L. C. K. Chan

Association between anthropometric measures of obesity and cardiovascular risk markers in a self-selected group of indigenous Australians

Background Indigenous Australians have a high prevalence of obesity and an unacceptably high rate of cardiovascular disease. Methods We conducted a cross-sectional analysis of 93 high-risk indigenous Australians to assess how strongly three anthropometric measures correlated with known cardiovascular risk factors. Results Both waist circumference and body mass index were strongly associated with important risk factors. The waist: hip ratio was less useful. Waist circumference was the only measure that significantly correlated with the urine albumin creatinine ratio (ρ = 0.14; P =0.04). Conclusion Measuring the waist circumference is a cheap, effective way of monitoring cardiovascular risk.

Correlates of preclinical cardiovascular disease in Indigenous and Non-Indigenous Australians: a case control study.

BackgroundThe high frequency of premature death from cardiovascular disease in indigenous Australians is often attributed to the high prevalence of risk factors, especially type II diabetes mellitus (DM). We evaluated the relationship of ethnicity to atherosclerotic burden, as evidenced by carotid intima-media thickness (IMT), independent of risk factor status.MethodsWe studied 227 subjects (147 men; 50 ± 13 y): 119 indigenous subjects with (IDM, n = 54), and without DM (InDM, n = 65), 108 Caucasian subjects with (CDM, n = 52), and without DM (CnDM, n = 56). IMT was measured according to standard methods and compared with clinical data and cardiovascular risk factors.ResultsIn subjects both with and without DM, IMT was significantly greater in indigenous subjects. There were no significant differences in gender, body mass index (BMI), systolic blood pressure (SBP), or diastolic blood pressure (DBP) between any of the groups, and subjects with DM showed no difference in plasma HbA1c. Cardiovascular risk factors were significantly more prevalent in indigenous subjects. Nonetheless, ethnicity (β = -0.34; p < 0.0001), age (β = 0.48; p < 0.0001), and smoking (β = 0.13; p < 0.007) were independent predictors of IMT in multiple linear regression models.ConclusionEthnicity appears to be an independent correlate of preclinical cardiovascular disease, even after correction for the high prevalence of cardiovascular risk factors in indigenous Australians. Standard approaches to control currently known risk factors are vital to reduce the burden of cardiovascular disease, but in themselves may be insufficient to fully address the high prevalence in this population.

Ethnicity is an independent correlate of preclinical cardiovascular disease in indigenous Australians

