Diagnostic Imaging Strategies for Patients with Suspected Coronary Artery Disease

In this thesis, our aim was to determine and optimize the diagnostic work-up for patients who are suspected of having coronary artery disease (CAD). We showed that the diagnostic performance of stress perfusion magnetic resonance imaging (MRI) compares favorably to the diagnostic performance of single-photon emission computed tomography (SPECT). If both tests can be performed in a patient, then stress perfusion MRI should be the preferred test, even more so because it does not involve exposure to radiation. We demonstrated that the coronary CT calcium score has predictive value beyond existing cardiovascular risk factors for diagnosing obstructive CAD in patients with chest pain. The CT coronary calcium score could be considered as an initial triage test in patients with a low pre-test probability of CAD, preventing (unnecessary) further work-up if the score is zero, and justifying further testing when coronary calcium is present. The optimal diagnostic strategy depends on the pre-test probability of CAD, which is traditionally estimated based on the Diamond & Forrester method or the Duke Clinical Score. We demonstrated that these prediction rules systematically overestimate the probability of CAD and we updated the models based on contemporary data. An online probability calculator was developed that provides systematically lower (but more accurate) estimates of the pre-test probability. Although we did not study the clinical impact of implementing our new prediction model, a more accurate estimate of the pre-test probability is likely to lead to better decisions regarding further testing and it could potentially reduce costs since less high probabilities are predicted which in turn may prevent unnecessary diagnostic work-up. Lastly, we evaluated the long term effectiveness and costs of coronary CT angiography in various different settings and for various countries. In the Dutch setting, coronary CT angiography was found to be cost-effective as triage test prior to catheter-based coronary angiography (CAG) if the pre-test probability was below 44% in men and below 37% in women. CT coronary calcium scoring with or without subsequent coronary CT angiography as initial strategy for patients presenting with stable chest pain was less expensive and equally effective compared to standard-of-care. Finally, we showed that a strategy using coronary CT angiography, if positive followed by cardiac magnetic resonance imaging (CMR) was cost-effective compared to strategies with coronary CT angiography and CMR alone, for the United States, the United Kingdom, as well as the Netherlands. All-in-all, our updated prediction models combined with the results from our decision models and cost-effectiveness analyses provide a practical framework for efficient implementation of diagnostic imaging tests, in particular for the CT coronary calcium score and coronary CT angiography.

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