Heart attack rates have fallen by 74% in London over the last two decades, mainly due to better hypertension and cholesterol control, as well as a decline in smoking, researchers from University College London Medical School reported in the European Heart Journal. However, weight gain may negatively affect future rates, the authors warn. They added that the 74% drop might have been 11% greater if more had been done to stop the progressively rising rates of overweight and obesity.

The researchers gathered data from the long-running Whitehall II study, which contains details on 9,453 London civil servants. Heart attack rates dropped on average by 6.5% per year from 1985 to 2004.

The following four factors are thought to be responsible for 56% of this reduction in heart attack risk: Falling levels of LDL-cholesterol (bad cholesterol) Rising levels of HDL-cholesterol (good cholesterol Better controlled hypertension (high blood pressure) Fewer people smoking Although there was an increase in fruit and vegetable intake, it was so small that the contribution was deemed statistically insignificant.

The authors wrote that alcohol and bread consumption, as well as physical activity trends made no notable impact.

The steady rise in the civil servants' BMI (body mass index) was linked to a rise in risk of heart attack of 11% over the two decades.

Senior research associate, Ms Sarah Hardoon, said:

"The substantial decline in myocardial infarction over two decades to 2004, of which more than half could be attributed to favorable trends in well-known risk factors, highlights what can be achieved and emphasizes the value of the measures taken to combat risky levels of cholesterol and blood pressure, and to promote healthier lifestyles.

However, although these favorable trends seem to have outweighed the negative contribution of rising BMI over recent decades, continued increases in BMI may reduce further, and even reverse, the decline in the incidence of heart attacks in the future. Therefore, the rising BMI in the UK and in other countries needs urgent attention."

Hardoon says more research is needed to find out what other factors contributed to the rest of the reduction in myocardial infarctions (heart attacks). The researchers believe there are several possible explanations.

Ms Sarah Hardoon, said:

"It could well be that we have underestimated the contribution of various risk factors. There may be some imprecision in the measurements, particularly for those that derive from questionnaires, such as diet, physical activity and alcohol consumption. Also, we have not captured the small fluctuations in the risk factors that occur. Had the risk factors all been measured precisely and we had captured the fluctuations in them, we might have explained a greater portion of the decline. Alternatively, there may have been favourable trends in other contributory factors not measured here, such as early treatment."

The authors write that this drop in non-HDL cholesterol had the greatest impact on heart attack rates, and may reflect increased use of statins and other cholesterol-lowering therapies, as well as healthier lifestyles. 11% of the civil servants in the study were taking statins.

"Rising adiposity curbing decline in the incidence of myocardial infarction: 20-year follow-up of British man and women in the Whitehall II cohort"
European Heart Journal. doi:10.1093/eurheartj/ehr142



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