Stress Load and Ascending Aortic Aneurysms: An Observational, Longitudinal, Single-Center Study Using Computational Fluid Dynamics

Ascending aortic aneurysm (AAoA) is a silent disease with high mortality; however, the factors associated with a worse prognosis are not completely understood. The objective of this observational, longitudinal, single-center study was to identify the hemodynamic patterns and their influence on AAoA growth using computational fluid dynamics (CFD), focusing on the effects of geometrical variations on aortic hemodynamics. Personalized anatomic models were obtained from angiotomography scans of 30 patients in two different years (with intervals of one to three years between them), of which 16 (53%) showed aneurysm growth (defined as an increase in the ascending aorta volume by 5% or more). Numerically determined velocity and pressure fields were compared with the outcome of aneurysm growth. Through a statistical analysis, hemodynamic characteristics were found to be associated with aneurysm growth: average and maximum high pressure (superior to 100 Pa); average and maximum high wall shear stress (superior to 7 Pa) combined with high pressure (>100 Pa); and stress load over time (maximum pressure multiplied by the time interval between the exams). This study provides insights into a worse prognosis of this serious disease and may collaborate for the expansion of knowledge about mechanobiology in the progression of AAoA.

Autonomic denervation, myocardial hypoperfusion and fibrosis may predict ventricular arrhythmia in the early stages of Chagas cardiomyopathy

BACKGROUND

Sudden cardiac death (SCD) can be the first clinical event of Chagas heart disease (CHD). However, current guidelines contain no clear recommendation for early cardioverter-defibrillator implantation. Using imaging modalities, we evaluated associations among autonomic denervation, myocardial hypoperfusion, fibrosis and ventricular arrhythmia in CHD.

METHODS AND RESULTS

Twenty-nine patients with CHD and preserved left ventricular function underwent 123I-metaiodobenzylguanidine (MIBG) scintigraphy, 99mTc-methoxyisobutylisonitrile (MIBI) myocardial perfusion and cardiac magnetic resonance imaging (MRI). They were divided into arrhythmic (≥ 6 ventricular premature complexes/h and/or non-sustained ventricular tachycardia on 24-hour Holter, n = 15) and non-arrhythmic (< 6 ventricular premature complexes/h and no ventricular tachycardia; n = 14) groups. The arrhythmic group had higher denervation scores from MIBG imaging (23.2 ± 18.7 vs 5.6 ± 4.9; P < .01), hypoperfusion scores from MIBI SPECT (4.7 ± 6.8 vs 0.29 ± 0.6: P = .02), innervation/perfusion mismatch scores (18.5 ± 17.5 vs 5.4 ± 4.8; P = .01) and fibrosis by late gadolinium enhancement on MRI (14.3% ± 13.5% vs 4.0% ± 2.9%; P = .04) than the non-arrhythmic group.

CONCLUSION

These imaging parameters were associated with ventricular arrhythmia in early CHD and may enable risk stratification and the implementation of primary preventive strategies for SCD.

Analysis of Three-Dimensional Scar Architecture and Conducting Channels by High-Resolution Contrast-Enhanced Cardiac Magnetic Resonance Imaging in Chagas Heart Disease

Background:

We aimed to describe the morphology of the border zone of viable myocardium surrounded by scarring in patients with Chagas heart disease and study their association with clinical events.

Methods:

Adult patients with Chagas heart disease (n=22; 55% females; 65.5 years, SD 10.1) were included. Patients underwent high-resolution contrast-enhanced cardiac magnetic resonance using myocardial delayed enhancement with postprocessing analysis to identify the core scar area and border zone channels number, mass, and length. The association between border zone channel parameters and the combined end-point (cardiovascular mortality or internal cardiac defibrillator implantation) was tested by multivariable Cox proportional hazard regression analyses. The significance level was set at 0.05. Data are presented as the mean (standard deviation [SD]) or median (interquartile range).

Results:

A total of 44 border zone channels (1[1-3] per patient) were identified. The border zone channel mass per patient was 1.25 (0.48-4.39) g, and the extension in layers of the border zone channels per patient was 2.4 (1.0-4.25). Most border zone channels were identified in the midwall location. Six patients presented the studied end-point during a mean follow-up of 4.9 years (SD 1.6). Border zone channel extension in layers was associated with the studied end-point independent from left ventricular ejection fraction or fibrosis mass (HR=2.03; 95% CI 1.15-3.60).

Conclusions:

High-resolution contrast-enhanced cardiac magnetic resonance can identify border zone channels in patients with Chagas heart disease. Moreover, border zone channel extension was independently associated with clinical events.

Cardiac Fibrosis and Changes in Left Ventricle Function in Patients with Chronic Chagas Heart Disease

BACKGROUND

Chagas heart disease (CHD) is a slow progressing condition with fibrosis as the main histopathological finding.

OBJECTIVES

To study if cardiac fibrosis increases over time and correlates with increase in left ventricular (LV) size and reduction of ejection fraction (EF) in chronic CHD.

