Combined assessment of myocardial perfusion and diastolic function enhances risk stratification in patients with anterior wall myocardial infarction.

OBJECTIVE: Evaluate the utility of a combined risk stratification scheme including diastolic dysfunction and "no-reflow," to identify high-risk patients following acute myocardial infarction (AMI). BACKGROUND: Recent studies have demonstrated that the "no-reflow" phenomenon (defined by myocardial contrast echocardiography) and severe diastolic dysfunction (identified by Doppler echocardiography) identify patients at high risk for mortality following AMI. METHODS: We evaluated 111 patients with recent anterior acute myocardial infarction from July 2000 to June 2004. Diastolic function and myocardial perfusion was evaluated by echocardiography. Patients were placed into 1 of 3 groups based on diastolic function and myocardial perfusion: Group 1 (normal perfusion and normal diastolic function), Group 2 (abnormal perfusion or abnormal diastolic function), and Group 3 (abnormal perfusion and abnormal diastolic function). We compared the long term all-cause mortality within these groups. RESULTS: Patients in each group were similar with respect to myocardial infarction size as defined by biomarkers, extent and severity of coronary artery disease, and medical and interventional therapy. Mortality was much higher in Group 3 (26.9%) compared to Group 1 (0%) and Group 2 (15.2%) (p = 0.048). CONCLUSION: Combined assessment of diastolic function and myocardial perfusion enhances risk stratification post myocardial infarction.

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=20% and or=20% and

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.

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.