Antibiotics 'boost heart function'

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hi

Saturday, 2 March, 2002

An antibiotic has been shown to improve how the heart and blood vessels function in angina patients in a UK study.

Scientists have for some years believed that a specific bacterium or virus might damage the endothelium, the lining of arteries and blood vessels.

Damage to the endothelium can lead to atherosclerotic plaques, the build-up of fatty materials within the walls of the arteries, and potentially to angina and heart attacks.

The UK research was carried out on people who had the Chlamydia pneumoniae bacteria, which causes acute respiratory infections in their blood.

This research adds to our knowledge by showing that antibiotics may act in the same way as anti-inflammatory drugs by reducing inflammation in the arteries

British Heart Foundation  

C. pneumoniae was selected because it is a common infection which has previously been found in the plaque of people with coronary artery disease.

The researchers looked at 40 men aged over 55, all of whom had coronary artery disease.

They were either given the antibiotic azithromycin or a placebo for five weeks.

Blood flow

The study, carried out by researchers at St George's Medical School, London, measured the efficiency of participants' blood flow in the brachial artery in the arm.

In a healthy artery, which also has a healthy endothelium, blood vessels are able to relax if the blood flow increases - called flow-mediated dilation.

Measures of substances in the blood which indicate damage to the endothelium, and levels of protein present when there is inflammation, were also checked.

Patients were examined before and after the study.

Those given the antibiotic showed improved flow-mediated dilation and a fall in the levels in the markers for endothelial problems.

But researchers suggest the antibiotic may not be benefiting patients because the antibiotic's benefit on patients with high levels of C. pneumoniae antibodies was essentially the same as those with low levels.

It is possible that the drug works directly to reduce inflammation, as azithromycin is in a class of drugs called macrolides, which have anti-inflammatory effects.

Inflammation is one of the body's responses to infection. But azithromycin did not reduce the levels of C-reactive protein in this study.

Targetted treatments

Juan Carlos Kaski, a professor of cardiovascular science at St. George's, who carried out the research, said: "We have found in this study that treatment with azithromycin, an antibiotic used to treat C. pneumoniae infections, improved the function of the endothelium."

He said the antibiotic appeared to allow the artery to widen when it needed to.

Researchers must now try to identify why antibiotics benefit cardiovascular health.

Professor Kaski suggested the research could eventually result in even better antibiotics or even a vaccine.

A spokeswoman for the British Heart Foundation told BBC News Online: "Recent evidence has shown that inflammation of the arteries may be an important risk factor for future heart attacks and strokes.

"Bacteria such as C. pneumoniae or Helicobacter pylori may have an effect on the coronary arteries and some anti-inflammatory drugs such as aspirin have been shown to help reduce this effect.

"This research adds to our knowledge by showing that antibiotics may act in the same way as anti-inflammatory drugs by reducing inflammation in the arteries. It is still unclear what mechanism causes these drugs to have this benefit.

"In the long term more large-scale randomised studies are needed to further validate these findings.

"Until then, people need to remember that many other factors such as smoking, cholesterol and high blood pressure also aggravate the lining of the arteries causing inflammation that can lead to coronary heart disease."

The research is published in Circulation: Journal of the American Heart Association

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