Long-term prospective assessment of left ventricular thrombus in anterior wall acute myocardial infarction and implications for a rational approach to embolic risk

EACVI recommendations on cardiovascular imaging for the detection of embolic sources: endorsed by the Canadian Society of Echocardiography

Cardioaortic embolism to the brain accounts for approximately 15-30% of ischaemic strokes and is often referred to as 'cardioembolic stroke'. One-quarter of patients have more than one cardiac source of embolism and 15% have significant cerebrovascular atherosclerosis. After a careful work-up, up to 30% of ischaemic strokes remain 'cryptogenic', recently redefined as 'embolic strokes of undetermined source'. The diagnosis of cardioembolic stroke remains difficult because a potential cardiac source of embolism does not establish the stroke mechanism. The role of cardiac imaging-transthoracic echocardiography (TTE), transoesophageal echocardiography (TOE), cardiac computed tomography (CT), and magnetic resonance imaging (MRI)-in the diagnosis of potential cardiac sources of embolism, and for therapeutic guidance, is reviewed in these recommendations. Contrast TTE/TOE is highly accurate for detecting left atrial appendage thrombosis in patients with atrial fibrillation, valvular and prosthesis vegetations and thrombosis, aortic arch atheroma, patent foramen ovale, atrial septal defect, and intracardiac tumours. Both CT and MRI are highly accurate for detecting cavity thrombosis, intracardiac tumours, and valvular prosthesis thrombosis. Thus, CT and cardiac magnetic resonance should be considered in addition to TTE and TOE in the detection of a cardiac source of embolism. We propose a diagnostic algorithm where vascular imaging and contrast TTE/TOE are considered the first-line tool in the search for a cardiac source of embolism. CT and MRI are considered as alternative and complementary tools, and their indications are described on a case-by-case approach.

Prognostic Relevance of Left Ventricular Thrombus Motility: Assessment by Pulsed Wave Tissue Doppler Imaging

Pulsed wave tissue Doppler imaging (PW-TDI) easily detects motion of cardiac structures. Hence, PW-TDI could be of value for assessing potentially cardioembolic masses. We sought to evaluate the prognostic value of left ventricular (LV) thrombus mobility assessed by PW-TDI. In 83 consecutive patients with echocardiographically detected LV thrombi, PW-TDI echocardiographic study was performed. At 1-year follow-up, the composite of major adverse cardiovascular events (MACE) defined as all-cause mortality plus hospitalizations for stroke/systemic embolism was evaluated. Seventy-two patients (77.1 ± 13.1 year/old, 32 males) were studied. All thrombi were located at the LV apex. At 1-year follow-up, 17 cardioembolic events occurred. By univariable Cox analysis, variables associated with MACE were heart rate (hazard ratio: 1.02, 95% CI: 1.00-1.05; P = .03), thrombi with mobile free edge (hazard ratio: 3.25, 95% CI: 1.25-8.44; P = .01), hypoechoic thrombi (hazard ratio: 2.86, 95% CI: 1.10-7.42; P = .03), and mass peak antegrade velocity (Va) ≥10 cm/s (hazard ratio: 8.79, 95% CI: 2.00-38.5; P = .004). By multivariable analysis, thrombi with mobile free edge (hazard ratio: 3.54, 95% CI: 1.23-10.2; P = .02), and mass peak Va ≥10 cm/s (hazard ratio: 7.97, 95% CI: 1.60-39.6; P = .01) retained statistical significance. Mass peak Va ≥10 cm/s predicted the composite end point with 94% sensitivity and 85% specificity (area under the curve = 0.86). In conclusion, PW-TDI allows objective prognostication of LV thrombi embolic risk.

Long-Term Embolic Outcomes After Detection of Left Ventricular Thrombus by Late Gadolinium Enhancement Cardiovascular Magnetic Resonance Imaging: A Matched Cohort Study

BACKGROUND

Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging is more sensitive than echocardiography for the detection of intracardiac thrombus because of its unique ability to identify thrombus based on tissue characteristics related to avascularity. The long-term prognostic significance of left ventricular (LV) thrombus detected by LGE CMR is unknown.

