Insight into heart infection

Prof David Murdoch, of the pathology department at the University of Otago, Christchurch.
Prof David Murdoch, of the pathology department at the University of Otago, Christchurch.
A major international study led by New Zealand clinicians and scientists will contribute to changes in the diagnosis and treatment of infective endocarditis (IE), researchers say.

Endocarditis is an infection of a heart valve and, internationally, has an 18% in-hospital mortality rate that has not changed in the last 25 years.

Internationally, the mortality rate one year after diagnosis is even worse, approaching 40%.

The disease also has other serious health impacts such as stroke, blood clots, heart failure and other ongoing complications.

Among New Zealand patients admitted to hospital with IE, the in-hospital death rate is about 10%, significantly lower than the overall international figure, researchers say.

About 300 people enter hospital in New Zealand every year with IE and 42% undergo heart valve replacement surgery (50% internationally).

"It's going to have an influence," lead researcher, Prof David Murdoch, of the University of Otago's Christchurch campus, said of the new study.

"Data from this will go into every textbook," Prof Murdoch, who heads the Christchurch pathology department, said in an interview.

The study showed how to better treat the disease and to "reduce the stubbornly high mortality rate".

The research showed that IE was "often an acute and serious illness that needs to be diagnosed and treated quickly, with antibiotics and often surgery, in order to save lives", he said.

Some changes in medical education would also result from the study, which had tested "all the old dogma" about the disease.

The study concluded that some of the classical clinical features of the disease that are taught to all medical students now occur only in a minority of patients.

This meant that clinicians would have to reassess how they diagnosed and treated this acute disease, and that medical guidelines would have to be adjusted, he said.

The study reveals that the bacterium Staphylococcus aureus is the most common cause of IE in much of the world, and that IE commonly follows degeneration of the heart valves with ageing.

This contrasted with earlier studies that linked it to heart valve damage following rheumatic fever in younger age groups.

One of the more interesting findings was that 25% of patients with IE contracted the bacterial infection following health care, or after invasive medical care, particularly in the United States.

• This is the first major international study which has examined the presentation, causes and outcome of infective endocarditis.

It is the largest study of IE, involving 2781 patients from 58 hospitals in 25 countries, including New Zealand hospitals in Auckland, Wellington and Christchurch.

The research is published in Archives of Internal Medicine.

 

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