The impact of obesity on early postoperative atrial fibrillation burden

Artificial intelligence-based analysis of body composition predicts outcome in patients receiving long-term mechanical circulatory support

BACKGROUND

Obesity is a known cardiovascular risk factor and associated with higher postoperative complication rates in patients undergoing cardiac surgery. In heart failure (HF), conflicting evidence in terms of survival has been reported, whereas sarcopenia is associated with poor prognosis. An increasing number of HF patients require left ventricular assist device (LVAD) implantations. The postoperative mortality has improved in recent years but is still relatively high. The impact of body composition on outcome in this population remains unclear. The aim of this investigation was to examine the preoperative computed tomography (CT) body composition as a predictor of the postoperative outcome in advanced HF patients, who receive LVAD implantations.

METHODS

Preoperative CT scans of 137 patients who received LVADs between 2015 and 2020 were retrospectively analysed using an artificial intelligence (AI)-powered automated software tool based on a convolutional neural network, U-net, developed for image segmentation (Visage Version 7.1, Visage Imaging GmbH, Berlin, Germany). Assessment of body composition included visceral and subcutaneous adipose tissue areas (VAT and SAT), psoas and total abdominal muscle areas and sarcopenia (defined by lumbar skeletal muscle indexes). The body composition parameters were correlated with postoperative major complication rates, survival and postoperative 6-min walk distance (6MWD) and quality of life (QoL).

RESULTS

The mean age of patients was 58.21 ± 11.9 years; 122 (89.1%) were male. Most patients had severe HF requiring inotropes (Interagency Registry for Mechanically Assisted Circulatory Support [INTERMACS] profile I-III, 71.9%) secondary to coronary artery diseases or dilated cardiomyopathy (96.4%). Forty-four (32.1%) patients were obese (body mass index ≥ 30 kg/m2 ), 96 (70.1%) were sarcopene and 19 (13.9%) were sarcopene obese. Adipose tissue was associated with a significantly higher risk of postoperative infections (VAT 172.23 cm2 [54.96, 288.32 cm2 ] vs. 124.04 cm2 [56.57, 186.25 cm2 ], P = 0.022) and in-hospital mortality (VAT 168.11 cm2 [134.19, 285.27 cm2 ] vs. 135.42 cm2 [49.44, 227.91 cm2 ], P = 0.033; SAT 227.28 cm2 [139.38, 304.35 cm2 ] vs. 173.81 cm2 [97.65, 254.16 cm2 ], P = 0.009). Obese patients showed no improvement of 6MWD and QoL within 6 months postoperatively (obese: +0.94 ± 161.44 months, P = 0.982; non-obese: +166.90 ± 139.00 months, P < 0.000; obese: +0.088 ± 0.421, P = 0.376; non-obese: +0.199 ± 0.324, P = 0.002, respectively). Sarcopenia did not influence the postoperative outcome and survival within 1 year after LVAD implantation.

CONCLUSIONS

Preoperative AI-based CT body composition identifies patients with poor outcome after LVAD implantation. Greater adipose tissue areas are associated with an increased risk for postoperative infections, in-hospital mortality and impaired 6MWD and QoL within 6 months postoperatively.

Characteristics of Postoperative Atrial Fibrillation and the Effect of Posterior Pericardiotomy

BACKGROUND

Postoperative atrial fibrillation (POAF) is a frequent complication of cardiac surgery. However, only a few detailed descriptions of the arrhythmia have been reported. We aim to describe the characteristics, outcomes, and variables associated with POAF and to evaluate how posterior pericardiotomy (PP) affects POAF characteristics.

METHODS

In this post hoc analysis of the Posterior left pericardiotomy for the prevention of AtriaL fibrillation After Cardiac Surgery (PALACS) trial, we describe POAF characteristics based on continuous in-hospital telemetry data.

