Visceral adiposity and left ventricular remodeling: The Multi-Ethnic Study of Atherosclerosis.

BACKGROUND AND AIMS: Visceral fat (VF) is a source of pro-inflammatory adipokines implicated in cardiac remodeling. We sought to determine the impact of visceral fat and subcutaneous fat (SQ) depots on left ventricular (LV) structure, function, and geometry in the Multi-Ethnic Study of Atherosclerosis (MESA). METHODS AND RESULTS: We performed a post-hoc analysis on 1151 participants from MESA with cardiac magnetic resonance quantification of LV mass and LV mass-to-volume ratio (LVMV, an index of concentricity) and computed tomographic-derived SQ and VF area. Multivariable regression models to estimate association between height-indexed SQ and VF area (per cm(2)/m) with height-indexed LV mass (per height(2.7)) and LVMV were constructed, adjusted for clinical, biochemical, and demographic covariates. We found that both VF and SQ area were associated with height-indexed LV mass (ρ = 0.36 and 0.12, P < 0.0001, respectively), while only VF area was associated with LVMV (ρ = 0.28, P < 0.0001). Individuals with above-median VF had lower LV ejection fraction, greater indexed LV volumes and mass, and higher LVMV (all P < 0.001). In multivariable models adjusted for weight, VF (but not SQ) area was associated with LV concentricity and LV mass index, across both sexes. CONCLUSION: Visceral adiposity is independently associated with LV concentricity, a precursor to heart failure. Further study into the role of VF in LV remodeling as a potential therapeutic target is warranted.

Periaortic fat and cardiovascular risk: a comparison of high-risk older adults and age-matched healthy controls.

OBJECTIVE: Fat accumulation around the heart and aorta may impact cardiovascular (CV) health. The purpose of this study was to conduct a systematic investigation to examine potential associations of these fat depots with risk factors for CV events, which has not been done before. METHODS: Pericardial fat, periaortic fat around the ascending aorta (AA), descending aorta (DA) and aortic arch, and abdominal subcutaneous and visceral fat were measured by MRI in older adults with (n = 385, 69 ± 8 years, 52% female) and without (n = 50, 69 ± 8 years, 58% female) risk factors for a CV event. RESULTS: Individuals with CV risk factors exhibited greater fat volumes across all fat depots compared with those without risk factors. In analysis of covariance accounting for age, gender, race/ethnicity, diabetes, hypertension, coronary artery disease, smoking and body mass index (BMI), individuals with risk factors possessed higher epicardial, pericardial, AA, DA and abdominal visceral fat (P < 0.05). When matched one-to-one on age, gender, race/ethnicity and BMI, AA and DA fat were higher in those with versus without CV risk factors (P < 0.01). CONCLUSIONS: Older adults with a high risk for CV events have greater periaortic fat than low-risk adults, even after accounting for BMI. More studies are needed to determine whether greater periaortic fat predicts future CV events.

Changes in Physical Activity, Functional Capacity, and Cardiac Function during Breast Cancer Therapy.

