It's not often that people are concerned there aren't enough deaths, but it's happening in the UK.

Thanks to lifestyle changes and effective treatments, deaths from coronary heart disease have been steadily falling since the late 1960s, say the authors of a new study in the journal Heart.

But rising trends in obesity and diabetes threaten to halt or even reverse the “hard fought gains” in cutting deaths from heart disease, they warn. And these trends are much more likely to become apparent among younger Britons first, say the authors.

The authors assessed death rates for coronary artery heart disease in England and Wales between1984 and 2004, using national figures. They used the data to calculate heart disease death rates grouped by age for British adults aged 35 years and older.

The results showed that, overall, deaths from coronary heart disease fell by almost 55% among men and by 48% among women over the two decades. The average annual decline in heart deaths steadily increased every decade to reach almost 5.5% for men and over 4% for women from 2000 onwards. But when the figures were unpicked by age, they showed that death rates from heart disease among younger Britons were lower and now seem to be levelling off.

For 35 to 44 year old men the decline in death rates was 35%, and for those aged 45 to 54 it was 47%. And between 2000 and 2004, there was virtually no fall in death rates from heart disease among those aged between 35 and 44.

In 45 to 54 year old women, the annual decline in death rates was 38%, and while rates in those aged 35 to 44 continued to fall, the numbers of heart attacks were few.

“The party is over, and complacency runs a high risk,” they conclude. “The flattening trends in [coronary heart disease] mortality rates among younger adults suggest that the cardiovascular disease epidemic is not being controlled.”

A similar pattern has emerged in the United States, where rates of obesity and diabetes are also soaring.