Each year, more than 600,000 people die of sudden cardiac arrest in North America and Europe, usually because of a heart attack or a heart rhythm disturbance.
When medical personnel arrive, nearly 70 percent of victims have ventricular fibrillation, in which the heart's main pumping chambers flutter wildly and pump little blood. Less than 20 percent of these patients survive to go home.
About 30 percent of victims, usually patients who have been down longer, have asystole, and nearly all die.
For a century, cardiac arrest victims have been given epinephrine, a synthetic adrenaline that constricts blood vessels and boosts blood pressure. It is often administered when shocking the heart with a defibrillator fails to revive the patient.
Vasopressin, a synthetic hormone that narrows blood vessels, has been around for decades. A few years ago, the International Liaison Committee on Resuscitation revised its guidelines to add vasopressin as an alternative first drug. That was partly because epinephrine sometimes increases irregular rhythms and decreases oxygen supply to the brain after resuscitation.
Researchers studied 1,186 cardiac arrest patients treated in 33 communities in Austria, Germany and Switzerland from 1999 to 2002.
After ambulance crews tried defibrillation, half the patients not resuscitated then got one or more injections of vasopressin and the other half got epinephrine.Using vasopressin improved the chances of reaching a hospital alive by about 40 percent, and tripled the chances of going home from the hospital, in patients with the most deadly type of cardiac arrest, asystole, where all heart activity has stopped. Still, only 5 percent who got vasopressin made it home.
Researchers say their findings should soon change international guidelines for treating people in cardiac arrest outside a hospital .
However these advances should be translated into a new standard of care as soon as possible.
Researchers say they want to go one step further and inject both vasopressin and epinephrine, because that showed the most benefit and saved eight crucial minutes.
"If truly confirmed by another study it would be a major advancement in the treatment of asystole," say specialists.