Weight change after a one-time preventive cardiology clinic visit.

AIM: The effect of a one-time visit to a cardiovascular health clinic (CVHC) on weight change remains unknown. Our study examined the effects of such a visit for subjects undergoing medical and preventive evaluations. METHODS: The study screened 836 subjects with a baseline BMI>25 kg/m2 and a follow-up weight at least 6 months from the initial visit. Patients with active cardiac disease were excluded. Data were obtained through a medical record review. The study included 342 patients with a mean baseline weight of 93.1 kg and BMI of 31.0 kg/m2. RESULTS AND CONCLUSION: Mean subsequent weight was 92.4 kg, representing a weight loss of 0.76 kg (P=0.005). Subjects with a previously documented weight showed a trend toward weight gain before the baseline visit. Mean weight loss was higher when the referring provider documented a weight-related diagnosis or plan (-1.63 vs. -0.23 kg, P=0.01), when the CVHC encounter occurred with an MD rather than a PhD-level exercise physiologist (-1.50 vs. 0.03 kg, P=0.004), and when the CVHC provider documented a weight-related diagnosis (-1.39 vs. -0.18 kg, P=0.02) or recommended diet changes (-1.09 vs. 0.75 kg, P=0.01). Individuals undergoing a preventive evaluation had lower mean weight loss (-0.13 vs. -1.49 kg, P=0.02). A single encounter in the CVHC reversed the trend toward weight gain. Characteristics associated with weight loss were referral for weight issues, encounter with an MD provider, and provision of diet recommendations. Patients undergoing medical evaluation had more weight loss than participants in a preventive health program.

Endothelial function and cardiovascular risk stratification in menopausal women.

BACKGROUND: Peripheral arterial, endothelium-dependent, flow-mediated reactive hyperemia is reduced in individuals with atherosclerosis. This study tested the hypothesis that digital tonometry, as a surrogate of endothelial function, is useful to stratify cardiovascular risk in recently menopausal women who are asymptomatic for cardiovascular disease. METHODS: Women undergoing screening for the Kronos Early Estrogen Prevention Study (KEEPS) were evaluated for conventional risk factors, flow-mediated reactive hyperemia by digital tonometry (RHI), carotid intima-media thickness (CIMT) by ultrasound, and coronary arterial calcium (CAC) by 64-slice CT scanner. RESULTS: One hundred and two non-diabetic Caucasian women (53.0 +/- 2.3 years old, 18.0 +/- 9.0 months past their last menses) participated; 72% were never-smokers. Fourteen women had positive CAC scores (range 0.5-133 Agatston units); CIMT ranged from 0.57 to 1.06 mm. RHI ranged from 1.26 to 5.44. RHI did not correlate with time past menopause, CAC, CIMT, total cholesterol or low density lipoprotein cholesterol. The significant negative correlation of RHI with body mass index (r = -0.21, p = 0.031) was lost in non-smokers (r = - 0.17, p = 0.14). There was also a negative correlation of high density lipoprotein cholesterol with CAC, both in the overall group and non-smokers (rho = -0.20, p = 0.05 and rho = -0.27, p = 0.02, respectively). CONCLUSIONS: RHI varies widely in healthy women within the first 3 years of menopause. RHI was not associated with standard risk assessment algorithms, CAC or CIMT. RHI may indicate an additional, independent component and non-invasive tool to further stratify cardiovascular risk in recently menopausal women. As KEEPS continues, data on RHI will provide information regarding hormonal therapy, endovascular biology and atherosclerotic risk.

Reproducibility of two coronary calcium quantification algorithms in patients with different degrees of calcification.