RESULTS

Of 420 patients, 103 (24.5%) developed POAF. Median time to onset was 50.3 hours; 70.9% of events occurred within 3 days. Hemodynamic instability and rapid ventricular response occurred in 8.7% and 51.5% of cases, respectively. Most POAF patients received antiarrhythmics (97.1%), 22.3% electrical cardioversion, and 40.8% systemic anticoagulation. Median POAF duration was 24.0 hours; 70.9% of cases resolved within 36 hours. Median POAF burden was 15.9%. All patients were in sinus rhythm at follow-up. POAF was associated with longer hospitalization (7 vs 6 days; P < .001), but not increased mortality or morbidity. PP reduced POAF incidence (17.7% vs 31.3%; P = .001), especially after postoperative day 2 (time to POAF onset 41.9 vs 57.1 hours; P = .01). Age was associated with POAF. Female sex, coronary artery bypass grafting, beta blockers, and PP were inversely associated.

CONCLUSIONS

POAF remains frequent after cardiac surgery. Hemodynamic instability is rare, although rapid ventricular response and need for electrical cardioversion are frequent. POAF burden is significant, and the arrhythmias resolve within 30 days. PP reduces POAF especially after postoperative day 2.

Impact of Obesity on Atrial Electrophysiological Substrate

(1) Background. Obesity is a well-established worldwide recognised risk factor for atrial fibrillation (AF). Prior review papers reported on the associations between obesity and AF development, but not on the relation between obesity and atrial electrophysiology. We therefore conducted a systematic review to describe the current knowledge of the characteristics of the atrial electrophysiological substrate in obese individuals and how they relate to the development of AF. (2) Methods. A search was conducted in Pubmed, Embase, and the Cochrane Library for publications evaluating the impact of obesity on atrial electrophysiology, electrical substrates, and their relation to the development of AF. (3) Results. A systematic literature search retrieved 477 potential publications based on the inclusion criteria; 76 full-text articles were selected for the present systematic review. The literature demonstrated that obesity predisposes to not only a higher AF incidence but also to more extensive atrial electrophysiological abnormalities increasing susceptibility to AF development. (4) Conclusion. Obesity may predispose to an overall increase in atrial electropathology, consisting of an increase in the slowing of the conduction, conduction block, low-voltage areas, and complex fractionated electrograms. To determine the impact of obesity-induced atrial electrical abnormalities on the long-term clinical outcome, further prospective studies are mandatory.

Effectiveness of pharmacological cardioversion of new-onset atrial fibrillation during thoracic surgery operations: a single-centre experience

OBJECTIVE

Prophylactic pharmacological conversion agents could reduce the incidence of postoperative atrial fibrillation (AF) in patients undergoing thoracic operations. The current study examined whether the use of pharmacological conversion agents could help to restore sinus rhythm in patients with AF newly developed during thoracic operations.

METHODS

Medical records of 18,605 patients from January 1, 2015 to December 31, 2019, at the Shanghai Chest Hospital were reviewed. Patients with non-sinus rhythm prior to the surgery (n = 128) were excluded from data analysis. The final analysis included 18,477 patients (n = 16,292 undergoing lung operations; n = 2,185 undergoing esophageal operations).

RESULTS

Intraoperative AF (defined as AF lasting for at least 5 min) occurred in 646 out of a total of 18,477 subjects (3.49%). Within the 646 subjects, 258 received pharmacological conversion agents during the surgery. sinus rhythm was restored in 20.15% (52/248) of patients treated with pharmacological cardioversion and in 20.87% (81/399) patients not receiving pharmacological intervention. In a subgroup analysis of the 258 patients receiving pharmacological conversion agents, recovery of sinus rhythm was highest in beta-blocker group (35.59%, 21/59 vs. 15.78%, 15/95 in amiodarone group, p = 0.008, 5.55%, and 1/18 in amiodarone plus beta-blockers group, p = 0.016). The incidence of hypotension was higher in pharmacological conversion (27.5% vs. 9.3% in patients not receiving pharmacological intervention, p < 0.001). In subjects not recovering to sinus rhythm during the surgery (n = 513), electrical cardioversion in post-anesthesia care unit (PACU) restored sinus rhythm in > 98% of the cases (155/158 vs. 63/355 in subjects not receiving cardioversion; p < 0.001).