METHODS

We performed a matched cohort study of consecutive adult patients with LV thrombus detected by LGE CMR who were matched on the date of CMR, age, and LV ejection fraction to up to 3 patients without LV thrombus. We investigated the long-term incidence of a composite of embolic events: stroke, transient ischemic attack, or extracranial systemic arterial embolism. We also compared outcomes among patients with LV thrombus detected by LGE CMR stratified by whether the LV thrombus was also detected by echocardiography or not.

RESULTS

Of 157 LV thrombus patients, 155 were matched to 400 non-LV thrombus patients. During a median follow-up of 3.3 years, the cumulative incidence of embolism was significantly higher in LV thrombus patients compared with the matched non-LV thrombus patients (P<0.001), with annualized rates of 3.7% and 0.8% for LV thrombus and matched non-LV thrombus patients, respectively. LV thrombus was the only independent predictor of the composite embolic end point (hazard ratio, 3.99 [95% CI, 1.54-10.35]; P=0.004). The cumulative incidence of embolism was not different in patients with LV thrombus that was also detected by echocardiography versus patients with LV thrombus not detected by echocardiography (P=0.25).

CONCLUSIONS

Despite contemporary antithrombotic treatment, LV thrombus detected by LGE CMR is associated with a 4-fold higher long-term incidence of embolism compared with matched non-LV thrombus patients. LV thrombus detected by LGE CMR but not by echocardiography is associated with a similar risk of embolism as that detected by both LGE CMR and echocardiography.

Relationship of left ventricular thrombus formation and adverse outcomes in acute anterior myocardial infarction in patients treated with primary percutaneous coronary intervention

BACKGROUND

The incidence of left ventricular thrombus (LVT) is 4% to 15% in patients with anterior acute ST-segment elevation myocardial infarction (ant-AMI) in the era of primary percutaneous coronary intervention (PPCI). And patients with LVT have higher in-hospital mortality.

HYPOTHESIS

There is a relationship between LVT formation and 1-year major adverse cardio-cerebrovascular events (MACCE) in patients with ant-AMI treated by PPCI.

METHODS

Our study population included 1488 consecutive patients with ant-AMI. The primary endpoint was the incidence of MACCE within 1 year after AMI. The secondary endpoint was the thrombosis disappearance.

RESULTS

A total of 106 (7.1%) patients were diagnosed with LVT and 1382 (92.9%) patients without LVT. Patients with LVT had a higher incidence of MACCE than in patients without LVT (21.7%vs10.3%; P < 0.001). Univariate analysis showed LVT was associated with an increase in MACCE risk (odds ratio [OR] = 2.40; 95% confidence interval [CI] [1.37-4.21]; P < 0.001). When examining MACCE components individually, LVT was only associated with the incidence of congestive heart failure (OR = 2.41; 95% CI [1.29-4.58]; P = 0.001). After adjustment for principal confounders, LVT remained an independent risk factor for MACCE (HR = 2.28; 95% CI [1.12-6.38]; P = 0.020). Other independent predictors include 24-hour LVEF, creatine kinase peak value, and age. Further analysis found patients with LVT in international normalized ratio (INR) ≥ 2 group had lower MACCE risk and higher thrombus disappearance than in INR < 2 group (13.5%vs29.6%; P = 0.044; 90.4%vs74.1%; P = 0.029).

CONCLUSION

For patients with ant-AMI treated by PPCI, LVT is an independent predictor of 1-year MACCE events. Treatment with vitamin K antagonist in the therapeutic range (INR ≥ 2) has the potential to reduce MACCE risk and promote disappearance of thrombus.

Incidence, diagnostic methods, and evolution of left ventricular thrombus in patients with anterior myocardial infarction and low left ventricular ejection fraction: a prospective multicenter study

BACKGROUND AND OBJECTIVES

We aimed to assess the incidence and evolution of left ventricular (LV) thrombi in a high-risk population of patients with LV systolic dysfunction after anterior myocardial infarction (ant-MI). We also compared the accuracy of transthoracic echocardiography (TTE) and cardiac magnetic resonance imaging with contrast-delayed enhancement (CMR-DE) in detecting LV thrombi.

