Insulin resistance and subclinical abnormalities of global and regional left ventricular function in patients with aortic valve sclerosis

BACKGROUND: Insulin resistance, as a key mediator of metabolic syndrome, is thought to be associated with pathogenesis of calcific aortic valve disease and altered left ventricular (LV) function and structure. However, in patients with aortic valve sclerosis (AVS), the association between insulin resistance and subclinical impairment of LV function is not fully elucidated. METHODS: We studied 57 patients (mean age 70 ± 8 years, 22 women) with asymptomatic AVS but normal LV ejection fraction in echocardiography. LV longitudinal and circumferential strain and strain rate was analyzed using two-dimensional speckle tracking echocardiography. Patients with uncontrolled hypertension and diabetes mellitus, chronic kidney disease, and concomitant coronary artery disease were excluded. They were divided into the insulin-resistant group (AVS+IR; N = 28) and no insulin-resistant group (AVS-IR; N = 29) according to the median value of homeostatic model assessment index. Computed tomography scans were also performed to measure the aortic valve calcium score and the visceral adipose tissue (VAT) area. In addition, age- and sex- adjusted 28 control subjects were recruited for the comparison. RESULTS: There were no significant differences in LV ejection fraction or mass index among the groups. The AVS+IR group had a higher aortic valve calcium score (median 94 versus 21, P = 0.022) and a larger VAT area (113 ± 42 cm(2) versus 77 ± 38 cm(2), P = 0.001) than the AVS-IR group. Notably, LV global longitudinal strain, strain rate (SR), and early diastolic SR were significantly lower in the AVS+IR group than in the AVS-IR group and in control subjects (strain: -16.2 ± 1.6% versus -17.2 ± 1.2% and -18.9 ± 0.8%; SR: -1.18 ± 0.26 s(-1) versus -1.32 ± 0.21 s(-1) and -1.52 ± 0.08 s(-1); early diastolic SR: -1.09 ± 0.23 s(-1) versus -1.23 ± 0.18 s(-1) and -1.35 ± 0.12 s(-1); P < 0.05 for all comparison), whereas circumferential function were not significantly different. Multiple linear regression analyses revealed insulin resistance as an independent determinant of LV longitudinal strain (P = 0.017), SR (P = 0.047), and early diastolic SR (P = 0.049) regardless of LV mass index or VAT area. CONCLUSIONS: Insulin resistance is a powerful independent predictor of subclinical LV dysfunction regardless of concomitant visceral obesity and LV hypertrophy. Thus, it may be a novel therapeutic target to prevent subsequent heart failure in patients with AVS

Association Between Visceral Adipose Tissue Area and Coronary Plaque Morphology Assessed by CT Angiography

ObjectivesWe sought to investigate the association between visceral adipose tissue (VAT) with the presence, extent, and characteristics of noncalcified coronary plaques (NCPs) using 64-slice computed tomography angiography (CTA).BackgroundAlthough visceral adiposity is associated with cardiovascular events, its association with NCP burden and vulnerability is not well known.MethodsThe study population consisted of 427 patients (age 67 ± 11 years; 63% men) with proven or suspected coronary artery disease who underwent 64-slice CTA. We assessed the presence and number of NCPs for each patient. The extent of NCP was tested for the difference between high (≥2) and low (≤1) counts. We further evaluated the vulnerable characteristics of NCPs with positive remodeling (remodeling index >1.05), low CT density (≤38 HU), and the presence of adjacent spotty calcium. Plain abdominal scans were also performed to measure the VAT and subcutaneous adipose tissue area.ResultsA total of 260 (61%) patients had identifiable NCPs. Multivariate analyses revealed that increased VAT area (per 1 standard deviation, 58 cm2) was significantly associated with both the presence (odds ratio [OR]: 1.68; 95% confidence interval [CI]: 1.28 to 2.22) and extent (OR: 1.31; 95% CI: 1.03 to 1.68) of NCP. Other body composition measures, including subcutaneous adipose tissue area, body mass index, and waist circumference were not significantly associated with either presence or extent of NCP. Increased VAT area was also independently associated with the presence of NCP with positive remodeling (OR: 1.71; 95% CI: 1.18 to 2.53), low CT density (OR: 1.69; 95% CI: 1.17 to 2.47), and adjacent spotty calcium (OR: 1.52; 95% CI: 1.03 to 2.27).ConclusionsIncreased VAT area was significantly associated with NCP burden and vulnerable characteristics identified by CTA. Our findings may explain the excessive cardiovascular risk in patients with visceral adiposity, and support the potential role of CTA to improve risk stratification in such patients

