Ethnic differences in cardiac structure and function assessed by MRI in healthy South Asian and White European people: A UK Biobank Study.

BACKGROUND: Echocardiographic studies indicate South Asian people have smaller ventricular volumes, lower mass and more concentric remodelling than White European people, but there are no data using cardiac MRI (CMR). We aimed to compare CMR quantified cardiac structure and function in White European and South Asian people. METHODS: Healthy White European and South Asian participants in the UK Biobank Imaging CMR sub-study were identified by excluding those with a history of cardiovascular disease, hypertension, obesity or diabetes. Ethnic groups were matched by age and sex. Cardiac volumes, mass and feature tracking strain were compared. RESULTS: 121 matched pairs (77 male/44 female, mean age 58 ± 8 years) of South Asian and White European participants were included. South Asian males and females had smaller absolute but not indexed left ventricular (LV) volumes, and smaller absolute and indexed right ventricular volumes, with lower absolute and indexed LV mass and lower LV mass:volume than White European participants. Although there were no differences in ventricular or atrial ejection fractions, LV global longitudinal strain was higher in South Asian females than White European females but not males, and global circumferential strain was higher in both male and South Asian females than White European females. Peak early diastolic strain rates were higher in South Asian versus White European males, but not different between South Asian and White European females. CONCLUSIONS: Contrary to echocardiographic studies, South Asian participants in the UK Biobank study had less concentric remodelling and higher global circumferential strain than White European subjects. These findings emphasise the importance of sex- and ethnic- specific normal ranges for cardiac volumes and function.

Response to a low-energy meal replacement plan on glycometabolic profile and reverse cardiac remodelling in type 2 diabetes: a comparison between South Asians and White Europeans.

Background: South Asians (SA) constitute a quarter of the global population and are disproportionally affected by both type 2 diabetes (T2D) and heart failure. There remains limited data of the acceptability and efficacy of low-energy meal replacement plans to induce remission of T2D in SA. Objectives: The objective of this exploratory secondary analysis of the DIASTOLIC study was to determine if there was a differential uptake, glycometabolic and cardiovascular response to a low-energy meal replacement plan (MRP) between SA and White European (WE) people with T2D. Methods: Obese adults with T2D without symptomatic cardiovascular disease were allocated a low-energy (~810 kcal/day) MRP as part of the DIASTOLIC study (NCT02590822). Comprehensive multiparametric cardiovascular magnetic resonance imaging, echocardiography, cardiopulmonary exercise testing and metabolic profiling were undertaken at baseline and 12 weeks. A comparison of change at 12 weeks between groups with baseline adjustment was undertaken. Results: Fifteen WE and 12 SAs were allocated the MRP. All WE participants completed the MRP versus 8/12 (66%) SAs. The degree of concentric left ventricular remodelling was similar between ethnicities. Despite similar weight loss and reduction in liver fat percentage, SA had a lower reduction in Homeostatic Model Assessment for Insulin Resistance [-5.7 (95% CI: -7.3, -4.2) versus -8.6 (-9.7, -7.6), p = 0.005] and visceral adiposity compared to WE [-0.43% (-0.61, -0.25) versus -0.80% (-0.91, -0.68), p = 0.002]. Exercise capacity increased in WE with no change observed in SA. There was a trend towards more reverse remodelling in WE compared to SAs. Conclusions: Compliance to the MRP was lower in SA versus WE. Overall, those completing the MRP saw improvements in weight, body composition and indices of glycaemic control irrespective of ethnicity. Whilst improvements in VAT and insulin resistance appear to be dampened in SA versus WE, given the small sample, larger studies are required to confirm or challenge this potential ethnic disparity. Trail registration: NCT02590822.