Melodie Downey

Determinants of subclinical diabetic heart disease

Aims/hypothesisSubclinical left ventricular (LV) dysfunction has been shown by tissue Doppler and strain imaging in diabetic patients in the absence of coronary disease or LV hypertrophy, but the prevalence and aetiology of this finding remain unclear. This study sought to identify the prevalence and the determinants of subclinical diabetic heart disease.MethodsA group of 219 unselected patients with type 2 diabetes without known cardiac disease underwent resting and stress echocardiography. After exclusion of coronary artery disease or LV hypertrophy, the remaining 120 patients (age 57±10 years, 73 male) were studied with tissue Doppler imaging. Peak systolic strain of each wall and systolic (Sm) and diastolic (Em) velocity of each basal segment were measured from the three apical views and averaged for each patient. Significant subclinical LV dysfunction was identified according to Sm and Em normal ranges adjusted by age and sex. Strain and Em were correlated with clinical, therapeutic, echocardiographic and biochemical variables, and significant independent associations were sought using a multiple linear regression model.ResultsSignificant subclinical LV dysfunction was present in 27% diabetic patients. Myocardial systolic dysfunction by peak strain was independently associated with glycosylated haemoglobin level (p<0.001) and lack of angiotensin-converting enzyme inhibitor treatment (p=0.003). Myocardial diastolic function (Em) was independently predicted by age (p=0.013), hypertension (p=0.001), insulin (p=0.008) and metformin (p=0.01) treatment.Conclusions/interpretationIn patients with diabetes mellitus, subclinical LV dysfunction is common and associated with poor diabetic control, advancing age, hypertension and metformin treatment; ACE inhibitor and insulin therapies appear to be protective.

Derivation of the distensibility coefficient using tissue Doppler as a marker of arterial function.

To date, the main cardiovascular application of TDI (tissue Doppler imaging) has been in myocardial evaluation. In the present study, we investigated the feasibility and reproducibility of assessing arterial elasticity using the DC (distensibility coefficient) measured by TDI, the correlation of this with the DC obtained by other methods and the DC in patients with various degrees of cardiovascular risk. We studied 450 subjects (256 men; age, 51+/-10 years) with and without risk factors of cardiovascular disease. Arterial displacement was measured from TDI, and B-mode and M-mode images of the common carotid artery in the longitudinal plane, and the DC with each method was compared. Linear regression showed a good correlation between all three methods. The results for TDI and B-mode were comparable [(21+/-10) compared with (21+/-10)x10(-3)/kPa respectively; P=not significant], but there were significant differences between TDI and M-mode [(21+/-10) compared with (31+/-13)x10(-3)/kPa respectively; P<0.0001] and between B-mode and M-mode [(21+/-10) compared with (31+/-13)x10(-3)/kPa respectively; P<0.0001]. Similarly, Bland-Altman analysis showed the least variability in the DC between TDI and B-mode, and there were no significant differences between the average measurements. The TDI DC also had the lowest paired difference for inter-observer variability [(-0.1+/-1.1)x10(-3)/kPa; P=not significant]. In conclusion, the results of the present study suggest that TDI of the carotid arteries is feasible, comparable with B-mode measurements, more robust than M-mode and less variable than the other methods.