Left ventricular myocardial oxygen demand and subclinical dysfunction in patients with severe obesity referred for bariatric surgery

Association of Left Atrial Stiffness With Risk of Cryptogenic Ischemic Stroke in Young Adults

Background

Incidence of cryptogenic ischemic stroke (CIS) in young adults is increasing. Early left atrial (LA) myopathy might be 1 of the underlying mechanisms, but this has only been scarcely explored.

Objectives

The purpose of this study was to assess the association between increased LA stiffness and CIS in young adults.

Methods

In the multicenter SECRETO (Searching for Explanations for Cryptogenic Stroke in the Young: Revealing the Etiology, Triggers, and Outcome) study, LA function was analyzed by speckle tracking echocardiography in 150 CIS patients (aged 18-49 years) and 150 age- and sex-matched controls. Minimum and maximum LA volumes, LA reservoir and contractile strain were measured. LA stiffness was calculated by the ratio: mitral peak E-wave velocity divided by mitral annular e' velocity (E/e')/LA reservoir strain and considered increased if ≥0.22. Increased LA volumes, LA stiffness, and/or reduced LA strain indicated LA myopathy. Logistic regression was used to determine the relation between LA stiffness and CIS and the clinical variables associated with LA stiffness.

Results

Increased LA stiffness was found in 36% of patients and in 18% of controls (P < 0.001). Increased LA stiffness was associated with a 2.4-fold (95% CI: 1.1-5.3) higher risk of CIS after adjustment for age, sex, comorbidities, and echocardiographic confounders (P = 0.03). In patients, obesity, pre-CIS antihypertensive treatment, older age, and lower LA contractile strain were all related to increased LA stiffness (all P < 0.05).

Conclusions

LA myopathy with increased LA stiffness and impaired LA mechanics more than doubles the risk of CIS in patients under the age of 50 years. This provides new insights into the link between LA dysfunction and CIS at young ages. (Searching for Explanations for Cryptogenic Stroke in the Young: Revealing the Etiology, Triggers, and Outcome [SECRETO]; NCT01934725).

Preoperative risk factors associated with left ventricular dysfunction after bariatric surgery

A large proportion of patients with severe obesity remain with left ventricular (LV) dysfunction after bariatric surgery. We assessed whether preoperative evaluation by echocardiography and inflammatory proteins can identify this high-risk group. In the Bariatric Surgery on the West Coast of Norway study, 75 patients (44 ± 10 years, body mass index [BMI] 41.5 ± 4.7 kg/m2) were prospectively evaluated by echocardiography and inflammatory proteins (high-sensitivity C-reactive protein [hsCRP], serum amyloid A [SAA] and calprotectin) before and one year after Roux-en-Y gastric bypass surgery. LV mechanics was assessed by the midwall shortening (MWS) and global longitudinal strain (GLS). Bariatric surgery improved BMI and GLS, and lowered hsCRP, calprotectin and SAA (p < 0.05). MWS remained unchanged and 35% of patients had impaired MWS at 1-year follow-up. A preoperative risk index including sex, hypertension, ejection fraction (EF) and high hsCRP (index 1) or SAA (index 2) predicted low 1-year MWS with 81% sensitivity/71% specificity (index 1), and 77% sensitivity/77% specificity (index 2) in ROC analyses (AUC 0.80 and 0.79, p < 0.001). Among individuals with severe obesity, women and patients with hypertension, increased serum levels of inflammatory proteins and reduced EF are at high risk of impaired LV midwall mechanics 1 year after bariatric surgery.ClinicalTrials.gov identifier NCT01533142 February 15, 2012.

