Noninvasive prediction of residual blood flow within the risk area during acute myocardial infarction: a multicenter validation study of patients undergoing direct coronary angioplasty

BACKGROUND: In a previous study from a single center, radionuclide measures of collateral flow with technetium 99m sestamibi have been shown to be significantly associated with angiographic residual (antegrade and collateral) flow and independent predictors of final infarct size in acute myocardial infarction. This study examined whether the previously described radionuclide measures of blood flow to the infarct zone were reproducible with different laboratories and imaging systems. METHODS AND RESULTS: Residual flow to the infarct zone was assessed by both invasive and noninvasive methods in 77 patients with first-time myocardial infarction (32 anterior, 45 nonanterior). All patients underwent acute coronary angiography before any intervention within 8 hours of the onset of chest pain (4.0 +/- 1.5 hours; range 1.2 to 7.9 hours). 99mTc sestamibi was injected intravenously before reperfusion therapy, and tomographic imaging was performed 1 to 6 hours after injection. A central core laboratory processed the acquired images from three centers, each with a unique camera and computer system. Three previously published methods based on the severity of the acute perfusion defect were used to measure residual flow to the infarct zone (nadir, severity index, area). Antegrade (Thrombolysis in Myocardial Infarction flow) and collateral flow before direct angioplasty were blindly graded on a four-point scale (0 to 3) from the acute angiogram. The simple sum of the two grades was defined as the angiographic flow index, representing residual flow to the jeopardized zone. All three noninvasive measures of residual flow were highly associated with the angiographic flow index in a linear fashion: severity index (p = 0.0006), area (p = 0.003), and nadir (minimum/maximum counts; p = 0.004). This association was independent of the laboratory where the data were acquired. CONCLUSIONS: Despite different laboratories and camera systems, radionuclide measures of residual flow were highly associated with the angiographic flow index before reperfusion therapy. These results suggest that these measures are applicable on a broader scale for the noninvasive determination of collateral and antegrade flow in acute myocardial infarction.     

Intravenous immunoglobulin inhibits IgE production in human B lymphocytes

This study sought to determine the prevalence of spontaneous reperfusion of an infarct-related artery (IRA) and associated myocardial salvage in the absence of thrombolysis or angioplasty. Twenty-one patients with acute myocardial infarction received only heparin and aspirin. At a median of 18 hours after presentation, 12 patients (57%) had angiographic patency of the IRA. Technetium-99m sestamibi was injected acutely on presentation and again at hospital discharge. Acute and final perfusion defect sizes were measured. Their difference, myocardial salvage, was calculated along with salvage index (myocardial salvage/acute defect). Comparing patients with a patent versus occluded IRA, myocardium at risk was similar (16% +/- 12% vs 12% +/- 9% left ventricle, p = NS); however, myocardial salvage (9% +/- 9% vs -2% +/- 7% left ventricle, p = 0.01), and salvage index (0.62 +/- 0.37 vs 0.19 +/- 0.33, p = 0.01) were greater in patients with spontaneous reperfusion. Resolution of chest pain was greater in patients with a patent IRA (100% vs 55%, p = 0.003). Spontaneous reperfusion of the IRA occurs frequently in patients with acute myocardial infarction and is associated with significant myocardial salvage.     

The biochemical inhibition mode of bredinin-5''-monophosphate on DNA polymerase beta

