The possibility of death from severe types of heart attack rises by about 10 percent for each hour that the patient takes to reach the hospital and get treatment, a study conducted in Europe reveals.

Researchers analyzed data of over 6,200 patients from the Danish Medical registries who were taken to hospital by an ambulance for an ST-segment elevation myocardinal infaction or STEMI - a serious type of heart attack where the artery gets blocked.

Dr. Christian Juhl Terkelsen, the lead researcher and a cardiologist at the Aarhus University Hospital in Denmark said analysis of the data, collected between January 2002 and December 2008, suggested that the longer an artery was blocked, the more the heart muscles were damaged resulting in greater risk of death.

It was seen that patients who waited up to four hours before being treated had a mortality rate of 30.8 per cent while those who received treatment within two hours saw this rate fall to 23.3 percent. In the group where patients got treatment within the hour, only 15.4 percent died.

The research team suggested that the more alert the healthcare systems become, the less are chances of patients dying of heart attacks. Patients who suffer this type of attack are usually treated using balloon angioplasty.

The study, published in the Journal of American Medical Association, included three hospitals that offered primary percutaneous coronary intervention (PCI) or balloon angioplasty. The process involves threading a catheter into the artery and a balloon at the end that is inflated to help widen it. When the tube is removed, a stent is left behind to prevent the artery from narrowing again.

It is estimated that about 400,000 people across the United States have a STEMI heart attack each year with the American Heart Association working with hospitals and emergency medical services to develop more coordinated, regional systems of care for heart attacks.