FUNCTIONAL AND ANATOMICAL CARDIAC IMAGING IN PATIENTS WITH CORONARY ARTERY STENTS
Abdou Elhendy, M.D., Ph.D., Marshfield Clinic, Marshfield, WI, USA
Coronary artery stenting has been shown to improve myocardial function, and ameliorate angina. The number of complex interventional procedures has recently increased due to technical advances. However, myocardial perfusion may be compromised after coronary stenting by acute thrombosis or the development of fibrointimal hyperplasia leading to decline in left ventricular function and increased risk of myocardial infarction. The diagnosis of in stent stenosis is a clinically important, though a challenging task, particularly in patients with no cardiac symptoms. Although, coronary angiography is considered the golden standard, the associated risk and cost prohibits its routine use for that purpose.
Cardiac stress imaging techniques play important clinical role in evaluation of in stent stenosis and assessing adequacy of revascularization. Stress echocardiography with exercise or dobutamine is widely used and provides fair accuracy. The use of myocardial contrast agents improves accuracy and allows detection of perfusion abnormalities. Stress radionuclide imaging is widely available and accurately predicts extent of coronary artery disease. Small studies showed lower specificity shortly after stenting. Stress imaging techniques provide incremental prognostic information after coronary stenting. Stress echocardiography and radionuclide imaging are appropriately indicated in symptomatic patients and in those with incomplete revascularization. Cardiac CT angiography is highly sensitive for diagnosis of coronary artery stenosis. Average sensitivity and specificity for diagnosis of in stent stenosis in pooled data are 79% and 81% respectively. Feasibility is very limited in small (<3 mm) stents and in stents with thick struts.
In conclusion, non-invasive imaging modalities provide useful functional and anatomical information after coronary stenting. The choice of particular modality depends on recognition of advantages and limitations of each technique, and expertise with particular type of imaging.