Stress test parameters weakly predictive of left main coronary artery disease

Clinical and stress testing parameters do not make good predictors of left main coronary artery disease (LMD) on computed tomography angiography (CTA) in patients with moderate or severe ischaemia, a study has shown. Anatomical imaging is necessary to rule out LMD in this population.

A team of investigators conducted a post hoc analysis of the ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) Trial. Randomized and nonrandomized participants with locally determined moderate or severe ischaemia on nonimaging exercise tolerance test (ETT), stress nuclear myocardial perfusion imaging, or stress echocardiography followed by CTA to exclude LMD, were included in the analysis.

Core laboratories read the stress tests. Prior coronary artery bypass grafting was not included. Finally, the investigators generated a stepped multivariate model to identify predictors of LMD, first without and then with stress testing parameters.

Of the 5,146 participants (mean age 63 years, 74 percent male) identified, 414 (8 percent) had LMD. The following factors were predictive of LMD: older age (p<0.001), male sex (p<0.01), absence of prior myocardial infarction (p<0.009), transient ischaemic dilation of the left ventricle on stress echocardiography (p=0.05), magnitude of ST-segment depression on ETT (p=0.004), and peak metabolic equivalents achieved on ETT (p=0.001).

The models, on the other hand, did not strongly predict LMD (C-index 0.643 and 0.684).

“Detection of ≥50-percent diameter stenosis LMD has prognostic and therapeutic implications,” the investigators said. “Noninvasive stress imaging or an ETT are the most common methods to detect obstructive coronary artery disease.”