Julius Traber

Myocardial steatosis, cardiac remodelling and fitness in insulin-sensitive and insulin-resistant obese women

Background Obesity predisposes to heart failure and premature cardiovascular death, particularly in sedentary women. In animal models and in men with type 2 diabetes mellitus, impaired cardiac function is associated with myocardial triglyceride (MTG) accumulation. Lipotoxic injury from altered myocardial metabolism may be causative. Whether such association also exists in obese, non-diabetic women is unknown. Objective To explore the relation between MTG content, cardiac remodelling and cardiorespiratory fitness in obese, insulin-sensitive and insulin-resistant non-diabetic women. Design Cross-sectional investigation. Setting Academic clinical research centre. Patients 65 Overweight/obese and sedentary, but otherwise healthy women (body mass index 33±4 kg/m2; age 45±10 years). Interventions None. Main outcome measures Cardiac structure and function measured by cardiovascular magnetic resonance imaging and MTG content of the interventricular septum by 1H MR spectroscopy. Additional outcomes were cardiopulmonary fitness and insulin sensitivity during oral glucose tolerance testing. Results Insulin resistance (composite insulin sensitivity index (C-ISI) <4.6) was present in 29 women. MTG content was higher (0.83±0.30 vs 0.61±0.23, p=0.002) and left ventricular diastolic (p<0.01), but not systolic function was reduced in women with insulin resistance compared with insulin-sensitive women. The remodelling index defined as left ventricular mass divided by end-diastolic volume was increased in women with impaired glucose tolerance (p=0.006). Furthermore, cardiopulmonary fitness was equal in both groups, but was inversely correlated with MTG (r=−0.28, p=0.02). Conclusions In overweight and obese women, insulin resistance is associated with increased MTG content, cardiac remodelling and reduced diastolic function. Clinical Trial Registration ClinicalTrials.gov NCT00956566.

Left Ventricular Mass and Function With Reduced-Fat or Reduced-Carbohydrate Hypocaloric Diets in Overweight and Obese Subjects

In animals, carbohydrate and fat composition during dietary interventions influenced cardiac metabolism, structure, and function. Because reduced-carbohydrate and reduced-fat hypocaloric diets are commonly used in the treatment of obesity, we investigated whether these interventions differentially affect left ventricular mass, cardiac function, and blood pressure. We randomized 170 overweight and obese subjects (body mass index, 32.9±4.4; range, 26.5–45.4 kg/m2) to 6-month hypocaloric diets with either reduced carbohydrate intake or reduced fat intake. We obtained cardiac MRI and ambulatory blood pressure recordings over 24 hours before and after 6 months. Ninety subjects completing the intervention period had a full cardiac MRI data set. Subjects lost 7.3±4.0 kg (7.9±3.8%) with reduced-carbohydrate diet and 6.2±4.2 kg (6.7±4.4%) with reduced-fat diet (P<0.001 within each group; P=not significant between interventions). Caloric restriction led to similar significant decreases in left ventricular mass with low-carbohydrate diets (5.4±5.4 g) or low-fat diets (5.2±4.8 g; P<0.001 within each group; P=not significant between interventions). Systolic and diastolic left ventricular function did not change with either diet. The 24-hour systolic blood pressure decreased similarly with both interventions. Body weight change (&bgr;=0.33; P=0.02) and percentage of ingested n-3 polyunsaturated fatty acids (&bgr;=−0.27; P=0.03) predicted changes in left ventricular mass. In conclusion, weight loss induced by reduced-fat diets or reduced-carbohydrate diets similarly improved left ventricular mass in overweight and obese subjects over a 6-month period. However, n-3 polyunsaturated fatty acid ingestion may have an independent beneficial effect on left ventricular mass.

Moderate dietary weight loss reduces myocardial steatosis in obese and overweight women