PURPOSE: To evaluate the reproducibility of coronary calcium quantification algorithms by electron beam CT (EBT) in patients with different amounts of calcified plaque using the conventional (Agatston) score and an area score and to demonstrate a potential application of these results for evaluation of follow-up scans. METHODS: In 50 consecutive patients. the conventional calcium score (CCS = Agatston score) and the area score (AS) were summed for each artery and patient. Data were analyzed in four groups according to degrees of calcification: 0 (absent-minimal): CCS 0-9, I (mild): CCS 10-99, II (moderate): CCS 100-399, III (severe): CCS > or = 400. We determined and compared the reproducibility for each algorithm within and among groups. RESULTS: Median percent reproducibility improved with increasing amounts of calcified plaque for the CCS and the AS (p = 0.002 and p = 0.004, respectively). We demonstrate how these reproducibility values can be used to evaluate long-term follow-up studies. The reduction of median reproducibility per patient using the AS vs. the CCS was 32% (13 vs. 19%, respectively). On a vessel-by-vessel basis, the reduction of median reproducibility was 7% (24.3 vs. 22.6%, CCS vs. AS, p < 0.02), which was attributable to a 45% reduction in reproducibility in arteries with mild scores (46.1 vs. 25.5%, CCS vs. AS, p < 0.005). CONCLUSION: The AS has an improved reproducibility compared with the CCS, especially in patients with small amounts of coronary calcifications which may prove clinically useful. Different reproducibility values in different degrees of calcification can be used for an individual assessment of changes in amounts of coronary calcification.

Coronary microvascular functional reserve: quantification of long-term changes with electron-beam CT preliminary results in a porcine model.

PURPOSE: To evaluate the ability of electron-beam computed tomography (CT) to help quantify long-term changes in coronary microvascular functional reserve in a porcine model. MATERIALS AND METHODS: Electron-beam CT-based intramyocardial blood volume and perfusion and Doppler ultrasonography (US)-based intracoronary blood flow were obtained in 13 pigs at baseline and again 3 months later. Measurements were obtained at rest and after the administration of adenosine. The short-term variation during 30 minutes of electron-beam CT measurements was assessed in nine additional pigs. RESULTS: Short-term variation of blood volume and perfusion averaged 8% and 9%, respectively, and was similar for both weight groups at rest and after adenosine administration. At rest, intracoronary blood flow, blood volume, and perfusion remained unchanged from baseline to follow-up. Long-term increases (percentage change with adenosine relative to that at rest) in blood volume and perfusion reserves were consistent with increasing intracoronary blood flow reserves. Despite these long-term changes in intracoronary blood flow, blood volume, and perfusion, the blood volume-to-perfusion relationship suggests a similar blood volume distribution among different microvascular functional components in normal porcine myocardium at both weight groups. CONCLUSION: Electron-beam CT may be of value for quantifying long-term changes in intramyocardial microvascular function.

Evaluation of the coronary venous system using electron beam computed tomography.

New therapeutic strategies in interventional cardiology and electrophysiology involve the coronary veins. This study examines the potential usefulness of electron beam computed tomography to obtain detailed noninvasive definition of the coronary venous anatomy and of arteriovenous relationships. Electron beam computed tomography allows acquisition and three-dimensional reconstruction of tomographic images of the beating heart with high spatial and temporal resolution. Contrast-enhanced, thin-section electron beam computed tomographic coronary arteriographic images of 34 patients (21 men and 13 women, age 60+/-10 years) were analyzed. The visibility of the coronary veins and their spatial relationship to the coronary arteries were assessed qualitatively on two- and three-dimensional displays. The coronary sinus was visible in 91%, the great cardiac vein in 100%, the middle cardiac vein in 88%, at least one vein overlying the lateral surface of the left ventricle in 97%, the anterior interventricular vein in 97%, and the small cardiac vein in 68%. A left marginal and a left posterior vein were seen in 44%, one of the two in 38%, and neither in 3%. The course of the anterior interventricular vein was parallel to the left anterior coronary artery in 79% and a crossover between the two vessels at an obtuse angle occurred in 12%. Contrast-enhanced electron beam computed tomography imaging of the heart noninvasively provides information on the coronary venous system and arteriovenous relationships that may help guide new interventional procedures.