PURPOSE: Functional capacity and cardiac function can decline during breast cancer (BC) therapy. In non-cancer populations, higher physical activity (PA) is associated with better physical function and cardiac health. This study compared baseline PA, functional capacity, and cardiac function between women with and without BC and tested if greater PA participation was related to higher functional capacity and/or better heart function after three months of BC therapy. METHODS: Data was collected in 104 women without BC (82% Caucasian, baseline only) and 110 women with stage I-III BC (82% Caucasian) before therapy and after three months of treatment. Participants self-reported PA and underwent six-minute walk distance (6MWD) testing to measure functional capacity and cardiovascular magnetic resonance to assess left ventricular ejection fraction (LVEF). Analyses were adjusted for age, race, body mass index (BMI), and medication use. RESULTS: The BC group was older (56.2 ± 10.7 vs 52.1 ± 14.7 yrs, P=0.02) with a higher average BMI than the non-cancer group (30.3 ± 6.8 vs 27.7 ± 6.2 kg/m2, P<0.01). Pre-treatment, BC participants reported lower PA scores (27.9 ± 2.8 vs 34.9 ± 2.8, P=0.04) with similar 6MWD and LVEF relative to those without cancer (485 ± 11 vs 496 ± 11 m, P=0.4 and 59.7 ± 0.7 vs 58.9 ± 0.8%, P=0.37, respectively). After three months of BC therapy, declines were observed for PA scores (27.9 ± 2.8 vs 18.3 ± 2.5, P=0.02), 6MWD (485 ± 11 vs 428 ± 10 m, P<0.001), and LVEF (59.7 ± 0.7 vs 56.1 ± 0.7%, P<0.001). Compared to BC participants who reported no PA at three months (n=24, 22%), BC women who reported any PA (n=78, 86%) had higher 6MWD (442 ± 11 vs 389 ± 17 m, P=0.006) but similar LVEF (56.5 ± 0.9 vs 55.3 ± 1.5%, p=0.5). Women who reported any PA were less likely to exhibit an LVEF below normal (<50%) or decline in LVEF of 'â•10 points compared to inactive women (BMI-adjusted, OR [95% CI]: 0.27 [0.09, 0.85]). CONCLUSIONS: These preliminary results indicate that self-reported PA, LVEF and 6MWD decline in the first three months of BC treatment, but PA participation during BC treatment may mitigate declines in functional capacity and cardiac function. Further research is needed to identify barriers and facilitators of PA participation during BC therapy. FUNDING: Data collection was funded by the Wake Forest NCORP Research Base grant 2UG1CA189824 with support of the NCI Community Oncology Research Program (NCORP). Additional funding for this study was provided by grants from the National Institutes of Health, National Cancer Institute (1R01CA199167 and 5T32CA093423). CLINICAL TRIAL ID: NCT02791581 for WF97415 UPBEAT.

Pericardial fat is associated with carotid stiffness in the Multi-Ethnic Study of Atherosclerosis.

BACKGROUND AND AIMS: Arterial stiffness is a prominent feature of vascular aging and a risk factor for cardiovascular disease (CVD). Fat around the heart and blood vessels (i.e. pericardial fat, Pfat) may contribute to arterial stiffness via a local paracrine effect of adipose tissue on the surrounding vasculature. Thus, we determined the association between Pfat and carotid stiffness in 5770 participants (mean age 62 years, 53% female, 25% African American, 24% Hispanic, and 13% Chinese) from the Multi-Ethnic Study of Atherosclerosis. METHODS AND RESULTS: Pfat was measured by computed tomography, and ultrasonography of the common carotid artery was used to calculate the distensibility coefficient (DC) and Young's modulus (YM). Lower DC and higher YM values indicate stiffer arteries. Pfat quartile was highly associated with demographic, behavioral, anthropometric, hemodynamic, metabolic, and disease variables in both men and women. After adjusting for height, clinical site, CVD risk factors, and medications, a 1 standard deviation (41.91 cm(3)) increment in Pfat was associated with a 0.00007±0.00002 1/mm Hg lower DC (p=0.0002) in men and a 48.1±15.1 mm Hg/mm higher YM in women (p=0.002). Additional adjustment for C-reactive protein, coronary artery calcification, and carotid intima-media thickness had only modest effects. More importantly, adjusting for body mass index and waist circumference did not significantly change the overall results. CONCLUSION: Higher Pfat is associated with higher carotid stiffness, independent of traditional CVD risk factors and obesity.

Utility of fast cine magnetic resonance imaging and display for the detection of myocardial ischemia in patients not well suited for second harmonic stress echocardiography.

