Clinical research study
Influence of Obesity on Outcomes in Atrial Fibrillation: Yet Another Obesity Paradox

Part of the study results were presented as a poster at the 30th Annual Scientific Sessions of the Heart Rhythm Society held in Boston, MA, May 2009.
https://doi.org/10.1016/j.amjmed.2009.11.026Get rights and content

Abstract

Background

Obese patients have favorable outcomes in congestive heart failure, hypertension, peripheral vascular disease, and coronary artery disease. Obesity also has been linked with increased incidence of atrial fibrillation, but its influence on outcomes in atrial fibrillation patients has not been investigated. The objective of this research is to investigate the effect of obesity on outcomes in atrial fibrillation.

Methods

The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study was one of the largest multicenter trials of atrial fibrillation, with 4060 patients. Subjects were randomized to rate versus rhythm-control strategy. We performed a post hoc analysis of the National Heart, Lung and Blood Institute limited access dataset of atrial fibrillation patients who had body mass index (BMI) data available in the AFFIRM study. BMI data were not available on 1542 patients. Patients with BMI ≥18.5 were split into normal (18.5-25), overweight (25-30), and obese (>30) categories as per BMI (kg/m2). Multivariate Cox proportional hazards regression was used on the eligible 2492 patients. End points were all-cause mortality and cardiovascular mortality.

Results

Over three fourths of all patients in our cohort were overweight or obese. There were 304 deaths (103 among normal weight, 108 among overweight, and 93 among obese) and 148 cardiovascular deaths (54 among normal weight, 41 among overweight, and 53 among obese) over a mean period of 3 years of patient follow-up. On multivariate analysis, overweight (hazard ratio [HR] 0.64; 95% confidence interval [CI], 0.48-0.84; P = .001) and obese (HR 0.80; 95% CI, 0.68-0.93; P = .005) categories were associated with lower all-cause mortality as compared with normal weight. Overweight (HR 0.40; 95% CI, 0.26-0.60; P <.001) and obese patients (HR 0.77; 95% CI, 0.62-0.95; P = .01) also had lower cardiovascular mortality as compared with the normal weight patients.

Conclusions

Although in prior studies, obesity has been associated with increased risk of atrial fibrillation, an obesity paradox exists for outcomes in atrial fibrillation. Obese patients with atrial fibrillation appear to have better long-term outcomes than nonobese patients.

Section snippets

Methods

We performed a post hoc analysis of the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) Trial. A public-use limited-access dataset that was devoid of all patient identifiers was obtained from the National Heart, Lung and Blood Institute (NHLBI). None of the authors are affiliated with the NHLBI or were part of the AFFIRM trial. Appropriate Institutional Review Board approval was obtained from Wayne State University.

Details of the AFFIRM study have been described

Results

There were 637 patients with normal BMI, 965 in the overweight category, and 890 in the obese group. Baseline characteristics of patients in each group are shown in Table 1. Mean age for the entire study population was 69.5 ± 8 years, and 60.71% of the population were males; 16.57% had history of myocardial infarction and 21.31% had history of congestive heart failure. Mean BMI was 29.02 ± 5.9 kg/m2. A total of 304 deaths and 148 cardiovascular deaths occurred over the approximately 3-year/patient

Discussion

In our study, almost three fourths of all atrial fibrillation patients were obese or overweight. We report for the first time a beneficial effect of increasing BMI on outcomes in atrial fibrillation. Because the AFFIRM trial population is considered to be a reasonable representation of the general atrial fibrillation population, our study has significant implications. Similar “obesity paradoxes” have been observed among the elderly and for disorders such as acquired immune deficiency syndrome,

Acknowledgment

The authors would like to thank the National Heart, Lung and Blood Institute (NHLBI), Mr. Sean Coady (NHLBI), and Mr. Kevin Purkiser (NHLBI) for all their help and input.

References (53)

  • C.J. Lavie et al.

    The “obesity paradox”: is smoking/lung disease the explanation?

    Chest

    (2008)
  • C.J. Lavie et al.

    Obesity and cardiovascular disease: risk factor, paradox, and impact of weight loss

    J Am Coll Cardiol

    (2009)
  • P. McAuley et al.

    Body mass, fitness and survival in veteran patients: another obesity paradox?

    Am J Med

    (2007)
  • K. Kalantar-Zadeh et al.

    Reverse epidemiology of cardiovascular risk factors in maintenance dialysis patients

    Kidney Int

    (2003)
  • T.T. Issac et al.

    Role of inflammation in initiation and perpetuation of atrial fibrillation: a systematic review of the published data

    J Am Coll Cardiol

    (2007)
  • S.H. Lee et al.

    Tumor necrosis factor-alpha alters calcium handling and increases arrhythmogenesis of pulmonary vein cardiomyocytes

    Life Sci

    (2007)
  • M.A. Weber et al.

    Contrasting clinical properties and exercise responses in obese and lean hypertensive patients

    J Am Coll Cardiol

    (2001)
  • A. Rossi et al.

    Natriuretic peptide levels in atrial fibrillation: a prospective hormonal and Doppler-echocardiographic study

    J Am Coll Cardiol

    (2000)
  • M. Rauchhaus et al.

    The endotoxin-lipoprotein hypothesis

    Lancet

    (2000)
  • C.J. Boos et al.

    Endotoxemia, inflammation, and atrial fibrillation

    Am J Cardiol

    (2007)
  • T.B. Horwich et al.

    The relationship between obesity and mortality in patients with heart failure

    J Am Coll Cardiol

    (2001)
  • C.J. Lavie et al.

    The obesity paradox, weight loss, and coronary disease

    Am J Med

    (2009)
  • C.J. Lavie et al.

    Body composition and prognosis in chronic systolic heart failure: the obesity paradox

    Am J Cardiol

    (2003)
  • E. Braunwald

    Shattuck lecture—cardiovascular medicine at the turn of the millennium: triumphs, concerns, and opportunities

    N Engl J Med

    (1997)
  • Y. Miyasaka et al.

    Secular trends in incidence of atrial fibrillation in Olmsted County, Minnesota, 1980 to 2000, and implications on the projections for future prevalence

    Circulation

    (2006)
  • E.J. Benjamin et al.

    Impact of atrial fibrillation on the risk of death: the Framingham Heart Study

    Circulation

    (1998)
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    Funding: None.

    Conflict of Interest: None of the authors have any financial disclosure or conflict of interest to report. None of the study authors are associated with the National Heart, Lung and Blood Institute or the Atrial Fibrillation Follow-up Investigation of Rhythm Management trial.

    Authorship: All authors had access to the data and were involved in the conception, data analysis, and writing of the manuscript.

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