We sought to determine the relative impact of myocardial scar and viability on post-infarct left ventricular (LV) remodeling in medically-treated patients with LV dysfunction. Forty patients with chronic ischemic heart disease (age 64±9, EF 40±11%) underwent rest-redistribution Tl201 SPECT (scar = 50% transmural extent), A global index of scarring for each patient (CMR scar score) was calculated as the sum of transmural extent scores in all segts. LV end diastolic volumes (LVEDV) and LV end systolic volumes (LVESV) were measured by real-time threedimensional echo at baseline and median of 12 months follow-up. There was a significant positive correlation between change in LVEDV with number of scar segts by all three imaging techniques (LVEDV: SPECT scar, r = 0.62, p 15%) was predicted bySPECTscars(AUC= 0.79),DbEscars(AUC= 0.76),CMR scars (AUC= 0.70), and CMR scar score (AUC 0.72). There were no significant differences between any of the ROC curves (Z score <0.74). Number of SPECT scars (p = 0.002), DbE scars (p = 0.01), CMR scars (p = 0.004), and CMR scar score (p = 0.03) were independent predictors of LVEDV. The extent of scar tissue can predict global LV remodeling irrespective of cardiac imaging technique but myocardial viability may not be protective against LV remodeling in medically-treated patients.Transmural extent of infarction (TME) may be an important determinant of functional recovery and remodeling. Recent animal data suggest that strain rate imaging (SRI) maybe able to identify subendocardial ischemia.We compared SRI and cyclic variation of integrated backscatter (CVIB) for predicting TME in the quantitative assessment of regional subepicardial function. Forty-nine (n = 49) postmyocardial infarct patients (61±10 years, EF 41±10%) underwent tissue Doppler echocardiography (TDE) and contrast enhanced magnetic resonance imaging (CMR). A15 mm×2mm sampling volume (tracked to wall motion) was placed over the long axis subepicardial region of each segment during TDE offline analysis to measure peak longitudinal systolic strain rate (SR), peak longitudinal systolic strain (PS), and CVIB. Findingswere compared with TME classified into two categories of scar thickness by CMR: Non-transmural (TME≤50%), and transmural (TME > 50%). Of 213 segments identified with resting wall motion abnormalities, 145 segments showed delayed hyperenhancement on CMR. SR, PS and CVIB were similar with no significant differences between transmural and non-transmural infarcts regardless of the echo modality.Revascularization (RVS) of scar segts does not lead to recovery of left ventricular (LV) function, but its effect on post-infarct remodeling is unclear. We examined the impact of RVS on regional remodeling in different transmural extents of scar (TME). Dobutamine echo (DbE) and contrast enhanced magnetic resonance imaging (ce- MRI) were performed in 72 pts post MI (age 63±10, EF 49±12%). Pts were selected for RVS (n = 31) or medical treatment (n = 41). Segts were classified as scar if there were no contractile reserve during lowdose DbE.TMEwas measured by ce-MRI; a cutoff of 75% was used to differentiate transmural (TM) from non-transmural (NT) scars. Regional end systolic (ESV) and end diastolic volumes (EDV) were measured at baseline and 12 months follow up.Of 218 segts identified as scar on DbE, 164wereNTand 54 were TM on ce-MRI. Revascularization was performed to 62 NT and 11 TM segts. In the RVS group, there was reverse remodeling with significant reduction in LV volumes in NT (ESV, 6.8±3.2 ml versus 5.8±3.7 ml, p = 0.002; EDV, 10.9±4.9 ml versus 9.8±5.6 ml, p = 0.02), but no significant change in volumes in TM (ESV, 6.9±3.7 ml versus 5.4±2.1 ml, p = 0.09; EDV, 10.2±4.4 ml versus 9.4±4.3 ml, p = 0.5). In the medically treated group, there were no changes in LV volumes in both NT (ESV, 12.0±11.9 ml versus 12.7±13.8 ml, p = 0.3; EDV, 12.5±7.8 ml versus 12.6±9.7 ml, p = 0.8) and TM (ESV, 8.0±3.8 ml versus 7.9±4.6 ml, p = 0.8; EDV, 10.3±4.8 ml versus 10.4±5.4 ml, p = 0.9). Despite absence of contractile reserve on DbE, NT benefit from coronary revascularization with regional reverse LV remodeling.Left ventricular (LV) volumes have important prognostic implications in patients with chronic ischemic heart disease. We sought to examine the accuracy and reproducibility of real-time 3D echo (RT-3DE) compared to TI-201 single photon emission computed tomography (SPECT) and cardiac magnetic resonance imaging (MRI). Thirty (n = 30) patients (age 62±9 years, 23 men) with chronic ischemic heart disease underwent LV volume assessment with RT-3DE, SPECT, and MRI. Ano vel semi-automated border detection algorithmwas used by RT-3DE. End diastolic volumes (EDV) and end systolic volumes (ESV) measured by RT3DE and SPECT were compared to MRI as the standard of reference. RT-3DE and SPECT volumes showed excellent correlation with MRI (Table). Both RT- 3DE and SPECT underestimated LV volumes compared to MRI (ESV, SPECT 74±58 ml versus RT-3DE 95±48 ml versus MRI 96±54 ml); (EDV, SPECT 121±61 ml versus RT-3DE 169±61 ml versus MRI 179±56 ml). The degree of ESV underestimation with RT-3DE was not significant.