Abstract P105: Clinical Factors Associated With Left Ventricular Ejection Fraction Disparity in Patients With Left Ventricular Dysfunction Undergoing Multimodality Imaging

Background: Drug and device therapy of heart failure is increasingly determined based on left ventricular ejection fraction (LVEF) partition values. Many patients undergo both single photon emission computed tomography (SPECT) and echocardiographic assessment of LVEF. Significant disparity frequently exists between these 2 techniques, even when testing is performed near simultaneously in clinically stable patients.

Objective: We aimed to determine clinical predictors of LVEF disparity in patients undergoing multimodality testing.

Methods: Between January 2006 and July 2007, 2937 patients underwent both echo and SPECT testing within a 7 day period. Of these, 119 patients had an LVEF <50% by 1 or both techniques, and an absolute LVEF difference between the 2 techniques of at least 10%. A control group comprising of 118 patients had an LVEF <50% by 1 or both techniques, and an absolute LVEF difference between the 2 techniques of less than 10%. In a logistic model with a stepwise selection method 30 candidate clinical variables were available to be selected in the model.

Results: The predictive model resulted in five variables: Atrial Fibrillation, Severe mitral regurgitation, Left ventricular hypertrophy, high basal heart rate during echocardiogram and Paced rhythm. The model obtained good predictability(c=0.82) and fit (Hosmer-Lemeshow p=0.51). The point estimates and odds ratios are shown in the figure below.

Conclusions: In patients with LVEF < 50%, atrial fibrillation, severe mitral regurgitation, left ventricular hypertrophy, high basal heart rate during echocardiogram and paced rhythm are associated with a >10% LVEF disparity between the two imaging techniques.

Cardiovascular screening with electrocardiography and echocardiography in collegiate athletes

BACKGROUND

Current guidelines for preparticipation screening of competitive athletes in the US include a comprehensive history and physical examination. The objective of this study was to determine the incremental value of electrocardiography and echocardiography added to a screening program consisting of history and physical examination in college athletes.

METHODS

Competitive collegiate athletes at a single university underwent prospective collection of medical history, physical examination, 12-lead electrocardiography, and 2-dimensional echocardiography. Electrocardiograms (ECGs) were classified as normal, mildly abnormal, or distinctly abnormal according to previously published criteria. Eligibility for competition was determined using criteria from the 36(th) Bethesda Conference on Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities.

RESULTS

In 964 consecutive athletes, ECGs were classified as abnormal in 334 (35%), of which 95 (10%) were distinctly abnormal. Distinct ECG abnormalities were more common in men than women (15% vs 6%, P<.001) as well as black compared with white athletes (18% vs 8%, P<.001). Echocardiographic and electrocardiographic findings initially resulted in exclusion of 9 athletes from competition, including 1 for long QT syndrome and 1 for aortic root dilatation; 7 athletes with Wolff-Parkinson-White patterns were ultimately cleared for participation. (Four received further evaluation and treatment, and 3 were determined to not need treatment.) After multivariable adjustment, black race was a statistically significant predictor of distinctly abnormal ECGs (relative risk 1.82, 95% confidence interval, 1.22-2.73; P=.01).

CONCLUSIONS

Distinctly abnormal ECGs were found in 10% of athletes and were most common in black men. Noninvasive screening using both electrocardiography and echocardiography resulted in identification of 9 athletes with important cardiovascular conditions, 2 of whom were excluded from competition. These findings offer a framework for performing preparticipation screening for competitive collegiate athletes.

Cardiac toxicity screening by echocardiography in healthy volunteers: a study of the effects of diurnal variation and use of a core laboratory on the reproducibility of left ventricular function measurement

BACKGROUND

In investigational medicinal products testing centers (IMP), reliable methods for monitoring early signs of cardiotoxicity of a potential new drug in healthy volunteers are essential. This study examines what levels of left ventricular ejection fraction (LVEF) variance can be achieved with two-dimensional echocardiography (2DE) in a core laboratory versus a site laboratory. Diurnal variability of LVEF and diastolic parameters were also reviewed.

METHODS AND RESULTS

64 healthy males, (age range 18-40 years), with optimal echo windows were recruited. Two-dimensional and tissue Doppler (TDI) echocardiography was performed by one dedicated sonographer using an Acuson Sequoia C256 machine. Heart rate and blood pressure were recorded simultaneously. Echocardiograms were performed at set time points (0, 1, 4, and 20 hours) on all subjects. The images were analyzed independently by one on-site, unblinded, sonographer reader (site lab) and one experienced off-site blinded physician over reader (core lab). The core lab showed significantly less variance in LVEF measurements than the site lab (5.5% vs. 19.9%). There was no significant diurnal variation in mean blood pressure, LVEF or E:A ratio measurements over 20 hours.

CONCLUSIONS

The core lab had better reproducibility and significantly less variance in LVEF measurements by 2DE than the site lab. There was no diurnal variation in LV function measurement.

A retrospective comparison of mortality in critically ill hospitalized patients undergoing echocardiography with and without an ultrasound contrast agent

OBJECTIVES

To compare acute mortality in critically ill hospitalized patients undergoing echocardiography with and without an ultrasound contrast agent (UCA).

BACKGROUND

Because of serious cardiopulmonary reactions reported immediately after administration of perflutren-containing UCAs, the FDA required a black box safety warning for this class of agents, including perflutren protein-type A microspheres injectable suspension.

