Anna Lisa Crowley

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.

Unrecognized Non-Q-Wave Myocardial Infarction: Prevalence and Prognostic Significance in Patients with Suspected Coronary Disease

Using delayed-enhancement cardiovascular magnetic resonance, Han Kim and colleagues show that in patients with suspected coronary disease the prevalence of unrecognized myocardial infarction without Q-waves is more than 3-fold higher than that with Q-waves and predicts subsequent mortality.

Venous thrombosis in patients with short- and long-term central venous catheter-associated Staphylococcus aureus bacteremia*

Objective: Infection and thrombosis are important complications of intravascular catheters. The purpose of this study was to determine the incidence of thrombosis in patients with central venous catheter–associated Staphylococcus aureus bacteremia and the utility of physical examination for diagnosing upper extremity or neck venous thrombosis. Design: Prospective observational cohort. Setting: Tertiary care facility. Patients: In all, 65 consecutive patients with catheter-associated S. aureus bacteremia with central venous catheters of the internal jugular, brachial, or subclavian veins were eligible for participation. Intervention: From July 1999 through August 2004, enrolled patients underwent physical examination and ultrasonography independently to identify the presence of catheter-associated thrombosis. Study ultrasonograms were interpreted blindly using defined criteria. Outcomes were defined at 12-wk follow-up. Measurements and Main Results: A total of 48 patients were enrolled. By ultrasonography, definite or possible thrombosis was present in 34 of 48 patients (71%) in this cohort. Death or recurrent bacteremia occurred in 11/34 (32%) infected patients with thrombosis and two of 14 (14%) infected patients without thrombosis (p = .29). Sensitivity of all physical examination findings, either alone or in combination, was low (≤24%). Only engorged veins upon hand elevation and the presence of multiple physical examination abnormalities were specific (100% each). Conclusions: Thrombosis is a common complication of central venous catheter–associated S. aureus bacteremia. Patients with central venous catheter–associated S. aureus bacteremia should undergo ultrasonography to detect thromboses even if the physical examination is normal.

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.

Relationship of T2-Weighted MRI Myocardial Hyperintensity and the Ischemic Area-At-Risk

RATIONALE After acute myocardial infarction (MI), delineating the area-at-risk (AAR) is crucial for measuring how much, if any, ischemic myocardium has been salvaged. T2-weighted MRI is promoted as an excellent method to delineate the AAR. However, the evidence supporting the validity of this method to measure the AAR is indirect, and it has never been validated with direct anatomic measurements. OBJECTIVE To determine whether T2-weighted MRI delineates the AAR. METHODS AND RESULTS Twenty-one canines and 24 patients with acute MI were studied. We compared bright-blood and black-blood T2-weighted MRI with images of the AAR and MI by histopathology in canines and with MI by in vivo delayed-enhancement MRI in canines and patients. Abnormal regions on MRI and pathology were compared by (a) quantitative measurement of the transmural-extent of the abnormality and (b) picture matching of contours. We found no relationship between the transmural-extent of T2-hyperintense regions and that of the AAR (bright-blood-T2: r=0.06, P=0.69; black-blood-T2: r=0.01, P=0.97). Instead, there was a strong correlation with that of infarction (bright-blood-T2: r=0.94, P<0.0001; black-blood-T2: r=0.95, P<0.0001). Additionally, contour analysis demonstrated a fingerprint match of T2-hyperintense regions with the intricate contour of infarcted regions by delayed-enhancement MRI. Similarly, in patients there was a close correspondence between contours of T2-hyperintense and infarcted regions, and the transmural-extent of these regions were highly correlated (bright-blood-T2: r=0.82, P<0.0001; black-blood-T2: r=0.83, P<0.0001). CONCLUSION T2-weighted MRI does not depict the AAR. Accordingly, T2-weighted MRI should not be used to measure myocardial salvage, either to inform patient management decisions or to evaluate novel therapies for acute MI.

Direct en face imaging of secundum atrial septal defects by velocity-encoded cardiovascular magnetic resonance in patients evaluated for possible transcatheter closure.