Measurement and display of regional myocardial motion during post infarct treatment.

Quantitative assessment of 3-D regional heart motion has significant potential to provide more specific diagnosis of cardiac malfunction than currently possible. Using functional parametric mapping, regional myocardial motion during a cardiac cycle can be color-mapped onto a deformable heart model to provide better understanding of the structure-to-function relationships in the myocardium, including regional patterns of akinesis or dyskinesis associated with ischemia or infarction. In this study, 3-D reconstructions of human hearts were obtained from Electron-Beam Computed Tomography [1] (EB-CT), comparing stages of treatment after myocardial infarction.

Use of a new myocardial centroid for measurement of regional myocardial dysfunction by electron beam computed tomography: comparison with technetium-99m sestamibi infarct size quantification.

RATIONALE AND OBJECTIVES: The study compared the performance of conventional endocardial and epicardial centroid algorithms with the new "myocardial" centroid algorithm in patients with anterior myocardial infarction. "Floating" endocardial or epicardial centroid algorithms, commonly used in tomographic imaging methods to assess regional motion, may misrepresent left ventricular regional myocardial function in the presence of markedly asymmetric left ventricular contraction. METHODS: A new centroid algorithm based on regional myocardial mass distribution was tested in 29 patients with a first anterior myocardial infarction and was compared with conventional centroid algorithms. Direct comparisons in 60 equal sectors at one midventricular level per patient were performed between electron beam computed tomography and technetium-99m sestamibi single-photon emission computed tomography. The thresholds of regional myocardial function used to define infarction were varied for regional ejection fraction from 20% to 40% and for regional wall thickening from 0 to 4 mm. Regression and Bland-Altman analysis were used to compare infarct size by regional myocardial function with infarct size by sestamibi single-photon emission computed tomography. RESULTS: The new myocardial centroid showed the least shift toward infarcted myocardium from diastole to systole and had the highest amplitudes of the measurement curves for regional ejection fraction and regional wall thickening. The optimal regional myocardial function thresholds for each centroid algorithm for regional ejection fraction were endocardial, 30% (R = 0.62; mean difference to sestamibi, -0.5% +/- 22.1% tomographic infarct size points); epicardial, 30% (R = 0.79; mean difference, 2.2% +/- 13.1% tomographic infarct size points); and new myocardial, 25% (R = 0.88; mean difference, -0.6% +/- 9.5% tomographic infarct size points). The optimal thresholds for regional wall thickening were endocardial, 1 mm (R = 0.70; mean difference, -2.2% +/- 14.3% tomographic infarct size points); epicardial, 1 mm (R = 0.78; mean difference, -4.6% +/- 12.7% tomographic infarct size points); and new myocardial, 2 mm (R = 0.71; mean difference, 2.1% +/- 14.1% tomographic infarct size points). The best agreement (R = 0.88) between electron beam computed tomography infarct size and sestamibi single-photon emission computed tomography infarct size was achieved with regional ejection fraction and the new myocardial centroid algorithm. CONCLUSIONS: In asymmetrically contracting left ventricles, the new myocardial centroid algorithm is superior to conventional methods for tomographic analysis of regional myocardial function.

Minimally invasive evaluation of coronary microvascular function by electron beam computed tomography.

