Aside from the aforementioned studies on USA and New Zealand subjects, a team of British researchers wrote in 2005 that while there was no spike in death rates on Christmas day, there was one observed in the United Kingdom on New Year's Day.
Among researchers, the question of cause has always been up in the air.
Mr Knight said more work needed to be done to understand if restricted access to healthcare facilities might combine with other risk factors to result in the spike in cardiac deaths.
A new study published in the Journal of the American Heart Association lays blame at the feet of Father Christmas, not colder temperatures, thanks to a ideal comparison group: New Zealanders, a culturally similar population that celebrates Christmas during their summer time. Also, the winter in New Zealand is like the summer in the US. People in this country experience their summer weather from December through February, but still celebrate Christmas on December 25, because the country was once an English colony. They came up with an "expected" number of deaths for each day of the year.
Another explanation may have to do with a terminally ill patients' will to live and hold off death for a day that is important to them.
It also found that the average age of people who died during the Christmas period was slightly lower - 76.2 compared with 77.1 years at other times of the year.
Researchers found that deaths due to heart attack increased by 4.2 percent in Christmas season and they blame stress for the deaths.
This is now the third time the Christmas cardiac death effect has been measured in a different part of the world. England, like the US, celebrates Christmas during wintertime. These researchers analysed 25 years of mortality data from New Zealand. He stated that people travel a lot during the festive season and often land up in unknown places where they are unable to get medical care on time if compared to the places they know.
Lead author Josh Knight, a researcher at the University of Melbourne's Centre for Health Policy, said delays in seeking medical help were also contributing factors.
Other causes that could increase the risk of dying of a heart attack during Christmas are the emotional stress associated with the season and changes in the diet and alcohol consumption, but researchers could not determine what is exactly behind the higher risk of having a heart attack during Christmas time.
Prior research has shown that deaths increase around the holidays, but researchers wanted to distinguish between the effect of winter and the effect of the holidays themselves.
"The ability of individuals to modify their date of death based on dates of significance has been both confirmed and refuted in other studies; however, it remains a possible explanation for this holiday effect", Knight and colleagues wrote.