BACKGROUND: Both glucose-insulin-potassium (GIK) and tri-iodothyronine (T3) may 
improve cardiovascular performance after coronary artery surgery (CABG) but 
their effects have not been directly compared and the effects of combined 
treatment are unknown.
METHODS AND RESULTS: In 2 consecutive randomized double-blind placebo-controlled 
trials, in patients undergoing first time isolated on-pump CABG between January 
2000 and September 2004, 440 patients were recruited and randomized to either 
placebo (5% dextrose) (n=160), GIK (40% dextrose, K+ 100 mmol.L(-1), insulin 70 
u.L(-1)) (0.75 mL.kg(-1) h(-1)) (n=157), T3 (0.8 microg.kg(-1) followed by 0.113 
microg.kg(-1) h(-1)) (n=63) or GIK+T3 (n=60). GIK/placebo therapy was 
administered from start of operation until 6 hours after removal of aortic 
cross-clamp (AXC) and T3/placebo was administered for a 6-hour period from 
removal of AXC. Serial hemodynamic measurements were taken up to 12 hours after 
removal of AXC and troponin I (cTnI) levels were assayed to 72 hours. Cardiac 
index (CI) was significantly increased in both the GIK and GIK/T3 group in the 
first 6 hours compared with placebo (P<0.001 for both) and T3 therapy (P=0.009 
and 0.029, respectively). T3 therapy increased CI versus placebo between 6 and 
12 hours after AXC removal (P=0.01) but combination therapy did not. Release of 
cTnI was lower in all treatment groups at 6 and 12 hours after removal of AXC.
CONCLUSIONS: Treatment with GIK, T3, and GIK/T3 improves hemodynamic performance 
and results in reduced cTnI release in patients undergoing on-pump CABG surgery. 
Combination therapy does not provide added hemodynamic effect.