Incidence of left-ventricular thrombosis after acute transmural myocardial infarction. Serial evaluation by two-dimensional echocardiography

In vivo ultrasonic tissue characterization of human intracardiac masses

Interactions between an ultrasonic signal and cardiac tissue have been used to characterize the histologic state of myocardium in vitro. To assess the utility of in vivo ultrasonic tissue characterization, stochastic analysis was applied to the digitized echocardiographic signals from 15 patients with 2-dimensional echocardiograms suggesting intracardiac masses. Ten subjects with echocardiograms suggesting mural thrombi underwent subsequent surgery or necropsy, which confirmed thrombi in 6 and revealed no thrombi (designated artifact) in 4. Five other patients had intracardiac tumors. The amplitudes within the digitized ultrasonic signals were displayed as histograms, which were described by a parameter k that represented the degree to which each histogram departed from a totally random probability density function. In 5 of 6 thrombi, k = 0, but in all 4 artifacts, k greater than 0. The sixth thrombus had k = 0.5 due to the specular effect of the interface between the thrombus' 2 lobes. All 5 tumors had k greater than 0. Ultrasonic tissue characterization using a stochastic analysis of backscatter can be performed in vivo and helps differentiate thrombus from artifact and tumor in the heart.

Effect of infarct location on the in-hospital prognosis of patients with first transmural myocardial infarction

We studied the in-hospital prognosis of 1105 patients who had their first transmural myocardial infarction; 611 patients (55.3%) had anterior myocardial infarction (AMI) and 494 (44.7%) had inferior myocardial infarction (IMI). Patients with IMI had a significantly lower in-hospital mortality rate (9.1% vs 15.6%, p = 0.0014) and significantly lower prevalences of congestive heart failure (39.4% vs 47.6%, p = 0.0066), cardiogenic shock ( 8.7% vs 12.6%, p = 0.0384) and conduction defects (left anterior hemiblock, right bundle branch block and intraventricular conduction defect). The patients with AMI had significantly higher peak enzyme levels, and a greater percentage of them (40.1% vs 25.9%) had SGOT greater than 240 IU/l, whereas more patients with IMI (34.6% vs 27.8%) had SGOT less than 120 IU/l (p = 0.0001). When the parallel subgroups were compared according to the peak SGOT levels (less than 120, 120-240, and greater than 240 IU/l, the differences in the mortality and morbidity between the two infarct locations diminished. However, patients with AMI still had a less favorable outcome. Logistic regression analysis demonstrated that both the peak enzyme level and the infarct location had an independent influence on the in-hospital prognosis of patients with first transmural infarction.

Refractory left ventricular failure: use of two-dimensional echocardiography in identification of thrombi

A 65-year-old woman was hospitalized several times after having an acute anteroseptal transmural infarction. Her course was complicated by recurrent ventricular tachycardia and severe left ventricular failure. Chest x-ray films showed pulmonary congestion and mild right pleural effusion. Two-dimensional echocardiography revealed a large left ventricular thrombus, which resolved after two months of treatment. The course of anticoagulation was later complicated by massive gastrointestinal hemorrhage. Finally, the patient died in her sleep, probably as a result of arrhythmia. An autopsy revealed extensive left ventricular mural thrombi. The early identification of left ventricular thrombus by two-dimensional echocardiography has lifesaving implications. It is possible that, with proper medical management, further formation of pulmonary emboli could be prevented.

Pathogenesis of left ventricular aneurysms: an experimental study in the rat model

Left ventricular aneurysms, convex protrusions at sites of transmural scar, are clinically recognized late after myocardial infarction because of their hemodynamic or arrhythmic complications. Whether aneurysms develop from dilation of freshly infarcted myocardium early after myocardial infarction or from late dilation of scar is not known. To investigate this question, the time course of changes in shape of the left ventricle early and late after myocardial infarction was studied. One hundred forty-one myocardial infarcts were produced in rats by coronary ligation, and the animals were killed at time periods of up to 6 weeks. True aneurysms developed as early as 2 weeks and only in rats with a transmural infarct. The percent of rats that manifested "aneurysmal shape changes" (defined as a protrusion of the full thickness of the left ventricular wall) increased from day 1 to day 5, but did not change significantly thereafter. The extent of left ventricular dilation in hearts with early aneurysmal shape changes did not progress significantly up to day 42. Accordingly, in the rat, regional aneurysmal shape alterations are due not to late dilation of scare tissue, but rather to "expansion" of freshly necrotic myocardium within the first 5 days of infarction. Thus, early changes in shape appear to determine late aneurysm formation.