METHODS

This study used the largest hospital service-level database in the U.S. All adult patients undergoing in-patient echocardiography between January 2003 and October 2005 were identified (n = 2,588,722, of which 22,499 received perflutren protein-type A microspheres injectable suspension). Of the 22,499 contrast echocardiography patients, 2,900 had diagnoses meeting criteria for critical illness (heart failure, acute myocardial infarction, arrhythmia, respiratory failure, pulmonary embolism, emphysema, and pulmonary hypertension). To control for the differences between the contrast and noncontrast patients, we used propensity score matching. Variables used in the construction of the propensity score included comorbidities, demographic factors, hospital-specific factors, level of care, and mechanical ventilation status. Patients receiving contrast echocardiography were matched to 4 control patients who received noncontrast echocardiography. Conditional logistic regression was used to estimate mortality effects.

RESULTS

There were 167 deaths in the study among critically ill patients, 38 of 2,900 from the contrast group and 129 of 11,600 from the control group. The contrast agent was not associated with an increase in same-day mortality (odds ratio: 1.18; 95% confidence interval: 0.82 to 1.71; p = 0.37). Before matching, contrast patients showed greater morbidity than noncontrast patients (Deyo-Charlson comorbidity score 2.45 vs. 2.25, p < 0.0001). After propensity score matching, these differences were significantly reduced, showing that both groups were well balanced.

CONCLUSIONS

There is no increase in mortality in critically ill patients undergoing echocardiography with the UCA compared with case-matched control patients.

Safety and Risk-Benefit Profile of Microbubble Contrast Agents in Echocardiography

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Temporal obesity trends in patients undergoing transthoracic echocardiography 2002-2006

In a recent data brief, the National Center for Health Statistics reported that obesity prevalence has plateaued in recent years, with no increase in obesity from 2003 to 2006. We have subjectively observed a marked increase in clinically severe obesity over this same period in patients presenting to our echocardiographic laboratory. The aim of this study was to determine temporal trends in obesity prevalence in patients presenting for transthoracic echocardiographic studies. A retrospective database analysis was performed using the Cardiovascular Consultants (Kansas City, Missouri) database (ProSolv Cardiovascular, Indianapolis, Indiana). The height and weight of patients who underwent transthoracic echocardiography in 2002 (n = 10,804) and 2006 (n = 17,556) were obtained. Body mass index was calculated as weight/height squared. Patients were grouped into 1 of 6 body mass index categories (underweight, normal weight, overweight, obese, morbidly obese, or super obese). Continuous variables were compared using Student's t test, and categorical variables were compared using chi-square test. In the 2 years, approximately (1/3) of patients were normal weight and (1/3) of patients were overweight. Obesity prevalence increased significantly (by nearly 8%) over the study period, with 28.1% of patients in the obese category by 2006. Clinically severe obesity (morbidly obese and super obese) increased dramatically from 2002 to 2006 (16%, p <0.008, and 41.7%, p <0.001, increases, respectively). In conclusion, clinically severe obesity has markedly increased in our midwestern echocardiographic laboratory in the period from 2002 to 2006.

Usefulness of left ventricular diastolic dysfunction as a predictor of one-year rehospitalization in survivors of acute myocardial infarction

Presence of severe left ventricular (LV) diastolic function has been shown to independently predict risk of heart failure or death after acute myocardial infarction (AMI). We aimed to determine whether common echocardiographic parameters and (LV) diastolic function evaluated during AMI hospitalization can predict the risk of rehospitalization, up to 1 year after AMI. One hundred ninety consecutive patients with AMI, who were prospectively enrolled in a longitudinal post-AMI registry, had survived for 1 year, and had a clinically indicated echocardiogram during the index admission, were included in the study. The independent effect of diastolic dysfunction on 1-year all-cause rehospitalization was assessed using multivariable proportional hazards regression. Average age was 62.5 years, 93% were Caucasian, 66% were men, and mean LV ejection fraction was 46%. At 1 year, 78 patients (41%) had been rehospitalized >or=1 time. In multivariable analysis, presence of severe LV diastolic dysfunction was the only echocardiographic variable that predicted increased risk of rehospitalization 1 year after AMI (hazard ration 3.31, 95% confidence interval 1.26 to 8.69). Seventy-eight percent of patients with severe LV diastolic dysfunction (restrictive diastolic physiology) compared with 30% with normal diastolic function (p = 0.0052) and 37% with nonrestrictive physiology during the index admission were rehospitalized. In conclusion, severe LV diastolic dysfunction is the only echocardiographic predictor of rehospitalization in survivors of AMI and routine assessment of diastolic function during AMI hospitalization can provide additional prognostic risk stratification at dismissal.

Transoesophageal echocardiographic diagnosis of pulmonary arteriovenous malformation in a patient with ischaemic stroke

We report a case of an ischaemic stroke secondary to an isolated pulmonary arteriovenous malformation. In this case, transoesophageal echocardiogram played a pivotal role in shunt identification, exclusion of atrial septal defect, and definitive diagnosis and localization of the pulmonary arteriovenous malformations. Pulmonary arteriovenous malformations should be excluded in all patients with cryptogenic stroke.