BACKGROUND: Some patients referred for pharmacological stress testing with transthoracic echocardiography (TTE) are unable to undergo testing owing to poor acoustic windows. Fast cine MRI can be used to assess left ventricular contraction, but its utility for detection of myocardial ischemia in patients poorly suited for echocardiography is unknown. METHODS AND RESULTS: One hundred fifty-three patients (86 men and 67 women aged 30 to 88 years) with poor acoustic windows that prevented adequate second harmonic TTE imaging were consecutively referred for MRI to diagnose inducible myocardial ischemia during intravenous dobutamine and atropine. Diagnostic studies were completed in an average of 53 minutes. No patients experienced myocardial infarction, ventricular fibrillation, exacerbation of congestive heart failure, or death. In patients who underwent computer-assisted quantitative coronary angiography, the sensitivity and specificity for detecting a >50% luminal diameter narrowing were 83% and 83%, respectively. In the 103 patients with a negative MRI examination, the cardiovascular occurrence-free survival rate was 97%. CONCLUSIONS: Fast cine cardiac MRI provides a mechanism to assess left ventricular contraction and diagnose inducible myocardial ischemia in patients not well suited for stress echocardiography.

Assessment of coronary arterial restenosis with phase-contrast magnetic resonance imaging measurements of coronary flow reserve.

BACKGROUND: After successful percutaneous coronary arterial revascularization, 25% to 60% of subjects have restenosis, a recurrent coronary arterial narrowing at the site of the intervention. At present, restenosis is usually detected invasively with contrast coronary angiography. This study was performed to determine if phase-contrast MRI (PC-MRI) could be used to detect restenosis noninvasively in patients with recurrent chest pain after percutaneous revascularization. METHODS AND RESULTS: Seventeen patients (15 men, 2 women, age 36 to 77 years) with recurrent chest pain >3 months after successful percutaneous intervention underwent PC-MRI measurements of coronary artery flow reserve followed by assessments of stenosis severity with computer-assisted quantitative coronary angiography. The intervention was performed in the left anterior descending coronary artery in 15 patients, one of its diagonal branches in 2 patients, and the right coronary artery in 1 patient. A PC-MRI coronary flow reserve value /=70% and >/=50%, respectively. CONCLUSIONS: Assessments of coronary flow reserve with PC-MRI can be used to identify flow-limiting stenoses (luminal diameter narrowings >70%) in patients with recurrent chest pain in the months after a successful percutaneous intervention.

Visualization and functional assessment of proximal and middle left anterior descending coronary stenoses in humans with magnetic resonance imaging.

BACKGROUND: Coronary artery bypass grafting improves survival in patients with >70% luminal diameter narrowing of the 3 major epicardial coronary arteries, particularly if there is involvement of the proximal portion of the left anterior descending (LAD) coronary artery. Measurement of coronary flow reserve can be used to identify functionally important luminal narrowing of the LAD artery. Although magnetic resonance imaging (MRI) has been used to visualize coronary arteries and to measure flow reserve noninvasively, the utility of MRI for detecting significant LAD stenoses is unknown. METHODS AND RESULTS: Thirty subjects (23 men, 7 women, age 36 to 77 years) underwent MRI visualization of the left main and LAD coronary arteries as well as measurement of flow in the proximal, middle, or distal LAD both at rest and after intravenous adenosine (140 microgram/kg per minute). Immediately thereafter, contrast coronary angiography and when feasible, intracoronary Doppler assessments of coronary flow reserve, were performed. There was a statistically significant correlation between MRI assessments of coronary flow reserve and (a) assessments of coronary arterial stenosis severity by quantitative coronary angiography and (b) invasive measurements of coronary flow reserve (P<0.0001 for both). In comparison to computer-assisted quantitative coronary angiography, the sensitivity and specificity of MRI for identifying a stenosis >70% in the distal left main or proximal/middle LAD arteries was 100% and 83%, respectively. CONCLUSIONS: Noninvasive MRI measures of coronary flow reserve correlated well with similar measures obtained with the use of intracoronary Doppler flow wires and predicted significant coronary stenoses (>70%) with a high degree of sensitivity and specificity. MRI-based measurement of coronary flow reserve may prove useful for identification of patients likely to obtain a survival benefit from coronary artery bypass grafting.

