stress testing and CTA, a total of 5146 patients who had not undergone previous coronary artery bypass grafts, and who had interpretable ischemia testing with the use of a modality other than cardiac MRI, were enrolled in the study. Overall, 8.0% of these individuals had LMD. The median participant age was 63 years and 74% of the patients were men.

Participants with LMD were significantly more likely to be men (P <.01), to be older (P <.001), to have an absence of previous MI (P <.009), to exhibit transient ischemic dilation of the left ventricle on stress echocardiography (P =.05), to exhibit maximum ST-segment depression on ETT (P =.004), and to have peak exercise metabolic equivalents attained on ETT (P <.001). The C-index for the clinical logistic model was 0.643. The C-index for the current model was marginally, but statistically significantly, improved compared with the clinical model, at 0.684 (P <.001).

A major limitation of the present study is the fact that the researchers analyzed left main stenosis via use of the 50% threshold; however, not all 50% to 70% left main stenosis may be flow-limiting. Further, exercise hemodynamic data were unavailable in a large number of patients with stress imaging.

The investigators concluded that the findings from the current study demonstrate that stress testing offers only incremental value over the use of clinical parameters for predicting LMD in patients with moderate or severe ischemia. “Thus, for most patients with moderate or severe ischemia, exclusion of LMD will require anatomical imaging with either CTA or invasive coronary angiography,” the investigators wrote.

Disclosure: Some of the study authors have declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 


Senior R, Reynolds HR, Min JK, et al; ISCHEMIA Research Group. Predictors of left main coronary artery disease in the ISCHEMIA trialJ Am Coll Cardiol. Published online February 14, 2022. doi:10.1016/j.jacc.2021.11.052

This article originally appeared on The Cardiology Advisor