METHODS

We prospectively included 100 consecutive patients with LV ejection fraction (LVEF) <45% at the first TTE performed <7 days after ant-MI. A second evaluation with TTE and CMR-DE (by blinded examiners) was performed at 30 days. A third TTE and assessment of clinical status were performed between 6 and 12 months after ant-MI.

RESULTS

Patients (males 71%; mean age 59.1 ± 12.1 years; mean LVEF 33.5% ± 6.0%) were included at a median of 5.5 days (interquartile range 25th-75th percentile 4.25-6.0 days) after ant-MI. Thrombi were detected among 26 (26%) patients at a median of 12.0 days after ant-MI (7 patients at 1-7 days after MI; 15 at 8-30 days; and 4 after day 30). Sensitivity and specificity for LV thrombi detection were 94.7% and 98.5%, respectively, for TTE as compared with CMR-DE. Most thrombi (n = 24; 92.3%) disappeared after triple antithrombotic therapy (vitamin K antagonist in addition to dual antiplatelet therapy).

CONCLUSION

Left ventricular thrombus is a frequent complication after ant-MI with systolic dysfunction. When a search for thrombus is prespecified, the accuracy of TTE is high as compared with CMR-DE. The best antithrombotic strategy is not known.

LV thrombus detection by routine echocardiography: insights into performance characteristics using delayed enhancement CMR

OBJECTIVES

This study sought to evaluate performance characteristics of routine echo for left ventricular thrombus (LVT).

BACKGROUND

Although the utility of dedicated echocardiography (echo) for LVT is established, echo is widely used as a general test for which LVT is rarely the primary indication. We used delayed-enhancement cardiac magnetic resonance (DE-CMR) as a reference to evaluate LVT detection by routine echo.

METHODS

Dedicated LVT assessment using DE-CMR was prospectively performed in patients with left ventricular systolic dysfunction. Echoes were done as part of routine clinical care. Echo and CMR were independently read for LVT and related indexes of LVT size, shape, and image quality/diagnostic confidence. Follow-up was done for embolic events and pathology validation of LVT.

RESULTS

In this study, 243 patients had routine clinical echo and dedicated CMR within 1 week without intervening events. Follow-up supported DE-CMR as a reference standard, with >5-fold difference in endpoints between patients with versus without LVT by DE-CMR (p = 0.02). LVT prevalence was 10% by DE-CMR. Echo contrast was used in 4% of patients. Echo sensitivity and specificity were 33% and 91%, with positive and negative predictive values of 29% and 93%. Among patients with possible LVT as the clinical indication for echo, sensitivity and positive predictive value were markedly higher (60%, 75%). Regarding sensitivity, echo performance related to LVT morphology and mirrored cine-CMR, with protuberant thrombus typically missed when small (p ≤ 0.02). There was also a strong trend to miss mural thrombus irrespective of size (p = 0.06). Concerning positive predictive value, echo performance related to image quality, with lower diagnostic confidence scores for echoes read positive for LVT in discordance with DE-CMR compared with echoes concordant with DE-CMR (p < 0.02).

CONCLUSIONS

Routine echo with rare contrast use can yield misleading results concerning LVT. Echo performance is improved when large protuberant thrombus is present and when the clinical indication is specifically for LVT assessment.

Contrast-enhanced anatomic imaging as compared to contrast-enhanced tissue characterization for detection of left ventricular thrombus

OBJECTIVES

This study sought to compare contrast-enhanced anatomic imaging and contrast-enhanced tissue characterization (delayed-enhancement cardiac magnetic resonance [DE-CMR]) for left ventricular (LV) thrombus detection.

BACKGROUND

Contrast echocardiography (echo) detects LV thrombus based on anatomic appearance, whereas DE-CMR imaging detects thrombus based on tissue characteristics. Although DE-CMR has been validated as an accurate technique for thrombus, its utility compared with contrast echo is unknown.

METHODS

Multimodality imaging was performed in 121 patients at high risk for thrombus due to myocardial infarction or heart failure. Imaging included 3 anatomic imaging techniques for thrombus detection (contrast echo, noncontrast echo, cine-CMR) and a reference of DE-CMR tissue characterization. LV structural parameters were quantified to identify markers for thrombus and predictors of additive utility of contrast-enhanced thrombus imaging.

