Immediately giving someone having a heart attack a dose of glucose mixed with insulin and potassium (known as “GIK”) could reduce their chance of cardiac arrest or dying by 50%, according to new research presented at the American College of Cardiology’s 61st Annual Scientific Session in Chicago this week.

Dr Harry P. Selker, executive director of the Institute for Clinical Research and Health Policy Studies at Tufts Medical Center, led the study with co-principal investigator and project director Dr Joni Beshansky.

Selker told the press:

“Acute coronary syndromes represent the largest cause of death in this country. GIK is a very inexpensive treatment that appears to have promise in reducing those deaths and morbidity.”

GIK contains glucose, to provide the heart with fuel when there is a reduced blood supply, and insulin to help move the glucose into the cells. Potassium is added because infusing glucose with insulin can cause potassium levels to become too low.

The trial, called the “IMMEDIATE Trial”, is the first to show GIK is an effective treatment for use by paramedics in “real world community settings” said Selker, and as such may have important implications for how we treat heart attacks.

IMMEDIATE stands for Immediate Myocardial Metabolic Enhancement During Initial Assessment and Treatment in Emergency Care.

It is the first trial to give patients GIK at the very first signs of an impending heart attack, while they are still in the community, rather than waiting until they reach hospital and undergo diagnosis.

“When started immediately in the home or on the way to the hospital – even before the diagnosis is completely established – GIK appears to reduce the size of heart attacks and to reduce by half the risk of having a cardiac arrest or dying,” said Selker.

He said previous trials using GIK have shown patchy results, probably because it was administered too late.

The treatment costs about $50.

The researchers trained paramedics working in 36 Emergency Medical Services systems in 13 cities around the US how to administer GIK to a patient after first establishing they were about to have or were in the throes of having a heart attack.

To decide whether GIK would be likely to help, the paramedics had to first use an electrocardiograph-based acute cardiac ischemia time-insensitive predictive (ACI-TIPI) instrument and interpret the accompanying thrombolytic predictive instrument decision support that prints patient-specific predictions on the top of the electrocardiogram.

From those predictions the paramedics could then decide whether patients were likely to benefit from GIK treatment.

Altogether, 911 patients took part in the study. They were randomly assigned to receive either GIK or a placebo.

The results showed that compared to patients treated with a placebo, those who received GIK straight after being diagnosed with acute coronary syndrome (a group of symptoms that indicates a heart attack is either about to happen or is already happening), were 50% less likely to experience cardiac arrest, where the heart stops beating, or die. This was in spite of the fact the GIK did not stop the heart attack from occuring.

And, for the first month afterwards, patients who received GIK were 40% less likely to experience cardiac arrest, die, or have to be hospitalized due to heart failure.

For patients experiencing ST-elevation heart attacks, which require immediate treatment, the effect was even more striking: those receivng GIK had a 60% reduced likelihood of cardiac arrest or death.

Giving GIK immediately also reduced the severity of heart tissue damage due to the heart attack.

In patients receiving placebo, 10% of the heart tissue was damaged, on average, compared to 2% for those who received GIK.

Plus, GIK did not appear to harm the 23% of patients whose suspected heart attacks turned out later to be false alarms.

Selker said more people die of heart attacks outside hospitals than inside them. He and his colleagues wanted to do something about that, and come up with something effective that can be used anywhere.

“Hundreds of thousands of people per year are dying out in the community; we wanted to direct our attention to those patients,” he said.

The team are following up the study participants at six and 12 months to evaluate the long-term effects of GIK.

The National Heart, Lung and Blood Institute, which are part of the National Institutes of Health, funded the study.

Written by Catharine Paddock PhD