Obesity Paradox in Atrial Fibrillation: Implications for Outcomes and Relationship with Oral Anticoagulant Drugs

Clinical Outcomes in Metabolically Healthy and Unhealthy Obese and Overweight Patients With Atrial Fibrillation: Findings From the GLORIA-AF Registry

OBJECTIVE

To explore the association between metabolic status, body mass index (BMI), and natural history of patients with atrial fibrillation (AF).

METHODS

The global, prospective GLORIA-AF Registry Phase II and III included patients with recent diagnosis of AF between November 2011 and December 2014 for Phase II and between January 2014 and December 2016 for Phase III. With this analysis, we categorized patients with AF according to BMI (normal weight [18.5 to 24.9 kg/m2], overweight [25.0 to 29.9 kg/m2], obese [30.0 to 60.0 kg/m2]) and metabolic status (presence of hypertension, diabetes, and hyperlipidemia). We analyzed risk of major outcomes using multivariable Cox regression analyses; the primary outcome was the composite of all-cause death and major adverse cardiovascular events.

RESULTS

There were 24,828 (mean age, 70.1±10.3 years; 44.6% female) patients with AF included. Higher BMI was associated with metabolically unhealthy status and higher odds of receiving oral anticoagulants and other treatments. Normal-weight unhealthy patients showed a higher risk of the primary composite outcome (adjusted hazard ratio [aHR], 1.20; 95% CI, 1.01 to 1.42) and thromboembolism, whereas a lower risk of cardiovascular death (aHR, 0.35; 95% CI, 0.14 to 0.88) and major adverse cardiovascular events (aHR, 0.56; 95% CI, 0.33 to 0.93) was observed in metabolically healthy obese individuals. Unhealthy metabolic groups were also associated with increased risk of major bleeding (aHR, 1.51 [95% CI, 1.04 to 2.20] and aHR, 1.96 [95% CI, 1.34 to 2.85] in overweight and obese groups, respectively).

CONCLUSION

Increasing BMI was associated with poor metabolic status and with more intensive treatment. Prognosis was heterogeneous between BMI groups, with metabolically unhealthy patients showing higher risk of adverse events.

Fibrinaloid Microclots and Atrial Fibrillation

Atrial fibrillation (AF) is a comorbidity of a variety of other chronic, inflammatory diseases for which fibrinaloid microclots are a known accompaniment (and in some cases, a cause, with a mechanistic basis). Clots are, of course, a well-known consequence of atrial fibrillation. We here ask the question whether the fibrinaloid microclots seen in plasma or serum may in fact also be a cause of (or contributor to) the development of AF. We consider known 'risk factors' for AF, and in particular, exogenous stimuli such as infection and air pollution by particulates, both of which are known to cause AF. The external accompaniments of both bacterial (lipopolysaccharide and lipoteichoic acids) and viral (SARS-CoV-2 spike protein) infections are known to stimulate fibrinaloid microclots when added in vitro, and fibrinaloid microclots, as with other amyloid proteins, can be cytotoxic, both by inducing hypoxia/reperfusion and by other means. Strokes and thromboembolisms are also common consequences of AF. Consequently, taking a systems approach, we review the considerable evidence in detail, which leads us to suggest that it is likely that microclots may well have an aetiological role in the development of AF. This has significant mechanistic and therapeutic implications.

The "obesity paradox" in patients with atrial fibrillation: Insights from the Gulf SAFE registry

BACKGROUND

The prognostic impact of obesity on patients with atrial fibrillation (AF) remains under-evaluated and controversial.

METHODS

Patients with AF from the Gulf Survey of Atrial Fibrillation Events (Gulf SAFE) registry were included, who were recruited from six countries in the Middle East Gulf region and followed for 12 months. A multivariable model was established to investigate the association of obesity with clinical outcomes, including stroke or systemic embolism (SE), bleeding, admission for heart failure (HF) or AF, all-cause mortality, and a composite outcome. Restricted cubic splines were depicted to illustrate the relationship between body mass index (BMI) and outcomes. Sensitivity analysis was also conducted.