CONCLUSIONS

Our experience shows that pharmacological conversion, in general, failed to show better treatment effectiveness on intraoperative new-onset AF within period of surgery except for beta-blockers. Patients with AF persisting beyond the surgery could be effectively managed with electrical cardioversion.

Impact of obesity on post-operative arrhythmias after congenital heart surgery in children and young adults

BACKGROUND

Obesity increases the risk of post-operative arrhythmias in adults undergoing cardiac surgery, but little is known regarding the impact of obesity on post-operative arrhythmias after CHD surgery.

METHODS

Patients undergoing CHD surgery from 2007 to 2019 were prospectively enrolled in the parent study. Telemetry was assessed daily, with documentation of all arrhythmias. Patients aged 2-20 years were categorised by body mass index percentile for age and sex (underweight <5, normal 5-85, overweight 85-95, and obese >95). Patients aged >20 years were categorised using absolute body mass index. We investigated the impact of body mass index category on arrhythmias using univariate and multivariate analysis.

RESULTS

There were 1250 operative cases: 12% underweight, 65% normal weight, 12% overweight, and 11% obese. Post-operative arrhythmias were observed in 38%. Body mass index was significantly higher in those with arrhythmias (18.8 versus 17.8, p = 0.003). There was a linear relationship between body mass index category and incidence of arrhythmias: underweight 33%, normal 38%, overweight 42%, and obese 45% (p = 0.017 for trend). In multivariate analysis, body mass index category was independently associated with post-operative arrhythmias (p = 0.021), with odds ratio 1.64 in obese patients as compared to normal-weight patients (p = 0.036). In addition, aortic cross-clamp time (OR 1.007, p = 0.002) and maximal vasoactive-inotropic score in the first 48 hours (OR 1.03, p = 0.04) were associated with post-operative arrhythmias.

CONCLUSION

Body mass index is independently associated with incidence of post-operative arrhythmias in children after CHD surgery.

Prehabilitation of Cardiac Surgical Patients, Part 1: Anemia, Diabetes Mellitus, Obesity, Sleep Apnea, and Cardiac Rehabilitation

The concept of "prehabilitation" consists of screening for and identification of pre-existing disorders followed by medical optimization. This is performed for many types of surgery, but may have profound impacts on outcomes particularly in cardiac surgery given the multiple comorbidities typically carried by these patients. Components of prehabilitation include direct medical intervention by preoperative specialists as well as significant care coordination and shared decision making. In this two-part review, the authors describe existing evidence to support the optimization of various preoperative problems and present a few institutional protocols utilized by our center for cardiac presurgical care. This first installment will focus on the management of anemia, obesity, sleep apnea, diabetes, and cardiac rehabilitation prior to surgery. The second will focus on frailty, malnutrition, respiratory disease, alcohol and smoking cessation, and depression.

Atrial fibrillation following coronary artery bypass graft: Where do we stand?

Atrial fibrillation (AF) is the most common atrial arrhythmia following coronary artery bypass graft (CABG). Its prevalence is 15-45% and is associated with poor long-term prognosis. Risk factors can be patient-related, intraoperative, and/or postoperative. Therapeutic and preventive strategies have been developed to curtail AF burden. Cardioversion is recommended for unstable or symptomatic patients and rate control if asymptomatic. Anticoagulation is challenging with risk of thromboembolism and bleeding. However, patients should be anticoagulated after cardioversion or if AF persists >48 h and risk factors of stroke exist. A minimum of 4 weeks is recommended but longer duration should be considered in patients at high risk of stroke irrespective of recurrence of AF.

A double-blind randomised controlled trial on the effect of Tocovid, a tocotrienol-rich capsule on postoperative atrial fibrillation at the National Heart Institute, Kuala Lumpur: an interim blinded analysis

INTRODUCTION

Post-operative atrial fibrillation (POAF) is associated with poorer outcomes, increased resource utilisation, morbidity and mortality. Its pathogenesis is initiated by systemic inflammation and oxidative stress. It is hypothesised that a potent antioxidant and anti-inflammatory agent such as tocotrienol, an isomer of Vitamin E, could reduce or prevent POAF.