BACKGROUND: We previously demonstrated that in vivo electron-beam computed tomography (EBCT)-based indicator-dilution methods provide an estimate of intramyocardial blood volume (BV) and perfusion (F), which relate as BV=aF+b radicalF, where a characterizes the recruitable (exchange) and b the nonrecruitable (conduit) component of the myocardial microcirculation. In the present study, we compared BV and F with intracoronary Doppler ultrasound-based coronary blood flow (CBF) as a method for detecting and quantifying differential responses of these microvascular components to vasoactive drugs in normal (control) and hypercholesterolemic (HC) pigs. METHODS AND RESULTS: BV and F values were obtained from contrast-enhanced EBCT studies in 14 HC and 14 control pigs. BV, F, and CBF values were obtained at baseline (intracoronary infusion of saline) and after 5 minutes each of intracoronary infusion of adenosine (100 microgram. kg(-1). min(-1)) and nitroglycerin (40 microgram/min). BV and CBF reserves in response to adenosine were attenuated in HC pigs compared with controls (90+/-36% versus 127+/-42%, P<0.03, and 485+/-182% versus 688+/-160%, P<0.01, respectively). The relationship between BV and F showed consistently lower recruitable BV in HC versus control pigs. Nonrecruitable BV reserve in response to adenosine was attenuated in HC compared with controls (77+/-20% versus 135+/-28%, P<0.001). Our findings are consistent with HC-induced impairment of intramyocardial resistance vessel function. CONCLUSIONS: EBCT technology allows minimally invasive evaluation of intramyocardial microcirculatory function and permits assessment of microvascular BV distribution in different functional components. This method may be of value in evaluating the coronary microcirculation in pathophysiological states such as hypercholesterolemia.

Differentiation of intracardiac tumors and thrombi by echocardiographic tissue characterization: comparison of an artificial neural network and human observers.

The feasibility of classifying ultrasound images of intracardiac tumors and thrombi with a neural network-based algorithm was compared with the performance of experienced echocardiographers. The neural network used statistical descriptors of the apparent echocardiographic texture of the masses, and the blinded echocardiographers were given photographic prints of enlarged regions of interest without clinical data. The network classified 66% of the images correctly and the echocardiographers, 83%. The network and echocardiographers agreed in 88% of the images. Human observers usually base their classification of intracardiac masses on clinical data. The echocardiographic texture of tumors is quantitatively different from that of thrombi. This difference can be recognized by a neural network and potentially be useful in assisting with the diagnosis when clinical clues are insufficient.

[Economic aspects of using electron beam computerized tomography]. / Okonomische Aspekte bei der Anwendung der Elektronenstrahlcomputertomographie.

Electron beam computed tomography (EBCT) allows visualization and quantification of calcium in the coronary arteries. This has been demonstrated to correlate well with the overall plaque burden in the coronary arteries. EBCT is, therefore, well suited for the detection of early stages of coronary atherosclerosis. Especially in asymptomatic patients with several risk factors, staging coronary artery disease by coronary calcium, scanning may allow prognostic assessment and guide preventive and therapeutic interventions. To date, only scant data are available regarding the cost effectiveness and the economic impact of this imaging technique. In this manuscript we compare various methods for the diagnosis of coronary artery disease using a theoretical model and review the results of a prospective trial in our emergency room of coronary calcium scanning in patients with acute chest pain. Using Framingham data and prognostic data from long-term follow-up, we discuss the impact of coronary calcification scanning on primary preventive measures and its economical consequences. EBCT is a promising technique which has created a lot of attention due to its ease of application. It is currently undergoing critical appraisal in the medical literature. Further randomized prospective trials are needed (and underway, i.e., MESA, EDIC, CARDIA II) to better define its value and limitations in the clinical arena.

Comparison of two different software systems for electron-beam CT-derived quantification of coronary calcification.