Mortality rates and clinical predictors of reduced survival after cardioverter defibrillator implantation

We aimed to identify mortality rates and clinical predictors of reduced survival in a large cohort of patients after implantation of an implantable cardioverter-defibrillator (ICD). Although existing data from clinical trials report annual mortality after ICD implantation from 2% to 9%, there are few data available on mortality rates or predictors of reduced survival in this patient population in clinical practice. In this single-center, retrospective analysis of 286 patients who underwent ICD implantation between June 1, 2000 and December 30, 2003, candidate predictors of mortality were assessed and subjected to multivariable analysis. Outcomes were documented using the Social Security Death Master File and hospital medical records. Overall annualized mortality was 11.3% after ICD implantation. Mortality rates in patients with left ventricular ejection fraction (LVEF) <25% were 27.2% at 1 year and 50.5% at 3 years. Digoxin (hazard ratio 1.86, 95% confidence interval [CI] 1.21 to 2.86, p = 0.0046) and loop diuretics (hazard ratio 1.59, 95% CI 1.06 to 2.38, p = 0.024) were associated with reduced survival. Angiotensin-converting enzyme inhibitor or aldosterone receptor blocker use was associated with reduced mortality (hazard ratio 0.50, 95% CI 0.31 to 0.80, p = 0.0038). In conclusion, mortality after ICD implantation is higher than demonstrated in primary or secondary prevention ICD trials; LVEF remains a potent predictor of mortality after ICD implantation, particularly in patients with an LVEF <25%; loop diuretic and digoxin use is associated with an approximate twofold increase in mortality in this population; and angiotensin-converting enzyme inhibitor or aldosterone receptor blocker use is associated with improved survival after ICD implantation.

Safety and Risk—Benefit Profile of Microbubble Contrast Agents in Echocardiography

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Clinical Predictors of Left Atrial Thrombus and Spontaneous Echocardiographic Contrast in Patients with Atrial Fibrillation

OBJECTIVES

We sought to determine the relationship between clinical risk factors for systemic thromboembolism in patients with atrial fibrillation and the prevalence of left atrial (LA) spontaneous echocontrast (SEC) and LA thrombus (LAT).

BACKGROUND

Atrial fibrillation is associated with an increased risk of systemic thromboembolism. LA SEC and LAT also predict thromboembolic events. The relationship between clinical risk factors for systemic thromboembolism and prevalence of LA SEC and LAT is unknown.

METHODS

In all, 524 patients with atrial fibrillation underwent transesophageal echocardiography between August 2000 and March 2005. Clinical risk factors for systemic thromboembolism were determined for each patient. A CHADS(2) score ranging from 0 to 6 was calculated for each patient as: congestive heart failure = 1 point; hypertension = 1 point; age 75 years or older = 1 point; diabetes mellitus = 1 point; and history of stroke including transient ischemic attack or systemic embolism = 2 points. Transesophageal echocardiography reports were reviewed for the presence of LA SEC and LAT. Univariate and multivariable models were structured to assess which clinical risk factors predicted the presence of LA SEC or LAT.

RESULTS

In a multivariable model, age 75 years or older, previous thromboembolic event, and left ventricular ejection fraction (LVEF) less than 40% predicted LA SEC, whereas LVEF less than 40% was the only predictor of LAT. LA SEC was present in 24% of patients with a CHADS(2) score of 0, but was present in 58% with a CHADS(2) score of 5 or 6 (P < .0001). LAT was present in 3% percent of patients with a CHADS(2) score of 0, but in 17% of patients with a CHADS(2) score of 5 or 6 (P = .0026).

CONCLUSION

Age 75 years or older, previous thromboembolic event, and LVEF less than 40% predict presence of LA SEC. LVEF less than 40% is the only multivariate predictor of LAT. The prevalence of LA SEC and LAT increases with increasing CHADS(2) score.

Rapid bioprosthetic valve degeneration resulting in severe mitral stenosis

A 61-year-old man presented 9 months after bioprosthetic mitral valve implantation with progressive exertional dyspnea. Transesophageal echocardiography revealed severe mitral stenosis with diffuse leaflet thickening but no calcification. Subsequent pathologic examination of the valve demonstrated infiltrating fibroconnective tissue and chronic inflammation. Careful echocardiographic follow-up of this valve type may be warranted, especially in patients with early recurrent symptoms.

Transesophageal echocardiographic diagnosis of left atrial appendage occluder device infection

The safety and efficacy of a left atrial appendage closure device is currently under evaluation in a large-scale multi-center clinical trial. We report an initial case of left atrial appendage occluder device infection with Staphylococcus aureus; transesophageal echocardiography played a pivotal role in diagnosis and treatment.

Clinical and echocardiographic markers of mortality risk in patients with atrial fibrillation

Atrial fibrillation (AF) is independently associated with increases in cardiovascular and all-cause mortality. Although cardiovascular co-morbidities predict stroke risk in AF, their relation with mortality has not been well described. To identify clinical and echocardiographic markers of mortality in patients with AF, 524 patients with AF underwent transesophageal echocardiography from August 2000 to March 2005. Clinical risk factors for systemic thromboembolism were determined for each patient. A CHADS2 (congestive heart failure, hypertension, age>75 years, diabetes, and previous stroke or transient ischemic attack) score ranging from 0 to 6 was calculated for each patient. Transesophageal echocardiographic reports were reviewed for the presence of left atrial spontaneous echocardiographic contrast, left atrial thrombus, the left ventricular ejection fraction, aortic arch atheroma, and the presence and severity of mitral regurgitation. Mortality data were obtained from the Social Security Death Master File. Univariate and multivariate models were structured to assess which variables predicted mortality. In a multivariate model, a history of heart failure, age>75 years, the absence of systemic anticoagulation with warfarin, the presence of left atrial spontaneous echocardiographic contrast, and greater than moderate mitral regurgitation were independent predictors of mortality. Increasing CHADS2 score was also an independent predictor of mortality. A CHADS2 score of 5 or 6 was associated with a >50-fold increase in mortality compared with patients with CHADS2 scores of 0. In conclusion, a history of heart failure, age>or=75 years, the absence of chronic oral anticoagulation, a CHADS2 score>0, and greater than moderate mitral regurgitation are independent predictors of mortality in patients with AF.

