A study published early online in JAMA to coincide with its presentation at the American College of Cardiology’s annual scientific sessions, reveals that patients with chest pain who received an intravenous solution of glucose-insulin-potassium (GIK) had no reduced risk of progressing to a heart attack and no improved 30-day survival regardless of GIK’s association with lower rates of cardiac arrests or in-hospital deaths.
According to laboratory studies, immediate intravenous GIK decreases ischemia-related arrhythmias and myocardial injury in cardiac ischemia, whilst the background information in the article states:
“The potential benefit of GIK is thought to be related to timeliness of administration after onset of cardiac ischemia, especially for prevention of cardiac arrest, for which risk is highest the first hour of acute coronary syndromes [ACS; such as heart attack or unstable angina]/acute myocardial infarction (AMI; heart attack).
To date, clinical trials of GIK may have missed the opportunity to detect this effect, because enrollment and treatment have awaited hospital diagnosis of MI, most often ST-elevation myocardial infarction (STEMI; a certain pattern on an electrocardiogram following a heart attack], hours after ischemic symptom onset and initial coronary occlusion blockage). To achieve the potential benefits related to early treatment, GIK ideally should be administered on presentation of ACS in the out-of-hospital setting rather than awaiting diagnosis of MI or STEMI at the hospital.”
Harry P. Selker, M.D., M.S.P.H., of Tufts Medical Center and Tufts University School of Medicine in Boston and his team performed a randomized, placebo-controlled multi-center trial (Immediate Myocardial Metabolic Enhancement During Initial Assessment and Treatment in Emergency care (IMMEDIATE) Trial), in which they examined the impact of out-of-hospital emergency medical service (EMS) administration of GIK in the first hours of suspected ACS on progression to heart attack, including other outcomes, such as heart failure (HF), cardiac arrest and death.
The trial took place in 13 U.S. cities involving 36 EMS agencies from December 2006 to July 2011, in which paramedics randomized 911 (871 enrolled) patients with a high probability of ACS that was determined with the help of an electrocardiograph (ECG). All participants had suspected ACS and MI, with 86% complaining of chest pain. 71% of the patients were male aged 63.6 years (average). The participants were randomized at the 90 minute-midpoint following the start of their ischemic symptoms, with paramedics in out-of-hospital settings administering a total of 411 patients with GIK solution and 460 patients with identical-looking 5% glucose placebo. The treatment was continued for 12 hours and the results were as follows:
| OUT-OF-HOSPITAL SETTING | GIK Group (411 patients) | Placebo Group (460 patients) |
| Primary endpoint | ||
| Progression to heart attack | 48.7% | 52.6% |
| Secondary endpoints | ||
| 30-day mortality | 4.4% | 6.1% |
| Composite end point of cardiac arrest or in-hospital mortality | 4.4% | 8.7% |
| IMMEDIATE TRIAL | GIK Group (163 patients) | Placebo Group (194 patients) |
| Primary endpoint of patients with ST-segment elevation on initial out-of-hospital ECG | ||
| Progression to heart attack | 85.3% | 88.7% |
| Secondary endpoints | ||
| 30-day mortality | 4.9% | 7.7% |
| Composite end point of cardiac arrest or in-hospital mortality | 6.1% | 14.4% |
According to the researchers, there was no difference between the GIK and placebo groups in rates of progression to MI for patients’ treated within the first hour. However, the composite of cardiac arrest or in-hospital mortality was higher in the placebo group than in the GIK group.
The researchers note that the reason why patients with ST-segment elevation had a better outcome may be that those in the IMMEDIATE trial were treated much sooner.
They authors conclude:
“Further studies are needed to assess the out-of-hospital use of GIK as therapy for
patients with ACS.”
Written by Petra Rattue