Cardiovascular risk assessment and atherosclerosis phenotype by coronary computed tomography angiography in a cohort of Italian patients with type 1 diabetes mellitus

Objective Mortality rates are 2- to 4-fold higher in people with type 1 diabetes mellitus (T1DM) than in the general population. Cardiovascular disease (CVD) is the main cause of such excess mortality, with CVD events occurring over a decade earlier than expected. However, while epidemiological studies on CVD and type 2 diabetes mellitus are numerous, less information is available on the prevalence of CVD in patients with T1DM. The primary aim of the study was to evaluate the prevalence of CAD at coronary CT angiography (CCTA) in consecutive T1DM patients referred to our diabetic center and to assess the characteristics of coronary plaques in this population. Materials and Methods We prospectively enrolled 109 consecutive T1DM patients referred to our diabetic unit center in CARDT1 study. Patients underwent a non-contrast CT for calculation of Calcium Score and a CCTA. Patients were stratified into three risk groups according to the STENO T1 RISK ENGINE and the ESC score. After the finding of CCTA patients were also divided into three groups: normal (no coronary plaques), non-obstructive CAD (lesions ,50%), and obstructive CAD (lesions >50%). The number of segments with any obstructive plaque also was recorded. Each coronary segment was evaluated for the presence of calcified and mixed plaques. Results The analytic study population consisted of 88 patients. Fourty-seven were male (53%) and the mean age was 46.42±13.09 years old with a mean duration of diabetes of 24 years. According to the Steno Type 1 Risk Engine, the mean estimated risk of CVD events over 5 years was 5.1% and 10% over 10 years. Thirty-five patients (48%) and 15 (20%) were classified as low and high Steno Risk, respectively. Moreover 45 (51%) patients have completely normal coronary arteries, 32 (36%) non obstructive CAD and 11 (12%) obstructive CAD. In patients with obstructive CAD the duration of diabetes was significantly higher than in those with no CAD and not obstructive CAD (40 years vs 17 years and 27 years, respectively, p<0.0001). Eighty-three% of low risk Steno Score T1DM have normal coronary arteries while 21% of high risk Steno score patients had obstructive CAD and 14% of high Steno risk have no plaque at CTCA. The number of coronary segments diseased was 1.5 (median) in non-obstructive CAD patients and 4 in obstructive CAD patients (p<0.0001). Among 118 coronary segments diseased, in 51 segments there was a calcified disease and in 65 there was a non prevalent calcified atherosclerotic disease Conclusions CCTA is able to restratify the risk of CAD in T1DM according to the presence or absence of CAD. In contrast with T2 diabetic patients who have a prevalent calcified and diffuse disease, T1DM patients have a more focal and fibrolipidic pattern of CAD.