Two-dimensional echocardiographic appearance of left ventricular thrombi with systemic emboli after myocardial infarction

Neurologic complications of myocardial infarction

Cardiac disease, in particular coronary artery disease, is the leading cause of mortality in developed nations. Strokes can complicate cardiac disease - either as result of left ventricular dysfunction and associated thrombus formation or of therapy for the cardiac disease. Antiplatelet drugs and anticoagulants routinely used to treat cardiac disease increase the risk for hemorrhagic stroke.

Surgical thrombectomy of two left ventricular thrombi in a child with acute myocarditis

Myocarditis is a potentially life-threatening disease. Although ventricular thrombus formation in myocarditis is rare, it carries the risk of serious complications. We report on a 10-year-old previously healthy girl presenting with 2 large left ventricular thrombi in acute lymphocytic acute myocarditis. No coagulation disorder was found. Her clinical course and mobile thrombi characteristics prompted us to carry out an urgent surgical thrombectomy rather than primary anticoagulation therapy. The patient has recovered well without clinical signs of thromboembolism.

Efficacy of high dose intravenous heparin for treatment of left ventricular thrombi with high embolic risk

OBJECTIVES

This study was performed to assess the efficacy of high dose intravenous heparin to treat mobile or protruding left ventricular thrombi as detected by serial echocardiography.

BACKGROUND

The presence of mobile and protruding left ventricular thrombi greatly increases the risk of arterial embolization, yet optimal therapy, be it thrombolysis, anticoagulation or surgical removal, has not been defined.

METHODS

Full dose heparin, 31,291 +/- 7,980 (mean +/- SD) IU/day, to prolong partial thromboplastin time to at least twice normal, was administered intravenously to 23 consecutive patients with 25 mobile and protruding thrombi. Patients were prospectively evaluated for hemorrhagic complications and embolic events during therapy. The presence or absence of thrombi and their size and characteristics were assessed by serial echocardiography.

RESULTS

In all 23 patients left ventricular thrombi decreased in size, with disappearance of the high risk features. The duration of high dose heparin infusion was 7 to 22 days (mean 14 +/- 4). Thrombus size was reduced from 3.9 +/- 2.6 to 0.16 +/- 0.38 cm2, and thrombus disappeared entirely in 19 (83%) of 23 patients. No embolic events were detected during treatment, and the only complication was an upper gastrointestinal hemorrhage that was successfully treated medically.

CONCLUSION

High dose intravenous heparin is a highly effective and safe treatment for completely resolving left ventricular thrombi with high risk features for embolization. Most such thrombi disappear completely within 1 to 3 weeks of this treatment without embolic or hemorrhagic complications.

Heart disease in patients with stroke: incidence, impact, and implications for rehabilitation. Part 1: Classification and prevalence

Heart disease is found in about 75% of patients who have suffered a stroke. Cardiovascular diseases can be risk factors, etiologic mechanisms, associated conditions, or direct consequences of stroke. Cardiac comorbidity may delay initiation of rehabilitation, complicate the course and care of the patient with stroke, inhibit participation in a therapeutic exercise program, limit functional outcomes, and contribute to early mortality in the individual with cerebrovascular disease. Part 1 of this two-part article describes the various forms of heart disease that may be seen in stroke patients, and reviews the incidence figures for each type of associated cardiac condition.

Use of echocardiography in detecting cardiac sources of embolus

Up to 20% of all ischemic strokes are felt to be the result of emboli from the heart. High resolution transthoracic (TTE) and transesophageal (TEE) echocardiography have been the principal diagnostic tools for detecting associated cardiac abnormalities and for guiding medical and surgical approaches to these patients. In addition to identifying the precise location and morphological characteristics of intracardiac masses, echocardiography has improved our ability to predict embolic potential of these masses. Specific cardiac lesions that are predisposed to stroke and are readily identifiable by echocardiography include: cardiac thrombi, valvular vegetations, cardiac tumors, aortic atheroma, atrial septal aneurysm, and regional left ventricular wall abnormalities. Careful interrogation of patients with cerebrovascular accidents has identified a potential cardiac source of embolus in approximately 30%. This is largely due to the advent of TEE, which has provided much better assessment of posterior cardiac chambers including left atrium and left atrial appendage. Use of TEE in identifying a cardiac source of embolus is indicated in patients with stroke who are young, have no apparent cerebrovascular disease, or have recurrent embolic events. Echocardiography is an essential diagnostic tool in evaluating patients with a suspected cardiac source of embolus. TTE and TEE provide invaluable information regarding the majority of cardiac sources of embolus.

