Left ventricular thrombus and stroke after acute myocardial infarction

Abstract: A left ventricular thrombus develops in approximately 40% of patients following an anterior myocardial infarction. Embolization from these thrombi has been regarded as the most important cause of stroke following a myocardial infarction. The occurrence and characteristics of left ventricular thrombi and stroke after anterior myocardial infarction may, however, have changed after the introduction of aspirin and thrombolytics as standard therapy.The occurrence of left ventricular thrombi was examined in 99 patients with an acute anterior myocardial infarction, 74 of whom were treated with streptokinase. Thrombi were equally common in the thrombolysis group (46%, 95% confidence interval [Cl], 35-57%) as in the non-thrombolysis group (40%, 95% Cl, 21-59%). The risk of thrombus formation was related to the degree of left ventricular segmental dysfunction.Using serial echocardiographic examinations, the formation and resolution of thrombi was found to be highly dynamic. The majority of thrombi diagnosed during the hospital stay had resolved at follow-up one month later, irrespective of treatment with streptokinase or anticoagulants. The development of new thrombi was, however, observed at every follow-up examination interval.One-hundred-and-twenty-four patients suffering a stroke within 28 days of an acute myocardial infarction were identified in the northern Sweden MONICA stroke registry between 1985 and 1994. The overall event rate of ischemic myocardial infarction-related stroke was 1.07%. The risk of a stroke was highest duringt he first 5 days after the infarction. Only approximately half the strokes were preceded by an anterior myocardial infarction. In a case-control analysis, atrial fibrillation (chronic or new onset), ST elevation and a history of a previous stroke were found to be independent predictors of stroke. There was a long-term trend towards a lower incidence and event rate for myocardial infarction-related stroke.Clinical stroke characteristics were examined in 103 patients with a first-ever stroke within 28 days of a myocardial infarction and compared with stroke characteristics in 206 control subjects without a recent myocardial infarction. The sudden onset of neurological symptoms, an impairment of consciousness, a progression in neurological deficits and a stroke of the total anterior circulation infarction subclass were more common in cases than in controls. The risk of a recurrent stroke during one year of follow-up was not influenced by a recent myocardial infarction, but patients who had suffered a myocardial infarction had markedly higher mortality.To conclude, thrombolytic treatment does not reduce the occurrence of left ventricular thrombi after a myocardial infarction. The risk of thrombus formation is related to the extent of the myocardial injury. The development and resolution of thrombi is a highly dynamic process. There is a long-term trend towards a lower incidence and event rate of ischemic stroke after a myocardial infarction. Although the clinical stroke characteristics differ, they are not specific enough to differentiate between patients with and without a recent myocardial infarction.