Metabolic syndrome significantly boosts the chances of heart failure in middle age, suggests research published ahead of print in Heart.

Metabolic syndrome refers to a cluster of conditions, including obesity, high blood pressure, unfavourable blood fat levels, and diabetes.

The researchers base their findings on regular monitoring of more than 2,300 men who were aged 50 between 1970 and 1974 and who were tracked until the age of 70.

The presence of metabolic syndrome at the start of the study was strongly associated with the subsequent development of heart failure. Men with the syndrome were almost twice as likely to develop heart failure as those without.

This was independent of any other established risk factors for heart failure, such as coronary artery disease, a heart attack, smoking, and poorly working heart valves.

The authors suggest that metabolic syndrome may directly affect the heart itself as well as boosting the build up of fatty deposits in the arteries.

The likely mechanism is insulin resistance and the subsequent excess insulin circulating in the blood, say the authors. Insulin may excessively enlarge the heart muscle (myocardium), so impairing its capacity.

High circulating levels of insulin also stimulate the sympathetic nervous system, thought to be a risk factor in heart failure, and cause heart muscle cells to wither and/or stiffen.

British Medical Journal