Late-Onset A-fib After MI Signals More Hospitalizations, Emergency Visits

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In patients with myocardial infarction (MI), the presence of atrial fibrillation (A-fib), particularly when it occurs a month or more after the initial infarct, is associated with greater health care resource utilization, according to research published online August 17, 2013, ahead of print in the American Heart Journal. The finding reinforces the importance of using evidence-based therapies to manage such patients, the authors say.

Investigators led by Veronique Roger, MD, MPH, of the Mayo Clinic (Rochester, MN), compared the risk of hospitalizations, emergency department (ED) visits, and outpatient visits in 1,502 MI patients with vs. without A-fib as well as the impact of the timing of A-fib within the first cohort. All patients presented to Mayo Clinic facilities in Olmsted County, MN, between November 2002 and December 2010.

Of the overall study population, 237 patients had prior A-fib, 163 developed new-onset A-fib (<30 days post MI), and 113 developed late-onset A-fib (≥30 days post MI). During a mean follow-up of 3.9 years, a history of A-fib, particularly late-onset, was associated with an increased risk of hospitalization and other health care utilization metrics, even after risk factor adjustment (table 1).

Table 1. Risk of Subsequent Health Care Utilization for Patients With vs. Without A-fib

Adjusted HRa

Prior A-fib
(95% CI)
(n = 237)

New-Onset A-fib
(95% CI)
(n = 163)

Late-Onset A-fib
(95% CI)
(n = 113)

Hospitalizations

1.50
(1.25-1.81)

1.24
(1.02-1.50)

1.79
(1.35-2.38)

ER Visitsa

1.39
(1.15-1.69)

1.11
(0.90-1.36)

1.56
(1.20-2.01)

Outpatient Office Visitsa

1.39
(1.24-1.57)

1.20
(1.04-1.38)

1.58
(1.35-1.85)

a Adjusted for age, sex, BMI, ever smoking, eGFR, STEMI, Killip class, peak troponin, hypertension, hyperlipidemia, diabetes, heart failure, COPD, recurrent MI, and heart failure post-MI.

The association of A-fib status with hospitalization was higher for cardiovascular compared with noncardiovascular hospitalization, regardless of A-fib timing.

“Our data . . . confirm that [A-fib] is an important prognostic indicator in MI patients,” the authors say. “However, the evidence base for management of patients with coexisting MI and A-fib is limited; and additional trials are needed to improve evidence-based management strategies for these individuals.”

Late-Onset A-fib is a Marker of . . . ?

In a telephone interview with TCTMD, Neal S. Kleiman, MD, of Methodist DeBakey Heart and Vascular Center (Houston, TX), pointed out that patients with late-onset A-fib had more variables associated with a poor prognosis, such as older age, female sex, and heart failure. Though the authors adjusted for these factors, statistical adjustments are never perfect and only control for recognized factors, he added.

Late onset-A-fib is probably a prognostic marker, Dr. Kleiman admitted, “but the real question is, is it a marker for underlying illness or someone paying less attention to using established therapies in these patients? Should someone have gotten an ACE inhibitor and didn’t?” Even though a greater proportion of patients with late-onset A-fib were treated with ACE inhibitors or angiotensin receptor blockers than in the other groups, “it may well be that the proportion who needed an ACE inhibitor and didn’t get it was higher in the late-onset A-fib group,” he observed. Another possibility, he added, is that late-onset patients may have received suboptimal dosing.

“The message I [take from this study] is, if somebody’s got indications for established, evidence-based therapies, you have to pay attention to that,” Dr. Kleiman concluded.

 


Source:
Chamberlain AM, Bielinski SJ, Weston SA, et al. Atrial fibrillation in myocardial infarction patients: Impact on health care utilization. Am Heart J 2013;Epub ahead of print.

 

 

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Disclosures
  • Drs. Roger and Kleiman report no relevant conflicts of interest.

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