Usefulness of myocardial contrast echocardiography in predicting late mortality in patients with anterior wall acute myocardial infarction

We investigated whether myocardial contrast echocardiography (MCE) performed soon after acute myocardial infarction (AMI) improves risk stratification for late mortality. MCE after AMI identifies microvascular "no-reflow" and predicts early outcomes; however, the predictive value of MCE for late mortality is unknown. One hundred sixty-seven patients with anterior AMI and left ventricular dysfunction underwent MCE 2 days after admission, and a perfusion score index (PSI) was calculated. Long-term follow-up (mean 39 months) was available for all patients. Patients with normal and abnormal perfusion had similar baseline characteristics. Myocardial contrast echocardiographic PSI was a predictor of mortality as a continuous variable (odds ratio 3.2 for each 1.0 increase in PSI, 95% confidence interval 1.1 to 9.7, p = 0.04). In a logistic regression model, age (odds ratio 2.6 per decade, 95% confidence interval 1.6 to 4.4, p = 0.0002) and PSI (odds ratio 4.5 for each 1.0 increase in PSI, 95% confidence interval 1.3 to 15.4, p = 0.02) were the only significant predictors of mortality. In a subanalysis comparing patients >70 years old with abnormal PSI with all other patients, Kaplan-Meier estimates showed a marked difference in survival over a mean follow-up of 39 months (24% vs 4% mortality, p = 0.0002). In conclusion, MCE refines risk stratification soon after anterior AMI in patients with left ventricular dysfunction. Patients at very high and very low risk of mortality can be identified, and myocardial contrast echocardiographic data are incrementally useful compared with existing clinical and angiographic variables.

Contrast administration reduces interobserver variability in determination of left ventricular ejection fraction in patients with left ventricular dysfunction and good baseline endocardial border delineation

Echocardiographic contrast agents improve endocardial border delineation in patients with technically difficult baseline studies. With medical and device therapy for heart failure increasingly based on left ventricular (LV) ejection fraction (EF) partition values, the accurate and reproducible assessment of LV function is necessary. It was hypothesized that routine contrast enhancement would significantly reduce interobserver variability in the determination of LVEFs in a cohort of patients with LV dysfunction and good baseline endocardial delineation. All patients underwent baseline noncontrast studies followed by contrast-enhanced imaging using Definity. Two experienced echocardiographers, blinded to the clinical data, determined LVEFs using 4 different techniques: noncontrast estimated (NCE), noncontrast calculated (NCC), contrast estimated (CE), and contrast calculated (CC). Using a mixed-model procedure that allows for fixed and random events, the variance due to error and that due to the patient was obtained (interclass correlation). The proportion of variation due to the reader was calculated as 1--interclass correlation. Mean standardized percentage differences ([reader 1 EF--reader 2 EF]/mean EF) were also calculated for each method. The proportion of variation due to the reader was smallest in the CC group and largest in the NCC group (NCE = 0.21, NCC = 0.33, CE = 0.25, CC = 0.11). The results were similar when only patients with NCE EFs >or=20% and <or=50% were analyzed (NCE = 0.29, NCC = 0.47, CE = 0.33, CC = 0.15). The mean standardized percentage difference between readers was smallest in the CC group for all patients and for those with NCE EFs >or=20% and <or=50%. In conclusion, contrast administration reduces interobserver variability in LVEF assessment, even in patients with good baseline endocardial border delineation, and should be used routinely regardless of the perceived adequacy of baseline images, especially if the LVEF is >or=20% and <or=50%.

Transesophageal echocardiographic diagnosis of Aspergillus fumigatus aortitis after percutaneous coronary intervention

Aspergillus aortitis is an uncommon infection with high mortality and has been reported in patients after cardiopulmonary bypass. We report the first case of Aspergillus aortitis in an immunocompetent man immediately after percutaneous coronary intervention to an aortocoronary bypass graft. In this case, transesophageal echocardiography played a pivotal role in diagnosis.

Pulmonary Hemodynamic Effects of Dipyridamole Infusion in Patients with Normal and Elevated Pulmonary Artery Systolic Pressure Receiving PB127

BACKGROUND

Intravenous administration of microspheres used as ultrasound contrast agents may potentially alter pulmonary hemodynamics. PB127 (POINT Biomedical Corp., San Carlos, CA) is an investigational ultrasound perfusion-imaging agent used in conjunction with dipyridamole to diagnose coronary artery disease. The effects of PB127 alone or in combination with dipyridamole on pulmonary hemodynamics have not been described.

METHODS

We studied 20 patients, including 10 with elevated screening pulmonary artery systolic pressure (>35 mm Hg). Doppler-derived pulmonary hemodynamics were determined before and after continuous infusion of PB127 (0.175 mg/kg diluted in 5% dextrose) or 5% dextrose. Patients then received dipyridamole (0.56 mg/kg) and hemodynamics were again assessed.

RESULTS

During PB127/dextrose infusion, there were no significant changes in pulmonary hemodynamics compared with baseline. After dipyridamole, there were small increases in pulmonary artery systolic pressure and in pulmonary flow and a reduction in pulmonary vascular resistance. These changes occurred in patients with normal and elevated pulmonary artery systolic pressure.

CONCLUSION

PB127 infusion does not alter pulmonary hemodynamics. Mild alterations of pulmonary hemodynamics occur after dipyridamole administration.

