SAN FRANCISCO – What do individuals with rheumatoid arthritis, systemic lupus erythematosus, and inflammatory bowel disease have in common?
They all have debilitating chronic diseases that throw off high levels of systemic inflammation. And what’s more, they share a newly recognized predisposition to atrial fibrillation compared with the general population, according to two studies presented at the annual meeting of the Heart Rhythm Society.
Dr. Prabhat Hebbar and his coworkers used the Nationwide Inpatient Sample database for 2008, which contains discharge diagnoses for roughly 1,000 U.S. hospitals in 40 states, to identify 86,497 patients with the diagnosis of atrial fibrillation (AF) and 100,000 randomly selected controls from the rest of the database.
The frequency of rheumatoid arthritis among patients with AF was 0.28%, compared with 0.13% in controls not having AF. The frequency of SLE in the AF population was 0.05%, compared with 0.12% in controls.
However, after adjusting for demographic factors – for example, patients with SLE were skewed considerably younger than were those with AF, and the AF group had significantly higher rates of comorbidities including hypertension, diabetes, and chronic obstructive pulmonary disease – the adjusted odds ratio for rheumatoid arthritis in patients with AF was 1.65. An identical odds ratio of 1.65 was found for SLE in AF patients, according to Dr. Hebbar of the University of Arkansas for Health Sciences, Little Rock.
The explanation for this association lies in the likely pathogenic role inflammation plays in AF. This inflammation can result from the physical handling of the heart during cardiac surgery, with the consequence of postoperative new-onset AF. Or the trigger can be the systemic inflammation that’s a key part of a chronic rheumatologic or gut disease.
This point was underscored by Dr. Deepak J. Pattanshetty in a separate retrospective cohort study. He and his coworkers reviewed the records of 142 patients with inflammatory bowel disease (IBD) at Metro Health Medical Center in Cleveland, and compared them with a large general population described in the Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) study of 1.89 million enrollees in Kaiser Permanente Northern California (JAMA 2001;285:2370-5).
The prevalence of AF in the IBD patients was 11%, compared with 0.95% in the Kaiser Permanente controls without IBD. This disparity is all the more striking given that the IBD patients were significantly younger, with a mean age of 57 years, compared with 71 years for controls.
Atrial fibrillation is the most common sustained arrhythmia. Its prevalence in the general population is strongly age-dependent, with a rate of less than 1.7% in individuals under age 65, rising to 4%-9% in 65- to 80-year-olds, and to 10% or more after age 80, noted Dr. Pattanshetty.
There were no significant differences between the IBD cohort and the controls in terms of hypertension, diabetes, and other conventional risk factors for AF. The explanation for the 11-fold increased prevalence of AF seen in patients with IBD probably is that recurrent flares of the gut disease are known to lead to increased systemic levels of C-reactive protein and inflammatory cytokines including interleukin-6. These could predispose to the atrial arrhythmia, said Dr. Pattanshetty.
The associations between AF and rheumatologic and gastrointestinal diseases not only provide insight into the pathogenesis of the arrhythmia, but also have a practical implication for patient care. Patients with these systemic diseases need to understand that they are at elevated risk for the arrhythmia, and that if they feel symptoms such as a rapid or irregular heart beat they should seek medical attention so that if they do have AF their stroke risk can be managed appropriately.
Dr. Hebbar and Dr. Pattanshetty declared having no financial conflicts of interest.