Evaluation of coronary lesions has for many years relied on the assessment of the “lumenogram” but it has changed nowadays to more physiologic measurements of haemodynamic significance, Professor E Eeckhout from Lausanne pointed out.
Modern tools for such comprehensive assessment of stenosis severity include non-invasive methods, such as scintigraphiy, multi-slice computed tomography (MSCT), magnetic resonance imaging (MRI) and positron emission tomography (PET), as well as invasive methods. In multivessel CAD (MVD) the appropriate choice of treatment is particularly important and, thus, the adequate use of available diagnostic tools should be decided carefully.
Dr J M Knuuti from Turku, Finland summarised the data from scintigraphic evaluation, which showed good correlation between size and number of perfusion defects and clinical end points. The inclusion of information about left ventricular size and function by gated SPECT analysis further enhances the prognostic impact of myocardial scintigraphy.
MRI perfusion studies are promising for improved evaluation of functional consequences of coronary stenoses, and studies are ongoing to establish the accuracy of stress perfusion and delayed enhancement with this imaging modality. PET provides quantitative, functional information on perfusion, function and viability of the myocardium, but has the limitation of low availability, high cost and limited prognostic data for multivessel disease.
Dr. P Vanhoenacker from Aalst, Belgium, then discussed the current value of MSCT in evaluating CAD, where it is recommended only for patients with the intermediate pre-test likelihood of CAD in current guidelines. More recent fields of research include the assessment of “soft”, potentially vulnerable plaque, exclusion of significant CAD in enzyme-negative acute chest pain and the post CABG patient with atypical symptoms or before planned bypass graft PCI. To date, however, many obstacles have to be overcome before MSCT can become a reliable tool for assessing stenosis severity and plaque morphology.
Fractional flow reserve is the invasive method to assess stenosis severity and is now the only well established technique for this purpose in the cath lab. Prospective studies have proven the safety of deferring patients with intermediate lesions for PCI at a latter time period, Dr W F Fearon from Stanford University in the USA reported.