Left ventricular thrombosis and arterial embolism in acute anterior myocardial infarction

To study left ventricular thrombus (LVT) formation and arterial embolism (AE), 106 consecutive patients with a first acute anterior myocardial infarction (AAMI) underwent two-dimensional echocardiography before discharge. Repeated assessments for detection of AE were performed. Patients were non-randomly allocated to either no heparin, low-dose heparin or high-dose heparin. LVT was found in 25 (26.9%) of 93 patients with technically satisfactory echocardiograms. Left ventricular (LV) wall motion impairment (P = 0.0017) and treatment with either heparin or low-dose heparin (P = 0.0019) were independent predictors of LVT formation. AE, all strokes, occurred in 10 patients (9.4%) and was strongly associated with high age (P = 0.0013). In conclusion, LVT and AE are frequent complications to AAMI. LV wall motion impairment predisposes for LVT and low-dose heparin seems not to prevent these complications.

Antithrombotic therapy in left ventricular thrombosis and systemic embolism

Left ventricular (LV) thrombi are responsible for significant morbidity and mortality in our society. Twenty-five percent of cardiogenic emboli are associated with acute and chronic myocardial infarction. With the development of noninvasive imaging techniques LV thrombi have been increasingly recognized as an important clinical entity; the imaging method of choice is two-dimensional echocardiography. LV mural thrombi occur in one third of Q wave anterior myocardial infarctions; their occurrence in patients with non-Q wave infarction and inferior Q wave myocardial infarction is less than 5%. More than half of all LV thrombi are formed within 48 hours of acute myocardial infarction, and nearly all thrombi have been formed within a week of infarction. The development of an LV thrombus is associated with some risk of systemic embolization. To prevent LV thrombosis and systemic embolism, full-dose heparin followed by warfarin therapy for at least 3 months is indicated for patients with large anterior infarctions and those with heart failure. The use of thrombolytic therapy does not reduce the risk of LV thrombus formation; few data exist on whether early coronary angioplasty reduces the risk of LV thrombus formation and the risk of embolization. The proper treatment for patients with chronic LV thrombi remains unknown.

Role of Doppler echocardiography in coronary artery disease

Doppler echocardiography can have a major role in the evaluation of patients with coronary artery disease. This review deals with the imaging planes in relation to coronary vascular territories and the role of Doppler echocardiography in evaluating patients with acute and chronic ischemic syndromes.

Left ventricular thrombectomy in the early postinfarction period

Emergency left ventricular thrombectomy was performed on four patients soon after infarction. In three patients surgery was carried out after embolisation had occurred and when a large, residual, protruding, mobile thrombus remained in the left ventricle. Surgery was performed in the fourth patient after a high risk thrombus was detected and initial attempts to lyse it had failed. All four patients had an uneventful recovery and were discharged within two weeks of surgery. These cases indicate that the therapeutic option of left ventricular thrombectomy is feasible for patients with acute infarcts and problematic left ventricular thrombi.

Echocardiography in coronary artery disease

Echocardiography has a major role in the evaluation of patients with CAD. To obtain the maximal amount of information using this technique, certain basic principles relating to regional myocardial mechanics during ischemia and flow-function relations are required. In addition, a detailed knowledge of cardiac anatomy and the three-dimensional orientation of the heart within the chest cavity is required to access meaningful information from two-dimensional planes. Furthermore, skill is also required in acquiring data in proper imaging planes and in separating true (actual pathology) from the false (artifacts, etc.). Echocardiography is not a "mature" technology. It is still developing and it is sometimes difficult to keep up with the advances. However, keeping abreast of these developments is essential to fully exploit the advantages of this technique. In addition, knowledge of the ever-changing aspects of CAD is required in order to correctly interpret visual information in context of a particular patient. Finally, more clinical studies are needed to further define the role of echocardiographic techniques in patients with CAD.