Detection of left ventricular thrombus by two-dimensional echocardiography: sensitivity, specificity, and causes of uncertainty

To define the sensitivity, specificity and predictive accuracy of two-dimensional echocardiographic detection of left ventricular thrombus, the echocardiograms of 78 patients who had independent proof of the presence or absence of a left ventricular thrombus were interpreted without knowledge of any clinical data. The presence of thrombus was established by autopsy in four patients, by aneurysmectomy in three, and by indium-111 platelet imaging in 15; the absence of thrombus was proved by autopsy in 55 patients and by aneurysmectomy in one patient. The characteristics of true-positive and false-positive echocardiograms, interobserver variability, and clinical features associated with proved thrombus were also defined. The echocardiogram was positive for thrombus in 22 patients, equivocal in seven and negative in 49. For detection of thrombus, a positive or equivocal echocardiogram had a sensitivity of 95% (21 of 22), a specificity of 86% (48 of 56), and a predictive value of 72% (21 of 29); the predictive value of a negative study was 98% (48 of 49). Considering positive and equivocal studies separately, the predictive value of a positive study was 86% (19 of 22), while that of an equivocal study was only 29% (two of seven). Compared with patients who had no thrombus, patients with proved thrombus had a higher prevalence of electrocardiographic transmural anterior infarction (86% vs 13%), left ventricular aneurysm (73% vs 5%), and clinical systemic emboli (36% vs 7%) (all p less than 0.05). These clinical features help to identify a subset of patients most likely to have left ventricular thrombi who may benefit from echocardiography. Two-dimensional echocardiography is highly sensitive in detecting left ventricular thrombus, but false-positive studies are relatively common. Several echocardiographic criteria derived from analysis of the true and false positives in this study may help minimize diagnostic errors.

Comparison of Indium-111 platelet scintigraphy and two-dimensional echocardiography in the diagnosis of left ventricular thrombi

In a study comparing indium-111 platelet scintigraphy and two-dimensional echocardiography as methods of identifying left ventricular thrombi, the results obtained with both techniques were verified at surgery or autopsy in 53 patients--34 with left ventricular aneurysms, and 19 with mitral-valve disease. Left ventricular thrombi were found at surgery or autopsy in 14 of the patients with aneurysms and in none of those with mitral-valve disease. Thirteen of 53 echocardiograms (25 per cent) were technically inadequate and excluded from the analysis. In the group with aneurysms, the sensitivity of scintigraphy in detecting thrombi was 71 per cent, and that of echocardiography was 77 per cent. The specificity of scintigraphy was 100 per cent, and that of echocardiography was 93 per cent. We conclude that indium-111 platelet scintigraphy and two-dimensional echocardiography have useful and complementary roles in the detection of left ventricular thrombi. Both these noninvasive techniques can be used to monitor therapy.

Current status of anticoagulant therapy

Anticoagulant therapy has stood the test to time. Full-dose heparin and warfarin prevent recurring pulmonary embolism and deep venous thrombosis. Their use is indicated in patients who have experienced venous thromboembolism unless contraindications are compelling. Low-dose heparin is successful in preventing the initial episode of venous thrombosis in most patients at high risk for the development of thrombophlebitis. Warfarin reduces the incidence of systemic embolization in patients with heart disease and atrial fibrillation and in patients with artificial heart valves. Evidence is accumulating to suggest that warfarin may still retain an important role in the management of patients with myocardial infarction. However, bleeding remains an inevitable risk in patients receiving anticoagulant therapy. The risk, however, can be diminished when both the physician and patient understand the mechanism of action of the drugs and the factors that predispose to bleeding.