RESULTS

A total of 1,804 patients with AF and recorded BMI entered the final analysis (mean age 56.2 ± 16.1 years, 47.0% female); 559 (31.0%) were obese (BMI over 30 kg/m2). In multivariable analysis, obesity was associated with reduced risks of stroke/systematic embolism [adjusted odds ratio (aOR) 0.40, 95% confidence interval (CI), 0.18-0.89], bleeding [aOR 0.44, 95%CI, 0.26-0.74], HF admission (aOR 0.61, 95%CI, 0.41-0.90) and the composite outcome (aOR 0.65, 95%CI, 0.50-0.84). As a continuous variable, higher BMI was associated with lower risks for stroke/SE, bleeding, HF admission, all-cause mortality, and the composite outcome as demonstrated by the accumulated incidence of events and restricted cubic splines. This "protective effect" of obesity was more prominent in some subgroups of patients.

CONCLUSION

Among patients with AF, obesity and higher BMI were associated with a more favorable prognosis in the Gulf SAFE registry. The underlying mechanisms for this obesity "paradox" merit further exploration.

Impact of anthropometric factors on outcomes in atrial fibrillation patients: analysis on 10 220 patients from the European Society of Cardiology (ESC)-European Heart Rhythm Association (EHRA) EurObservational Research Programme on Atrial Fibrillation (EORP-AF) general long-term registry

AIM

To investigate the association of anthropometric parameters [height, weight, body mass index (BMI), body surface area (BSA), and lean body mass (LBM)] with outcomes in atrial fibrillation (AF).

METHODS AND RESULTS

Ten-thousand two-hundred twenty patients were enrolled [40.3% females, median age 70 (62-77) years, followed for 728 (interquartile range 653-745) days]. Sex-specific tertiles were considered for the five anthropometric variables. At the end of follow-up, survival free from all-cause death was worse in the lowest tertiles for all the anthropometric variables analyzed. On multivariable Cox regression analysis, an independent association with all-cause death was found for the lowest vs. middle tertile when body weight (hazard ratio [HR] 1.66, 95%CI 1.23-2.23), BMI (HR 1.65, 95%CI 1.23-2.21), and BSA (HR 1.49, 95%CI 1.11-2.01) were analysed in female sex, as well as for body weight in male patients (HR 1.61, 95%CI 1.25-2.07). Conversely, the risk of MACE was lower for the highest tertile (vs. middle tertile) of BSA and LBM in males and for the highest tertile of weight and BSA in female patients. A higher occurrence of haemorrhagic events was found for female patients in the lowest tertile of height [odds ratio (OR) 1.90, 95%CI 1.23-2.94] and LBM (OR 2.13, 95%CI 1.40-3.26).

CONCLUSIONS

In AF patients height, weight, BMI, BSA, and LBM were associated with clinical outcomes, with all-cause death being higher for patients presenting lower values of these variables, i.e. in the lowest tertiles of distribution. The anthropometric variables independently associated with other outcomes were also different between male and female subjects.

Impact of body mass index on the outcome of elderly patients treated with transcatheter aortic valve implantation

Underweight or overweight patients with cardiovascular diseases are associated with different outcomes. However, the data on the relation between body mass index (BMI) and outcomes after transcatheter aortic valve implantation (TAVI) are not homogeneous. The aim of this study was to assess the role of low BMI on short and long-term mortality in real-world patients undergoing TAVI. We retrospectively included patients undergoing TAVI for severe aortic valve stenosis. Patients were classified into three BMI categories: underweight (< 20 kg/m²), normal weight (20-24.9 kg/m²) and overweight/obese (≥ 25 kg/m²). Our primary endpoint was long-term all-cause mortality. The secondary endpoint was 30-day all-cause mortality. A total of 794 patients were included [mean age 82.3 ± 5.3, 53% females]. After a median follow-up of 2.2 years, all-cause mortality was 18.1%. Patients in the lowest BMI group showed a higher mortality rate as compared to those with higher BMI values. At the multivariate Cox regression analysis, as compared to the normal BMI group, BMI < 20 kg/m² was associated with long-term mortality independently of baseline risk factors and postprocedural adverse events (hazard ratio [HR] 2.29, 95% confidence interval [CI] 1.30-4.03] and HR 2.61, 95% CI 1.48-4.60, respectively). The highest BMI values were found to be protective for both short- and long-term mortality as compared to lower BMI values even after applying the same adjustments. In our cohort, BMI values under 20 kg/m² were independent predictors of increased long-term mortality. Conversely, the highest BMI values were associated with lower mortality rates both at short- and long-term follow-up.