Natural history of left ventricular thrombi: their appearance and resolution in the posthospitalization period of acute myocardial infarction

A series of 198 consecutive patients with acute myocardial infarction were prospectively studied before hospital discharge and during 24.0 +/- 8.6 months of follow-up. A predischarge thrombus was found in 38 (31%) of 124 patients with anterior infarction but in none of 74 patients with inferior infarction (p less than 0.001). Early thrombolytic therapy in 34 patients did not decrease the rate of thrombus occurrence. Acute anterior infarction, ejection fraction less than or equal to 35% and apical dyskinesia or aneurysm (but not akinesia) were significantly related to the appearance of thrombus during hospitalization by stepwise logistic regression analysis. Echocardiographic follow-up of 159 patients for at least 6 months (mean 26.6 +/- 8.4) revealed that thrombus disappeared in 14 (48%) of 29. Disappearance of thrombus was related to predischarge apical akinesia (but not dyskinesia) and to warfarin therapy during the follow-up period. A new thrombus first appeared after hospital discharge in 13 of 130 patients, and in 7 of the 13 it resolved during further follow-up. Thus, 30% (13 of 42) of thrombi in these patients appeared after discharge from the hospital. Three factors were related to occurrence of new thrombi during the follow-up period: deterioration in left ventricular ejection fraction, predischarge ejection fraction less than or equal to 35% and ventricular aneurysm or dyskinesia. Systemic embolism occurred in six patients, all with a predischarge thrombus (p less than 0.001). Mobility of the thrombus was the only variable significantly related to subsequent embolic events (p = 0.001) by logistic regression analysis. Thus, the predischarge echocardiogram identifies patients with thrombus and those at highest risk of embolic events. It can indicate patients who are likely to have thrombus resolution and those at risk of developing a new thrombus after hospital discharge. Follow-up echocardiograms may help in guiding the length of long-term anticoagulant therapy. Four additional patients with a predischarge apical mobile thrombus (not part of the consecutive series) received thrombolytic therapy. In two of the four, lysis of thrombus was achieved without complications, but systemic embolism occurred in the other two, and proved fatal in one.

Decision analysis concerning the application of echocardiography to the diagnosis and treatment of mural thrombi after anterior wall acute myocardial infarction

The diagnostic and therapeutic approach to the problem of mural thrombi after acute myocardial infarction is uncertain. It is clear that the main therapeutic goal is the prevention of embolic strokes. Although it is known that the incidence of thrombi is greatest after anterior wall infarctions, there is uncertainty concerning (1) the probability of a mural thrombus; (2) the sensitivity and specificity of echocardiography in making the diagnosis; (3) the probability that a thrombus will embolize and result in a cerebrovascular accident (CVA); (4) the efficacy of warfarin in preventing embolization; and (5) the probability of bleeding with and without warfarin. To study this problem in patients who have had an anterior wall myocardial infarction, a model was created in which reasonable estimates for the unknown parameters were determined from published medical studies. The model was designed to consider patients if they were or were not treated during the initial hospitalization with heparin. The probability of thrombus was estimated at 0.30, sensitivity and specificity of echocardiography at 0.85 and 0.85, probability that a thrombus will embolize at 0.15, efficacy of anticoagulation of 0.75, probability of bleeding with warfarin at 0.03 and probability of bleeding without warfarin at 0.005. Probabilities of a CVA and of bleeding with and without warfarin were determined if all patients were anticoagulated, if patients with positive echocardiographic results were treated, if patients with negative echocardiographic results were treated and if echocardiographically guided therapy was instituted in which patients with positive echocardiographic results are treated and patients with negative results are not treated.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of thrombolytic treatment followed by full dose anticoagulation on the frequency of left ventricular thrombi in acute myocardial infarction

This study evaluated the influence of thrombolysis followed by full anticoagulation on the frequency of left ventricular (LV) thrombi after acute myocardial infarction (AMI). Nineteen consecutive patients with a first anterior wall AMI who received 1,500,000 IU of streptokinase within 3 hours of symptom onset, followed by full anticoagulation, underwent echocardiographic studies within 24 hours of symptoms, and then on days 2, 3, 5, 7, 12, 30 and 90. Forty-four patients, with comparable clinical features and echocardiographic protocol but without antithrombotic therapy, served as the control group. LV thrombi developed in 4 of 19 (21%) treated patients and in 23 of 44 (52%) control subjects (p = 0.02). LV aneurysm or major wall motion abnormalities were noted in 8 of 19 (42%) treated patients and in 30 of 44 (68%) control subjects (p less than 0.05). No significant difference was found between treated and untreated patients when comparing the incidence of thrombi in the subgroups of patients with aneurysm or major wall motion abnormalities (3 of 8 vs 21 of 30) and in the subgroups with less extensive LV dysfunction. Thrombi disappeared during hospitalization in 3 of 4 treated patients, but in none of the controls. Fewer patients treated with intravenous streptokinase followed by full anticoagulation developed LV thrombi compared to patients treated with conventional therapy. This difference may be related to a reduced occurrence of major LV wall motion abnormalities. Resolution of thrombi frequently occurs in the hospital phase of AMI; therefore, only frequent echocardiographic examinations can assess the true frequency of LV thrombi.