Myocardial Contrast Echocardiographic Estimates of Infarct Size Predict Likelihood of Left Ventricular Remodeling After Acute Anterior Wall Myocardial Infarction

OBJECTIVES

We sought to determine the utility of myocardial contrast echocardiography (MCE) in predicting left ventricular (LV) remodeling (LVR) in patients with a recent anterior wall myocardial infarction and residual regional LV akinesis.

BACKGROUND

Although recent studies have shown that MCE predicts recovery of regional and global LV systolic function after myocardial infarction, the relationship between myocardial perfusion patterns and likelihood of subsequent LVR has not been extensively studied.

METHODS

In all, 50 patients (mean age 62 years) underwent contrast-enhanced echocardiography for determination of LV volumes and ejection fraction, and MCE, 2 days after admission, with follow-up contrast-enhanced echocardiography 6 months later. LVR was defined as greater than 15% increase in LV end-diastolic volume index at follow-up.

RESULTS

LVR occurred in 19 patients (38%) (group 1), with stable LV volumes in 31 patients (62%) (group 2). Routine clinical and angiographic variables did not differ between groups 1 and 2. Both transmural extent of infarction and number of abnormally perfused myocardial segments (assessed by MCE) predicted LVR. LVR occurred in 55% of patients with transmural perfusion defects, and was less common in those with subendocardial perfusion defects or normal perfusion (31% and 21%, respectively). The mean percent increase in LV size was significantly greater for transmural infarcts (15 +/- 7%) versus subendocardial infarcts or normal perfusion (-1 +/- 8 and 8 +/- 8, respectively). When more than 5 myocardial segments were abnormally perfused, remodeling always occurred and was extensive.

CONCLUSIONS

MCE markers of infarct size are useful in predicting subsequent risk of LVR after myocardial infarction. Routine performance of MCE studies in select patients early after infarction may be helpful in further refining risk stratification.

Usefulness of myocardial contrast echocardiography in predicting global left ventricular functional recovery after anterior wall acute myocardial infarction

Although multiple recent studies have shown that myocardial contrast echocardiography (MCE) reliably differentiates between regional stunning and necrosis after acute myocardial infarction (AMI), prognosis is more closely related to measures of global left ventricular systolic function. One hundred fifteen patients underwent baseline wall motion assessment and MCE 2 days after admission and follow-up echocardiography a mean of 69 days later. Good agreement was found between perfusion score index and follow-up wall motion score index, indicating that MCE performed early after anterior wall AMI may be clinically useful in routine post-AMI risk stratification.

Reperfusion assessment using myocardial contrast echocardiography in patients with ST-segment elevation acute myocardial infarction

In this study, 29 patients underwent myocardial contrast echocardiography after presentation with ST-segment elevation acute myocardial infarction but before coronary angiography using a continuous infusion of microbubbles and real-time imaging with a low mechanical index. Patients with transmural perfusion defects at presentation subsequently had much larger infarctions (as measured by peak creatine phosphokinase-MB fraction) than did those with normal perfusion, indicating that myocardial contrast echocardiography may be a useful means to determine adequacy of reperfusion after thrombolytic therapy and in the selection of patients for adjunctive treatment, such as "rescue angioplasty."

Real-time assessment of myocardial perfusion during balloon angioplasty of the left anterior descending coronary artery

Balloon occlusion and release during elective percutaneous coronary intervention (PCI) provides a unique opportunity to study dynamic temporal alterations in myocardial perfusion in a controlled setting. These changes in flow and volume mimic those that occur during presentation with, and successful therapy of, ST-segment elevation acute myocardial infarction (AMI). Eleven patients underwent myocardial contrast echocardiography (MCE) using a continuous infusion of Definity at baseline, during coronary occlusion, and during reactive hyperemia immediately after balloon deflation. Fifty separate flow state sequences were acquired, and off-line analysis was performed to determine myocardial contrast intensity within a region of interest in the distribution of the left anterior descending artery (LAD). A reader blinded to flow state also performed qualitative evaluation (perfusion or lack of perfusion). Quantitative analysis demonstrated significant differences in myocardial contrast intensity by flow state (p = 0.0001 for occlusion vs reperfusion). Qualitative assessment demonstrated a high rate of correct classification (92%). Real-time myocardial perfusion assessment using MCE accurately differentiates coronary occlusion and reactive hyperemia in humans by qualitative and quantitative assessment. This technique may be clinically useful in assessing the efficacy of thrombolytic therapy in ST-segment elevation AMI and in clinical trial assessment of new drugs and devices aimed at limitation of infarct size.

Combined assessment of microvascular integrity and contractile reserve improves differentiation of stunning and necrosis after acute anterior wall myocardial infarction

OBJECTIVES

We sought to determine the relative accuracy of myocardial contrast echocardiography (MCE) and low-dose dobutamine echocardiography (LDDE) in predicting recovery of left ventricular (LV) function in patients with a recent anterior wall myocardial infarction (MI).

BACKGROUND

Left ventricular dysfunction after acute MI may be secondary to myocardial stunning or necrosis. Myocardial contrast echocardiography allows real-time echocardiographic perfusion assessment from a venous injection of a fluorocarbon-based contrast agent. Although this technique is promising, it has not been compared with LDDE.

METHODS

Forty-six patients underwent baseline wall motion assessment, MCE, and LDDE two days after admission, as well as follow-up echocardiography after a mean period of 53 days.

