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Aortic fat pad destruction and post operative atrial fibrillation
1Cardiac Surgery Associates, The Edward Cardiovascular Institute, Edward Hospital, Naperville, IL, USA.
Introduction:
Atrial arrhythmias are a common complication of cardiac surgery. Reports describing pericardiac neurogenic tissue led us to hypothesize that removal of the aortic fat pad could cause an autonomic imbalance and contribute to atrial arrhythmias following cardiac surgery.
Methods:
A randomized prospective pilot study (n =131) was conducted to test our hypotheses. Patients underwent conventional cardio-pulmonary bypass surgery (CPB) or off pump coronary bypass surgery (OPCAB). The fat pad was either left intact or removed. The incidence of de novo atrial arrhythmias during the patient's hospital stay was tabulated. Patients with peri-operative myocardial infarction or pre-existing atrial or supraventricular arrhythmias were excluded. The randomization schedule was made subservient to clinical judgment at surgery. After promising preliminary results, an extension study (n =189 patients, total patients =320) was performed which employed the same definitions and interventions but was a sample of convenience. The data of this second study have not been previously published.
Results:
In the pilot study, in demographically similar groups, logistic regression demonstrated a significantly elevated atrial arrhythmia incidence when the fat pad was removed (Odds ratio 3.49, 95% confidence intervals 1.09 to 11.18). A chi-square analysis of these same data, however, (4 fibrillations in 58 patients with fat pad intact versus 15 fibrillation in 73 patients with fat pad removed; P = 0.051) suggested that the importance of the fat pad status was not definite. Overall, atrial arrhythmias were present in 19 of 131 patients (14.5%). In the extension study, in contrast to the pilot data, the data did not demonstrate any contribution of fat pad status to the incidence of atrial fibrillation.
Conclusions:
Although we feel that our hypothesis remains viable, retention of the aortic fat pad during coronary artery bypass surgery may not be related to a decreased incidence of post operative atrial arrhythmias.