Several studies have already investigated changes in deaths from heart attack in many countries around the world, but reasons for the decline in deaths in England are still not known. Researchers from the University of Oxford set out to identify the possible causes of this reduction.
Using national hospital and mortality data, they looked at 840,175 men and women in England who had suffered from a total of 861,134 heart attacks between 2002 and 2010. Overall, the death rates for heart attacks fell by 50% in men and 53% in women.
The researchers investigated how much of the decline in death rates resulted from a decrease in the occurrence of new heart attacks, and how much was a result of improved survival after heart attack. They concluded that just over half of the decline in total death can be attributed to a decline in the number of new heart attacks, and just under half to a decline in the death rate after heart attack.
The substantial drop in the rate of occurrence of heart attacks reflects the impact of both primary and secondary prevention through beneficial changes in the health of the population with respect to cardiovascular risk factors, say the researchers, while the improvements in death rates following hospital admission are likely to reflect major improvements in NHS care over the recent years.
61% of the people who experienced heart attack were men, 36% of heart attack cases were fatal and 73% occurred in those aged 65 and over. Out of 311,419 fatal heart attacks, 70% were sudden deaths that occurred without an admission to hospital.
The factors behind the decrease in heart attack mortality differed by age, sex and geographic area. The greatest declines in heart attack event rate and mortality were seen among middle-aged individuals, whereas the smallest declines were seen for the younger and older age groups in both men and women. Rising rates of obesity and diabetes may help explain the lack of improvement in the occurrence of heart attacks among the youngest age group.
The authors say that further research is required to gain a clearer understanding of the specific elements of prevention and treatment that have contributed to the fall in death rates.
In an accompanying editorial, Hugh Tunstall-Pedoe from the Institute of Cardiovascular Research at the University of Dundee argues that death rates from heart attacks have only fallen in "rich nations" whereas they continue to rise in many others. He suggests that more data is needed from the other countries to reach a conclusion, but that resources to obtain data are scarce.