RESULTS

Perfusion by MCE predicted recovery of segmental function with a sensitivity of 69%, specificity of 85%, positive predictive value of 74%, negative predictive value of 81%, and overall accuracy of 78%. Contractile reserve by LDDE predicted recovery of segmental function with a sensitivity of 50%, specificity of 88%, positive predictive value of 72%, negative predictive value of 73%, and overall accuracy of 73%. Concordant test results occurred in 74% of segments and further increased the overall accuracy to 85%. The mean wall motion score at follow-up was significantly better in perfused versus nonperfused segments (1.9 vs. 2.6, p < 0.0001) and in segments with contractile reserve, compared with segments lacking contractile reserve (1.9 vs. 2.5, p < 0.0001).

CONCLUSION

Myocardial contrast echocardiography compares favorably with LDDE in predicting recovery of regional LV dysfunction after acute anterior wall MI. Concordant contractile reserve and myocardial perfusion results further enhance the diagnostic accuracy.

Full-motion pulse inversion power Doppler contrast echocardiography differentiates stunning from necrosis and predicts recovery of left ventricular function after acute myocardial infarction

OBJECTIVES

The goal of this study was to determine, in patients with a recent myocardial infarction (MI) and residual wall motion abnormalities within the distribution of the infarct-related artery, whether normal perfusion by myocardial contrast echocardiography (MCE) would accurately predict recovery of segmental left ventricular (LV) function.

BACKGROUND

Left ventricular dysfunction after acute MI may be secondary to myocardial stunning or necrosis. Recent technical innovations in contrast echocardiography, including pulse inversion imaging and power Doppler, now allow full-motion echocardiographic perfusion assessment from a venous injection of fluorocarbon-based contrast agent.

METHODS

Thirty-four patients with recent MI underwent baseline wall motion assessment and MCE two days after admission and follow-up echocardiography a mean of 55 days later.

RESULTS

Perfusion by MCE predicted recovery of segmental function with a sensitivity of 77%, specificity of 83%, positive predictive value of 90% and overall accuracy of 79%. The mean wall motion score at follow-up was significantly better in perfused, compared with nonperfused, segments (1.4 vs. 2.2, p < 0.0001). Additionally, 90% of perfused segments improved, while the majority of nonperfused segments remained unchanged.

CONCLUSIONS

Full-motion MCE utilizing an intravenous fluorocarbon-based agent and pulse inversion power Doppler techniques, identifies stunned myocardium, and accurately predicts recovery of segmental LV function in patients with recent MI.

Determinants of diastolic myocardial tissue Doppler velocities: influences of relaxation and preload

Myocardial tissue Doppler echocardiography (TDE) has been proposed as a tool for the assessment of diastolic function. Controversy exists regarding whether TDE measurements are influenced by preload. In this study, left ventricular volume and high-fidelity pressures were obtained in eight closed-chest dogs during intermittent caval occlusion. The time constant of isovolumic ventricular relaxation (tau) was altered with varying doses of dobutamine and esmolol. Peak early diastolic myocardial (E(m)) and transmitral (E) velocities were measured before and after preload reduction. The relative effects of changes in preload and relaxation were determined for E(m) and compared with their effects on E. The following results were observed: caval occlusion significantly decreased E (DeltaE = 16.4 +/- 3.3 cm/s, 36.6 +/- 13.7%, P < 0.01) and E(m) (DeltaE(m) = 1. 3 +/- 0.4 cm/s, 32.5 +/- 26.1%, P < 0.01) under baseline conditions. However, preload reduction was similar for E under all lusitropic conditions (P = not significant), but these effects on E(m) decreased with worsening relaxation. At tau < 50 ms, changes in E(m) with preload reduction were significantly greater (DeltaE(m) = 2.8 +/- 0.6 cm/s) than at tau = 50-65 ms (DeltaE(m) = 1.2 +/- 0.2 cm/s) and at tau >65 ms (DeltaE(m) = 0.5 +/- 0.1 cm/s, P < 0.05). We concluded that TDE E(m) is preload dependent. However, this effect decreases with worsening relaxation.

Real-time transmission of full-motion echocardiography over a high-speed data network: impact of data rate and network quality of service

With high-resolution network transmission required for telemedicine, education, and guided-image acquisition, the impact of errors and transmission rates on image quality needs evaluation.

METHODS

We transmitted clinical echocardiograms from 2 National Aeronautics and Space Administration (NASA) research centers with the use of Motion Picture Expert Group-2 (MPEG-2) encoding and asynchronous transmission mode (ATM) network protocol over the NASA Research and Education Network. Data rates and network quality (cell losses [CLR], errors [CER], and delay variability [CVD]) were altered and image quality was judged.

RESULTS

At speeds of 3 to 5 megabits per second (Mbps), digital images were superior to those on videotape; at 2 Mbps, images were equivalent. Increasing CLR caused occasional, brief pauses. Extreme CER and CDV increases still yielded high-quality images.

CONCLUSIONS

Real-time echocardiographic acquisition, guidance, and transmission is feasible with the use of MPEG-2 and ATM with broadcast quality seen above 3 Mbps, even with severe network quality degradation. These techniques can be applied to telemedicine and used for planned echocardiography aboard the International Space Station.