RESULTS

Twenty-four patients had thrombus by DE-CMR. Patients with thrombus had larger infarcts (by DE-CMR), more aneurysms, and lower LV ejection fraction (by CMR and echo) than those without thrombus. Contrast echo nearly doubled sensitivity (61% vs. 33%, p < 0.05) and yielded improved accuracy (92% vs. 82%, p < 0.01) versus noncontrast echo. Patients who derived incremental diagnostic utility from DE-CMR had lower LV ejection fraction versus those in whom noncontrast echo alone accurately assessed thrombus (35 +/- 9% vs. 42 +/- 14%, p < 0.01), with a similar trend for patients who derived incremental benefit from contrast echo (p = 0.08). Contrast echo and cine-CMR closely agreed on the diagnosis of thrombus (kappa = 0.79, p < 0.001). Thrombus prevalence was lower by contrast echo than DE-CMR (p < 0.05). Thrombus detected by DE-CMR but not by contrast echo was more likely to be mural in shape or, when apical, small in volume (p < 0.05).

CONCLUSIONS

Echo contrast in high-risk patients markedly improves detection of LV thrombus, but does not detect a substantial number of thrombi identified by DE-CMR tissue characterization. Thrombi detected by DE-CMR but not by contrast echo are typically mural in shape or small in volume.

Detection of left ventricular thrombus by delayed-enhancement cardiovascular magnetic resonance prevalence and markers in patients with systolic dysfunction

OBJECTIVES

This study sought to assess the prevalence and markers of left ventricular (LV) thrombus among patients with systolic dysfunction.

BACKGROUND

Prior studies have yielded discordant findings regarding prevalence and markers of LV thrombus. Delayed-enhancement cardiovascular magnetic resonance (DE-CMR) identifies thrombus on the basis of tissue characteristics rather than just anatomical appearance and is potentially highly accurate.

METHODS

Prevalence of thrombus by DE-CMR was determined in 784 consecutive patients with systolic dysfunction (left ventricular ejection fraction [LVEF] <50%) imaged between July 2002 and July 2004. Patients were recruited from 2 separate institutions: a tertiary-care referral center and an outpatient clinic. Comparison to cine-cardiovascular magnetic resonance (CMR) was performed. Follow-up was undertaken for thrombus verification via pathology evaluation or documented embolic event within 6 months after CMR. Clinical and imaging parameters were assessed to determine risk factors for thrombus.

RESULTS

Among this at-risk population (age 60 +/- 14 years; LVEF 32 +/- 11%), DE-CMR detected thrombus in 7% (55 patients) and cine-CMR in 4.7% (37 patients, p < 0.005). Follow-up was consistent with DE-CMR as a better reference standard than cine-CMR, including 100% detection among 5 patients with thrombus verified by pathology (cine-CMR, 40% detection), and logistic regression analysis testing the contributions of DE-CMR and cine-CMR simultaneously, which showed that only the presence of thrombus by DE-CMR was associated with follow-up end points (p < 0.005). Cine-CMR generally missed small intracavitary and small or large mural thrombus. In addition to traditional indices such as low LVEF and ischemic cardiomyopathy, multivariable analysis showed that increased myocardial scarring, an additional parameter available from DE-CMR, was an independent risk factor for thrombus.

CONCLUSIONS

In a broad cross section of patients with systolic dysfunction, thrombus prevalence was 7% by DE-CMR and included small intracavitary and small or large mural thrombus missed by cine-CMR. Prevalence increased with worse LVEF, ischemic etiology, and increased myocardial scarring.

Usefulness of contrast echocardiography for assessment of left ventricular thrombus after acute myocardial infarction

Fifty consecutive patients referred to a coronary care unit for acute anterior myocardial infarction with ST-segment elevation underwent coronary arteriography, left ventricular (LV) angiography, and revascularization. Transthoracic echocardiography was systematically performed using fundamental imaging, second harmonic imaging, and contrast agents to assess the LV chamber. Six patients (12%) presented with a confirmed LV mural thrombus. Thirty-five percent of patients with time to revascularization>3 hours presented with an LV mural thrombus versus 0 patients with time to revascularization<or=3 hours (p=0.003). The most accurate method of detecting LV mural thrombus was contrast echocardiography regardless of physician experience. No patient with a misdiagnosis of thrombus had an optimal acoustic window using fundamental imaging or second harmonic imaging. In conclusion, patients presenting with acute anterior myocardial infarction could benefit from contrast echocardiography for assessment of LV mural thrombus when acoustic windows are suboptimal and time to revascularization is >3 hours.