PURPOSE: To determine electrocardiographic features associated with myocardial salvage following reperfusion therapy in patients with inferior myocardial infarction. PATIENTS AND METHODS: Ninety-two consecutive patients with acute inferior myocardial infarction were treated with reperfusion therapy in a tertiary care center. Several features were measured on the presenting electrocardiogram, including the presence or absence of ST depression in the chest leads and the total magnitudes of ST elevation or depression, and were then evaluated for their association with myocardial salvage. Myocardial salvage (% of left ventricle) was the difference between myocardium at risk and final infarct size. Tomographic myocardial perfusion imaging with technetium-99m sestamibi was performed acutely to measure myocardium at risk and repeated prior to hospital discharge to measure final infarct size. RESULTS: The amount of myocardium at risk of infarction in the 92 patients was 19.1%+/-11.3% (range 1% to 68%), and the final infarct size was 10.6%+/-10.0% (range 0% to 45%). Thus, myocardial salvage in the 92 patients was 8.5%+/-8.4% (range -11% to 35%) of the left ventricle, or 0.51+/-0.38 (range 0.0 to 1.0) when expressed as a fraction of the myocardium at risk (salvage index). The presence or absence of anterior ST depression was the only one of seven electrocardiographic variables that was associated with myocardial salvage. Myocardial salvage was significantly greater in patients with anterior ST depression compared with those without it (10.6%+/-9.0% versus 5.9%+/-6.7%, P=0.025). Myocardium at risk was significantly greater in patients with anterior ST depression compared with those without the depression (22.8%+/-12.2% versus 14.6%+/-8.3%, P=0.0006), and infarct size tended to be larger (12.1%+/-10.4% versus 8.7%+/-9.4%, P=0.10). Myocardial salvage as a fraction of the myocardium at risk (salvage index) was similar between the two patient groups (0.52+/-0.37 versus 0.50+/-0.39, P=NS). CONCLUSION: The presence of anterior ST depression during inferior myocardial infarction identifies a group of patients with the potential for greater myocardial salvage with reperfusion therapy. Such patients derive greater absolute benefit from reperfusion therapy because they have a larger amount of myocardium at risk, although their response to therapy (salvage index) is not intrinsically different.     

Diagnosis of right ventricular infarction by overlap images of simultaneous dual emission computed tomography using technetium-99m pyrophosphate and thallium-201

The validity of dual energy single-photon emission computed tomography (SPECT) with technetium-99m pyrophosphate (Tc-99m PPi) and thallium-201 for the diagnosis of right ventricular (RV) infarction, and the clinical features of RV infarction, were investigated in 190 patients with acute myocardial infarction. Diagnosis of RV infarction was performed by Tc-99m PPi accumulation in the RV myocardium on thallium-201 and Tc-99m PPi over-lay images at the dual SPECT with simultaneous imaging taken 2 to 9 days after the onset of myocardial infarction. Thirty RV infarctions were found among the 190 patients with left ventricular infarction (15.8%): 29 (97%) in association with the inferior and 1 (3%) with the lateral infarction. Tc-99m PPi accumulation was mostly observed in the posterior wall of the right ventricle. A total occlusion or a severe stenosis of the right coronary artery was demonstrated angiographically in 92% of the patients with RV infarction. The prevalence of RV infarctions was significantly lower in patients who achieved successful early reperfusion than in those who did not (26.7 vs 68.4%, respectively, p < 0.01). However, a successful early reperfusion therapy could not significantly decrease the rate of RV involvement in patients without significant collateral flow (p < 0.01). Thus, dual isotope SPECT with Tc-99m PPi and thallium-201 can be used as a reliable method for the diagnosis of RV infarction.     

Prediction of myocardial viability: Tl-201 versus sestamibi versus teboroxime compared with FDG uptake

Several radionuclide imaging agents have been used for assessing the presence of myocardial viability. These include Tl-201 chloride, Tc-99m sestamibi, and Tc-99m teboroxime. Currently, the most reliable indicator is F-18 FDG, which accumulates in severely hypoperfused myocardium, indicating preserved metabolic activity. The presence of chronically ischemic myocardium that has preserved metabolic activity is referred to as "hibernating" myocardium. In this series, the ability of Tl-201, sestamibi, and teboroxime to establish the existence of viable myocardium was compared with that of F-18 FDG. Seventy-seven patients with ischemic cardiomyopathy were referred for determination of myocardial viability. FDG images were compared with representative resting blood-flow images obtained from either: 1) 24 hour Tl-201 reinjection-redistribution images, 2) resting sestamibi blood-flow images, or 3) early images from resting teboroxime washout analysis. Tl-201 was found to underestimate myocardial viability in 41% of patients, Tc-99m sestamibi underestimated viability in 38% of patients, and Tc-99m teboroxime underestimated viability in 26% of patients. There was no significant difference in the prediction of viable myocardium among the three radiopharmaceuticals, as all three underestimated myocardial viability.     

