Association Between Atrial Fibrillation and Costs After Myocardial Infarction: A Community Study.

BACKGROUND

The authors sought to estimate incremental economic impact of atrial fibrillation (AF) and the timing of its onset in myocardial infarction (MI) patients.

HYPOTHESIS

Concurrent AF and its timing are associated with higher costs in MI patients.

METHODS

This retrospective cohort study included incident MI patients from Olmsted County, Minnesota, treated between November 1, 2002, and December 31, 2010. We compared inflation-adjusted standardized costs accumulated between incident MI and end of follow-up among 3 groups by AF status and timing: no AF, new-onset AF (within 30 days after index MI), and prior AF. Multivariate adjustment of median costs accounted for right-censoring in costs.

RESULTS

The final study cohort had 1389 patients, with 989 in no AF, 163 in new-onset AF, and 237 in prior AF categories. Median follow-up times were 3.98, 3.23, and 2.55 years, respectively. Mean age at index was 67 years, with significantly younger patients in the no AF group (64 years vs 76 and 77 years, respectively; P < 0.001). New-onset and prior AF patients had more comorbid conditions (hypertension, heart failure, and chronic obstructive pulmonary disease). After accounting for differences in baseline characteristics, we found adjusted median (95% confidence interval) costs of $73 000 ($69 000-$76 000) for no AF; $85 000 ($81 000-$89 000) for new-onset AF; and $97 000 ($94 000-$100 000) for prior AF. Inpatient costs composed the largest share of total median costs (no AF, 82%; new-onset AF, 84%; prior AF, 83%).

CONCLUSIONS

Atrial fibrillation frequently coexists with MI and imposes incremental costs, mainly attributable to inpatient care. Timing of AF matters, as prior AF was found to be associated with higher costs than new-onset AF.