Determinants of left ventricular thrombus formation after primary percutaneous coronary intervention for anterior wall myocardial infarction

Previous studies have reported that left ventricular (LV) thrombus is a complication in 10-56% of ST-segment elevation acute anterior wall myocardial infarctions (AWMI). Data suggest that changes in acute myocardial infarction management such as early anticoagulation, thrombolysis, and most recently, primary percutaneous coronary intervention (PCI), may decrease thrombus occurrence. Early time to reperfusion has been shown to decrease mortality and improve LV function recovery. To determine if door-to-balloon time (DTBT) affects the incidence of LV thrombus, we retrospectively analyzed data on 43 consecutive patients who underwent successful PCI of a primary acute ST-segment elevation AWMI. Transthoracic echocardiography was performed for detecting LV thrombus and measuring LV ejection fraction (EF) within 5 days on all patients (average time: 2.17 days post event). Nineteen patients underwent PCI within 2 h of arrival to the Emergency Department (Group A, average 88 min) and 24 patients underwent PCI with DTBT of more than 2 h (Group B, average 193 min). Clinically significant LV thrombus was detected in 35% of all patients. The incidence of LV thrombus formation in Group A was not significantly different from that in Group B (42.1% vs. 29.0%, respectively; P = 0.52). The risk of LV thrombus was independent of in-hospital anticoagulation and medical management, peak enzyme levels, and LVEF but did relate to age (odds ratio = 1.96, 95% CI 1.03-3.73, P = 0.04 per decade). No embolic events in hospital were observed (average hospital stay 9.2 days). We conclude that the incidence of LV thrombus remains high despite PCI. Also, we find that DTBT in patients presenting with an ST-segment elevation AWMI does not affect the incidence of LV thrombus formation. Increased age, however, does appear to increase the risk of LV thrombus development.

Treatment of left ventricular thrombi with a low molecular weight heparin

BACKGROUND

Once a diagnosis of left ventricular thrombus has been established, the classical attitude consists in the administration of unfractionated heparin relayed by oral anticoagulation therapy. However, the use of unfractionated heparins in this indication was only assessed in an open, non-randomized study with no control group, including 23 patients. On the other hand, although low molecular weight heparins are routinely used in some departments, there are no studies available concerning these agents in this indication. The aim of this study was to evaluate the feasibility of low molecular weight heparin therapy in patients with left ventricular thrombi.

METHODS

The study was a prospective, non-randomized, open-label trial. All patients with a new left ventricular thrombus diagnosed between September 2000 and September 2003 received enoxaparine 100 IU/kg twice daily for a mean duration of 13 days. A relay treatment with fluindione was initiated on day 5. The left ventricular thrombus outcome was followed for 3 weeks by bi-weekly transthoracic echocardiography.

RESULTS

26 left ventricular thrombi were diagnosed over the 3-year study period: 19 in post-infarct patients with a history of anterior myocardial infarction and 7 in patients with dilated cardiomyopathy. The mean thrombus area decreased from 2.30+/-0.32 to 0.36+/-0.11 cm2 (p<0.0001). Nineteen thrombi out of twenty-six (73%) disappeared during the treatment period. No thrombocytopenia or hemorrhagic events were observed. One transient ischemic attack was reported.

CONCLUSION

This preliminary study suggests that low molecular weight heparins are well tolerated and efficient in terms of left ventricular thrombi disappearance or size reduction.

Association Between Serum C-Reactive Protein Elevation and Left Ventricular Thrombus Formation After First Anterior Myocardial Infarction

STUDY OBJECTIVES

Most left ventricular (LV) thrombi that occur after acute myocardial infarction (AMI) are formed within 2 weeks, when inflammatory cells have infiltrated into the necrotic myocardium. Inflammatory changes on the endocardial surface may induce platelet deposition and fibrin net formation through interaction with proinflammatory cytokines. We sought to determine the significance of the inflammatory response reflected by serum C-reactive protein (CRP) elevation in LV thrombus formation after AMI.