Left ventricular thrombus incidence and behavior studied by serial two-dimensional echocardiography in acute anterior myocardial infarction: left ventricular wall motion, systemic embolism and oral anticoagulation

Serial two-dimensional echocardiography was performed to detect left ventricular thrombus in 92 consecutive patients with a confirmed first acute anterior myocardial infarction. Thirty left ventricular thrombi were diagnosed in these 92 patients. The cumulative percent of identified thrombus in each echocardiographic examination in the surviving patients was 27% at less than 24 h; 57% at 48 to 72 h; 75% at 1 week and 96% at 2 weeks. The thrombus shape was defined as mural in 53% and protruding in 47% of patients. Systemic embolism (stroke) was noted during hospitalization in two patients with a protruding thrombus. At 12 weeks of follow-up, patients with thrombus had poorer (and almost unchanged from baseline) global left ventricular function as expressed by wall motion score compared with that of patients without thrombus, who exhibited significant improvement. Global left ventricular wall motion in patients with persisting or resolved thrombus was similar during follow-up. Apical wall motion worsened in 70% of the patients with persisting thrombus and in 25% of the patients with resolved thrombus (p less than 0.1). In the 22 surviving patients with thrombus, resolution or change in thrombus shape or size was noted in 14 of the 15 patients receiving anticoagulant therapy and in 4 of the 7 untreated patients. Six of the 18 patients with an early- (48 to 72 h) and none of the 12 patients with a later-formed thrombus died. Maximal serum enzyme levels, percent with Killip functional class III to IV and left ventricular wall motion score were higher in the patients with an early- than in those with a later-formed thrombus.(ABSTRACT TRUNCATED AT 250 WORDS)

Prospective two-dimensional echocardiographic evaluation of left ventricular thrombus and embolism after acute myocardial infarction

To determine whether two-dimensional echocardiography can identify patients with left ventricular thrombus after myocardial infarction who are prone to embolism, clinical and echocardiographic variables in 541 patients with a first infarction between 1979 and 1983 were studied prospectively. The first echocardiogram showed definite thrombus in 115 patients (Group 1, 21%) and no thrombus in 426 (Group 2, control). In Group 1, 27 patients (23%) had clinical evidence of systemic embolism related to the thrombus before referral (Group 1a) and 88 did not (Group 1b); these two groups were similar in age, gender and infarct location, but more Group 1a patients were within 1 month of the acute infarction. In both Groups 1a and 1b, the thrombus was found in apical views over asynergic zones, with no difference (p greater than 0.05) between the two groups in the size (average area from two views being 5.3 versus 4.5 cm2), type (protruding in apical views 30% versus 27%), location (apical 83% versus 86%; septal 11% versus 11%; posterior 4% versus 2%), extent of asynergy (31% versus 33%) and ejection fraction (33% versus 34%). However, the frequency of anticoagulant therapy was less (26% versus 63%, p less than 0.005), adjacent hyperkinesia greater (100% versus 49%, p less than 0.005) and thrombus mobility greater (81% versus 19%, p less than 0.005) in Group 1a than in Group 1b. Serial echocardiograms revealed a decreased size of the thrombus by 6 months in both Groups 1a and 1b, and little or no trace in 85% by 24 months. Thus, ventricular thrombus size, location and protrusion in apical views on echocardiography did not correlate with embolism. In contrast, thrombus mobility, the presence of adjacent hyperkinesia and thrombus protrusion assessed in multiple views appeared to be strong discriminators of thrombus prone to embolism. These echocardiographic features might provide a guide for the duration of anticoagulant therapy.

