And an even greater number, 55%, say they would call someone other than 999 first if they were experiencing chest pain - the main symptom of a heart attack.
The findings, from a YouGov poll, are revealed as the BHF today launches its 'Doubt Kills' campaign, urging people not to delay in calling 999 if they are experiencing chest pain. The campaign features a billboard advert showing a man with a belt tightening around his chest, with the caption 'A chest pain is your body saying call 999'.
Professor Peter Weissberg, BHF Medical Director, said: "These statistics portray a very worrying, and perhaps very British, reluctance to call 999 even in the most serious of emergencies. Maybe it is our natural reserve and stoicism, but it is costing lives.
"Every second counts when you are having a heart attack, and the quicker you call 999 the greater your chances of survival. Unfortunately too many people waste vital minutes questioning their symptoms - our message is if you're suffering chest pain, call 999 immediately, because doubt kills."
Evidence shows that people experiencing heart attack symptoms delay an average of 90 minutes before an ambulance is called. By the time treatment to restore blood flow to the heart is given, an average of 2 hours and 40 minutes have passed (2).
The YouGov poll showed that most people in Wales would first call their partner, friend, relative, GP or NHS Direct when experiencing chest pain - with 72% citing doubt about the seriousness of the situation to be what stops them dialling 999, and 43% preferring to 'wait and see' if their chest pain gets better.
The 'Doubt Kills' campaign aims to help reduce death and disability from coronary heart disease, which remains the UK's single biggest killer with over 6,000 deaths in Wales in 2004 (3).
Professor Weissberg added: "Someone suffers a heart attack every two minutes in the UK, and about one in three dies before reaching hospital. Many more suffer life-long debilitation because their heart muscle has been permanently damaged. Sadly many of these deaths and heart muscle damage could have been avoided if people had sought help immediately. Successful treatments for heart attacks are available in the form of clot-busting drugs and procedures to open blocked arteries.
"Central chest pain is the most common warning sign of a heart attack, but it does not have to be excruciating to be a serious problem. The most common mistake people make is to assume it is indigestion, so anyone experiencing bad indigestion-like symptoms should call for help, particularly if they are not prone to indigestion normally."
There are also other symptoms to be aware of such as a dull chest pain that radiates to the left arm or jaw, breathlessness and sweating - a combination of which can indicate urgent danger.
The campaign has the full backing of the Welsh Ambulance Services NHS Trust. Welcoming the launch, Trust Chief Executive Alan Murray said, "People need to know the potential significance of chest pain as a symptom of a heart attack. It is essential that all patients who suffer a heart attack receive treatment as soon as possible and the Welsh Ambulance Service is well placed to be the first link in the chain. There has been a big investment by the service in equipment and training for staff to ensure that anyone in Wales who suffers a heart attack can receive the best possible treatment as quickly as possible."
As part of the campaign, the BHF is sending more than 750,000 leaflets to all GP surgeries and Co-op Pharmacies and the campaign poster will go up on over 80 billboards across Wales. People are urged to visit the campaign website, bhf.org.uk/doubtkills, for more information about how to recognise the symptoms of a heart attack and what to do. The leaflet can also be ordered by calling 0870 600 6566. The campaign also has the backing of the Welsh Ambulance Service NHS Trust.