OBJECTIVE: The growing interest in coronary calcium quantification by electron-beam CT (EBCT) has led to the development of various software systems for the analysis of EBCT raw data, but it is unknown whether these software systems yield comparable results. METHODS: Two sets of EBCT scans were obtained in 73 asymptomatic patients less than 15 minutes apart. Both scans of each patient were analyzed using two different software systems, the Mayo Clinic software and the AccuImage Scoring System. The authors compared the calcium quantities yielded by the two different software systems, analyzed the interscan variability, and calculated the interobserver variability. Finally, they investigated the influence of the CT density factor inherent in the widely used Agatston score for the quantification of coronary calcium on reproducibility. RESULTS: The mean score determined by the Mayo Clinic software was 14% greater than that determined by the AccuImage system. The mean difference between the two systems was 14% +/- 25%, and the median difference was 3%. The relative mean and the median difference between the two scans of one patient were 15.3% and 6% determined by the AccuImage system and 17% and 6.5% determined by the Mayo Clinic software. The interobserver reliability calculated by the Mayo Clinic software was better than that of the AccuImage system. There was a trend for better reproducibility using calcium area rather than the Agatson score. CONCLUSIONS: Two different scoring systems do not necessarily yield the same result. Calcium quantities were systematically determined to be greater by one system than the other, and there were significant differences with regard to interobserver reliability. Hence, software should be tested with regard to reproducibility data, and the interpretation of calcium quantities should acknowledge which type of software was used.

Comparison of measurement of left ventricular ejection fraction by Tc-99m sestamibi first-pass angiography with electron beam computed tomography in patients with anterior wall acute myocardial infarction.

The goal of this study was to compare measurements of left ventricular (LV) ejection fraction (EF) by first-pass radionuclide angiography ("first-pass angiography") using technetium-99m (Tc-99m) sestamibi with those by contrast-enhanced electron beam computed tomography ("electron beam tomography") as a reference technique in patients with an anterior wall acute myocardial infarction (AMI). Twenty-five patients with first Q-wave anterior wall AMI underwent paired electron beam tomographic and first-pass angiographic studies (mean, 1 day apart). Fourteen patients had 2 sets of measurements of the LVEF obtained by both methods (separated by at least 6 weeks), for a total of 39 paired measurements. LVEF by electron beam tomography was calculated from absolute systolic and diastolic LV chamber volumes. LV volumes by electron beam tomography were 199 +/- 51 ml at end-diastole and 111 +/- 42 ml at end-systole. Mean LVEF was 45 +/- 11% by first-pass tomography and 46 +/- 9% by electron beam tomography. The linear correlation coefficient between both methods was 0.82 (p <0.0001), with slope = 1.0, y-intercept = -1.1, and SEE = 6.1. The mean difference between the 2 methods was -0.7 +/- 6.0 EF units (p = 0.75). The correlation between the differences and means of both methods was 0.34 (p = 0.04), indicating a trend for first-pass angiography to overestimate LVEF in the higher range. LVEFs measured by first-pass angiography in patients with abnormal LV geometry and contraction patterns caused by anterior wall AMI agree well with those measured by electron beam tomography in the clinically relevant range.

Coronary calcification by electron beam computed tomography and obstructive coronary artery disease: a model for costs and effectiveness of diagnosis as compared with conventional cardiac testing methods.

OBJECTIVES: The purpose of this study was to determine if electron beam computed tomography (EBCT) has potential as a cost-effective approach to diagnosis of obstructive coronary disease. BACKGROUND: Coronary calcification quantified by EBCT is closely related to the extent of atherosclerosis. METHODS: A model based upon published sensitivities (Se)/specificities (Sp) for diagnosis in an ambulatory patient of obstructive coronary disease (> or =50% stenosis) and population prevalence was tested for angiography alone, or treadmill exercise, stress echocardiography, stress thallium or predetermined EBCT calcium score outpoints, followed by angiography if indicated. RESULTS: Total direct testing costs increased in proportion to disease prevalence whereas cost-effectiveness, direct costs/patient diagnosed correctly with disease, decreased as a function of prevalence. Using an EBCT calcium score of 168 (Se/Sp = 71%/90%) provided for the least costly and most cost-effective noninvasive pathway. Calcium scores of 80 (Se/Sp = 84%/84%) and 37 (Se/Sp = 90%/77%) were also cost-effective when prevalence of disease was < or =70%; but results for a >0 calcium score (Se/Sp = 95%/46%) cutpoint were not superior to conventional methods. Calcium score cutpoints of 37, 80 or 168 provided similar or superior overall negative and positive predictive values to conventional noninvasive testing pathways across all prevalence subgroups. CONCLUSIONS: In ambulatory patients evaluated for obstructive coronary disease, a testing pathway utilizing quantification of coronary calcium by EBCT as an initial noninvasive testing approach minimized direct costs, and maximized cost-effectiveness in population groups with low/ moderate disease prevalence (< or =70%); as expected, direct angiography as the first and only test proved most cost-effective in patients with a high prevalence (>70%) of disease.