Surgical removal of a mobile, pedunculated left ventricular thrombus: report of 4 cases

During an 11-month period, 4 patients underwent surgical removal of a mobile, pedunculated left ventricular thrombus. All 4 patients had a history of myocardial infarction. Two of the 4 patients had systemic emboli, and in the 2 others, the ventricular thrombi were removed to prevent emboli. The thrombus was removed during the acute phase of myocardial infarction in 2 patients and one and two years, respectively, following the infarct in the remaining 2 patients. Concomitant coronary artery bypass grafting was performed in 3 patients. There were no early or late deaths, and none of the patients had clinical or echocardiographic evidence of recurrent thrombi or emboli at follow-up 3 to 15 months later. These results indicate that left ventricular thrombectomy might be an effective treatment for patients with mobile, pedunculated, left ventricular thrombi. However, additional experience is required to compare surgical and medical treatment.

Risk factors for embolisation in patients with left ventricular thrombi and acute myocardial infarction

Risk factors for systemic embolisation in patients with ventricular thrombi caused by an acute myocardial infarction were studied in 150 consecutive patients with an infarction of the anterior wall. Serial echocardiograms were performed 2-10 days after the acute event and patients were followed up for three months. Anticoagulation treatment was started only after the detection of thrombi. Of the 55 patients in whom a thrombus developed, 15 (27%) had peripheral emboli between 6-62 days; but only two (2%) of 95 patients without thrombus had emboli. Among 15 variables, the best single predictors of embolisation were age greater than 68 years (80% sensitive, 85% specific), pendulous thrombus (60%, 93%), and independent thrombus mobility (60%, 85%). Logistic regression analysis showed that a formula that included patient age, thrombus area, and the length of thrombus in the ventricular lumen predicted embolisation (sensitivity 87%, specificity 88%). There was no correlation between age and the thrombus variables. The risk of embolisation from left ventricular thrombi in acute anterior myocardial infarction can be accurately assessed from patient age and echocardiographic features. The risk of peripheral emboli is high in patients with left ventricular thrombi and those aged greater than 68.

Increased embolic risk in patients with left ventricular thrombi

Although left ventricular thrombi are associated with an increased embolic risk in the first few weeks after acute myocardial infarction, the long-term risk remains undefined. To ascertain the incidence of strictly defined systemic emboli, we followed 85 patients with echocardiographically documented left ventricular thrombi. At the time of the entry echocardiogram, most patients (n = 57) had remote myocardial infarction, while 19 had recent (less than 1 month) infarction, and nine had idiopathic cardiomyopathy. Because of the difficulty in classifying events as embolic in patients with advanced atherosclerosis, a matched control group of 91 patients without thrombi was also studied. The thrombus and control groups were similar with regard to recent myocardial infarction, remote infarction, anterior infarction, ejection fraction, atrial fibrillation, echocardiographic referral for source of emboli, and warfarin therapy. During a mean follow-up of 22 months after echocardiography, embolic events occurred in 13% (11 of 85) of patients with thrombi compared with 2% (two of 91) control patients (p less than .01). The actuarial probability of being embolus free at 2 years after echocardiography was 86% in patients with thrombi compared with 97% in control patients (p less than .01). All embolic events occurred greater than 1 month after myocardial infarction (range 1 to 96 months). The only clinical or echocardiographic features predictive of embolization were protrusion and mobility of thrombus (both p less than .02). We conclude that the incidence of embolic events is definitely increased in patients with left ventricular thrombi compared with control subjects during long-term follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous morphologic changes in left ventricular thrombi: a prospective two-dimensional echocardiographic study

Previous retrospective echocardiographic studies have reported a higher embolic potential of left ventricular thrombi with protruding configuration and patterns of mobility. The present study was performed to prospectively assess the shape and mobility patterns of left ventricular thrombi and their spontaneous changes with time. Two-dimensional echocardiograms were obtained in 109 consecutive patients with acute anterior myocardial infarction within 24 hr of the onset of symptoms, every 24 hr until day 5, every 48 hr until day 15, and then every month for a follow-up of 1 to 29 (mean 14 +/- 8) months in the survivors. None of the patients were treated with anticoagulants or platelet inhibitors during the study period. Left ventricular thrombi, detected in 59 patients (54%), appeared from 1 to 362 (mean 12 +/- 47) days after myocardial infarction. At first detection, the shape was mural in 21 patients and protruding in 38; patterns of mobility were present in eight patients. During follow-up, changes in the shape of the thrombi were noted in 24 patients (41%; from mural to protruding in nine, from protruding to mural in 15). These variations were encountered between 2 and 490 (mean 64 +/- 117) days after the first observation of the thrombus. Patterns of mobility, previously detected in eight patients, disappeared in five of eight within 2 to 28 (mean 14 +/- 11) days.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of left ventricular thrombi by contrast-enhanced computed tomography and two-dimensional echocardiography