New directions in myocardial perfusion imaging

In recent years, substantial progress has been made in the field of nuclear cardiology. Pharmacologic stress perfusion imaging with intravenous administration of dipyridamole or adenosine provides comparable sensitivity and specificity values for detection of coronary artery disease (CAD) as exercise imaging and has been employed successfully for risk stratification prior to peripheral vascular or aortic surgery and after myocardial infarction. Detection of myocardial viability can be enhanced utilizing reinjection of a second dose of thallium-201 (Tl-201) at rest after acquisition of redistribution images with the single photon emission computerized tomography (SPECT) technique. Imaging solely in the resting state with Tl-201 can also provide information concerning presence of viable myocardium in asynergic regions that are stunned or hibernating. New technetium-99m (Tc-99m) perfusion agents have emerged in the clinical setting and have provided excellent predictive value for detection of CAD in patients with chest pain and permit simultaneous assessment of function and regional blood flow. Tc-99m Sestamibi, one of these agents, is also a valid marker of viability when assessing myocardial salvage after coronary reperfusion in acute myocardial infarction.     

Prospective identification of myocardial stunning using technetium-99m sestamibi-based measurements of infarct size

OBJECTIVES: We sought to prospectively identify patients with stunning and hyperkinesia at hospital discharge on the basis of mismatches between left ventricular (LV) function and infarct size as assessed by technetium-99m (Tc-99m) sestamibi perfusion tomographic imaging. BACKGROUND: Mechanical indexes of LV function may not accurately reflect myocardial damage after acute myocardial infarction (MI) because of myocardial stunning and compensatory hyperkinesia in noninfarct-related territories. Myocardial perfusion techniques are unaffected by these variables. METHODS: Eighty-four patients with acute MI underwent hospital admission and discharge Tc-99m-sestamibi tomographic imaging. Global LV ejection fraction (LVEF) was measured at hospital discharge and 6 weeks later. The perfusion defect size was quantified and expressed as a percentage of the LV. The discharge perfusion defect, which is a measure of infarct size, was used to predict the 6-week LVEF for each patient based on a previously reported regression equation. Patients were classified into one of three groups depending on whether their LVEF at hospital discharge fell within, above or below one standard error (6.8 LVEF points) of the predicted 6-week LVEF. RESULTS: There were 48 patients classified as having a "match" between function and infarct size; these patients demonstrated no significant change in LVEF at 6 weeks. There were 21 patients (25%) classified as "mismatch stunned" who had discharge LVEFs lower than those predicted by infarct size. These patients demonstrated a significant improvement in mean LVEF at 6 weeks (mean [+/-SD] discharge LVEF 0.41 +/- 0.08, 6-week LVEF 0.47 +/- 0.10; p = 0.003). Fifteen patients (18%) were classified as "mismatch-hyperkinetic." The mean LVEF for these patients significantly declined at 6 weeks (discharge LVEF 0.64 +/- 0.06, 6-week LVEF 0.58 +/- 0.09; p = 0.002). There was a marked increase in LVEF within the infarct zone (8 +/- 15 LVEF points; p = 0.03) for patients predicted to have stunning and a marked decline in LVEF outside the infarct zone (9 +/- 15 LVEF points; p = 0.06) in patients predicted to have hyperkinesia. Both discharge LVEF (p < 0.0001) and group classification (p = 0.005) were independent predictors of LVEF 6 weeks later. CONCLUSIONS: Perfusion imaging with Tc-99m-sestamibi can identify post-MI patients at hospital discharge in whom LV function is discordant with the measured infarct size. Patients with stunning have late increases in LVEF; patients with hyperkinesia have late decreases. This methodology, performed at discharge, is predictive of late changes in LV function.     

