One-sixth of heart attack deaths in England might be the result of hospital doctors failing to spot potentially life-threatening symptoms.
The findings from a major study of almost 136,000 cases of fatal heart attack between 2006 and 2010 indicate that many patients are dying because of missed warning signs.
Symptoms of a heart attack include sudden chest pain or a "crushing" sensation that might spread down either arm, while patients may also experience nausea or shortness of breath.
But some heart attacks have more subtle symptoms that can be overlooked.
Of the fatal heart attack victims studied, 21,677 - almost 16 per cent of the total - had been admitted to hospital up to four weeks before their death.
Yet no mention of heart attack symptoms was made in their hospital records.
Symptoms such as fainting, shortness of breath and chest pain would have been evident up to a month before death in some of these patients, said the researchers.
Lead scientist Dr Perviz Asaria, from the School of Public Health at Imperial College London, said: "Doctors are very good at treating heart attacks when they are the main cause of admission, but we don't do very well treating secondary heart attacks or at picking up subtle signs which might point to a heart attack death in the near future."
The team examined records of 446,744 NHS hospital stays involving heart attacks between 2006 and 2010, as well as the history of all 135,950 heart attack deaths in England during the four years.
The total number of patients who died included those who had a fatal heart attack in hospital or at home or elsewhere.
Now the researchers, whose findings appear in The Lancet Public Health journal, are calling for a deeper investigation into why avoidable deaths were occurring.
"We cannot yet say why these signs are being missed, which is why more detailed research must be conducted to make recommendations for change," said co-author Professor Majid Ezzati, also from Imperial's School of Public Health.
"This might include updated guidance for healthcare professionals, changes in clinical culture, or allowing doctors more time to examine patients and look at their previous records."