Administration of an intravenous perfluorocarbon contrast agent improves echocardiographic determination of left ventricular volumes and ejection fraction: comparison with cine magnetic resonance imaging.

OBJECTIVES: The purpose of this study was to determine whether contrast-enhanced transthoracic echocardiography improves the evaluation of left ventricular (LV) volumes and ejection fraction (EF). BACKGROUND: Echocardiographic assessment of LV volumes and EF is widely used but may be inaccurate when the endocardium is not completely visualized. Recently the intravenous (i.v.) administration of perfluorocarbon microbubbles has been shown to enhance opacification of the LV cavity, but the utility of these agents to improve the echocardiographic assessment of LV systolic function is unknown. METHODS: In 40 subjects (29 men and 11 women, aged 24 to 81 years) an assessment of LV volumes and EF was performed with a magnetic resonance imaging examination, followed immediately by a transthoracic echocardiogram before and after the intravenous administration of 2% dodecafluoropentane emulsion (EchoGen; Sonus Pharmaceuticals, Bothell, Washington). RESULTS: Contrast enhanced the echocardiographic assessment of LV end diastolic volume (p < 0.02), end systolic volume (p < 0.01) and LVEF (p < 0.03). The percentage of subjects in whom the correct echocardiographic classification EF was normal, mild to moderately depressed or severely reduced improved significantly after contrast enhancement (from 71% before contrast to 94% after, p < 0.03). These findings were most striking in the subjects with two or more adjacent endocardial segments not visualized at baseline. CONCLUSIONS: Administration of an intravenous contrast agent improves the ability to accurately assess LV volumes and EF in humans. Contrast enhancement is most useful in subjects with two or more adjacent endocardial segments not seen at baseline.

Cardiac cycle-dependent changes in aortic area and distensibility are reduced in older patients with isolated diastolic heart failure and correlate with exercise intolerance.

OBJECTIVES: The goal of this study was to determine if cardiac cycle-dependent changes in proximal thoracic aortic area and distensibility are associated with exercise intolerance in elderly patients with diastolic heart failure (DHF). BACKGROUND: Aortic compliance declines substantially with age. We hypothesized that a reduction in cardiac cycle-dependent changes in thoracic aortic area and distensibility (above that which occurs with aging) could be associated with the exercise intolerance that is prominent in elderly diastolic heart failure patients. METHODS: Thirty subjects (20 healthy individuals [10 < 30 years of age and 10 > 60 years of age] and 10 individuals > the age of 60 years with DHF) underwent a magnetic resonance imaging (MRI) study of the heart and proximal thoracic aorta followed within 48 h by maximal exercise ergometry with expired gas analysis. RESULTS: The patients with DHF had higher resting brachial pulse and systolic blood pressure, left ventricular mass, aortic wall thickness and mean aortic flow velocity, and, compared with healthy older subjects, they had a significant reduction in MRI-assessed cardiac cycle-dependent change in aortic area and distensibility (p < 0.0001) that correlated with diminished peak exercise oxygen consumption (r = 0.79). After controlling for age and gender in a multivariate analysis, thoracic aortic distensibility was a significant predictor of peak exercise oxygen consumption (p < 0.04). CONCLUSIONS: Older patients with isolated DHF have reduced cardiac cycle-dependent changes in proximal thoracic aortic area and distensibility (beyond that which occurs with normal aging), and this correlates with and may contribute to their severe exercise intolerance.

Dobutamine magnetic resonance imaging with myocardial tagging quantitatively predicts improvement in regional function after revascularization.

