Early warning signs may have been missed in up to one in six people who died of a heart attack in English hospitals, a study suggests, according to BBC.
All heart attack admissions and deaths between 2006 and 2010 were analysed.
Imperial College London researchers found 16% of those who died had been admitted to hospital in the previous 28 days. Some had warning signs like chest pain.
The British Heart Foundation has called the research "concerning".
The study authors from the School of Public Health at Imperial College say more research is "urgently needed".
The research, published in the Lancet, looked at the hospital records of all 135,950 deaths in England due to heart attacks over the four-year period.
The records showed whether the person had been admitted to hospital in the previous four weeks and whether signs of a heart attack were recorded as the primary reason for the hospital admission, a secondary reason or not recorded at all.