Cerebral Microembolism in Acute Myocardial Infarction

Abstract

Background and Purpose-This study was undertaken to determine the frequency of cerebral microemboli (high-intensity transient signals; HITS) detected by transcranial Doppler (TCD) in patients with acute myocardial infarction (AMI) and to relate them to the various putative risk factors and clinical embolic events. Methods-We investigated 112 consecutive patients within 72 hours of admission to an acute coronary care unit using TCD to monitor for cerebral microemboli. Twelve patients were excluded because of failure of ultrasound insonation. All patients had 2-dimensional echocardiograms within the study period. Results-HITS were detected in 17% of patients, with significantly higher frequency in patients with reduced (Ͻ65%) left ventricular (LV) ejection fraction (Pϭ0.019), akinetic LV segments (Pϭ0.002), and LV thrombus (Pϭ0.015). A marginally significant (Pϭ0.059) increase of HITS was found in patients with anterior AMI. Stroke was significantly more frequent in patients with cerebral microemboli (Pϭ0.01). Conclusions-HITS were detected in 17% of patients in spite of adequate antithrombotic therapy and were increased in patients with reduced LV function, akinetic myocardial segments, and LV thrombus. They were present in all 3 patients with stroke and may represent a predictor of clinical embolic events. (Stroke. 1999;30:2679-2682.)

Prevalence of Embolic Signals in Acute Coronary Syndromes

“…10 The in-hospital incidence of stroke events was 0.5% and that of TIA was 1.0%; these data concur with a study showing a reduction over time in the incidence of adverse cardiovascular events in patients hospitalized for an ACS. 13 In our study, none of the patients who had a stroke or a TIA had presented ES.…”

“…13 The report of a 17% prevalence of ES in patients with ACS was based on 100 patients with myocardial infarction recruited between 1997 and 1999. 10 Since then, treatments for …”

“…Given the rapid dissemination of primary percutaneous interventions as preferred therapy for myocardial infarction, 20,21 thrombolytic therapy was used in up to 45% of patients in the 1990s, whereas only 9% of patients received this treatment in our sample, and none of these had ES. Apart from differences in ACS treatment, patients in the previous study 10 were older, only had myocardial infarctions, and had worse ejection fraction and more akinetic segments (Table 4). These differences may reflect selection of different populations, but also reflect the substantial improvement in ACS outcomes witnessed in recent years.…”

“…One of these, tirofiban, has been shown to stop ES in patients with a TIA and unstable carotid disease. 19,20 In the study by Nadareishvili et al, 10 there was a trend toward an increase in the frequency of ES in patients treated with thrombolysis (22.2% versus 12.7%; Pϭ0.285); the authors hypothesized that clot fragmentation could produce microemboli in patients who had not received aspirin (16.1% versus 28.5%; Pϭ0.339). Given the rapid dissemination of primary percutaneous interventions as preferred therapy for myocardial infarction, 20,21 thrombolytic therapy was used in up to 45% of patients in the 1990s, whereas only 9% of patients received this treatment in our sample, and none of these had ES.…”

“…9 Only one study published in 1999 reported a prevalence of ES as high as 17% in patients with myocardial infarction with a mean rate of ES of 0.5Ϯ1.6 per 30 minutes; the authors found that the presence of ES was related to postmyocardial stroke. 10 Since then, how-ever, antithrombotic treatment for ACS has changed, which may have modified the prevalence of ES.…”