Comparison of tissue harmonic imaging with contrast (sonicated albumin echocardiography and Doppler myocardial imaging for enhancing endocardial border resolution

Endocardial resolution during 2-dimensional echocardiography is technically limited in at least 10% to 15% of patients. Recently, several ultrasound imaging innovations have been introduced that may improve endocardial resolution and decrease the proportion of technically difficult studies. This study compares tissue harmonic imaging, intravenous sonicated albumin, and Doppler myocardial imaging in patients with technically difficult echocardiograms. Twenty-eight patients with known or suspected cardiac disease and poor baseline endocardial resolution were studied. Only harmonic imaging (conventional and optimized for tissue) was superior to baseline fundamental imaging (p <0.001). Harmonic imaging was superior to baseline imaging in all myocardial regions and in the majority of patients, including those with the worst baseline studies.

Clinical applications of transpulmonary contrast echocardiography

BACKGROUND

The recent development of new fluorocarbon-based echocardiographic contrast agents that are capable of opacification of the left-sided cardiac chambers after intravenous injection is a major new advance in diagnostic cardiac imaging.

METHODS AND RESULTS

This is a review article focusing on these novel contrast agents, new echocardiographic imaging techniques to optimize their efficacy, and their clinical applications. Specific clinical applications of these agents are (1) enhancement of endocardial border definition to improve assessment of regional and global left ventricular function, (2) myocardial perfusion imaging by intravenous contrast echocardiography, (3) augmentation of spectral and color flow Doppler images, and (4) tissue-specific targeting of microbubbles for delivery of therapeutic agents.

CONCLUSIONS

New intravenous contrast agents offer the possibility to assess myocardial perfusion echocardiographically. It is also possible to use these agents for delivery of therapeutic agents, including gene therapy.

Digital echocardiography

Continued improvement in the computer price-to-performance ratio and the adoption of international standards have enhanced the feasibility of completely digital echocardiographic laboratories that were initially described more than a decade ago. Digital archival has distinct advantages over analog recording, including improved laboratory efficiency, capability of side-by-side comparison of current and historical studies, streamlined image storage, and enhanced interinstitution image transfer. Studies have demonstrated that clinical and electronic image compression allows efficient storage of data, without affecting diagnostic accuracy. Finally, digital echocardiography has important telemedicine applications.

Digital echocardiographic laboratory: where do we stand?

The transition to an all-digital echocardiographic laboratory has been slow despite the advantages of digital echocardiography, the dramatic improvement in computer technology, and the acceptance by all major vendors and professional organizations of the Digital Imaging and Communications in Medicine image-formatting standard. This review article examines some current issues in digital echocardiography, including types of digital output, disk versus network exchange, digital and clinical compression techniques, and the choice of image storage format. Although specific exceptions exist, we conclude that the optimal solution will be one based on a network exchange of formatted images that follow the Digital Imaging and Communications in Medicine standard, now available from several manufacturers. For a clinical interpretation, modest compression with the Joint Photography Expert Group algorithm appears acceptable, though possible enhancements to this compression standard are also discussed. We hope this review will enable the echocardiographic community to make more intelligent choices as digital storage and transmission products become available in the marketplace.

Usefulness of isometric hand grip exercise in detecting coronary artery disease during dobutamine atropine stress echocardiography in patients with either stable angina pectoris or another type of positive stress test

Dobutamine atropine stress echocardiography (DASE) detects coronary artery disease (CAD) by increasing myocardial oxygen demand causing ischemia. The sensitivity of the test for detection of CAD is reduced in patients with submaximal stress. We hypothesized that increasing cardiac work load by adding isometric exercise would improve the detection of ischemia during DASE. We studied 31 patients, mean age 57+/-11 years, with angiographically documented CAD. Patients underwent DASE using incremental dobutamine doses from 5 to 40 microg/kg/min, followed by atropine if peak heart rate was <85% of predicted maximal. Hand grip was then performed for 2 minutes at 33% of maximal voluntary contraction, while dobutamine infusion was maintained at the peak dose. The addition of hand grip during dobutamine stress was associated with a significant increase in systolic blood pressure (143+/-21 vs 164+/-24 mm Hg, p = 0.001) and left ventricular end-systolic circumferential wall stress (72+/-30 x 10(3) dynes/cm2 vs 132+/-34 x 10(3) dynes/cm2, p = 0.004). Wall motion score index increased from 1.0 at rest to 1.15+/-0.18 with dobutamine (p = 0.0004 vs rest), and increased further to 1.29+/-0.22 with the addition of hand grip (p = 0.004 vs dobutamine). Ischemia was detected in 19 patients (62%) with dobutamine-atropine stress alone and in 25 (83%) after the addition of hand grip (p <0.05). The addition of hand grip during DASE is feasible, and improves the detection of myocardial ischemia.

Detection of myocardial perfusion defects by contrast echocardiography in the setting of acute myocardial ischemia with residual antegrade flow

Although myocardial contrast echocardiography accurately demarcates area at risk during total coronary occlusion, the ability of MCE to delineate area at risk in the presence of residual antegrade flow is unknown. We hypothesized that perfusion defects in myocardial segments supplied by severe coronary stenoses with residual antegrade flow could be detected by MCE using intravenous FS069. We studied 13 open-chest dogs using an intravenous injection of FS069 during intermittent harmonic imaging. Images were collected at baseline, during acute ischemia with residual antegrade flow, physiologic hyperemia (release of stenosis), and total coronary occlusion. Regional myocardial blood flow was assessed using colored microspheres. MCE risk area during acute ischemia with residual antegrade flow and total occlusion was planimetered and compared with pathologic risk area (area unstained by monastral blue). Background-subtracted peak videointensity in the risk area was assessed for all flow states. Regional myocardial blood flow confirmed expected flow states, being significantly greater during physiologic hyperemia (4.16 +/- 1.22 ml/min/g) than at baseline (0.71 +/- 0.19 ml/min/g) and significantly diminished during coronary stenosis with residual antegrade flow (0.20 +/- 0.16 ml/min/g) and total occlusion (0.09 +/- 0.06 ml/min/g; p < 0.0001). Myocardial risk area by MCE during coronary stenosis with residual antegrade flow correlated well with pathologic risk area determined by monastral blue staining (r = 0.86). Peak videointensity during coronary stenosis (111 +/- 27) was significantly less than at baseline (157 +/- 50) but greater than during total occlusion (81 +/- 34; p < 0.0001). In conclusion, intravenous FS069 in conjunction with intermittent harmonic imaging delineates area at risk in ischemic myocardium supplied by a coronary stenoses with residual antegrade flow. The presence of a perfusion defect on MCE does not necessarily imply that the coronary artery is totally occluded.