DESIGN

We examined 160 patients with first anterior AMI. Peak serum creatine kinase (CK) and CRP levels were determined by serial measurements. Echocardiography was performed 10 to 14 days after the onset. We assessed the association between the elevation of serum CRP levels and LV thrombus formation after AMI.

RESULTS

LV thrombus was observed in 13 patients (8%). There was no difference in age, sex, coronary risk factors, preinfarction angina, use of revascularization therapy and anticoagulant therapy, platelet count, and fibrinogen level on hospital admission between the two groups. The mean (+/- SD) peak serum CRP level was markedly increased in patients with LV thrombus compared to those without (18.0 +/- 12.6 vs 9.4 +/- 8.1 mg/dL; p = 0.001), despite their having similar peak CK levels. Multivariate analysis showed that a peak CRP level of > or =20 mg/dL was an independent predictor of thrombus formation (relative risk, 4.82; p = 0.037) among variables including older age (> or =60 years old), peak CK level (> or =3,000 IU/L), and peak WBC count (> or =12,000 cells/ microL).

CONCLUSION

A greater elevation of serum CRP level was associated with a higher incidence of LV thrombus after AMI, suggesting an important role of the inflammatory response in mural thrombus formation.

Role of echocardiography in the assessment of left ventricular thrombus embolic potential after anterior acute myocardial infarction

The contribution of cardiac ultrasound in assessment of the embolic potential of left ventricular thrombi after anterior acute myocardial infarction was verified in a prospective study of serial echocardiograms (mean, 18.9 examinations per patient) obtained over a long-term period (1-72 months; mean, 38±12). The study population comprised 222 patients (162 men; age, 64±11 years) with a first anterior acute myocardial infarction, treated with thrombolysis (group A) or receiving no antithrombolic therapy (group B). Embolism occurred in a total of 12 patients (11 with a left ventricular thrombus; p<0.005) and was more frequent in group B (10 patients; p<0.04). Predictors of embolism were the absence of thrombolysis, detection of a left ventricular thrombus, protrusion or mobility of the thrombus, and morphologic changes in the thrombus over time. Patients in group A had a lower incidence of each of these predictors, and a higher thrombus resolution rate. An appropriate echocardiographic protocol is crucial to assessment of the embolic potential of left ventricular thrombi after anterior acute myocardial infarction and may help to identify candidates for aggressive antithrombotic therapy (c)2001 CHF, Inc.

Thromboembolism in heart failure: who should be treated?

The risk of thromboembolic complications in patients with heart failure and/or chronic left-ventricular systolic dysfunction is increased. Nevertheless, anticoagulant therapy in these patients is still a subject of debate. Atrial fibrillation is the only prospectively evaluated, proven thromboembolic risk factor and patients with atrial fibrillation benefit from long term anticoagulant therapy. The significance of other proposed thromboembolic risk factors in heart failure and/or chronic left-ventricular dysfunction such as gender, cause of myocardial disease, severity of heart failure, left-ventricular ejection fraction, left-ventricular thrombus, left ventricular aneurysm and history of previous thromboembolic event is less clear. This article summarizes key studies, assesses the incidence of thromboembolism, evaluates risk factors and proposes guidelines for anticoagulation of patients with heart failure and/or left ventricular systolic dysfunction.

[The clinical management guidelines of the Sociedad Española de Cardiología in acute myocardial infarct]

In the recent years, new possibilities have emerged in the diagnosis and management of acute myocardial infarction with ST segment elevation and its complications. Moreover, a deep transformation has taken place in the health care system organization, particularly in aspects related to care of patients presenting non-traumatic chest pain, both in pre-hospital and hospital areas. All these issues warrant a consensus document in Spain dealing with the role that these important changes should play in the whole management of myocardial infarction patients. This document revises and updates all the main clinical issues of acute myocardial infarction patients from the moment they contact with the health care system outside the hospital until they return home, after staying at the coronary care unit and the general hospitalization ward. All those aspects are considered not only in the uncomplicated myocardial infarction but also in the complicated one. This review also includes a set of recommendations on structural and organisational aspects, mainly referred to the prehospital and emergency levels.