Integration von funktioneller und morphologischer nichtinvasiver Bildgebung in die Evaluation von Patienten mit intermediärer Vortestwahrscheinlichkeit für eine koronare Herzkrankheit

The non-invasive clinical work-up of symptomatic persons with suspected coronary heart disease (CHD) is a stepwise procedure. Initially, the risk factors should be measured and quantified. The resting-EKG provides first diagnostic and prognostic information. In the absence of contraindications in subjects with sufficient exercise capacity and an intermediate pretest-likelihood of CHD, a treadmill- or bicycle-stress-ECG should be performed. When interpretation of the stress-ECG is limited, further diagnostic procedures should be considered. Traditionally, methods are being used that detect myocardial ischemia during physical or pharmacological stress. For pharmacological stress testing, vasodilating drugs (adenosin/dipyridamole) or positive inotropic substances (dobutamine) are established. For this purpose, stress-echocardiography, myocardial perfusion scintigraphy and recently stress-magnetic resonance imaging (MRI) are recommended. These tests provide sensitivities and specificities between 80-89% and 75-86%, respectively, for significant stenoses (>50%) and they provide additional prognostic information. However, reliable exclusion of significant disease is not possible. Predominantly advanced lesions show an ischemic response to stress, as coronary artery remodeling may preclude functional relevance earlier in the disease process. The patient may nonetheless be at risk in an asymptomatic stage and atypical symptoms are frequently observed. Direct visualization and quantification of coronary atherosclerosis has therefore been introduced as a complementary concept into clinical routine. With increasing coronary artery calcium (CAC) burden and increasing number of diseased vessels, the likelihood of significant stenosis somewhere in the coronary tree increases gradually. It is, however, not possible to draw conclusions on the degree of stenosis at the calcified site. Additional administration of contrast agent using latest multi-slice CT technology allows for detection of non-calcified plaque and high-grade lesions with a sensitivity and specificity of > 90%. High-grade proximal lesions can be directly sent for invasive interventional therapy, while patients with lesions of uncertain functional relevance should be sent for additional ischemia testing. Under consideration of contraindications and limitations of each technique, incorporating morphological and functional tests into the evaluation of patients with suspected CHD can improve clinical work-up. When selecting a specific technique, the availability and investigators' experience should be taken into consideration, to target image quality and the information gained to each patient individually.