BACKGROUND Excessive myocardial triglyceride (MTG) content in obesity and type 2 diabetes is associated with impaired cardiac function. Previous studies suggest that MTG could be mobilized through lifestyle interventions. We assessed influences of moderate dietary weight loss in non diabetic obese and overweight women on MTG content and cardiac function. METHODS We selected a subgroup of 38 women from the B-SMART study population. The B-SMART study compared weight loss and associated metabolic and cardiovascular markers with reduced-carbohydrate and reduced-fat hypocaloric diets. Selected subjects had completed a cardiac magnetic resonance (MR) scan including imaging and proton spectroscopy to assess cardiac structure and function as well as MTG content. RESULTS An average weight reduction of 5.4 ± 4.3 kg at six months was associated with a relative decrease of MTG of 25% (from 0.72 ± 0.29% at baseline to 0.54 ± 0.23% at follow-up, p<0.001). The response was similar with carbohydrate and fat restriction. Diastolic function expressed as ratio of peak filling rate in E- and A-Phase (PFRE/PFRA) was unchanged. Reductions of left atrial size (from 21.9 ± 4.0 cm(2) to 20.0 ± 3.7 cm(2), p=0.002), the normalized ratio of PFRE and early diastolic lengthening velocity PLV (from 8.2 ± 2.6 to 7.5 ± 2.5, p<0.001) and fat free mass (from 55.1 ± 6.9 kg to 52.7 ± 6.5 kg, p=0.007) reflected altered cardiac volume loading after diet, but did not correlate to MTG content. CONCLUSIONS Moderate dietary weight loss significantly reduced MTG content in women with uncomplicated overweight or obesity. Macronutrient composition of the diet did not significantly affect the extent of MTG reduction.

Fatty acid binding protein 4 predicts left ventricular mass and longitudinal function in overweight and obese women

Objective To explore whether increased adipocyte-derived serum fatty acid binding protein 4 (FABP4) predisposes to cardiac remodelling and left ventricular dysfunction in human obesity. Design Cross-sectional investigation. Setting Academic clinical research centre. Patients 108 overweight and obese non-diabetic women (body-mass index 33±5 kg/m²). Interventions None. Main outcome measures Relationship between serum FABP4 and abdominal adipose tissue quantified by MRI. Relationship between serum FABP4 and left ventricular morphology and function assessed by cardiac MRI. Results FABP4 was independently associated with visceral abdominal adipose tissue (β=0.34, p<0.01) and subcutaneous abdominal adipose tissue (β=0.22, p<0.05). After stratification into serum FABP4 tertiles, left ventricular masses were 92±16 g, 86±13 g and 81±12 g in women with high, intermediate and low FABP4 concentrations (p<0.01), respectively. Longitudinal systolic function was reduced by 8% in women with intermediate and high versus low FABP4 concentrations (p<0.01), whereas ejection fraction did not differ among tertiles (p=0.5). In multivariate linear analysis FABP4 remained an independent predictor of left ventricular mass (β=0.17, p<0.05) and reduced longitudinal fractional shortening (β=0.21, p<0.05). Conclusions In overweight and obese women, FABP4 showed an independent association with parameters of left ventricular remodelling.

Impact of surgical correction of pectus excavatum on cardiac function: insights on the right ventricle. A cardiovascular magnetic resonance study †

OBJECTIVES Pectus excavatum (PE) is often regarded as a cosmetic disease, while its effect on cardiac function is under debate. Data regarding cardiac function before and after surgical correction of PE are limited. We aimed to assess the impact of surgical correction of PE on cardiac function by cardiovascular magnetic resonance (CMR). METHODS CMR at 1.5 T was performed in 38 patients (mean age 21 ± 8.3; 31 men) before and after surgical correction to evaluate thoracic morphology, indices and its relation to three-dimensional left and right ventricular cardiac function. RESULTS Surgery was successful in all patients as shown by the Haller Index ratio of maximum transverse diameter of the chest wall and minimum sternovertebral distance [pre: 9.64 (95% CI 8.18-11.11) vs post: 3.0 (2.84-3.16), P < 0.0001]. Right ventricular ejection fraction (RVEF) was reduced before surgery and improved significantly at the 1-year follow-up [pre: 45.7% (43.9-47.4%) vs 48.3% (46.9-49.5%), P = 0.0004]. Left ventricular ejection fraction was normal before surgery, but showed a further improvement after 1 year [pre: 61.0% (59.3-62.7%) vs 62.7% (61.3-64.2%), P = 0.0165]. Cardiac compression and the asymmetry index changed directly after surgery and were stable at the 1-year follow-up [3.93 (3.53-4.33) vs 2.08 (1.98-2.19) and 2.36 (2.12-2.59) vs 1.38 (1.33-1.44), respectively; P < 0.0001 for both]. None of the obtained thoracic indices were predictors of the improvement of cardiac function. A reduced preoperative RVEF was predictive of RVEF improvement. CONCLUSIONS PE is associated with reduced RVEF, which improves after surgical correction. CMR has the capability of offering additional information prior to surgical correction.

Cardiac Involvement in Myotonic Dystrophy Type 2 Patients With Preserved Ejection Fraction: Detection by Cardiovascular Magnetic Resonance.