Measurement of myocardial infarct size by electron beam computed tomography: a comparison with 99mTc sestamibi.

RATIONALE AND OBJECTIVES: The authors sought to determine, using a variety of regional left ventricular ejection fraction (EF) and wall thickening (WTh) criteria, the applicability to measure left ventricular (LV) infarct size using electron-beam CT (EBCT) in patients as compared with technetium 99m (99mTc) sestamibi scanning as reference standard. METHODS: Twelve patients (age 57 +/- 11 years) underwent 99mTc sestamibi scanning and EBCT at hospital discharge after an acute index anterior myocardial infarction. Left ventricular infarct size was defined using standard 99mTc sestamibi scanning. Regional EF and WTh were analyzed on each EBCT scan with use of a floating epicardial centroid method. In five contiguous LV tomograms, the amount of infarcted myocardium was estimated using the following EF and WTh criteria: EF < or = 35%, 30%, 25%, 20%, and WTh < or = 2 mm, 1 mm, and 0 mm. RESULTS: Infarct size measured with 99mTc sestamibi was 33.3% (+/- 18.3%) (mean +/- SD, range 6%-54%) of the LV. Using an EF < or = 35% or absolute WTh < or = 2 mm as criteria for infarcted myocardium, EBCT yielded 28% (+/- 17%) and 27% (+/- 16%), respectively (P = NS, paired Student's t test, versus 99mTc sestamibi). Although, with use of the other criteria, EBCT tended to underestimate infarct size compared with 99mTc sestamibi, a close correlation across the entire range of infarct size determinations (range, 0.72-0.82) regardless of the underlying criteria suggested an internal consistency of the data. CONCLUSIONS: Quantitative analysis of regional myocardial function by EBCT allows an estimate of anterior infarct size when compared with 99mTc sestamibi. This suggests that in addition to previously established applications after acute myocardial infarction such as examination of cardiac volumes and mass, EBCT also may provide for infarct size determination.

Determination of ventricular ejection fraction: a comparison of available imaging methods. The Cardiovascular Imaging Working Group.

Knowledge of left ventricular ejection fraction has been shown to provide diagnostic and prognostic information in patients with known or suspected heart disease. In clinical practice, the ejection fraction can be determined by using one of the five currently available imaging techniques: contrast angiography, echocardiography, radionuclide techniques of blood pool and first pass imaging, electron beam computed tomography, and magnetic resonance imaging. In this review, we discuss the clinical application as well as the advantages and disadvantages of each of these methods as it relates to determination of ventricular ejection fraction.

[Electron beam tomography in cost effective diagnosis of coronary heart disease]. / Die Elektronenstrahltomographie in der kosteneffizienten Diagnostik der koronaren Herzkrankheit.

