Predictors of Left Main Coronary Artery Disease

Quick Takes

  • Stress testing offered only modest incremental value over clinical parameters for prediction of left main coronary artery disease (LMD) in patients with moderate or severe ischemia with suboptimal predictive value.
  • Transient ischemic dilation by stress echocardiography, the magnitude of ST-segment depression, and low achieved workload by exercise tolerance test were associated with LMD independent of clinical factors, but the discriminatory capacity of the model was modest.
  • There was high concordance of CTA and invasive angiography for LMD in the ISCHEMIA trial, and for most patients, exclusion of LMD will require anatomical imaging, with either CTA or invasive coronary angiography.

Study Questions:

What are the clinical and stress testing parameter predictors of left main coronary artery disease (LMD) detected on coronary computed tomography angiography (CTA)?

Methods:

The investigators conducted a post hoc analysis of the ISCHEMIA (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches) trial, including randomized and nonrandomized participants who had locally determined moderate or severe ischemia on nonimaging exercise tolerance test (ETT), stress nuclear myocardial perfusion imaging, or stress echocardiography followed by CTA to exclude LMD. Stress tests were read by core laboratories. Prior coronary artery bypass grafting was an exclusion. In a stepped multivariate model, the authors identified predictors of LMD, first without and then with stress testing parameters. The model’s ability to distinguish between patients with relatively high versus low likelihood of LMD >50% was assessed by calculating the C-index and by plotting the distribution of predicted probabilities of LMD >50% within each modality.

Results:

Among 5,146 participants (mean age 63 years, 74% male), 414 (8%) had LMD. Predictors of LMD were older age (p < 0.001), male sex (p < 0.01), absence of prior myocardial infarction (p < 0.009), transient ischemic 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 were weakly predictive of LMD (C-index 0.643 and 0.684).

Conclusions:

The authors concluded that in patients with moderate or severe ischemia, clinical and stress testing parameters were only weakly predictive of LMD on CTA.

Perspective:

This post hoc study suggests that stress testing offered only modest incremental value over clinical parameters for prediction of LMD in those with moderate or severe ischemia. Furthermore, transient ischemic dilation by stress echocardiography, and the magnitude of ST-segment depression, and low achieved workload by ETT were associated with LMD independent of clinical factors, but the discriminatory capacity of the model was modest. There was high concordance of CTA and invasive angiography for LMD in the ISCHEMIA trial, and for most patients, exclusion of LMD will require anatomical imaging, with either CTA or invasive coronary angiography.

Clinical Topics: Cardiovascular Care Team, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Atherosclerotic Disease (CAD/PAD), Interventions and Coronary Artery Disease, Interventions and Imaging, Angiography, Computed Tomography, Echocardiography/Ultrasound, Nuclear Imaging

Keywords: Computed Tomography Angiography, Coronary Angiography, Coronary Artery Disease, Coronary Stenosis, Diagnostic Imaging, Dilatation, Echocardiography, Stress, Exercise Test, Exercise Tolerance, Myocardial Infarction, Myocardial Ischemia, Myocardial Perfusion Imaging, Secondary Prevention, Tomography, X-Ray Computed, Workload


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