Segmental contractile reserve measured by dobutamine magnetic resonance imaging quantitatively predicts improvement in end-systolic wall thickness after revascularization. Segments with end-systolic wall thickness <7 mm at rest do not demonstrate contractile reserve or improve after revascularization.

Effect of contrast enhancement on transthoracic echocardiographic assessment of left ventricular regional wall motion.

The use of contrast-enhanced transthoracic echocardiography to evaluate left ventricular regional wall motion was determined by comparison of echocardiographic data with assessments obtained by magnetic resonance imaging. When left ventricular endocardial segments are well visualized after contrast enhancement, the ability to determine normal versus abnormal endocardial thickening with echocardiography is similar to cine magnetic resonance imaging.

Comparison of quantitative Doppler with magnetic resonance imaging for assessment of the severity of mitral regurgitation.

We compared quantitative Doppler echocardiography and cine magnetic resonance imaging for calculation of regurgitant volume and regurgitant fraction in mitral regurgitation. A good correlation was present between the 2 methods with some scatter in patients with severe mitral regurgitation and high regurgitant volumes.

Quantitation of cardiac output with velocity-encoded, phase-difference magnetic resonance imaging.

Velocity-encoded, phase-difference magnetic resonance imaging (MRI) previously has been used to measure flow in the aorta, as well as in the pulmonary, carotid, and renal arteries, but these measurements have not been validated against currently accepted invasive techniques. To determine the accuracy of velocity-encoded, phase-difference MRI measurements of cardiac output, 23 subjects (11 men and 12 women, aged 15 to 72 years) underwent velocity-encoded, phase-difference MRI measurements of cardiac output in the proximal aorta, followed immediately by cardiac catheterization, with measurement of cardiac output by the Fick principle and by thermodilution. For MRI, Fick, and thermodilution measurements, stroke volume was calculated by dividing cardiac output by heart rate. The magnetic resonance images were acquired in 1 to 3 minutes. For all patients, the agreement between measurements of stroke volume was 3 +/- 9 ml for MRI and Fick, -3 +/- 11 ml for MRI and thermodilution, and 0 +/- 8 ml for MRI and the average of Fick and thermodilution. Compared with standard invasive measurements, velocity-encoded, phase-difference MRI can accurately and rapidly determine cardiac output.

Comparison of quantitation of left ventricular volume, ejection fraction, and cardiac output in patients with atrial fibrillation by cine magnetic resonance imaging versus invasive measurements.

Currently available invasive and noninvasive techniques for the determination of left ventricular end-diastolic and end-systolic volumes, ejection fraction, and cardiac output are more time-consuming and potentially less accurate in patients with atrial fibrillation (AF) than in those with sinus rhythm. Although magnetic resonance imaging (MRI) can rapidly and accurately measure these variables in patients with sinus rhythm, its ability to do so in subjects with AF is not known. To determine if left ventricular volumes, ejection fraction, and cardiac output can be measured accurately in patients with AF using MRI, 26 subjects (13 women and 13 men, aged 15 to 76 years) in sinus rhythm (n = 13) or AF (n = 13) underwent MRI followed immediately by invasive measurements of these indexes. For those in AF, MRI measurements of left ventricular end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, and cardiac output correlated well with catheterization measurements (r = 0.90, 0.90, 0.95, 0.85, and 0.90, respectively). In addition, the mean difference between MRI and catheterization measurements was similar in subjects with AF and in those with sinus rhythm. Compared with standard invasive measurements, MRI provides an accurate noninvasive determination of left ventricular volumes, ejection fraction, and cardiac output in patients with AF.

Quantitative MR imaging of the heart.

MR imaging cardiac quantitation is accurate, highly reproducible, and feasible using equipment available in most hospitals. For determination of myocardial mass, evaluation of RV function, and quantitative measurements of flow in the great vessels and peripheral vasculature, MR imaging is the reference method. Availability of methods for rapid scanning and analysis will lead to increased use of cardiac MR imaging in quantifying cardiac function.