Impact of Epicardial Anterior Fat Pad Retention on Postcardiothoracic Surgery Atrial Fibrillation Incidence: The AFIST-III Study

1
Impact of Epicardial Anterior Fat Pad Retention
on Postcardiothoracic Surgery Atrial Fibrillation
Incidence The AFIST-III Study

• Impact of Epicardial Anterior Fat Pad Retention
  on Postcardiothoracic Surgery Atrial Fibrillation
  Incidence The AFIST-III Study
• C. Michael White, PharmD Stephen Sander, PharmD
  Craig I. Coleman, PharmD Robert Gallagher, MD
  Hiroyoshi Takata, MD Chester Humphrey, MD
  Nickole Henyan, PharmD Effie L. Gillespie,
  PharmD Jeffrey Kluger, MD
• Published in the Journal of the American College
  of Cardiology
• January 23, 2007

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The AFIST-III Study Background

• Drugs with antiadrenergic effects reduce
  postoperative atrial fibrillation (POAF).
• Because the epicardial anterior fat pad (AFP) is
  parasympathetically innervated, its routine
  excision during coronary artery bypass grafting
  (CABG) may precipitate autonomic imbalance and
  induce POAF.

White et al., JACC 2007 49(3) 298-303
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The AFIST-III Study Background

• Given conflicting preliminary data, the Atrial
  Fibrillation Suppression Trial-III (AFIST-III)
  was conducted to evaluate the impact of
  maintaining the AFP on POAF.
• Additionally, the present study evaluated the
  impact of AFP maintenance on heart rate
  variability, an established marker of
  parasympathetic tone, in order to explore the
  underlying mechanism.

White et al., JACC 2007 49(3) 298-303
4
The AFIST-III Study Study Design
180 patients undergoing CABG surgery mean age 66
10 yrs, 80 male, 5 previous atrial
fibrillation Randomized. Blinded.
Controlled. Exclusion Criteria Age lt 50 yrs
Atrial Arrhythmia at Enrollment Previous CABG
Enrolled in Competing Study Concomitant Valve
Replacement or MAZE Procedure Refusal to
Participate
R
AFP removal (n88)
AFP maintenance (n92)
30 day follow-up

• Primary Endpoint Incidence of POAF, total
  hospital costs
• Secondary Endpoint Heart rate variability,
  length of hospital stay, and the impact of AFP
  retention on safety parameters (another
  arrhythmia, MI, hypotension, bradycardia,
  mortality, and stroke).

White et al., JACC 2007 49(3) 298-303
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The AFIST-III Study Study Demographics
Characteristic AFP Removed (n88) AFP Maintained (n92) p-value
History of Atrial Fibrillation () 4.5 4.3 1.000
History of Smoking () 60.2 72.8 0.043
Left Ventricular EF () 52.6 12.3 52.4 12.5 0.905
Mitral Regurgitation () 19.3 10.9 0.135
On-pump surgery () 46.6 54.3 0.232
Vein Grafts (n) 2.0 1.3 2.4 1.3 0.059
White et al., JACC 2007 49(3) 298-303
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The AFIST-III Study Primary Endpoint
Difference in the Incidence of POAF between
Groups
p0.950

• There was no difference in the incidence of POAF,
  symptomatic POAF, or recurrent POAF between AFP
  removal and AFP maintenance groups

p0.835
Incidence of POAF ()
p0.905
White et al., JACC 2007 49(3) 298-303
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The AFIST-III Study Primary Endpoint
Difference in Total Hospital Costs between Groups
p0.647

• Because POAF was not impacted, there was no
  significant difference in total hospital costs
  between the AFP removed and the AFP maintained
  groups

Total Hospital Costs ()
White et al., JACC 2007 49(3) 298-303
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The AFIST-III Study Secondary Endpoint
Heart rate variability between the two groups
p0.05

• Subjects with AFP removal had lower HRV than
  those with AFP maintenance as determined by both
  the SDNN (p0.05) and the SDANN 5 (p0.003)

31.7 24.6
22.7 8.3
p0.003
17.1 11.9
Heart Rate Variability
10.1 5.5
White et al., JACC 2007 49(3) 298-303
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The AFIST-III Study Limitations

• The cardiothoracic surgeons were not blinded to
  study group allocation. However, the impact of
  not blinding the surgeon was minimized by
  blinding data collectors, clinicians who treated
  the patients, and the patients themselves.
• Use of other drugs to control POAF was not
  controlled for.

White et al., JACC 2007 49(3) 298-303
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The AFIST-III Study Summary

• AFP maintenance did not positively or negatively
  impact clinical end points, particularly POAF, in
  the AFIST-III study.
• Maintaining the AFP does not alter the incidence
  of POAF after CABG or total hospital costs in any
  appreciable way, even though it preserves
  parasympathetic tone.

White et al., JACC 2007 49(3) 298-303