Antibiotics cut stroke risk from heart infection

By Will Boggs, MD

NEW YORK (Reuters Health) - The risk of stroke in patients with infective endocarditis, an infection usually involving the heart valves, declines markedly after 1 week of antibiotic therapy, according to a report in the American Heart Journal.

Strokes associated with infective endocarditis may occur when debris that accumulates within the heart breaks off and travels through the blood vessels to the brain, causing a blockage that deprives brain tissue of oxygen. These types of strokes are called embolic strokes.

Dr. Stuart A. Dickerman from New York University School of Medicine, New York, and colleagues analyzed data from 1,437 patients admitted to a hospital with infective endocarditis to determine how frequently strokes occurred and to define the relationship between antibiotic therapy and the risk of subsequent stroke.

Overall, 219 patients, roughly 15 percent, experienced a stroke, the authors report. Of these patients, 185 had data available for analysis. Half of the strokes occurred before antibiotic therapy was started and half occurred afterward.

The daily rate of stroke fell markedly after antibiotics were begun and the rate continued to fall the longer these drugs were given. For instance, using antibiotic therapy for 2 weeks rather than 1 reduced the stroke rate by 65 percent. After 1 week of therapy, just 3.1 percent of endocarditis patients experienced a stroke.

Infection with a bacterium called Staphylococcus aureus and presence of bacterial growths on heart valves increased the risk of stroke. Whether the patient had a natural heart valve or an artificial one placed during a prior surgery did not affect the stroke risk.

Although surgery is often used to treat infective endocarditis, the results suggest that if the sole reason for surgery is to prevent stroke, then such an operation may not be needed after a week of antibiotic therapy, the authors conclude.

SOURCE: American Heart Journal, December 2007.