ORLANDO — Patients with poorly controlled and long-standing diabetes were about twice as likely to develop atrial fibrillation as people without diabetes in a case-control study with a total of more than 2,000 people.
This finding comes from the first reported study to examine in detail a link between diabetes and atrial fibrillation (AF), Dr. Sascha Dublin said while presenting a poster at a conference on cardiovascular disease epidemiology and prevention sponsored by the American Heart Association.
Diabetes may be linked to an increased vulnerability to developing AF through chronic inflammation, diastolic dysfunction and left atrial enlargement, or by the link of diabetes with obesity, which can lead to obstructive sleep apnea, a disorder that may increase the risk for AF, said Dr. Dublin, a physician at the Veterans Affairs Puget Sound Health Care System in Seattle.
The study involved people enrolled in a large Seattle-area HMO who were aged 30–84 years, and included men with hypertension and women with or without hypertension. The analysis focused on 877 patients who were newly diagnosed with AF in October 2001-September 2003, and 1,336 controls selected as a stratified, random sample.
The overall prevalence of diabetes was 23% among the patients with AF and 18% among the controls, a difference that was not statistically significant. In an analysis that focused on the efficacy of hyperglycemia control and on the duration of diabetes, patients with diabetes for more than the median (7.8 years) as well as a hemoglobin A1c level that was greater than the median (7.7%) were 2.1-fold more likely to have AF, compared with control individuals, a statistically significant difference. This analysis controlled for several possible confounders, including age, gender, calendar year, body mass index, and treatment for hypertension.
A second analysis of the prevalence of treated diabetes that controlled for all of these confounders as well as coronary artery disease and cardiovascular disease risk factors showed that patients with treated diabetes were significantly more likely to also have AF, compared with people without diabetes. Because this is the first evidence linking diabetes and AF, it's premature to make strong recommendations for revised patient management based on the findings, but it would be reasonable for physicians to have a heightened awareness for AF in patients with diabetes, especially if patients with diabetes present with new symptoms of fatigue, shortness of breath, or other symptoms of AF, Dr. Dublin said in an interview. Physicians should also be alert to the presence of heart-exam abnormalities in patients with diabetes and look for AF if an abnormality is found. It's also reasonable to screen patients with AF for diabetes with a fasting glucose test.
A possible link between diabetes and AF may also have treatment implications. It's currently not known whether any oral hypoglycemic medications affect AF. Some evidence exists that ACE inhibitors and angiotensin-receptor blockers, which are often used to treat diabetes, may decrease the risk of developing AF, but this possible effect needs further study.
Another issue to keep in mind is that β-blockers, a drug class that's often used for heart rate control in patients with AF, may worsen glycemic control in patients with diabetes. This also needs more study, Dr. Dublin said.