CT coronary angiography and cardiac MRI in cardiovascular risk assessment

Abstract

Part A. CT coronary angiography Multislice CT coronary angiography (CTCA) can non-invasively detect coronary artery obstruction and visualize calcified and non-calcified coronary artery atherosclerotic plaques. In a prospective multicenter study in 360 patients with acute and stable anginal syndromes we compared 64-slice CTCA to conventional coronary angiography (CCA). 64-slice CTCA could reliably rule out significant coronary artery disease in patients with stable and unstable anginal syndromes. However, a positive CTCA was frequently due to overestimation of non-significant lesions, which was mostly caused by coronary calcification. In this regard, in ourd study the additional value of CTCA was limited in patients with stable and unstable anginal syndromes with a calcium score > 10, and especially limited in those with a calcium score > 400. In contrast to CCA, in addition to stenosis detection, CTCA can characterize plaque phenotype (non-calcified, mixed or calcified). In the culprit plaque subanalysis, culprit plaques in unstable angina patients were more frequently non-calcified. Differences in CTCA plaque characteristics may improve the prediction of the individual risk of coronary events. Part B. Cardiac MRI Left ventricular hypertrophy is an established independent risk factor for the development of heart failure, coronary heart disease and stroke. Animal data and observational studies in humans demonstrate a continuous relation between left ventricular mass increase and the risk of cardiovascular events. This would call for early identification of patients with a large left ventricular mass. We measured left ventricular mass by cardiac MRI in 536 hypertensive subjects with symptomatic extra-cardiac atherosclerotic disease or marked risk factors for atherosclerosis to study the determinants of LV mass increase and develop a prediction model for left ventricular mass in such patients. Our study points towards differences in risk factor relations across populations with and without symptomatic atherosclerotic disease. One standard deviation increase in left ventricular mass indexed to body surface area corresponded with an increase in estimated absolute 5-year risk of major cardiovascular events and death of 1.4%. R2 of the prediction model was 45% after internal validation, which was higher than the R2 of previously reported models. Addition of electrocardiography data showed limited improvement of the model performance (R2 = 47%). In addition, delayed enhancement cardiac MRI was performed in the aforementioned subjects to investigate the prevalence and determinants of unrecognized myocardial infarction. Unrecognized myocardial infarction was defined as the presence of delayed enhancement without corresponding clinical history. An unrecognized myocardial infarction was present in 9.4% of all subjects; in 13.1% of men and in 3.7% of women. The risk of unrecognized myocardial infarction increased with the number of cardiovascular risk factors.