Impact of Bariatric Surgery on Cardiac Function and Structure in Chinese Patients with Obesity

Introduction: Obesity contributes to cardiac dysfunction and has an impact on atherosclerotic cardiovascular disease. Bariatric surgery (BS) is being considered a therapeutic option for patients with obesity and also can improve cardiac function. Very few studies considered the Chinese population. This study aimed to examine the effect of BS on cardiac function and structure in Chinese subjects with obesity. Methods: A single-center retrospective analysis of 143 patients with obesity was included. To observe and analyze the short-term, midterm, and long-term effects of BS on cardiovascular function and structure, the study population was divided into three groups according to the time of review. Fifty-two patients in group T1 (re-examination within 12 months); 53 patients in group T2 (re-examination within 12 to 24 months); and 38 patients in group T3 (re-examination over 24 months). The effects of BS on the cardiac function and structure were evaluated by analyzing the echocardiographic parameters. Results: After BS, body mass index (BMI) decreased from 39.7 ± 8.0 to 28.4 ± 6.4 kg/m2 (P < 0.001). Blood pressure decreased significantly. Left ventricular mass index (LVMI) decreased (43.7 ± 16.4 to 37.8 ± 13.4 g/m2.7, P < 0.001). The change in LVMI was correlated with the change in BMI (R2 = 0.14, P < 0.001). In subgroup analyses at different follow-ups, echocardiographic parameters showed varying degrees of change compared with the baseline. Conclusions: Significant weight loss by BS was associated with improved left ventricular structure and function in Chinese patients with obesity, suggesting potential favorable effects of BS on the cardiac function and structure.

Energy substrate metabolism and oxidative stress in metabolic cardiomyopathy

Metabolic cardiomyopathy is an emerging cause of heart failure in patients with obesity, insulin resistance, and diabetes. It is characterized by impaired myocardial metabolic flexibility, intramyocardial triglyceride accumulation, and lipotoxic damage in association with structural and functional alterations of the heart, unrelated to hypertension, coronary artery disease, and other cardiovascular diseases. Oxidative stress plays an important role in the development and progression of metabolic cardiomyopathy. Mitochondria are the most significant sources of reactive oxygen species (ROS) in cardiomyocytes. Disturbances in myocardial substrate metabolism induce mitochondrial adaptation and dysfunction, manifested as a mismatch between mitochondrial fatty acid oxidation and the electron transport chain (ETC) activity, which facilitates ROS production within the ETC components. In addition, non-ETC sources of mitochondrial ROS, such as β-oxidation of fatty acids, may also produce a considerable quantity of ROS in metabolic cardiomyopathy. Augmented ROS production in cardiomyocytes can induce a variety of effects, including the programming of myocardial energy substrate metabolism, modulation of metabolic inflammation, redox modification of ion channels and transporters, and cardiomyocyte apoptosis, ultimately leading to the structural and functional alterations of the heart. Based on the above mechanistic views, the present review summarizes the current understanding of the mechanisms underlying metabolic cardiomyopathy, focusing on the role of oxidative stress.

Could Systemic Inflammation in Healthy Individuals With Obesity Indicate Subclinical Atherosclerosis?

Obesity is one of today's pandemics. The link between obesity and inflammation is well established and contributes to atherogenesis. We aimed to determine the relationship between carotid intima-media thickness (cIMT) and inflammation in healthy obese patients (n = 289). The patients were referred to the outpatient clinic due to obesity but had no chronic diseases. Subclinical atherosclerosis was defined as present in participants with cIMT values greater than those expected according to their age group. In patients with subclinical atherosclerosis, the neutrophil-lymphocyte ratio (1.86 ± .65 vs 1.57 ± .45, P < .01), platelet-lymphocyte ratio (120.0 ± 41.2 vs 106.8 ± 30.5, P ≤ .01), and systemic immune-inflammatory index (SII) (550.0 ± 232.8 vs 430.4 ± 135.0, P ≤ .01) were found to be higher. SII was the only independent risk factor for developing subclinical atherosclerosis (odds ratio (OR): 1.995, odds ratio (95% confidence interval): 1.692-4.099), P = .004). The area under the curve (AUC) was .664 (95% CI: .605-.729, P ≤ .001), and the optimal cut-off value was 436.7 (69.3% sensitivity and 61.6% specificity). In conclusion, SII may indicate subclinical atherosclerosis in healthy obese patients, thus leading to early initiation of treatment to reduce cardiovascular morbidity and mortality.

