Phenotyping diabetic cardiomyopathy in Europeans and South Asians

Abstract

Background: The pathogenesis and cardiovascular impact of type 2 diabetes (T2D) may be different in South Asians compared with other ethnic groups. The phenotypic characterization of diabetic cardiomyopathy remains debated and little is known regarding differences in T2D-related cardiovascular remodeling across ethnicities. We aimed to characterize the differences in left ventricular (LV) diastolic and systolic function, LV structure, myocardial tissue characteristics and aortic stiffness between T2D patients and controls and to assess the differences in T2D-related cardiovascular remodeling between South Asians and Europeans.

Methods: T2D patients and controls of South Asian and European descent underwent 3 Tesla cardiovascular magnetic resonance imaging (CMR) and cardiac proton-magnetic resonance spectroscopy (¹H-MRS). Differences in cardiovascular parameters between T2D patients and controls were examined using ANCOVA and were reported as mean (95% CI). Ethnic group comparisons in the association of T2D with cardiovascular remodeling were made by adding the interaction term between ethnicity and diabetes status to the model.

Results: A total of 131 individuals were included (54 South Asians [50.1 ± 8.7 years, 33% men, 33 patients vs. 21 controls) and 77 Europeans (58.8 ± 7.0 years, 56% men, 48 patients vs. 29 controls)]. The ratio of the transmitral early and late peak filling rate (E/A) was lower in T2D patients compared with controls, in South Asians [- 0.20 (- 0.36; - 0.03), P = 0.021] and Europeans [- 0.20 (- 0.36; - 0.04), P = 0.017], whereas global longitudinal strain and aortic pulse wave velocity were similar. South Asian T2D patients had a higher LV mass [+ 22 g (15; 30), P < 0.001] (P for interaction by ethnicity = 0.005) with a lower extracellular volume fraction [- 1.9% (- 3.4; - 0.4), P = 0.013] (P for interaction = 0.114), whilst European T2D patients had a higher myocardial triglyceride content [+ 0.59% (0.35; 0.84), P = 0.001] (P for interaction = 0.002) than their control group.

Conclusions: Diabetic cardiomyopathy was characterized by impaired LV diastolic function in South Asians and Europeans. Increased LV mass was solely observed among South Asian T2D patients, whereas differences in myocardial triglyceride content between T2D patients and controls were only present in the European cohort. The diabetic cardiomyopathy phenotype may differ between subsets of T2D patients, for example across ethnicities, and tailored strategies for T2D management may be required.

Keywords: Diabetes mellitus, type 2; Diabetic cardiomyopathies; European; Myocardial diffuse fibrosis; Myocardial steatosis; Proton-magnetic resonance spectroscopy; South Asian; T1 mapping.

Fig. 1

Cardiovascular parameters (boxplots depicting median, interquartile ranges and outliers) in European T2D patients (n = 48) and controls (n = 29) (*P < 0.05). In European T2D patients, the E/A ratio was lower than in the controls, LV concentricity was higher in parallel with a lower LV end-diastolic volume, and the myocardial triglyceride content was higher. E/A ratio of the transmitral early and late peak filling rate, ECV extracellular volume, LV left ventricular, Tg triglyceride

Fig. 2

Cardiovascular parameters (boxplots depicting median, interquartile ranges and outliers) in South Asian T2D patients (n = 33) compared with controls (n = 21) (*P < 0.05). In South Asian T2D patients, the E/A ratio was lower than in the controls and LV concentricity was higher in parallel with a higher LV mass. As both the LV extracellular volume and myocardial cell volume were higher, the ECV fraction was slightly lower in South Asian T2D patients than in controls. Abbreviations as in Fig. 1

Fig. 3

Diabetic cardiomyopathy phenotype in Europeans and South Asians. a Impaired LV diastolic function, as indicated by a lower ratio of the transmitral early and late peak filling rate (E/A) was identified as a common characteristic of diabetic cardiomyopathy in Europeans and South Asians. The E/A ratio was measured using 4D velocity-encoded MR after retrospective mitral valve tracking and through-plane motion correction (left image). An example of the transmitral flow rate curve in a T2D patient (South Asian 62-year-old woman with E/A: 0.95) and control (South Asian 57-year-old women with E/A: 1.25) is provided (right images). b In South Asian but not in European T2D patients the LV mass, measured on short-axis cine (upper image), was higher than in the control group and the extracellular volume fraction, measured in the mid-ventricular septum using T1 mapping (lower image), was decreased. In the presented South Asian T2D patient, LV mass was 97 g and extracellular volume fraction was 27%. c Among Europeans but not among South Asians the myocardial triglyceride content was different for T2D patients compared with controls. An example of cardiac proton-magnetic resonance spectroscopy (¹H-MRS) in a 45-year-old woman with T2D (left image) and in a 48-year-old non-diabetic woman (right image) of European descent is provided (myocardial triglyceride content (MTGC): 1.24% and 0.60%, respectively)