METHODS

Retrospective study that included 20 individuals (50% men; 60±10 years) with chronic CHD who underwent two cardiac magnetic resonance imaging (MRI) with late gadolinium enhancement with a minimum interval of four years between tests. LV volume, EF, and fibrosis mass were determined by cardiac MRI. Associations of fibrosis mass at the first cardiac MRI and changes in LV volume and EF at the second cardiac MRI were tested using logistic regression analysis. P values <0.05 were considered significant.

RESULTS

Patients were classified as follows: A (n=13; changes typical of CHD in the electrocardiogram and normal global and segmental LV systolic function) and B1 (n=7; LV wall motion abnormality and EF≥45%). Mean time between cardiac MRI studies was 5.4±0.5 years. LV fibrosis (in %LV mass) increased from 12.6±7.9% to 18.0±14.1% between MRI studies (p=0.02). Cardiac fibrosis mass at baseline was associated with decrease in >5 absolute units in LV EF from the first to the second MRI (OR 1.48, 95% CI 1.03-2.13, p=0.03). LV fibrosis mass was larger and increased between MRI studies in the group that presented decrease in LV EF between the tests.

CONCLUSIONS

Even patients at an initial stage of CHD show an increase in myocardial fibrosis over time, and the presence of LV fibrosis at baseline is associated with a decrease in LV systolic function.

Case Report: Malignant Ventricular Arrhythmias Mimicking Acute Coronary Syndrome in Chagas Disease

Chronic Chagas heart disease has different clinical manifestations including arrhythmias, heart failure, and stroke. Chest pain is one of the most common symptoms and when associated with changes in the electrocardiogram, such as T-wave changes, electrically inactive areas, and segmental wall motion abnormalities, may lead to a misdiagnosis of acute coronary syndrome (ACS). Here, we describe two patients with Chagas heart disease and syncope due to sustained ventricular tachycardia who were misdiagnosed with ACS, and discuss the role of novel imaging modalities in the differential diagnosis and risk stratification.

Associations between Cardiac Magnetic Resonance T1 Mapping Parameters and Ventricular Arrhythmia in Patients with Chagas Disease

Chronic Chagas disease can progress to myocardial involvement with intense fibrosis, which may predispose patients to sudden cardiac death through ventricular arrhythmia. The associations of myocardial fibrosis detected by cardiac magnetic resonance (CMR) parameters with non-sustained ventricular tachycardia (NSVT) were evaluated. This cross-sectional study included patients in early stages of Chagas disease (n = 47) and a control group (n = 15). Patients underwent cardiac evaluation, including CMR examination. Myocardial fibrosis assessment by CMR with measurement of late gadolinium enhancement (LGE), native T1, and extracellular volume (ECV) was performed. There was an increase in myocardial fibrosis CMR parameters and ventricular arrhythmias among different stages of Chagas disease, combined with a decrease in the left ventricular ejection fraction (LVEF) by CMR and also in the right ventricular systolic function by S' wave on tissue Doppler. Fibrosis mass and ECV were associated with the Rassi score, ventricular extrasystole, and E/e' ratio in a logistic regression model adjusted for age and gender. The ECV maintained an association with the presence of NSVT, even after adjustments for fibrosis mass and LVEF assessed by CMR. The receiver-operating characteristic area under the curve for global ECV (0.85; 95% CI: 0.71-0.99) and NSVT was greater than that for fibrosis mass (0.75; 95% CI: 0.54-0.96), although this difference was not statistically significant. Extracellular volume could be an early marker of increased risk of ventricular arrhythmia in Chagas disease, presenting an independent association with NSVT in the initial stages of chronic Chagas cardiomyopathy, even after adjustment for fibrosis mass and LVEF.

Influence of the tilt angle of Percutaneous Aortic Prosthesis on Velocity and Shear Stress Fields

Background

Due to the nature of the percutaneous prosthesis deployment process, a variation in its final position is expected. Prosthetic valve placement will define the spatial location of its effective orifice in relation to the aortic annulus. The blood flow pattern in the ascending aorta is related to the aortic remodeling process, and depends on the spatial location of the effective orifice. The hemodynamic effect of small variations in the angle of inclination of the effective orifice has not been studied in detail.

Objective

To implement an in vitro simulation to characterize the hydrodynamic blood flow pattern associated with small variations in the effective orifice inclination.

Methods

A three-dimensional aortic phantom was constructed, reproducing the anatomy of one patient submitted to percutaneous aortic valve implantation. Flow analysis was performed by use of the Particle Image Velocimetry technique. The flow pattern in the ascending aorta was characterized for six flow rate levels. In addition, six angles of inclination of the effective orifice were assessed.

Results

The effective orifice at the -4º and -2º angles directed the main flow towards the anterior wall of the aortic model, inducing asymmetric and high shear stress in that region. However, the effective orifice at the +3º and +5º angles mimics the physiological pattern, centralizing the main flow and promoting a symmetric distribution of shear stress.

Conclusion

The measurements performed suggest that small changes in the angle of inclination of the percutaneous prosthesis aid in the generation of a physiological hemodynamic pattern, and can contribute to reduce aortic remodeling.

