Predictive power of different obesity measures for the presence of diastolic dysfunction

Objective: Body mass index (BMI) and waist circumference (WC) as measures of obesity have some limitations. The aim of this study was to evaluate whether one measure could predict the presence of diastolic dysfunction (DD) more accurately than the other measures. Methods: A total of 91 obese patients without any other risk factors for DD were prospectively enrolled. Echocardiographic examination was performed. DD was defined and categorized according to recent guidelines. The study participants were divided into 2 groups according to the presence of DD. Weight, height, and WC were measured; BMI and waist-to-hip ratio (WHR) were calculated; and a body shape index (ABSI) was calculated as WC/(BMI2/3height1/2). The associations between ABSI, BMI, WHR, and WC and the presence of DD were examined using logistic regression analyses. Analysis of covariance was used to examine the differences. Results: WC and BMI were significantly greater in subjects with DD (p=0.049 and 0.051, respectively). A greater BMI, WC, and WHR increased the risk of the presence of DD (BMI-DD: odds ratio [OR]=1.096, p=0.024; WC-DD: OR=1.059, p=0.007; WHR-DD: OR=2.363, p=0.007). After adjustment for age and sex, only BMI continued to be significantly associated with DD (p=0.031). ABSI was not associated with DD. Conclusion: After adjustment for age and sex, BMI was the only predictor of DD in obesity. Despite its limitations, BMI may still be a potentially more accurate measure of DD compared with other obesity measures. © 2018 Turkish Society of Cardiology

Intramyocardial hemorrhage: An enigma for cardiac MRI?

Cardiovascular magnetic resonance (CMR) is a useful noninvasive technique for determining the presence of microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH), frequently occurring in patients after reperfused myocardial infarction (MI). MVO, or the so-called no-reflow phenomenon, is associated with adverse ventricular remodeling and a poor prognosis during follow-up. Similarly, IMH is considered a severe damage after revascularization by percutaneous primary coronary intervention (PPCI) or fibrinolysis, which represents a worse prognosis. However, the pathophysiology of IMH is not fully understood and imaging modalities might help to better understand that phenomenon. While, during the past decade, several studies examined the distribution patterns of late gadolinium enhancement with different CMR sequences, the standardized CMR protocol for assessment of IMH is not yet well established. The aim of this review is to evaluate the available literature on this issue, with particular regard to CMR sequences. New techniques, such as positron emission tomography/magnetic resonance imaging (PET/MRI), could be useful tools to explore molecular mechanisms of the myocardial infarction healing process

Magnetic resonance imaging of the right ventricle in human pulmonary hypertension

Pulmonary Hypertension (PH) is a rare but devastating illness which results in progressive right ventricular (RV) failure and early death. RV function determines survival in all patients with PH but it is difficult to measure accurately using existing clinical techniques. The choice and design of the experiments in this thesis was driven by a desire to improve our understanding of the reasons for right, and left,ventricular dysfunction in this context. Cardiovascular magnetic resonance (CMR)imaging was utilized throughout as it allows the non-invasive, direct and accurate study of both ventricles; at rest and during stress. In Chapter 3, CMR imaging was used to identify an NT-proBNP threshold (1685 ng/l, sensitivity 100%, specificity 94%) for the non-invasive detection of RV systolic dysfunction in patients with PH. In Chapter 4, contrast-enhanced-CMR was utilized for the first time in PH patients and revealed previously unidentified areas of myocardial fibrosis within the RV insertion points and interventricular septum. The extent of these areas correlated inversely with RV ejection fraction (r = -0.762, p < 0.001). Septal contrast enhancement was particularly associated with bowing of the interventricular septum. Finally, in Chapter 5, dobutamine stress-CMR was used to determine the individual reasons for right and left ventricular stroke volume impairment during exercise in PH patients. ∆ RV stroke volume appeared limited by diminished contractile reserve as ∆ RVEF was lower in PH patients (27%) compared to controls (38%) and ∆ RVEF correlated with ∆ RV stroke volume (r = 0.94, p < 0.001). ∆ LV stroke volume appeared limited by impaired filling, probably due to reduced LV preload as RV stroke volume and LV end-diastolic volume remained closely related at rest (r = 0.821, p < 0.001) and stress (r = 0.693, p = 0.003)

Pulmonary hypertension and heart failure : physiological markers assessed by cardiovascular magnetic resonance

Pulmonary hypertension (PH) is clinically and physiologically associated with heart failure, both with reduced and preserved ejection fraction (HFrEF and HFpEF). In HFpEF, the most likely underlying pathophysiological mechanism is an impairment of left ventricular relaxation named diastolic dysfunction. The close relationship between PH, diastolic dysfunction, and heart failure makes it difficult to clearly distinguish between them in clinical practice. Given the challenges around screening and diagnosis of both PH and diastolic dysfunction, better diagnostic tools are needed to complement the existing ones. Cardiovascular magnetic resonance (CMR) is considered the most accurate imaging modality in the assessment of myocardial anatomy and function. Furthermore, CMR offers the possibility of qualitatively and quantitatively assess blood flow in large and medium vessels. Constant technical innovations push to further develop the current clinical capabilities of CMR and enable better and faster diagnosis of cardiovascular diseases. In this thesis, we aimed to expand the current clinical capabilities of CMR in the diagnosis of pulmonary hypertension and diastolic dysfunction, which are not routinely assessed with this imaging modality. In Study I, we investigated the effect of body position in pulmonary blood flow distribution and documented a new variable, termed pulmonary vascular distensibility reserve, possibly related to left atrial pressure. In Study II, we found that CMR has a higher diagnostic yield than echocardiography for estimation of elevated pulmonary artery pressure. In Study III, CMR estimation of pulmonary artery pressure showed very good agreement with invasively measured pressure, and better sensitivity and accuracy than echocardiography. In Study IV, we developed a high temporal resolution CMR method to measure transmitral blood and myocardial tissue velocities, which had good agreement with echocardiography. Lastly, in Study V, we found that a comprehensive CMR method to diagnose and grade diastolic dysfunction showed very good agreement with echocardiography. These results suggest that novel and established CMR-based methods can diagnose pulmonary hypertension and diastolic dysfunction. Therefore, CMR may one day play an important role in the diagnostic investigation of these pathologies