Characterization of Noncalcified Coronary Plaques and Identification of Culprit Lesions in Patients With Acute Coronary Syndrome by 64-Slice Computed Tomography

ObjectivesWe sought to characterize noncalcified coronary atherosclerotic plaques in culprit and remote coronary atherosclerotic lesions in patients with acute coronary syndrome (ACS) with 64-slice computed tomography (CT).BackgroundLower CT density, positive remodeling, and adjacent spotty coronary calcium are characteristic vessel changes in unstable coronary plaques.MethodsOf 147 consecutive patients who underwent contrast-enhanced 64-slice CT examination for coronary artery visualization, 101 (ACS; n = 21, non-ACS; n = 80) having 228 noncalcified coronary atherosclerotic plaques (NCPs) were studied. Each NCP detected within the vessel wall was evaluated by determining minimum CT density, vascular remodeling index (RI), and morphology of adjacent calcium deposits.ResultsThe CT visualized more NCPs in ACS patients (65 lesions, 3.1 ± 1.2/patient) than in non-ACS patients (163 lesions, 2.0 ± 1.1/patient). Minimum CT density (24 ± 22 vs. 42 ± 29 Hounsfield units [HU], p < 0.01), RI (1.14 ± 0.18 vs. 1.08 ± 0.19, p = 0.02), and frequency of adjacent spotty calcium of NCPs (60% vs. 38%, p < 0.01) were significantly different between ACS and non-ACS patients. Frequency of NCPs with minimum CT density <40 HU, RI >1.05, and adjacent spotty calcium was approximately 2-fold higher in the ACS group than in the non-ACS group (43% vs. 22%, p < 0.01). In the ACS group, only RI was significantly different between 21 culprit and 44 nonculprit lesions (1.26 ± 0.16 vs. 1.09 ± 0.17, p < 0.01), and a larger RI (≥1.23) was independently related to the culprit lesions (odds ratio: 12.3; 95% confidential interval: 2.9 to 68.7, p < 0.01), but there was a substantial overlap of the distribution of RI values in these 2 groups of lesions.ConclusionsSixty-four-slice CT angiography demonstrates a higher prevalence of NCPs with vulnerable characteristics in patients with ACS as compared with stable clinical presentation

Accumulation of epicardial adipose tissue increases coronary morbidity in non-obese patients with suspected coronary artery disease

Background: We explored the relationship between epicardial adipose tissue (EAT) volume, body mass index (BMI) and the incidence of major coronary events in non-obese patients with suspected coronary artery disease (CAD). Methods: We measured EAT volume in a cohort of 722 patients who had undergone coronary computed tomography, and recorded subsequent occurrences of major coronary events (cardiac death and acute coronary syndrome), simultaneously evaluating all coronary events and all-cause death. Results: Eighteen patients experienced major coronary events: there were five cardiac deaths and 13 cases of acute coronary syndrome. BMI was inversely predictive of major coronary events (hazard ratio [HR], 0.74; 95% confidence interval [CI], 0.63–0.87; p < 0.001), but not for all-cause death. EAT volume predicted all coronary events (HR per 10 mL, 1.11; 95% CI, 1.03–1.19; p = 0.003). Although there was a trend suggestive of an inverse association with major coronary events, this was not statistically significant (HR per 10 mL, 1.10; 95% CI; 1.00–1.21; p = 0.059), and there was no significant relationship with all-cause death. When stratified by the first quartile (QI) of BMI (≤21.4 kg/m2) and median EAT volume (107 mL), the event rates in the high EAT volume and BMI QI group were significantly higher than those of other groups (adjusted HR, 5.45; 95% CI, 1.51–25.3 p = 0.009, compared with the low EAT volume and BMI QI group). Conclusion: Our findings suggest that suspected CAD patients with low BMI but high EAT volume are at an increased risk of major coronary events, but not all-cause death

Noninvasive assessment of coronary stents in patients by 16-slice computed tomography

