The incidence of stroke on cranial computed tomography (CT) and change in echocardiographic vegetation area was prospectively compared in a preliminary observational study involving nine patients with infective endocarditis randomized to either low-dose aspirin (75 mg d-1, Group I, n = 4) or no aspirin (Group II, n = 5). Two symptomatic cerebral infarcts and one myocardial infarct occurred in the controls, compared to no events in patients on aspirin during a total observation period of 343 d (range 28-49 d). The mean vegetation area decreased in the aspirin group (mean change = -0.24 cm2), compared to an increase in controls (mean change = +0.35 cm2). The platelet half-life (normal range 5-6 d), which was measured using Indium-111 radiolabelling, tended to be lower in Group II (4.6 +/- 0.2 vs. 3.9 +/- 0.5 d). No side-effects or complications attributable to aspirin were observed. A possible role for adjunctive aspirin therapy in the prevention of embolic complications in infective endocarditis is suggested, and warrants further study.

Local and generalized changes in coagulation may be important in the genesis of vegetations and embolism in infective endocarditis. To characterize such alterations, serial hematological investigations were performed on nine consecutive patients who satisfied the inclusion criteria. Platelet survival was measured by Indium111 labeling. Acute and convalescent samples were analyzed for fibrinogen, factor VIIIc, antithrombin III (AT III), fibrin/fibrinogen degradation products (FDPs), and platelet aggregation. The results suggest that in the active stage of the disease: (1) hypercoagulability may be caused by a rise in acute phase reactants, (2) an acceleration of coagulation and fibrinolysis may supervene, and (3) in some cases there is a reduction in platelet aggregation, possibly as a result of continued circulation of previously activated "exhausted" platelets.

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