Forty years of glucose-insulin-potassium (GIK) in cardiac surgery: a review of randomized, controlled trials.

Glucose-insulin-potassium (GIK) solutions have been used in cardiac surgery for more than 40 years. At that time, membrane-polarizing and stabilizing effects on cardiomyocyte's action potential were regarded the main benefit. Two meta-analyses described methodological flaws in the early studies (e.g., case numbers, randomization principles, and levels of significance), and came to clearly different recommendations with regard to the usage of GIK in the therapy of acute myocardial function. During the 70s, as promising therapies for the treatment of AMI had become available (e.g., beta-blockers and thrombolytic agents), the GIK technique was more widely introduced in cardiac surgery, e.g., during valve replacement. At present, 74 of 91 studies provide convincing evidence for the beneficial effects of insulin and/or GIK in cardiac surgery that go far beyond simple metabolic benefits and also include better recovery of myocardial tissue after ischemia. Yet, the exact underlying mechanisms remain still unknown. In this review article, two questions will be answered: why did GIK not become daily routine in cardiac surgery in spite of positive results from clinical studies, and does this technique merit more acceptance among the potential users? In view of the increasing number of older patients at higher risk, the demand for improving surgical procedures has renewed the interest in the GIK concept. The more recent literature suggests that the entire potential of GIK solutions has not been fully disclosed. A large single or multicenter trial with sound endpoints is mandatory.