Markers of Subclinical Atherosclerosis in Severe Obesity and One Year after Bariatric Surgery

Background: Aortic valve sclerosis (AVS), mitral valve sclerosis (MVS), remodeling of major arteries, and increased pericardial fat are associated with subclinical atherosclerosis. We assessed these markers of atherosclerosis in severely obese patients before and 1 year after bariatric surgery. Methods: Eighty-seven severely obese patients (43 ± 10 years, preoperative body mass index [BMI] 41.8 ± 5 kg/m2) underwent echocardiography before and 1 year after Roux-en-Y bypass surgery in the FatWest (Bariatric Surgery on the West Coast of Norway) study. We measured the end-diastolic aortic wall thickness (AWT), pericardial fat thickness at the right ventricular free wall, and AVS/MVS based on combined aortic leaflet thickness and hyperechoic valve lesions. Results: Postoperatively, patients experienced a reduction of 12.9 ± 3.9 kg/m2 in BMI, 0.5 ± 1.9 mm in AWT, 2.6 ± 2.3 mm in pericardial fat, and 45%/53% in AVS/MVS (p < 0.05). In multivariate regression analyses with adjustment for clinical and hemodynamic variables, less pericardial fat reduction was associated with male sex and higher 1-year blood pressure and BMI, and less AWT-reduction with higher age and 1-year BMI (p < 0.05). Persistent AVS and MVS were related to higher 1-year BMI and more advanced valve sclerosis preoperatively (p < 0.05). Conclusions: Markers of subclinical atherosclerosis decreases significantly 1 year after bariatric surgery, particularly in younger patients that achieve a BMI < 28 kg/m2.

One-year impact of bariatric surgery on left ventricular mechanics: results from the prospective FatWest study

Aims

Patients with severe obesity are predisposed to left ventricular (LV) hypertrophy, increased myocardial oxygen demand, and impaired myocardial mechanics. Bariatric surgery leads to rapid weight loss and improves cardiovascular risk profile. The present prospective study assesses whether LV wall mechanics improve 1 year after bariatric surgery.

Methods and results

Ninety-four severely obese patients [43 ± 10 years, 71% women, body mass index (BMI) 41.8 ± 4.9 kg/m², 57% with hypertension] underwent echocardiography before, 6 months and 1 year after gastric bypass surgery in the FatWest (Bariatric Surgery on the West Coast of Norway) study. We assessed LV mechanics by midwall shortening (MWS) and global longitudinal strain (GLS), LV power/mass as 0.222 × cardiac output × mean blood pressure (BP)/LV mass, and myocardial oxygen demand as the LV mass-wall stress-heart rate product. Surgery induced a significant reduction in BMI, heart rate, and BP (P < 0.001). Prevalence of LV hypertrophy fell from 35% to 19% 1 year after surgery (P < 0.001). The absolute value of GLS improved by—4.6% (i.e. 29% increase in GLS) while LV ejection fraction, MWS, and LV power/mass remained unchanged. In multivariate regression analyses, 1 year improvement in GLS was predicted by lower preoperative GLS, larger mean BP, and BMI reduction (all P < 0.05). Low 1-year MWS was associated with female sex, preoperative hypertension, and higher 1-year LV relative wall thickness and myocardial oxygen demand (all P < 0.001).

Conclusion

In severely obese patients, LV longitudinal function is largely recovered one year after bariatric surgery due to reduced afterload. LV midwall mechanics does not improve, particularly in women and patients with persistent LV geometric abnormalities.

ClinicalTrials.gov identifier

NCT01533142, 15 February 2012.