Background—Atrial septal defect (ASD) flow can be measured indirectly by velocity-encoded cardiovascular magnetic resonance (veCMR) of the pulmonary artery and aorta. Imaging the secundum ASD en face could potentially enable direct flow measurement and provide valuable information about ASD size, shape, location, and proximity to other structures. Methods and Results—Forty-four patients referred for possible transcatheter ASD closure underwent a comprehensive standard evaluation, including transesophageal and/or intracardiac echocardiography and invasive oximetry. CMR was performed in parallel and included direct en face veCMR after an optimal double-oblique imaging plane was determined that accounted for ASD flow direction and cardiac-cycle interatrial septal motion. ASD flow measured by direct en face veCMR correlated better with invasive oximetry than indirect (pulmonary artery and aorta) veCMR (r=0.80 versus r=0.66). Additionally, 95% limits of agreement were narrower (±3.9 versus ±5.1 L/min). En face veCMR determined that defects usually were eccentrically shaped (major/minor axis length >1.5) rather than circular, with 16% having extreme eccentricity (major/minor >2.0). Overall, ASD size by both veCMR and intracardiac echocardiography correlated with final device size; however, in small to medium defects (<3 cm2) and extremely eccentric defects, veCMR correlated better with final device size than did intracardiac echocardiography. Importantly, CMR identified additional information in 9 patients (20%) that altered clinical management. Specifically, en face veCMR detected additional defects (n=3), large ASD with insufficient rim tissue (n=2), and sinus venosus defect with anomalous pulmonary vein (n=1). Cine and/or morphological imaging detected interrupted inferior vena cava (n=2) and sinus of Valsalva aneurysm (n=1). Conclusions—En face veCMR with an optimized imaging plane can determine ASD flow, size, and morphology. CMR provided information incremental to comprehensive standard evaluation that altered clinical management in 20% of patients.

Prevalence and clinical characteristics associated with left atrial appendage thrombus in fully anticoagulated patients undergoing catheter-directed atrial fibrillation ablation.

LAA Thrombus Among Anticoagulated AF Patients. Introduction: Catheter‐directed atrial fibrillation (AF) ablation is contraindicated among patients with left atrial appendage (LAA) thrombus. The prevalence of LAA thrombus among fully anticoagulated patients undergoing AF ablation is unknown.

Choice of agreement indices for assessing and improving measurement reproducibility in a core laboratory setting

Clinical core laboratories, such as Echocardiography core laboratories, are increasingly used in clinical studies with imaging outcomes as primary, secondary, or surrogate endpoints. While many factors contribute to the quality of measurements of imaging variables, an essential step in ensuring the value of imaging data includes formal assessment and control of reproducibility via intra-observer and inter-observer reliability. There are many different agreement/reliability indices in the literature. However, different indices may lead to different conclusions and it is not clear which index is the preferred choice as an overall indication of data quality and a tool for providing guidance on improving quality and reliability in a core lab setting. In this paper, we pre-specify the desirable characteristics of an agreement index for assessing and improving reproducibility in a core lab setting; we compare existing agreement indices in terms of these characteristics to choose a preferred index. We conclude that, among the existing indices reviewed, the coverage probability for assessing agreement is the preferred agreement index on the basis of computational simplicity, its ability for rapid identification of discordant measurements to provide guidance for review and retraining, and its consistent evaluation of data quality across multiple reviewers, populations, and continuous/categorical data.

Quality Improvement Implementation: Improving Reproducibility in the Echocardiography Laboratory

BACKGROUND Interpretative variability can adversely affect echocardiographic reliability, but there is no widely accepted method to minimize variability and improve reproducibility. METHODS A continuous quality improvement process was devised that involves testing reproducibility by assessment of measurement differences followed by robust review, retraining, and retesting. Reproducibility was deemed acceptable if ≥80% of all interreader comparisons were within a prespecified acceptable difference. Readers not meeting this standard underwent retraining and retesting until acceptable reproducibility was achieved for the following parameters: left ventricular end-diastolic volume, biplane ejection fraction, mitral and aortic regurgitation, left ventricular outflow tract diameter, peak and mean aortic valve gradients, and aortic valve area. Eight hundred interreader comparisons for evaluation of reproducibility were generated from five readers interpreting 10 echocardiograms per testing cycle. The applicability and efficacy of this method were then evaluated by testing a second larger group of 10 readers and reevaluating reproducibility 1 year later. RESULTS All readers demonstrated acceptable reproducibility for biplane ejection fraction, mitral regurgitation, and peak and mean aortic valve gradients. Acceptable reproducibility for left ventricular end-diastolic volume, aortic regurgitation, and aortic valve area was achieved by four of five readers. No readers attained acceptable reproducibility on initial evaluation of left ventricular outflow tract diameter. After review and retraining, all readers demonstrated acceptable reproducibility, which was maintained on subsequent testing 1 year later. A second larger group of 10 readers was also evaluated and yielded similar results. CONCLUSIONS A continuous quality improvement process was devised that successfully reduced interpretative variability in echocardiography and improved reproducibility that was sustained over time.

Cardiovascular Complications of Breast Cancer Therapy in Older Adults

Older adults frequently have pre-existing and cancer-related risk factors for cardiovascular toxicity from cancer treatment. In this review, we discuss the risk factors and strategies for prevention and management of cardiovascular complications in older women with breast cancer.