Relationship between atherosclerotic burden and subclinical cardiac dysfunction in Type 2 Diabetes

Background The prevailing tenet in people with type 2 diabetes (T2D) is that a diabetic myocardial disorder occurs independently of traditional heart failure risk factors, such as coronary artery disease(1). Evidence supporting the existence of a distinct diabetic cardiomyopathy is primarily derived from small autopsy series, experimental and observational studies, without assessment of coronary atherosclerotic burden(2). Used in combination, echocardiography, cardiac magnetic resonance imaging (CMR) and cardiac computed tomography (CT) can non-invasively characterise the entire array of cardiac structural, functional, blood flow and tissue characteristic abnormalities, as well as the presence and extent of coronary artery disease, in people with T2D. Purpose We aimed to assess links between the presence and extent of coronary atherosclerosis and subclinical cardiac dysfunction in people with T2D with no known history of cardiovascular disease. We hypothesised that increasing atherosclerotic burden would be associated with higher prevalence of subclinical cardiac dysfunction. The primary outcome measure was the association between coronary artery calcium score (CAC) and left ventricular global longitudinal strain (LV GLS). Secondary outcomes were other markers of subclinical cardiac dysfunction (including diastolic function, myocardial blood flow, focal and diffuse myocardial fibrosis). Methods Adults with T2D and no prevalent cardiovascular disease or symptoms underwent comprehensive phenotyping, including same-day transthoracic echocardiography, non-contrast cardiac CT for CAC and multiparametric stress perfusion CMR with feature tracking strain analysis. Associations between CAC, stratified by quartiles of plaque burden (total Agatston score 0, 1 to 100, 101 to 400, and >400), and CMR markers of subclinical cardiac dysfunction were explored. Results A total of 526 subjects with T2D were included in this analysis, with fair representation across each of the pre-specified CAC strata (Table 1). Patients in higher quartiles of plaque burden were older, had a higher male prevalence and longer diabetes duration. However, HbA1c and LDL cholesterol were similar across groups. In a comparison of echocardiography and CMR features of subclinical cardiac dysfunction between CAC strata, adjusted for age, sex and ethnicity (Table 2), there were no differences in LV GLS across groups. Indexed LV volumes and mass, indexed left atrial volumes and E/e’, LV ejection fraction and global circumferential strain were also similar amongst CAC categories. However, indexed extracellular volume fraction was higher and stress myocardial blood flow lower progressively with increasing plaque burden. Conclusion Most features of subclinical cardiac dysfunction in T2D, including LV GLS, were not associated with increasing coronary plaque burden. However, higher plaque burden did correspond with more diffuse fibrosis and lower stress myocardial blood flow.