AIMS

The aim of this study is to determine whether a potent antioxidative and anti-inflammatory agent, Tocovid, a tocotrienol-rich capsule, could reduce the incidence of POAF and affect the mortality and morbidity as well as the duration of ICU, HDU and hospital stay.

METHODS

This study was planned as a prospective, randomised, controlled trial with parallel groups. The control group received placebo containing palm superolein while the treatment group received Tocovid capsules. We investigated the incidence of POAF, the length of hospital stay after surgery and the health-related quality of life.

RESULTS

Recruitment commenced in January 2019 but the preliminary results were unblinded as the study is still ongoing. Two-hundred and two patients have been recruited out of a target sample size of 250 as of January 2021. About 75% have completed the study and 6.4% were either lost during follow-up or withdrew; 4% of participants died. The mean age group was 61.44 ± 7.30 years with no statistical difference between the groups, with males having a preponderance for AF. The incidence of POAF was 24.36% and the mean time for developing POAF was 55.38 ± 29.9 h post-CABG. Obesity was not a predictive factor. No statistically significant difference was observed when comparing left atrial size, NYHA class, ejection fraction and the premorbid history. The mean cross-clamp time was 71 ± 34 min and the mean bypass time was 95 ± 46 min, with no difference between groups. There was a threefold increase in death among patients with POAF (p = 0.008) and an increase in the duration of ICU stay (p = 0.01), the total duration of hospital stay (p = 0.04) and reintubation (p = 0.045).

CONCLUSION

A relatively low incidence rate of POAF was noted although the study is still ongoing. It remains to be seen if our prophylactic intervention using Tocovid would effectively reduce the incidence of POAF. Clinical Registration Number: US National Library of Medicine. Clinical Trials - NCT03807037. Registered on 16th January 2019. Link: https://clinicaltrials.gov/ct2/show/NCT03807037.

Overweight and aging increase the risk of atrial fibrillation after cardiac surgery independently of left atrial size and left ventricular ejection fraction

BACKGROUND

Body mass index (BMI), age, left atrium (LA) dimension and left ventricular ejection fraction (LVEF) have been linked to post-operative atrial fibrillation (POAF) after cardiac surgery. The aim of this study was to better define the role of these risk factors.

METHODS

This retrospective cohort study evaluated 249 patients (without prior atrial dysrhythmia) undergoing cardiac or aortic surgery. Prior to surgery, the following data were collected: age, BMI, LA diameter, LA area, LVEF, thyroid stimulating hormone (TSH), creatinine and the presence of arterial hypertension (AH) and diabetes. Intraoperative data such as operation time, total clamp time, cardiopulmonary bypass time, and presence of pericardial/pleural effusion were also collected. Only patients without pre- and post-surgery prophylactic anti-arrhythmic therapy were included.

RESULTS

Patients with (N = 127, 51%) and without POAF (N = 122, 49%) were compared. No difference was observed for sex, LA diameter, LA area, LVEF, TSH, diabetes and use of ACE inhibitors or statins prior to intervention. Moreover, no difference was observed in terms of operation time, total clamp time, cardiopulmonary bypass time, and presence of pericardial/pleural effusion. However, patients with POAF were older (70.6 ± 10.7 vs. 60.4 ± 16.4 years, p = 0.001), had higher BMI (26.8 ± 4.5 vs. 24.9 ± 3.6 kg/m2, p = 0.001), higher baseline creatinine (1.06 ± 0.91 vs. 0.88 ± 0.32 mg/dL, p = 0.038) and a higher frequency of arterial hypertension (73.2% vs. 50%, p = 0.001) and Bentall procedure (24.4% vs. 9.8%, p = 0.023). Multivariate analysis showed that the only independent predictors of POAF were age (OR = 1.05, 95%CI 1.02-1.07, p = 0.001) and BMI (OR = 1.11 95%CI 1.03-1.2,p = 0.006).

