Hassanain Toma, MD

Iung B, Tubiana S, Klein I, Messika-Zeitoun D, Brochet E, Lepage L, et al. Determinants of Cerebral Lesions in Endocarditis on Systematic Cerebral Magnetic Resonance Imaging: A Prospective Study. Stroke. 2013

Patients with Infective endocarditis (IE) are at risk of developing ischemic strokes and cerebral microbleeds presumably due to septic emboli. However, it is difficult to predict which of these patients are at risk of such ischemic events. In this prospective study, Iung et al. performed cerebral magnetic resonance imaging (MRI) on 120 consecutive patients with left-sided IE, and analyzed their echocardiographic characteristics.

MRI revealed cerebral abnormalities in 82.5% of IE patients, of which 84.4% were asymptomatic. Using multivariate analysis, they demonstrated that ischemic strokes were significantly associated with Staphylococcus aureus IE (odds-ratio 2.65,), and vegetation length (odds-ratio 1.10 per mm). Further more, they determined that vegetation length of >4 mm were associated with ischemic strokes (sensitivity of 74.6%, specificity of 51.5%). Finally, microbleeds were significantly associated with prosthetic IE (OR 8.01) irrespective of anticoagulation usage.

Their findings potentially create a dilemma with respect to applying the current standard of care in managing large vegetations. Generally, valvular surgery is reserved for vegetation length of >10 mm, because this was previously demonstrated to be associated with embolic strokes on CT scans. By using a more sensitive test to evaluate the brain (ie. MRI), it’s clear that embolic strokes are a lot more common than previously thought. One would wonder if a more aggressive approach (ie. Surgical) should be offered to patients with vegetation size >4 mm. The author sites multiple studies that suggest small emboli and microbleeds may lead to cognitive decline and dementia.

Interestingly, the authors revealed that acute and chronic microbleeds were significantly more common in prosethetic IE, irrespective of anticoagulation usage. It is difficult to draw conclusion from this, since no pathophysiological mechanisms are known to explain this. However it raise the question of weather valvular surgery is independently associated with cerebral microbleeds. This is important for patients at they need to be aware of the possible longterm cognitive impact of such surgeries.