Heart attack patients are more likely to die if they arrive at the hospital at night or on a weekend, a large new review finds, Newsmax Health reports.

Mayo Clinic researchers Dr. Henry Ting and colleagues analyzed 48 studies that included a total of nearly 1.9 million patients to assess how arriving at hospitals during nights and weekends affected heart attack patients' risk of death. The studies were conducted in Canada, Europe and the United States.

The investigators concluded that heart attack patients who arrived at a hospital during off-hours had a 5 percent higher risk of death both while in the hospital and 30 days after discharge than those who arrived during regular hours. This led to an extra 6,000 deaths every year in the United States alone, according to the findings published Jan. 21 in the online edition of the BMJ.

The researchers said further studies are needed to examine factors that cause differences in levels of care during regular and off-hours, such as number of staff and their level of expertise.