“The obesity paradox” in patients with atrial fibrillation according to the results of the REKUR-AF study

Introduction: to evaluate the effect of excess body weight (EBW) and obesity on the survival of patients with atrial fibrillation (AF) in the REKUR-AF study.

Materials and methods: A subanalysis of patients with AF included in the REKUR-AF (382 people) study was performed. Survival rates were analyzed in three patient groups: patients with normal body mass index (BMI), EBW and obesity. Then the nature and significance of the influence of the studied factor on the prognosis in patients with AF were assessed.

Results and discussion: Patients with AF and normal BMI were significantly older than those with obesity and EBW (p&lt;0.001 and p=0.021, respectively). Among obese patients, hypertension was significantly (p=0.0015) more common (93.9%) compared to the group of patients with a normal BMI level (80.5%). The frequency of type 2 diabetes in obese patients prevailed over the same indicator in the groups of people with normal BMI and EBW (p=0.007 and p=0.020, respectively).

The analysis of the survival rate of patients with AF depending on the BMI level showed that this factor had a significant impact (p=0.013) on the prognosis. The group of individuals with a normal BMI level had a significantly lower survival rate than the cohort of patients with EBW (p=0.011) and OB (p=0.025). The final model for Cox regression analysis (χ2=53.06, p&lt;0.001) included the following factors: age, form of AF, BMI, presence/absence of type 2 diabetes, presence/absence of previous hospitalizations, presence/absence of hypertension, and presence/absence of oral anticoagulant (OAC) intake.

Conclusion: The obtained results do not make it possible to unambiguously interpret obesity as a predictor of a positive outcome in this category of individuals.

Direct Oral Anticoagulants in Patients with Obesity and Atrial Fibrillation: Position Paper of Italian National Association of Hospital Cardiologists (ANMCO)

The use of the direct oral anticoagulants dabigatran, rivaroxaban, apixaban and edoxaban (DOACs) offers some major advantages over warfarin and other vitamin K antagonists (VKAs). One advantage is the possibility to use a fixed dose in normal-weight patients, overweight patients and patients with obesity. However, the "one size fits all" strategy raised a concern regarding the possibility to undertreat patients with a high body mass index. No randomized controlled trials (RCTs) have ever compared VKAs and DOACs in this population. We analyzed data from the literature on DOAC pharmacokinetics and pharmacodynamics, results from the four pivotal phase III trials on non-valvular atrial fibrillation, retrospective observational studies and metanalyses. While we are aware of the limitation imposed by the absence of specific RCTs, we propose the position of the Italian Association of Hospital Cardiologists (ANMCO) on the use of DOACs in patients with obesity based on the existing evidence.

Optimizing indices of AF susceptibility and burden to evaluate AF severity, risk and outcomes