Contrast-enhanced computed tomography (CT) was compared with 2-dimensional echocardiography (2-D echo) for evaluation of left ventricular (LV) thrombus. Thirteen patients with coronary artery disease who had LV thrombus initially documented by 1 of the 2 techniques were then studied with the other technique. The findings of the studies were concordant in 8 of 13 patients, with a similar description of the presence, location and size of the LV thrombus and associated regional LV wall abnormalities. In 5 of 13 patients, the 2 techniques produced discordant data. Of these, 2 patients had false-negative results on 2-D echo owing to poor visualization of the LV apex; 1 patient had a false-positive result on 2-D echo related to misinterpretation of a prominent papillary muscle; 2 patients had false-negative CT results, 1 related to insufficient contrast infusion. The findings demonstrate that CT is a useful technique for evaluating LV thrombus, and may be particularly helpful when 2-D echo is technically limited or equivocal.

Classification of left ventricular thrombi by their history of systemic embolization using pattern recognition of two-dimensional echocardiograms

Although one can diagnose left ventricular (LV) thrombi by two-dimensional echocardiography (2DE), the factors associated with peripheral embolization, given a 2DE with LV thrombi, have not been well delineated. Therefore we looked at 2DE and clinical variables that included texture features in the 2DE of 38 patients whose 2DE had LV thrombi and questioned these patients to see if clinical embolization had occurred in the 8.9 +/- 6.1 month (+/- SD) average follow-up period. Eight patients, four with acute myocardial infarction (AMI) and four with dilated LV and decreased LV systolic wall motion, had clinically apparent leg or brain emboli, whereas the remaining patients did not. Emboli occurred within a week of obtaining the 2DE in question. The variables considered were the age of the patient, the type of heart disease present, warfarin administration, exercise tolerance, standard M-mode measurements, LV dyssynergy by 2DE, clot size and mobility, and gray scale statistics which include run length, Sobel edge points followed by 50% gradient thresholding, gray level second-order statistics, offset 1 and gray level difference statistics, offset 1. The values of the variables were then entered into an expert system (Expert Ease) in order to achieve classification of patients into emboli versus no emboli groups, while using a minimal number of variables. The only variables that were needed included run length, long runs emphasis, gray level difference statistics (entropy, contrast, mean, and angular second moment), gray level second-order statistics (contrast), and warfarin status. When probability statistics were applied to this schema, its accuracy was predicted to be at least 96%.(ABSTRACT TRUNCATED AT 250 WORDS)

Lysis of left ventricular thrombi with urokinase

In 16 patients with recent myocardial infarction (3 to 12 week old) and with large left ventricular thrombi systemic thrombolysis with urokinase was performed. Left ventricular thrombi were diagnosed by two-dimensional echocardiography; in all patients the mural thrombus was located in the area of recent myocardial infarction. Each of three patients suffered an embolic episode before the initiation of thrombolytic therapy and the episode caused a stroke in one. Urokinase was infused intravenously at a rate of 60,000 U/hr for 2 to 8 days in combination with intravenous heparin (200 units/kg X 12 hr). Left ventricular thrombi were successfully lysed in 10 of 16 patients, as determined by two-dimensional echocardiography. In four of the six remaining patients only partial thrombolysis was achieved and in two thrombolytic treatment failed. There was no evidence of embolic events during thrombolysis in any of the 16 patients. The success of thrombolysis seemed to depend on the age of the thrombus: the thrombus was dissolved in eight of nine patients undergoing thrombolysis within 4 weeks of the acute myocardial infarction vs in two of seven patients receiving treatment later (p = .057). The presence of a left ventricular aneurysm or depressed left ventricular function also appeared to reduce the likelihood of successful thrombolysis. All patients were discharged on oral anticoagulants. At 6 months follow-up (n = 9) no recurrence of left ventricular thrombus was found. These results show that left ventricular thrombi can be safely lysed by intravenous urokinase. However, for better definition of the risk and benefit of this new therapy further investigation is necessary.