The researchers examined data of 231,164 heart attack patients who were admitted to all hospitals in New Jersey from 1987 to 2002. Within a month of admission 12.9 percent of weekend heart attack patients died as compared to 12 percent of patients admitted on weekdays.

Figures from the American Heart Association show that 10,000 of the 200,000 heart attacks suffered by people every year are fatal. Most of these heart attacks are caused by blood clots, which hinder the smooth flow of blood in the arteries.

A procedure called angioplasty, which involves inserting a balloon into the blocked artery, is known to save lives. When performed within a few hours of the start of a heart attack, angioplasty has the ability to interrupt the attack.

However researchers at the Robert Wood Johnson Medical School in New Brunswick found that between 1999 to 2002, just 6.7 percent of weekend heart attack patients received angioplasty to open blocked arteries on the very day of their admission as compared to 10 percent of weekday heart attack patients.

"One in one hundred people with their first heart attack are going to die because hospital policies are not the same on the weekend as the weekday," said lead research William Kostis, who is a fourth-year medical student at the school.  He added that one out of every 100 heart attack patients who died did so "potentially unnecessarily.”

But Dr Kostis was also quick to stress that people who had a heart attack on a Saturday or Sunday were better off going to a hospital rather than waiting for Monday mornings.

The lack of adequate emergency facilities for performing angioplasties over the weekend appears to be the reason behind the increased mortality of heart attack patients during this period. "Patients admitted on weekends were less likely to undergo invasive cardiac procedures than were those admitted on weekdays," the researchers report in the New England Journal of Medicine.

Additionally the time between admission and the procedure was more for weekend heart attack patients rather than week day ones.

In an accompanying commentary in the same journal Donald Redelmeier and Chaim Bell of the University of Toronto said the study provided a practical insight into the plight of heart attack patients admitted to hospitals over the weekend.

However they were clear in pointing out that patients should not wait to see if they felt better over the weekend. “Second, if they are unsure of how sick they may be, they should contact their doctor by Friday, when staff are more available," Bell and Redelmeier wrote. "Third, if patients are hit by an emergency on the weekend, they should go to the hospital; patients who sustain a heart attack, for example, are far safer receiving weekend hospital care than staying at home."

An earlier study by Dr. Eric Peterson, a Duke University cardiologist had also found that angioplasty was less frequently performed over the weekend. However that study, which used a national sample of heart attack patients, did not find any significant reduction in mortality rates in weekday and weekend heart attack patients.

Even so other studies have documented that weekend heart attack patients appear to be sicker and waited longer before opting to get admitted. There is only a few hours interval between the beginning of a heart attack and the point of no return where even surgery will not help.

The current study had its limitations in that it did not analyze the severity of the heart attacks or the how sick patients were when they arrived at the hospital. Dr. Mark Hlatky, a cardiologist and professor of health research and policy at Stanford University, told The New York Times that the "weekend phenomenon" appeared to affect heart attack patients even in1987 to 1990 when angioplasty was almost never performed.

“So this is not as simple as ‘no doctor to do the procedure on weekends,’ ” Dr. Hlatky said. He added that staffing might also have played a role in the mortality rates affecting weekend heart attack patients. “I agree that we need to be ready 24/7 to take care of serious problems like heart attacks,” Dr. Hlatky added. “But I don’t think it’s the entire answer, and to say we can fix it with angiography is an oversimplification.”

Standard guidelines by the American College of Cardiology and the American Heart Association stress that reopening a clogged artery within 90 minutes of suffering a heart attack can reduce the risk of death by 40 percent. But a study by Yale University researchers published last November found that less than 30 percent of hospitals in the United States provide rapid angioplasty that is necessary to save lives of heart attack patients.