Intravenous glucose-insulin-potassium (GIK) is postulated to be beneficial in acute ischaemic syndromes via two mechanisms: by providing metabolic support to ischaemic myocardium, and by preventing arrhythmias and cardiac arrest due to ischaemia-related metabolic derangements.  Importantly, these benefits are most likely to be seen if GIK is started as soon as possible after the onset of myocardial ischaemia, therefore GIK should ideally be initiated in the out-of-hospital setting.

The Immediate Myocardial Metabolic Enhancement During Initial Assessment and Treatment in Emergency care (IMMEDIATE) trial tested out-of-hospital administration of GIK in the early stages of acute coronary syndrome (ACS).  The trial took place in 13 US cities over a five year period and enrolled 871 patients to either intravenous GIK solution (n=411) or 5% glucose placebo (n=460).  The primary endpoint was progression of ACS to myocardial infarction within 24 hours, as assessed by biomarkers and the ECG. Secondary endpoints included survival at 30 days, and a composite of cardiac arrest or in-hospital mortality.

The trial found no significant difference in the rate of progression to MI among patients who received GIK (48.7% vs. 52.6%, p=.28).  Although 30-day mortality was lower (4.4% vs. 6.1%, P=.28), this did not reach statistical significance, however the composite of cardiac arrest or in-hospital mortality occurred in 4.4% with GIK vs. 8.7% with placebo (P=.01).   Among patients with ST-elevation myocardial infarction, this difference was even more pronounced (6.1% vs. 14.4%, P=.01).

Conclusions:

Although out-of-hospital administration of intravenous GIK, compared with glucose placebo, did not reduce progression to MI nor improve 30-day mortality, it was associated with lower rates of a composite outcome of cardiac arrest or in-hospital mortality.

• Selker HP, Beshansky JR, Sheehan PR et al.  Out-of-Hospital Administration of Intravenous Glucose-Insulin-Potassium in Patients With Suspected Acute Coronary Syndromes. The IMMEDIATE Randomized Controlled Trial.  JAMA 2012;307:1925-1933.