CONCLUSIONS

These findings suggest that advanced age and a higher BMI are strong risk factors for POAF in patients without previous AF even in the presence of comparable LA dimensions and LVEF.

High variability in bodyweight is associated with an increased risk of atrial fibrillation in patients with type 2 diabetes mellitus: a nationwide cohort study

Background

Bodyweight variability is a risk factor for atrial fibrillation (AF). We aimed to examine the relationship between bodyweight variability and the risk of AF in patients with type 2 diabetes mellitus (DM), and whether this relationship was affected by baseline body mass index (BMI), weight change, or advanced diabetic stage.

Methods

A nationwide population-based cohort of 670,797 patients with type 2 DM from the Korean National Health Insurance Service database without a history of AF and with ≥ 3 measurements of bodyweight over a 5-year period were followed up for AF development. Intra-individual bodyweight variability was calculated using variability independent of mean, and high bodyweight variability was defined as the quintile with the highest variability with the lower four quintiles as reference.

Results

During a median of 7.0 years of follow-up, 22,019 patients (3.3%) newly developed AF. After multivariate adjustment, those in the highest quintile of bodyweight variability showed a higher risk of incident AF (HR 1.16, 95% CI 1.12–1.20) compared to those in the lower 4 quintiles with reference bodyweight variability, irrespective of baseline BMI group and direction of overall weight change. This association was greater in magnitude in subjects with lower BMI, those on insulin, and those with a DM duration of greater than 5 years. In sensitivity analyses, high bodyweight variability was consistently associated with AF development using other indices of variability and adjusting for glycemic variability.

Conclusions

High variability in bodyweight was associated with AF development, independently of traditional cardiovascular risk factors and baseline BMI. This association was stronger in underweight patients and with advanced diabetic stage. Weight fluctuation may interfere with the beneficial effects of weight loss and should be avoided when possible in weight control regimens for DM patients.

Heterogeneity in Conduction Underlies Obesity-Related Atrial Fibrillation Vulnerability

BACKGROUND

Obese patients are more vulnerable to development of atrial fibrillation but pathophysiology underlying this relation is only partly understood. The aim of this study is to compare the severity and extensiveness of conduction disorders between obese patients and nonobese patients measured at a high-resolution scale.

METHODS

Patients (N=212) undergoing cardiac surgery (male:161, 63±11 years) underwent epicardial mapping of the right atrium, Bachmann bundle, and left atrium during sinus rhythm. Conduction delay (CD) was defined as interelectrode conduction time of 7 to 11 ms and conduction block (CB) as conduction time ≥12 ms. Prevalence of CD/CB, continuous CDCB (cCDCB), length of CD/CB/cCDCB lines, and severity of CB were analyzed.

RESULTS

In obese patients, the overall incidence of CD (3.1% versus 2.6%; P=0.002), CB (1.8% versus 1.2%; P<0.001), and cCDCB (2.6% versus 1.9%; P<0.001) was higher and CD (P=0.012) and cCDCB (P<0.001) lines are longer. There were more conduction disorders at Bachmann bundle and this area has a higher incidence of CD (4.4% versus 3.3%, P=0.002), CB (3.1% versus 1.6%, P<0.001), cCDCB (4.6% versus 2.7%, P<0.001) and longer CD (P<0.001) or cCDCB (P=0.017) lines. The severity of CB is also higher, particularly in the Bachmann bundle (P=0.008) and pulmonary vein (P=0.020) areas. In addition, obese patients have a higher incidence of early de-novo postoperative atrial fibrillation (P=0.003). Body mass index (P=0.037) and the overall amount of CB (P=0.012) were independent predictors for incidence of early postoperative atrial fibrillation.

CONCLUSIONS

Compared with nonobese patients, obese patients have higher incidences of conduction disorders, which are also more extensive and more severe. These differences in heterogeneity in conduction are already present during sinus rhythm and may explain the higher vulnerability to atrial fibrillation of obese patients.