A blood pressure drug has been shown to cut deaths in patients who have had angina or previous heart attacks.
Patients with heart disease were given the drugs
The drug, perindopril, also reduces the risk of further attacks, according to the study of over 12,000 patients from 24 European countries.
Perindopril has already been shown to reduce patients' stroke risk.
The researchers, who are presenting their study to the European Society of Cardiology in Vienna, say it should be given as a preventative treatment.
Perindopril belongs to a class of drugs called ACE inhibitors which work by blocking the production of angiotensin II, a protein which makes blood vessels constrict.
The European trial on Reduction of Cardiac Events (Europa study) gave half of those taking part 8 mg of perindopril once daily or a dummy pill in addition to their existing medication, such as aspirin, statins and beta-blockers, for an average of four years.
The risk of death was cut by 11% in the group taking perindopril.
This group also saw a 24% reduction in heart attacks and a 39% reduction in heart failure cases in the patients living with stable heart disease.
The risk reduction was seen in all patient groups, whether or not they had conditions such as high blood pressure or diabetes, and irrespective of age.
Professor Kim Fox, of the Royal Brompton Hospital, London, one of the specialists who led the research, said: "Coronary disease is the most common type of heart disease and accounts for almost one third of all deaths, which is approximately 16 million deaths every year worldwide.
"Perindopril added to standard optimal therapy over a four year period would stop 100,000 heart attacks or cardiovascular deaths in a country with a population of 60 million.
"This is a major step forward and will have implications in the future management of coronary disease."
He told BBC News Online the study showed perindopril, could be more extensively prescribed than it is at the moment.
He said: "Whereas the drug had been used just in heart failure, it will be used in all people with heart problems."
"This means that it will be able to help people who have had angina, angioplasty and any by-pass surgery.
"It is an enormous benefit. If you are talking about aspirins and statins being the biggest drug advances then this is probably the next big one."
Prof Fox added: "This will make a further improvement in terms of the government reaching their targets they will probably overachieve when this is used."
He said there would be savings, not only to the NHS, but also to businesses who would have less days lost through ill health.
"The savings will be enormous."