Background: The usefulness of thin-slice mult-detector computed tomography (MDCT) has been highly expected to assess the lumens of coronary artery stents. We evaluated the usefulness of 16-slice MDCT to assess the in-stent lumen after coronary artery stenting. Methods: In 42 consecutive patients after coronary artery stenting, retrospective ECG-gated CT-angiography using 16-slice MDCT (0.5sec rotation time, 16×0.625-mm detector collimation) was performed. The qualitative assessability of the lumens of 61 coronary stents (14 different types) by MDCT and the reasons for nonassessability were investigated. Furthermore, the evaluation of in-stent restenosis in 21 assessable stents of 16 patients, including quantitative density analysis by MDCT, was performed and the results were compared with those of conventional coronary angiography (CAG). Results: Of 61 stents, 42 (68.9%) were assessable. The assessability of diameter 3.5-mm stents made of stainless steel or cobalt was high (88.6%, 31/35), that of 3.0-mm stents was low (57.9%, 11/19) and all 2.5-mm stents were non-assessable due to partial volume effects and metal artifacts of stents. The lumens of stents made of tantalum were totally obscured and the metal artifacts of Bestent2 (gold markers) and S670 were severer than others. All non-assessable stents due to banding artifact and calcification were implanted in segment #1-3 and #6, respectively. In comparison to CAG, MDCT correctly detected the 5 in-stent restenoses and identified absence of restenosis in the remaining 16 stents. The quantitative density analysis of in-stent restenoses was influenced strongly by the stent strut. Conclusion: Despite some limitations, 16-slice MSCT is sufficiently useful for assessment of various coronary stents in patients and can detect in-stent restenoses of assessable stents with high accuracy in comparison to CAG

Coronary Calcium Score as a Predictor for Coronary Artery Disease and Cardiac Events in Japanese High-Risk Patients

Background: Although the coronary artery calcium (CAC) score as measured with computed tomography (CT) is associated with cardiovascular mortality and morbidity in Western countries, little is known in Asian populations. Methods and Results: Three hundred and seventeen Japanese patients (205 men and 112 women) were followed in the study and they underwent both coronary angiography and CT for CAC measurements. The frequencies of angiographic coronary artery disease (CAD) were 5%, 36%, 76%, 80%, and 94% (P1,000 (n=49), respectively. In the average of 6.0 (range, 1-10) years follow-up period, 34 patients died including 13 from reasons of cardiac disease. In a Cox proportional hazard model after adjustment for age and sex, traditional coronary risk factors, previous myocardial infarction, and the need for revascularization, the hazard ratio for cardiac mortality in patients with a CAC score >1,000 was 2.98 (95% confidence interval: 1.15-9.40) compared with those with a CAC score=0-100. Conclusions: The CAC score has a predictive value for angiographical CAD and long-term mortality from cardiac disease in Japanese high-risk patients who undergo coronary angiography. (Circ J 2011; 75: 2424-2431

Association Between Plasma High-Molecular-Weight Adiponectin and Coronary Plaque Characteristics Assessed by Computed Tomography Angiography in Conditions of Visceral Adipose Accumulation

Background: Our group has previously reported that visceral adipose tissue (VAT) accumulation was associated with the extent and vulnerable characteristics of coronary plaques using coronary computed tomography angiography (CTA). An investigation of the associations between these coronary lesions with plasma adiponectin and leptin was performed. Methods and Results: A total of 394 patients (220 men and 174 women) in the study were referred for CTA. Plain abdominal scanning was simultaneously performed to evaluate VAT areas. The median level of plasma high-molecular-weight (HMW) adiponectin in patients with CTA-based obstructive coronary artery disease was significantly lower than that in patients without (men: 1.45 vs. 1.88μg/ml, P=0.002; women: 2.49 vs. 3.44μg/ml, P<0.001). Multivariate analyses revealed that a lower HMW adiponectin concentration was significantly associated with the presence (men: P=0.019; women: P=0.018) and involved segment numbers (men: P=0.001; women: P=0.003) of coronary plaques. Furthermore, it was significantly related to coronary plaque with all 3 vulnerable characteristics of positive remodeling, low CT density (≤38 Hounsfield units), and adjacent spotty calcium (men: P=0.019; women: P=0.016). These associations were also observed with VAT areas, but not with plasma leptin concentrations, in both genders. Conclusions: Lower plasma HMW adiponectin is associated with the presence, extent, and vulnerable characteristics of coronary plaques assessed by CTA in both genders.  (Circ J 2012; 76: 1687–1696