Safety and efficacy of QW7437, a new fluorocarbon-based echocardiographic contrast agent

The aim of this study was to evaluate the safety and efficacy of QW7437, a new fluorocarbon-based transpulmonary myocardial echocardiographic contrast agent. QW7437 is an anionically charged 2% dodecafluoropentane emulsion molecule, similar to EchoGen, a contrast agent previously shown to be efficacious in providing myocardial opacification by means of venous injection. This new agent has theoretical potential to provide greater safety and efficacy as a result of (1) reduced adherence to the negatively charged vascular endothelium and (2) reduced microbubble coalescence. Myocardial contrast echocardiography was performed in 10 dogs to evaluate the safety and efficacy of this agent. QW7437 (0.05 ml/kg) was injected as an intravenous bolus during intermittent harmonic epicardial imaging. Hemodynamic variables including heart rate, blood pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output, and arterial blood gases were determined at baseline and serially after contrast administration. Left ventricular fractional area shortening the regional myocardial blood flow at rest and during hyperemia (adenosine 140 micrograms/kg/min) were measured before and after contrast echocardiography. QW7437 provided dense myocardial opacification which persisted for more than 2 minutes in all subjects. This prolonged contrast effect did not result in significant changes in any hemodynamic variables, left ventricular function, or myocardial blood flow. Future studies should address the potential of this agent for human use.

Relation of contractile reserve during low-dose dobutamine echocardiography and angiographic extent and severity of coronary artery disease in the presence of left ventricular dysfunction

Contractile reserve, during low-dose dobutamine echocardiography, is frequently used for the assessment of myocardial viability in patients with coronary artery disease (CAD) and left ventricular (LV) dysfunction. Whether contractile reserve is affected by the severity of the underlying CAD is presently unknown. Accordingly, we studied 58 patients with stable CAD and LV dysfunction who underwent coronary angiography and low-dose dobutamine echocardiography. In each vascular region the worst stenosis was identified and quantitated as percent diameter stenosis. Segmental wall motion during echocardiography was scored visually and rest and dobutamine wall motion score indexes were calculated. Contractile reserve was defined as > or = 1 grade improvement in wall motion score of > or = 2 contiguous segments along with > or = 20% reduction in global wall motion score index with dobutamine. There was no difference between patients with (n = 26) and without (n = 32) contractile reserve in percent coronary stenosis (89 +/- 17% vs 87 +/- 17%, p = 0.6), number of coronary arteries with > 50% diameter stenosis (2.0 +/- 0.8 vs 2.2 +/- 0.7, p = 0.4), number of occluded coronary arteries (1.2 +/- 0.9 vs 1.1 +/- 0.9, p = 0.6), or the prevalence of collaterals demonstrated angiographically (61% vs 56%, p = 0.5). Our data demonstrates that in patients with CAD and LV dysfunction, the prevalence of contractile reserve during low-dose dobutamine echocardiography is independent of the angiographic extent and severity of CAD.

Accuracy of dobutamine echocardiography for detection of myocardial viability in patients with an occluded left anterior descending coronary artery

OBJECTIVES

We studied the accuracy of dobutamine echocardiography for the detection of myocardial viability in patients with an occluded left anterior descending coronary artery and regional ventricular dysfunction.

BACKGROUND

Contractile reserve during dobutamine echocardiography is an accurate marker of myocardial viability in patients with coronary stenoses and ventricular dysfunction. However, its accuracy in patients with an occluded vessel has not been evaluated.

METHODS

We studied 41 patients with > 50% stenosis of the left anterior descending coronary artery and regional ventricular dysfunction who underwent dobutamine echocardiography for detection of viable myocardium. Contractile reserve was defined as improvement in wall motion score of two or more contiguous septal or anterior segments during doubutamine echocardiography. Recovery of function was defined as improvement in rest wall motion score of two or more contiguous segments after revascularization.

RESULTS

Patients were classified into two groups according to the presence (n = 20) or absence (n = 21) of left anterior descending coronary artery occlusion. Contractile reserve was detected in 40% of patients with an occluded and 43% with a nonoccluded artery (p = 0.8). Of 41 patients, 27 underwent revascularization, 12 with and 15 without an occluded vessel. Recovery of function occurred in 6 (50%) of 12 patients in the occluded artery group and in 5 (33%) of 15 in the nonoccluded artery group (p = 0.4). Among patients with an occluded artery, the positive and negative predictive values of dobutamine echocardiography for recovery of function were 100% (95% confidence interval [CI] 48% to 100%) and 86% (95% CI 42% to 100%), respectively.

CONCLUSIONS

Our results indicate that contractile reserve during dobutamine echocardiography can be detected in patients with an occluded vessel and may be useful for predicting recovery of function after revascularization.