Prevalence and Prediction of Obstructive Coronary Artery Disease in Patients Undergoing Primary Heart Valve Surgery

Background

The prevalence of coronary artery disease (CAD) in valvular patients is similar to that of the general population, with the usual association with traditional risk factors. Nevertheless, the search for obstructive CAD is more aggressive in the preoperative period of patients with valvular heart disease, resulting in the indication of invasive coronary angiography (ICA) to almost all adult patients, because it is believed that coronary artery bypass surgery should be associated with valve replacement.

Objectives

To evaluate the prevalence of obstructive CAD and factors associated with it in adult candidates for primary heart valve surgery between 2001 and 2014 at the National Institute of Cardiology (INC) and, thus, derive and validate a predictive obstructive CAD score.

Methods

Cross-sectional study evaluating 2898 patients with indication for heart surgery of any etiology. Of those, 712 patients, who had valvular heart disease and underwent ICA in the 12 months prior to surgery, were included. The P value < 0.05 was adopted as statistical significance.

Results

The prevalence of obstructive CAD was 20%. A predictive model of obstructive CAD was created from multivariate logistic regression, using the variables age, chest pain, family history of CAD, systemic arterial hypertension, diabetes mellitus, dyslipidemia, smoking, and male gender. The model showed excellent correlation and calibration (R² = 0.98), as well as excellent accuracy (ROC of 0.848; 95%CI: 0.817-0.879) and validation (ROC of 0.877; 95%CI: 0.830 - 0.923) in different valve populations.

Conclusions

Obstructive CAD can be estimated from clinical data of adult candidates for valve repair surgery, using a simple, accurate and validated score, easy to apply in clinical practice, which may contribute to changes in the preoperative strategy of acquired heart valve surgery in patients with a lower probability of obstructive disease.

Factors Associated With Coronary Artery Disease Progression Assessed By Serial Coronary Computed Tomography Angiography

Background

Coronary computed tomography angiography (CCTA) allows for noninvasive coronary artery disease (CAD) phenotyping. Factors related to CAD progression are epidemiologically valuable.

Objective

To identify factors associated with CAD progression in patients undergoing sequential CCTA testing.

Methods

We retrospectively analyzed 384 consecutive patients who had at least two CCTA studies between December 2005 and March 2013. Due to limitations in the quantification of CAD progression, we excluded patients who had undergone surgical revascularization previously or percutaneous coronary intervention (PCI) between studies. CAD progression was defined as any increase in the adapted segment stenosis score (calculated using the number of diseased segments and stenosis severity) in all coronary segments without stent (in-stent restenosis was excluded from the analysis). Stepwise logistic regression was used to assess variables associated with CAD progression.

Results

From a final population of 234 patients, a total of 117 (50%) had CAD progression. In a model accounting for major CAD risk factors and other baseline characteristics, only age (odds ratio [OR] 1.04, 95% confidence interval [95%CI] 1.01-1.07), interstudy interval (OR 1.03, 95%CI 1.01-1.04), and past PCI (OR 3.66, 95%CI 1.77-7.55) showed an independent relationship with CAD progression.

Conclusions

A history of PCI with stent placement was independently associated with a 3.7-fold increase in the odds of CAD progression, excluding in-stent restenosis. Age and interstudy interval were also independent predictors of progression.

Evaluation of epicardial adipose tissue in familial partial lipodystrophy

BACKGROUND

Dunnigan type Familial Partial Lipodystrophy (FPLD) is characterized by loss of subcutaneous fat from the limbs and excessive accumulation on the visceral adipose tissue (VAT). Affected individuals have insulin resistance (IR), diabetes, dyslipidemia and early cardiovascular (CV) events, due to their imbalanced distribution of total body fat (TBF). Epicardial adipose tissue (EAT) is correlated with VAT. Hence, EAT could be a new index of cardiac and visceral adiposity with great potential as a marker of CV risk in FPLD.

OBJECTIVE

Compare EAT in FPLD patients versus healthy controls. Moreover, we aimed to verify if EFT is related to anthropometrical (ATPM) and Dual-Energy X-ray Absorptiometry (DEXA) measures, as well as laboratory blood findings. We postulated that FPLD patients have enlarged EAT.

METHODS

This is an observational, cross-sectional study. Six patients with a confirmed mutation in the LMNA gene for FPLD were enrolled in the study. Six sex, age and BMI-matched healthy controls were also selected. EFT was measured by transthoracic echocardiography (ECHO). All participants had body fat distribution evaluated by ATPM and by DEXA measures. Fasting blood samples were obtained for biochemical profiles and also for leptin measurements.

RESULTS

Median EFT was significantly higher in the FPLD group than in matched controls (6.0 ± 3.6 mm vs. 0.0 ± 2.04 mm; p = 0.0306). Additionally, FPLD patients had lower leptin values. There was no significant correlation between EAT and ATPM and DEXA measurements, nor laboratory findings.

CONCLUSIONS

This study demonstrates, for the first time, that EAT measured by ECHO is increased in FPLD patients, compared to healthy controls. However, it failed to prove a significant relation neither between EAT and DEXA, ATPM or laboratory variables analyzed.