According to a new U.S. study, paramedics armed with a cheap, three-ingredient injection cocktail were able to reduce heart attack patients' risk of dying by 50 per cent.
When the shot was given early to patients with signs of a heart attack, the mixture of glucose, insulin and potassium (GIK), showed remarkable success in preventing full cardiac arrest - when the heart stops beating - and even death. And each shot cocktail costs only about $US50, according to the research presented at the American College of Cardiology's 61st annual scientific meeting in Chicago. The Scientific Session, the premier cardiovascular medical meeting, brings cardiovascular professionals together to further advances in the field.
“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 co-principal investigator Harry Selker. “Because the trial is the first to show GIK is effective when used by paramedics in real-world community settings, it could have important implications for the treatment of heart attacks,” added Selker, executive director of the Institute for Clinical Research at Tufts Medical Center.
Previous trials using the formula were inconclusive, possibly because the shot was being given to patients too late, he said. But this trial randomized 911 patients to receive either the shot or a placebo immediately. The researchers trained paramedics in 36 Emergency Medical Services systems in 13 cities across the country to administer GIK after determining that a patient was likely having a threatened or already established heart attack using electrocardiograph-based ACI-TIPI (acute cardiac ischemia time-insensitive predictive instrument) and thrombolytic predictive instrument decision support that prints patient-specific predictions on the top of an electrocardiogram. The paramedics used these predictions to decide if a patient would likely benefit from treatment.
The treatment did not prevent heart attacks from occurring, but cut the likelihood of cardiac arrest by 50 per cent over patients who did not get the shot. The risk of immediate death in addition dropped by 50 per cent. The effects were visible over the month following the event as well, with patients given the shot 40 per cent less likely to die or be hospitalized for heart failure than those who did not.
In patients with a certain kind of heart attack in which a coronary artery becomes completely blocked, known as an ST-elevation heart attack, immediate GIK was associated with a 60 per cent reduction in cardiac arrest or death. Those who got GIK and were later confirmed to have had a heart attack saw an average of two per cent of their heart tissue damaged, compared to 10 per cent in the placebo group.
While 23 per cent of the suspected heart attacks in the study turned out to be false alarms, patients who got the GIK shot showed no negative side effects from the treatment.
The key difference in this trial compared to previous ones appeared to be the act of giving the shot right away, rather than waiting for a confirmed diagnosis at the hospital. Previous clinical trials have shown no consistent effect, likely because the GIK was given too late to help. This study, the “IMMEDIATE Trial,” was the first to test the effectiveness of administering GIK at the very first signs of a threatening heart attack, in the community, rather than waiting hours until the diagnosis was well-established at a hospital, as done in previous clinical trials.
“We wanted to do something that is effective and can be used anywhere,” said Selker. “More people die of heart attacks outside the hospital than inside the hospital. Hundreds of thousands of people per year are dying out in the community; we wanted to direct our attention to those patients.”
For now, the treatment is not widely available. Further research is planned to track the study participants over the next year and evaluate its longer-term effects and benefits. This study was funded by the NIH's National Heart, Lung and Blood Institute.