The findings suggest hundreds of thousands should be given statins or other heart pills if they suffer a chest infection or bladder problem.

A project tracking 1.2million patients found those admitted to hospital for pneumonia or urinary tract infections were 40 % more likely to have a heart attack within eight years. They were also 150 % more likely to suffer a stroke, Daily Mail reported.

This suggests infections have an even greater impact on heart health than obesity, which raises the risk of strokes and heart attacks by about 25 %.

The research team, from Aston Medical School in Birmingham and the University of Cambridge, believe this is because infections cause long-term inflammation in blood vessels – making them more prone to clotting and clogging.

Patients who suffer an infection should be treated in the same way as someone with high blood pressure, raised cholesterol or diabetes, the researchers said. This could involve prescribing statins or aspirin as a preventive measure to cut the risk to their heart.

Nearly 600,000 people are admitted to hospital with chest infections such as pneumonia in England every year. About 300,000 are admitted with urinary infections.

The study, which will be presented today at the American College of Cardiology conference in Orlando, also found that those who had had infections were more likely to die if they did suffer a heart attack or stroke.

They were three times more likely to die from a heart attack than those who had not had infections, and almost twice as likely to die if they had a stroke.

Cardiologist Dr Rahul Potluri, of Aston University, said: ‘Our figures suggest that those who are admitted to hospital with a respiratory or urinary tract infection are 40 per cent more likely to suffer a subsequent heart attack, and 2.5 times more likely to have a stroke, than patients who have had no such infection – and are considerably less likely to survive from these conditions.’

Experts have shown greater interest in the role of inflammation in heart disease after a study last year found that treating patients with anti-inflammatory canakinumab could cut their risk of having a heart attack by 24 per cent. Doctors say this drug – not yet available for heart patients – could represent the biggest breakthrough in cardiovascular medicine since statins were developed 30 years ago.

Dr Potluri said: ‘Infection appears to confer as much, if not more, of a risk for future heart disease and stroke as very well established risk factors such as high blood pressure and diabetes.

‘Although inflammation has been linked to atherosclerosis [when plaque builds up in arteries], this is the largest study to show that common infection is such a significant risk factor.’

Lead author Dr Paul Carter, an academic clinical fellow at the University of Cambridge, said: ‘The data illustrate a clear association between infections and life-threatening heart conditions and strokes – and the figures are too huge to ignore.

‘Serious infections are amongst the biggest causes of death in the UK directly, but our research shows infections that are severe enough to lead to hospitalisation may present a delayed risk in the form of atherosclerotic diseases.

‘The sheer number of people who could be affected presents a challenge that needs investigation.’