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A New Zealand-led international study has found a common bacteria is often the cause of the potentially fatal heart disease infective endocarditis (IE).
Endocarditis is an infection of a heart valve and has an 18% in-hospital death rate.
The one-year mortality rate is closer to 40%.
It can also be the cause of other complications including stroke, blood clots and heart failure.
The study of 2781 patients from 58 hospitals in 25 countries found that the bacterium staphylococcus aureus was the most common cause of IE and that it often followed degeneration of the heart valves with ageing.
"What this study does is that it enables us to be much more definitive about the contemporary causes of this serious disease and how to better treat it and reduce the stubbornly high mortality rate," said lead researcher Professor David Murdoch, based at the Christchurch campus of the University of Otago.
"In particular it has shown that infective endocarditis is often an acute and serious illness that needs to be diagnosed and treated quickly with antibiotics and often surgery in order to save lives."
About 300 people are hospitalised in New Zealand every year with infective endocarditis and the study showed that internationally five% undergo heart valve replacement surgery.