Incremental value of prognostic testing in patients with known or suspected ischemic heart disease: a basis for optimal utilization of exercise technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography

OBJECTIVES: This study assessed the incremental prognostic implications of normal and equivocal exercise technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) and sought to determine its incremental prognostic value, impact on patient management and cost implications. BACKGROUND: The prognostic implications of Tc-99m sestamibi SPECT are not well defined, and risk stratification using this test has not been explored. METHODS: We studied 1,702 patients referred for exercise Tc-99m sestamibi SPECT who were followed up for a mean (+/- SD) of 20 +/- 5 months. Patients with previous percutaneous transluminal coronary angioplasty or coronary artery bypass surgery were excluded. The SPECT studies were assessed using semiquantitative visual analysis. Cardiac death and myocardial infarction were considered "hard" events, and coronary angioplasty and bypass surgery > 60 days after testing were considered "soft" events. RESULTS: Of the 1,702 patients studied, 1,131 had normal or equivocal scan results. A total of 10 events occurred in this group (1 cardiac death and 1 myocardial infarction [0.2% hard events]; 4 coronary angioplasty and 4 bypass surgery procedures [0.7% soft events]). The rates of hard events and referral to catheterization after SPECT were similarly low in patients with a low (< 0.15), intermediate (0.15 to 0.85) and high (> 0.85) post-exercise treadmill test (ETT) likelihood of coronary artery disease. With respect to scan type, patients with normal, probably normal or equivocal scan results had similarly low hard event rates. In the 571 patients with abnormal scan results, there were 43 hard events (7.5%) and 42 soft events (7.4%) (p < 0.001 vs. 1,131 patients with normal scan results for both). When the complete spectrum of scan responses was considered, SPECT provided incremental prognostic value in all patient subgroups analyzed. However, the nuclear scan was cost-effective only in patients with interpretable exercise ECG responses and an intermediate to high post-ETT likelihood of coronary artery disease and in those with uninterpretable exercise ECG responses and an intermediate to high pre-ETT likelihood of coronary artery disease. CONCLUSIONS: Normal or equivocal exercise Tc-99m sestamibi study results are associated with a benign prognosis, even in patients with a high likelihood of coronary artery disease. Although incremental prognostic value is added by nuclear testing in all patient subgroups, a testing strategy incorporating nuclear testing proved to be cost-effective only in the groups with an intermediate to high likelihood of coronary artery disease before scanning.     

Value of acute rest sestamibi perfusion imaging for evaluation of patients admitted to the emergency department with chest pain

OBJECTIVES: This study sought to determine the ability of early perfusion imaging using technetium-99m sestamibi to predict adverse cardiac outcomes in patients who present to the emergency department with possible cardiac ischemia and nondiagnostic electrocardiograms (ECGs). BACKGROUND: Evaluation of patients presenting to the emergency department with possible acute coronary syndromes and nondiagnostic ECGs is problematic. Accurate risk stratification is necessary to prevent serious adverse outcomes. Initial results suggest that early perfusion imaging using technetium-99m sestamibi enables reliable risk stratification. METHODS: Patients presenting to the emergency department with a low to moderate probability of acute coronary syndromes underwent rapid sestamibi injection with gated single-photon emission computed tomographic imaging. Studies showing perfusion defects with associated wall motion abnormalities were considered positive. RESULTS: A total of 532 consecutive patients underwent serial myocardial marker analysis and rest perfusion imaging. Of these patients, perfusion imaging was positive in 171 (32%). Positive perfusion imaging was the only multivariate predictor of myocardial infarction (MI) (p < 0.0001, odds ratio [OR] 33, 95% confidence interval [CI] 7.7 to 141) and was the most important independent predictor of MI or revascularization (p < 0.0001, OR 14, 95% CI 7.3 to 25), followed by diabetes (p < 0.01, OR 2.8, 95% CI 1.5 to 5.1), typical angina (p = 0.01, OR 2.1, 95% CI 1.2 to 3.7) and male gender (p = 0.03, OR 1.9, 95% CI 1.1 to 3.5). The sensitivity of positive perfusion imaging for MI was 93% (95% CI 77% to 98%), and for MI or revascularization it was 81% (95% CI 71% to 88%), with negative predictive values of 99% (95% CI 98% to 100%) and 95% (95% CI 92% to 97%), respectively. CONCLUSIONS: Positive rest perfusion imaging accurately identified patients at high risk for adverse cardiac outcomes, whereas negative perfusion imaging identified a low risk patient group. Early perfusion imaging allows for rapid and accurate risk stratification of emergency department patients with possible cardiac ischemia and nondiagnostic ECGs.     

