Clinical research study
Coronary Ischemic Events after First Atrial Fibrillation: Risk and Survival

https://doi.org/10.1016/j.amjmed.2006.06.042Get rights and content

Abstract

Purpose

We aimed to determine the long-term, gender-specific incidence and mortality risk of coronary ischemic events after first atrial fibrillation (AF).

Methods

In this longitudinal cohort study, adult residents of Olmsted County, Minnesota, with an electrocardiogram-confirmed AF first documented in 1980 to 2000 and without prior coronary heart disease, were followed to 2004. The primary outcome was first coronary events (angina with angiographic confirmation, unstable angina, nonfatal myocardial infarction, or coronary death). Sex-specific incidence of coronary ischemic events and survival after development of such events were assessed using Cox proportional hazards modeling. Kaplan-Meier estimates of risks for coronary ischemic events were compared with those predicted by the Framingham equation.

Results

Of the 2768 subjects (mean age 71 years, 48% were men), 463 (17%) had a first coronary event during a follow-up of 6.0 ± 5.2 years. The unadjusted incidence was 31 per 1000 person-years, and there was no difference between men and women. The incidence was higher in men (hazard ratio 1.32, P = .004) after adjusting for age. The 10-year event estimates were 22% and 19% in men and women, respectively, by our Kaplan-Meier analyses, and 21% and 11%, respectively, by Framingham risk equation. The mortality risk after coronary events was higher in women (hazard ratio 2.99 vs 2.33; P = .044), even after multiple adjustment.

Conclusions

First AF marks a high risk for new coronary ischemic events in both men and women. AF conferred additional risk for coronary events beyond conventional risk prediction in women only. The excess mortality risk associated with the development of coronary events was significantly greater in women.

Section snippets

Study Setting

The community-based cohort study was approved by the Mayo Foundation Institutional Review Board. Olmsted County, Minnesota, is well suited for the conduct of studies with long-term follow-up because of a number of unique features.12 Geographically, the community is relatively isolated from other urban centers, and medical care is delivered by only a few health care providers, principally the Mayo Clinic and its associated hospitals. The majority of Olmsted County residents return to the Mayo

Results

A total of 4618 subjects (51% were men; mean age 73 years) were confirmed to have developed a first AF during 1980 to 2000. We excluded 1776 subjects (38%) because they had a history of coronary heart disease and 74 subjects (2%) because they had a coronary ischemic event that occurred on the same day as the first AF. The remaining 2768 subjects (48% were men, mean age 71 years, range 18-107 years) constituted the study population. Of these, 463 patients (17%) had a total of 841 coronary

Discussion

In our community-based cohort, the first AF marks a high risk for new coronary ischemic events in both men and women. In contrast with men, AF conferred an additional risk of ischemic events in women beyond conventional risk prediction. The excess mortality risk associated with the development of new coronary ischemic events was greater in women.

Limitations

There were inherent biases associated with the retrospective design. It is possible that the incidence of AF may have been underestimated, given that some patients may not have received care at the Mayo Clinic, although the underestimation would likely be small because the Mayo Clinic is the principal health care provider and referral center for Olmsted County.12 Also, we may have underestimated the coronary event rates because we did not include those who had presumed angina but did not have

Conclusions

Patients diagnosed with a first AF constitute a high-risk group for subsequent new coronary ischemic events. Although the age-adjusted incidence of such post-AF coronary ischemic events was higher in men, AF actually conferred an additional risk for the development of ischemic events, beyond conventional risk prediction, in women only. Further, the excess mortality risk associated with the development of post-AF new coronary events was greater in women.

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This study was supported by the American Heart Association National Scientist Development Grant. There is no financial conflict on the part of any author.

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