Atrial fibrillation in elderly patients after cardiac surgery: postoperative hemodynamics and low postoperative serum triiodothyronine.
OBJECTIVE
The purpose of this study was to evaluate serum triiodothyronine levels as a trigger of postoperative atrial fibrillation (AF) in elderly patients undergoing cardiac surgery and to study the possible association of serum triiodothyronine levels with preoperative and postoperative hemodynamics.


METHODS
Prospective study.


METHODS
University hospital.


METHODS
Forty-six consecutive nonemergency patients 65 years or older undergoing cardiac surgery during 1999 to 2000 in Tampere University Hospital, Tampere, Finland.


METHODS
Free serum T3 concentration was used as a measure of serum triiodothyronine levels. Samples were taken preoperatively, on the fourth postoperative day, and at the 3-month follow-up. The hemodynamic state of the patients was estimated by whole-body impedance cardiography preoperatively, during the intensive care unit period, daily until the fourth postoperative day, and at the 3-month follow-up.


RESULTS
AF occurred in 43% of the patients. The patients in the AF group had significantly more grafts (3.9 v 3.1, p = 0.02), and there was a small difference in age between the AF and non-AF groups (73 years v 69 years, p = 0.06). The free T3 concentration on the fourth postoperative day was significantly lower in the AF group (3.5 nmol/L v 4.6 nmol/L, p = 0.04). In logistic regression analysis, the independent predictors of AF were age, number of grafts, and serum free T3 concentration on the fourth postoperative day. In the group with low T3 concentration, the cardiac index was lower (1.4 v 1.8, p = 0.05) and the systemic vascular resistance index was higher (4,064 v 2,969, p = 0.04) but only immediately after the operation. Although the AF mostly appeared during the second to fourth postoperative days, there were no longer any differences in the hemodynamic state at that time.


CONCLUSIONS
In a group of elderly patients undergoing cardiac surgery, there was a strong association between a postoperative decrease of serum triiodothyronine levels and atrial fibrillation. The decrease of serum triiodothyronine levels was related to the changes of hemodynamic parameters only in the immediate postoperative period.
Kokkonen
Liisa
L
Department of Internal Medicine, Paijat-Hame Central Hospital, FIN-15850, Lahti, Finland. liisa.kokkonen@fimnet.fi
Majahalme
Silja
S
Kööbi
Tiit
T
Virtanen
Vesa
V
Salmi
Jorma
J
Huhtala
Heini
H
Tarkka
Matti
M
Mustonen
Jukka
J
D000368:Aged; D001145:Arrhythmias, Cardiac / Q000503:physiopathology; D001281:Atrial Fibrillation / Q000503:physiopathology*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000097:blood / Q000503:physiopathology*; D011446:Prospective Studies; D012039:Regional Blood Flow / Q000502:physiology; D013963:Thyroid Hormones / Q000097:blood; D014284:Triiodothyronine / Q000097:blood* / Q000172:deficiency; D016277:Ventricular Function, Left / Q000502:physiology
D013963:Thyroid Hormones; D014284:Triiodothyronine