A BOUT of cold or flu may be the prelude to a heart attack for people who never knew they were at risk, doctors have revealed, writes Alan MacDermid, Medical Correspondent.

Researchers identified a two-week window of danger after becoming ill - and said it applied to people with no record of risk factors.

It may be part of the explanation why deaths from heart attacks are more common in winter than in summer.

The American investigators used data from Britain to see whether the greater prevalence of colds and flu in winter might contribute.

Dr Christoph Meier and colleagues from the Boston Collaborative Drug Surveillance Program analysed information from 400 GP surgeries stored on a family doctor database in the UK.

Each heart attack patient was matched against four comparable patients who had not suffered one.

Doctors looked to see if in the 10 days before the heart attack, any of each group of patients had suffered an acute respiratory tract infection, such as a common cold or flu.

The findings showed that infections were significantly more common among the heart attack patients.

However, absolute risk was low - only 4% of heart attack cases had had an acute infection in the ten days beforehand.