BACKGROUND: Electron beam CT (EBCT) can acquire rapid, multiple thin-section tomograms of the beating heart in synchrony with the electrocardiogram and quantity coronary calcification without intravenous contrast. Coronary calcification is an active process exclusively associated with atherosclerotic plaque formation and regulated in a manner similar to the calcification of bone. Clinical studies have demonstrated that EBCT coronary calcification (1) follows a pattern similar to the epidemiology of coronary artery disease (CAD), (2) has a high sensitivity (90-95%) for coronary plaque and significant angiographic coronary stenoses, and (3) has the potential to assess the prognosis of patients with coronary atherosclerotic disease. Coronary calcium area or "score" correlates best with overall plaque burden within the coronary system. However, coronary calcium is of limited value in distinguishing coronary stenosis on a segment-by-segment basis. EBCT AND CAD: Due to spiraling health care costs, there is a need for cost-efficient strategies in the diagnosis and stratification of patients with known or suspected CAD. There are two major patient groups in which EBCT calcium scanning has a potential for cost-efficient application: (1) in asymptomatic, high-risk patients, identification of significant plaque burden may direct judicious use of long-term drug therapy or further investigation to those individuals most likely to benefit from an aggressive risk factor modification and medical program; (2) in patients with chest pain syndromes but no prior CAD, EBCT calcium scanning compares favorably with conventional diagnostic methods. In particular, using receiver operating characteristic analysis, the sensitivity and specificity of an EBCT calcium score of 80 in detecting obstructive CAD are both about 85%. Using a theoretical model, EBCT calcium scanning was found to be the most cost-effective approach to diagnosis in populations with a low-to-moderate likelihood of obstructive CAD when compared with treadmill exercise, stress thallium, and stress echocardiography. CONCLUSIONS: EBCT calcium scanning is not a substitute for coronary angiography, but it has clear advantages over other more traditional diagnostic methods for CAD. In particular, it can be performed conveniently and inexpensively in most patients. Additionally, the site and extent of calcification are intimately related to the atherosclerotic plaque burden. The analyses presented suggest that it may also provide a cost-effective clinical alternative in specific subsets of the population.

Progressive carcinoid heart disease after resection of primary ovarian carcinoid.

Primary ovarian carcinoid tumors are uncommon, and carcinoid heart disease is a rare complication. Although carcinoid syndrome and carcinoid heart disease typically occur in the setting of metastatic carcinoid tumor, particularly involving the liver, this is not necessarily the case in patients with primary ovarian carcinoid tumors. After surgical resection of an ovarian carcinoid tumor, the prognosis is excellent; however, carcinoid heart disease can continue to progress. The following is a case report of a patient who, despite having complete resection of a primary ovarian carcinoid tumor, went on to develop progressive, debilitating carcinoid heart disease. This is an important scenario to recognize, because proper management and surgical intervention in carcinoid heart disease can be lifesaving.

Nonparallel changes in global left ventricular chamber volume and muscle mass during the first year after transmural myocardial infarction in humans.

OBJECTIVES: This study was designed to serially assess time-dependent changes in both chamber volume and myocardial muscle mass after infarction in humans. BACKGROUND: Dilation of the left ventricular chamber has been previously described after transmural myocardial infarction. METHODS: Global left ventricular chamber volumes and muscle mass were quantified by using cine computed tomographic scanning in 18 patients at hospital discharge and 6 weeks, 6 months and 1 year after an initial transmural myocardial infarction (12 anterior and 6 inferior). No patient had heart failure during the initial hospital stay or on any subsequent follow-up visit. RESULTS: The patients with anterior myocardial infarction (estimated infarct extent 27 +/- 2% of left ventricle) demonstrated a progressive increase in left ventricular end-diastolic volume from 148 +/- 9 ml (mean +/- SEM) at hospital discharge to 180 +/- 9 ml at 1 year after infarction (p < 0.001). However, global left ventricular muscle mass decreased significantly during the 1st 6 weeks after infarction but returned by 1 year to nearly the value determined at hospital discharge (177 +/- 13 vs. 165 +/- 10 g, p = NS). The changes in global muscle mass did not parallel the steady and progressive increases in chamber end-diastolic volume. The end-diastolic chamber volume to muscle mass ratio, an index of global left ventricular wall tension, increased steadily after hospital discharge but remained level by 1 year after infarction. The time course of changes in global end-systolic chamber volume was roughly proportional to the concomitant changes in end-diastolic volume. During this same time period, left ventricular stroke volume remained constant or improved from that determined at baseline. Global left ventricular end-diastolic and end-systolic volumes remained relatively static during the 1st year in the patient subgroup with inferior wall myocardial infarction (estimated infarct extent 10 +/- 1% of left ventricle), but global muscle (myocardial) mass initially decreased and then increased in a pattern similar, although of smaller magnitude, to that observed in patients with anterior wall myocardial infarction. CONCLUSIONS: Overall, left ventricular end-diastolic and end-systolic chamber volumes increase progressively from hospital discharge to 1 year after an initial transmural myocardial infarction in patients with a moderately large anterior wall infarction but remain stable in patients with a small inferior wall infarction. Concurrently, total left ventricular muscle mass decreases significantly during the initial 6 weeks after infarction (presumed largely secondary to changes in the necrotic segments) but then returns to the hospital discharge baseline values by 1 year. These data are consistent with the late development of, at most, limited ventricular hypertrophy in the noninfarcted myocardium that occurs well after the early and progressive left ventricular chamber dilation observed in patients with a moderate to large myocardial infarction. These data, in particular as applied to patients with anterior infarction, suggest that ventricular wall tension is significantly elevated at least during the 1st year after an initial transmural myocardial infarction. These observations may explain the potential utility of agents aimed at reducing afterload or ventricular wall tension during the early convalescent phase after myocardial infarction.