Atrial fibrillation (AF) has heterogeneous patterns of presentation concerning symptoms, duration of episodes, AF burden, and the tendency to progress towards the terminal step of permanent AF. AF is associated with a risk of stroke/thromboembolism traditionally considered dependent on patient-level risk factors rather than AF type, AF burden, or other characterizations. However, the time spent in AF appears related to an incremental risk of stroke, as suggested by the higher risk of stroke in patients with clinical AF vs. subclinical episodes and in patients with non-paroxysmal AF vs. paroxysmal AF. In patients with device-detected atrial tachyarrhythmias, AF burden is a dynamic process with potential transitions from a lower to a higher maximum daily arrhythmia burden, thus justifying monitoring its temporal evolution. In clinical terms, the appearance of the first episode of AF, the characterization of the arrhythmia in a specific AF type, the progression of AF, and the response to rhythm control therapies, as well as the clinical outcomes, are all conditioned by underlying heart disease, risk factors, and comorbidities. Improved understanding is needed on how to monitor and modulate the effect of factors that condition AF susceptibility and modulate AF-associated outcomes. The increasing use of wearables and apps in practice and clinical research may be useful to predict and quantify AF burden and assess AF susceptibility at the individual patient level. This may help us reveal why AF stops and starts again, or why AF episodes, or burden, cluster. Additionally, whether the distribution of burden is associated with variations in the propensity to thrombosis or other clinical adverse events. Combining the improved methods for data analysis, clinical and translational science could be the basis for the early identification of the subset of patients at risk of progressing to a longer duration/higher burden of AF and the associated adverse outcomes.

Influence of BMI and geographical region on prescription of oral anticoagulants in newly diagnosed atrial fibrillation: The GLORIA-AF Registry Program

OBJECTIVE

To investigate the association between body mass index (BMI) and oral anticoagulant (OAC) prescription in atrial fibrillation (AF).

METHODS

Patients with newly diagnosed non-valvular AF (<3 months) with ≥1 stroke risk factors enrolled in the Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation (GLORIA-AF) in Asia, Europe and North America were evaluated.

RESULTS

The cohort (n = 13,793) comprised patients from all BMI categories (kg/m²): 1.4% were underweight (<18.5), 27.3% had a normal BMI (18.5 to <25), 37.9% were overweight (25 to <30), 19.3% were moderately obese (30 to <35), and 12.7% were morbidly obese (≥35). The highest proportion of Asians had a BMI of 18.5 to <25 kg/m², while the highest proportion of patients from Europe and North America were overweight and a substantial proportion of North Americans morbidly obese. In the multivariable analysis, the probability ratio of non-prescription of OAC, as compared to normal BMI, decreased for overweight (RR = 0.907), moderately obese (RR = 0.802) and severe very severe obese patients (RR = 0.659). Moreover, the probability ratio of non-prescription of OACs was increased in the Asia or North America regions, as compared with Europe, in patients aged <65 years or female patients, as well as in patients with prior bleeding or vascular disease.

CONCLUSIONS

The distribution of BMI differed among the continents. An increased BMI was associated with a lower probability of non-prescription of OACs, as compared with a normal BMI. The probability of non-prescription of OACs was increased in the Asia or North America regions, as compared with Europe.

Direct Oral Anticoagulants in Obesity: An Updated Literature Review

OBJECTIVE

To review literature on the use of direct-acting oral anticoagulants (DOACs) in patients with high body weight (BW) and/or high body mass index (BMI) and to make recommendations regarding use in this patient population.

DATA SOURCES

A search using PubMed was conducted (inception to April 13, 2020) using the term DOAC AND the terms obesity OR body weight. A separate search was also conducted with individual DOACs (dabigatran, apixaban, rivaroxaban, edoxaban) and the aforementioned terms.

STUDY SELECTION AND DATA EXTRACTION

Studies included examined the effect of BW and/or BMI on DOAC pharmacokinetics, efficacy, or safety. Included studies had DOAC indications of prevention of stroke in nonvalvular atrial fibrillation, or treatment or long-term prevention of venous thromboembolism.

DATA SYNTHESIS

The efficacy and safety of DOACs in patients with high BW/BMI has not yet been elucidated by randomized trials; however, 2016 international guidelines suggest avoiding their use in patients with a BW >120 kg or BMI >40 kg/m². Since 2016, several studies have been published examining use of DOACs in this patient population.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review thoroughly discusses the literature on DOACs in patients with a BW >120 kg or BMI >40 kg/m² pre-2016 and post-2016 guidelines.

CONCLUSIONS

Evidence indicates that each DOAC may have differences in outcomes when used in patients with a high BW/BMI. Currently, low-quality data are available that support avoiding dabigatran and considering apixaban or rivaroxaban; lack of sufficient data preclude a recommendation for edoxaban use in this patient population.