Men suffering from impotence should be screened for cardiovascular disease because it could be an early sign of the illness, Italian researchers said on Wednesday.

They believe erectile dysfunction (ED) could be a "sentinel of the heart," enabling doctors to detect heart disease before symptoms occur.

"A strict medical surveillance programme should be mandatory in patients with ED, multiple risk factors and no clinical artery disease," said Dr Piero Montorsi of the Institute of Cardiology at the University of Milan.

In a study of almost 300 men who suffered from impotence and and clogged arteries, 93 percent reported symptoms of ED between one to three years before experiencing angina -- chest pains and discomfort.

"Many patients with ED and multiple risk factors (for cardiovascular disease) are at a higher risk of developing, sooner or later, a coronary acute event," Montorsi told Reuters.

He and his team suggested that clogged arteries also have an impact on penile circulation. ED may develop earlier than heart disease because the penile artery has a smaller diameter than coronary arteries.

"This is probably the main reason why ED comes before coronary artery disease," said Montorsi whose findings are reported online by the European Heart Journal.

The researchers also discovered that the number of cases of erectile dysfunction was lower in men who had a heart attack involving one clogged blood vessel and higher in patients with many clogged arteries or chronic coronary syndrome (CCS).

"Age, multi-vessel coronary involvement, and CCS were independent predictors of ED," Montorsi said.

Coronary heart disease, a major killer in industrialised countries, occurs when there is a build up of plaque which clogs up the arteries and restricts blood flow.

High blood pressure, raised cholesterol levels, smoking, lack of exercise and diabetes are risk factors.

Cases of erectile dysfunction increase with age. About 5 percent of 40-year-old men and up to 25 percent of 65 year-olds experience ED. It can be caused by an illness or injury that affects the nerves or blood flow or the side effects of drugs.

"All men with ED and no cardiac symptoms need a detailed cardiac assessment, blood pressure measurement, fasting lipid profile and glucose, as well as lifestyle advice regarding weight and exercise," said Dr Graham Jackson, a cardiologist at Guy's and St Thomas' NHS Foundation Trust in London, in a statement.