Glucose-Insulin-Potassium and Tri-Iodothyronine Individually Improve Hemodynamic Performance and Are Associated With Reduced Troponin I Release After On-Pump Coronary Artery Bypass Grafting

Abstract

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 μg · kg −1 followed by 0.113 μg · 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.

Thyroid hormone and recovery of cardiac function in patients with acute myocardial infarction: a strong association?

“…Furthermore, T 3 cardioprotection was shown to be mediated via the suppression of the pro-apoptotic p38MAPK signaling pathway and be TRa1 receptor dependent (13,25). More importantly, in accordance with this experimental evidence, T 3 treatment resulted in marked increase of post-surgery cardiac function in patients undergoing cardiac bypass operations (27,28). Table 5 Multivariate linear regression analysis revealed that T 3 at 6 mo and gender and high-density lipoprotein (HDL) at early phase were independent predictors of myocardial function recovery (DEF%) after acute myocardial infarction.…”

Nonthyroidal Illness Syndrome in Cardiac Illness Involves Elevated Concentrations of 3,5-Diiodothyronine and Correlates with Atrial Remodeling

“…This condition is described as nonthyroidal illness syndrome (NTIS), euthyroid sick syndrome or TACITUS (thyroid allostasis in critical illness, tumors, uremia and starvation) and is accompanied by increased mortality and morbidity [3,4]. Several trials have demonstrated improved surrogate parameters after substitution therapy with T 3 in NTIS [5,6]. It could not be proven, however, that therapy with T 4 or T 3 ameliorates the overall outcome of affected patients [7,8].…”

Rebuilding the post-infarcted myocardium by activating ‘physiologic’ hypertrophic signaling pathways: the thyroid hormone paradigm

“…Thus, T3 may be considered as suitable therapeutic option for hemodynamic support in the setting of ischemia-reperfusion. This concept is now supported by recent data from Ranasinghe et al showing that T3 treatment during by-pass surgery increased cardiac index while limited the troponin release [63].…”