Background—Myotonic dystrophy type 2 (DM2) is a genetic disorder characterized by skeletal muscle symptoms, metabolic changes, and cardiac involvement. Histopathologic alterations of the skeletal muscle include fibrosis and fatty infiltration. The aim of this study was to investigate whether subclinical cardiac involvement in DM2 is already detectable in preserved left ventricular function by cardiovascular magnetic resonance. Methods and Results—Twenty-seven patients (mean age, 54±10 years; 20 females) with a genetically confirmed diagnosis of DM2 were compared with 17 healthy age- and sex-matched controls using a 1.5 T magnetic resonance imaging. For myocardial tissue differentiation, T1 and T2 mapping, fat/water-separated imaging, focal fibrosis imaging (late gadolinium enhancement [LGE]), and 1H magnetic resonance spectroscopy were performed. Extracellular volume fraction was calculated. Conduction abnormalities were diagnosed based on Groh criteria. LGE located subepicardial basal inferolateral was detectable in 22% of the patients. Extracellular volume was increased in this region and in the adjacent medial inferolateral segment (P=0.03 compared with healthy controls). In 21% of patients with DM2, fat deposits were detectable (all women). The control group showed no abnormalities. Myocardial triglycerides were not different in LGE-positive and LGE-negative subjects (P=0.47). Six patients had indicators for conduction disease (60% of LGE-positive patients and 12.5% of LGE-negative patients). Conclusions—In DM2, subclinical myocardial injury was already detectable in preserved left ventricular ejection fraction. Extracellular volume was also increased in regions with no focal fibrosis. Myocardial fibrosis was related to conduction abnormalities.

A Multicenter Cardiovascular MR Network for Tele-Training and Beyond: Setup and Initial Experiences

PURPOSE Training in cardiovascular MR (CMR) is an important topic in times of growing acceptance of the method for accurate diagnosis and management of cardiovascular disease. However, off-site training is becoming less acceptable with increasing cost and time pressures. We introduce a novel CMR network, capable of providing, remotely, part of CMR training and continuous expert support. By providing a technical and operational blueprint, we want to share our experience in building teaching networks. METHODS Conceptual, technical, and content-related characteristics of our teaching methods are introduced. A total of 97 participants in traditional fellowship CMR teaching and novel module-based network teaching were surveyed to assess their CMR performance. RESULTS The number of hospitals in our CMR network increased from five in 2009 to 14 in 2014. A total of 79% of network hospitals conducted >100 CMR scans annually. Among these network hospitals are four small institutions (<400 beds), and five medium-sized hospitals (400-1,000 beds). Network teaching reduced off-site training to only five weeks. The time to the first independently conducted CMR scans was one week, with network teaching, but >1 month for 32% of participants in traditional CMR teaching. The CMR network enables experts from distant locations to supervise and control CMR scans in a distant hospital, in real time. CONCLUSIONS CMR networks provide an efficient teaching platform with a minimum of off-site time for trainees. Real-time remote supervision and scan control capabilities support the decentralization of CMR expertise and enables even small and rurally located institutions to offer high-quality CMR scans.

Differentiation of acute and chronic myocardial infarction using T2-weighted imaging, late enhancement and T1 and T2 mapping - a pilot study at 3T

Background Qualitative assessment of myocardial T2-weighted and late enhancement (LGE) images has been demonstrated to differentiate acute from chronic myocardial infarction (AMI, CMI). Parametric mapping could help to overcome challenges in image quality and could contribute to making contrast media application obsolete. The aim of this pilot study was to analyze, whether T2and T1maps are useful to discriminate AMI from CMI.

Moderate dietary weight loss reduces myocardial triglycerides in obese women

Methods Non diabetic overweight and obese women were submitted to a six months hypocaloric diet with either fat or carbohydrate restriction. Cardiac structure and function was assessed by magnetic resonance imaging (MRI) and MTG content by proton spectroscopy (MRS) in 35 subjects at baseline and follow-up. Anthropometric and metabolic parameters as well as cardio-respiratory fitness were measured.

Assessment of acute radiation therapy-related cardiotoxicity by cardiovascular magnetic resonance

Methods We prospectively applied CMR at 1.5T before (a), at half-time (b) and after radiation therapy (c) in patients with different thoracic malignancies. Besides SSFP-based cine imaging for cardiac morphology and function, we performed preand post-contrast T1-mapping (MOLLI) as well as late gadolinium enhancement (LGE) imaging for tissue characterization. T1-times were assessed in a mid-ventricular short axis. LV Ejection Fraction (LVEF) and the partition coefficient l were calculated.