Risk stratification and coronary optical coherence tomography findings in asymptomatic patients with type 1 diabetes mellitus

Data for primary cardiovascular (CV) prevention of type 1 diabetes mellitus (DM) patients are lacking or based on type 2 DM patients at lower risk. Current guidelines do not include non-invasive means of risk stratification. Thin-cap fibroatheroma (TCFA) and simultaneous presence of several high-risk OCT plaque features are associated with higher risk of major adverse CV events. Aim of our study was to examine asymptomatic high-risk type 1 DM patients without prior history of CV disease by non-invasive means and selected very high-risk patients by coronary angiography and OCT.

152 asymptomatic patients (aged 30-67 years) with type 1 DM, duration of DM for at least 10 years, without prior history of atherosclerotic CV disease or target organ damage at high CV risk according to the European guidelines were examined with carotid ultrasound for carotid plaques and coronary artery calcium (CAC) score was estimated. Patients with CAC score of ≥ 400 and/or presence of 2 ≥ carotid plaques of ≥ 1.5mm width were considered at very high CV risk. These were subsequently evaluated by coronary angiography for the presence of obstructive coronary artery disease (defined as presence of ≥ 1 stenosis of ≥ 50%) as well as OCT of proximal major coronary vessels. OCT images were evaluated for the presence of TCFA (defined as lipid-rich plaque arc ≥ 90° and fibrous cap < 65μm) and very high-risk plaque (defined as TCFA phenotype, > 180° lipid arc, macrophages and MLA < 3.5 mm2). Furthermore, imaging features associated with plaque vulnerability were analysed including lipid-rich plaque, spotty calcium, calcified nodule, macrophage accumulation, neovascularization, intraluminal thrombus or plaque erosion.

The criteria of very high cardiovascular risk fulfilled 21/152 (13.8%) patients. Mean age was 61.4 years, 12 were female (57.1%), T1DM duration 35.8 years, baseline HbA1c 57.3 mmol/mol (= 7.4%) and LDL-cholesterol 2.4 mmol/l. Mean CAC score was 822 ±846 and mean number of carotid plaques was 2.6 ±1.1. Coronary angiography showed obstructive coronary artery disease in 9/21 (42.9%) patients, 4 patients underwent PCI and 1 patient CABG. 51/63 (80.1 %) of major coronary vessels were successfully examined by OCT. TCFA was present in 12/21 (57.1 %) and very high-risk plaque in 5/21 (23.8 %) patients. Out of 51 acquired OCT pullbacks of proximal segments of coronary arteries, following features of plaque vulnerability were detected: 43/51 (84.3%) lipid-rich plaques, 32/51 (62.8 %) spotty calcium, 7/51 (15.7 %) calcified nodules, 41/51 (80.4%) macrophage accumulations, 18/51 (35.3%) neovascularisations, 6/51 (11.8%) thrombi, 17/51 (33.3%) plaque erosions.

Asymptomatic type 1 diabetes mellitus patients, stratified by high coronary artery calcium score and carotid plaques to very high cardiovascular risk, present frequently with obstructive coronary artery disease and very high-risk plaques as well as thin-cap fibroatheromas on coronary arteries.