Serial tomographic imaging with technetium-99m-sestamibi for the assessment of infarct-related arterial patency following reperfusion therapy.

The purpose of this study was to determine the relationship of changes in the severity and extent of hypoperfusion on serial tomographic 99mTc-sestamibi images with patency of the infarct related artery during acute myocardial infarction. We studied 109 patients with acute myocardial infarction using tomographic 99mTc-sestamibi imaging acutely and at 18-48 hr later. Perfusion defect extent and defect area, an index of defect severity, were measured on both studies. Both defect extent and defect area were significantly (p = 0.0001) greater for anterior infarctions than for inferior and lateral infarctions. By two factor analysis of variance, the change in defect area varied significantly with both infarct location (p = 0.0001) and patency of the infarct-related artery (p = 0.002). The change in defect extent also varied significantly with both infarct location (p = 0.0001) and with patency of the infarct-related artery (p = 0.004). In patients with inferior myocardial infarction, a change in defect extent or defect area of greater than 4% or 0.017, respectively, had a positive predictive accuracy of 96% and 93%, respectively, for the identification of a patent infarct artery. Therefore, sequential changes on tomographic 99mTc-sestamibi images are of potential value for the noninvasive assessment of patency of the infarct-related artery.

Measurement of myocardium at risk by technetium-99m sestamibi: correlation with coronary angiography.

Previous studies have shown that tomographic perfusion imaging with technetium-99m sestamibi (RP-30A) can accurately measure the myocardium at risk during acute myocardial infarction. The ability of coronary angiography to predict the wide variability in myocardium at risk was studied in 21 patients with their first acute myocardial infarction. In blinded fashion, two experienced angiographers provided an overall "best estimate" of the percent of left ventricular myocardium at risk considering multiple angiographic variables--infarct-related artery, location of stenosis (proximal or nonproximal), vessel diameter, length, territory and the number and size of proximal branches and collateral vessels. Many of these individual variables showed a significant association with myocardium at risk. The most important angiographic variable was the mean best estimate of the two angiographers (r = 0.89, p less than 0.0001). However, the SEE was large (8.6% of the left ventricle) and angiography significantly (p less than 0.002) overestimated myocardium at risk. When patients with an anterior or an inferior infarct were considered separately, the angiographic best estimate had a weaker correlation with myocardium at risk measured by technetium-99m sestamibi in patients in both groups (anterior infarction r = 0.65, p = 0.04; inferior infarction r = 0.65, p = 0.04. Seven patients with an inferior infarct and myocardium at risk ranging from 7% to 32% of the left ventricle had identical angiographic best estimates. Although angiographic estimates correlate closely with measurements of myocardium at risk in groups of patients, their ability to predict the myocardium at risk in individual patients is limited.