Immediate angioplasty compared with the administration of a thrombolytic agent followed by conservative treatment for myocardial infarction. The Mayo Coronary Care Unit and Catheterization Laboratory Groups

BACKGROUND: Immediate angioplasty and the administration of a thrombolytic agent followed by conservative treatment are two approaches to the management of acute myocardial infarction, but these methods have not been compared prospectively. METHODS: We enrolled 108 patients with acute myocardial infarction in a randomized trial designed to test the hypothesis that immediate angioplasty (without previous thrombolytic therapy) may result in greater myocardial salvage than the administration of a thrombolytic agent followed by conservative treatment. The primary end point was the change in the size of the perfusion defect as assessed at admission and discharge by tomographic imaging with technetium-99m sestamibi, a myocardial perfusion agent that can measure myocardium at risk and final infarct size. RESULTS: End-point data were available for 56 patients randomly assigned to receive tissue plasminogen activator (mean [+/- SD] time to start of infusion, 232 +/- 174 minutes after the onset of chest pain) and 47 patients randomly assigned to receive angioplasty (first balloon inflation at 277 +/- 144 minutes). In the case of anterior infarction, myocardial salvage as assessed by imaging with technetium-99m sestamibi was 27 +/- 21 percent of the left ventricle for 22 patients in the thrombolysis group, as compared with 31 +/- 21 percent for 15 patients in the angioplasty group. For infarcts in all other locations, myocardial salvage was 7 +/- 13 percent for 34 patients in the thrombolysis group and 5 +/- 10 percent for 32 patients in the angioplasty group. After adjustment for infarct location, the difference in mean salvage between groups was 0 (P = 0.98), with a 95 percent confidence interval of +/- 6 percent of the left ventricle. CONCLUSIONS: In patients with acute myocardial infarction, immediate angioplasty does not appear to result in greater myocardial salvage than the administration of a thrombolytic agent followed by conservative treatment, although a small difference between these two therapeutic approaches cannot be excluded.     

Fast acquisition of myocardial SPECT images with Tc-99m sestamibi for the diagnosis of coronary artery disease

BACKGROUND: Shortening the acquisition time for myocardial single-photon emission computed tomographic (SPECT) imaging increases patient comfort and laboratory throughput. The purpose of this study was to compare the diagnostic accuracy for coronary artery disease detection of myocardial SPECT images acquired in 5 to 10 minutes versus 25 minutes using Tc-99m methoxyisobutylisonitrile (Tc-99m sestamibi) and a single-head gamma camera. METHODS AND RESULTS: Forty-one subjects had a standard 1-day rest/stress Tc-99m sestamibi myocardial SPECT study. Two sets of rest and stress images were acquired on the same day for each subject. One set of images was acquired with a 5- to 10-minute fast acquisition protocol; the second set of images was acquired with a 25-minute standard protocol. The accuracies of the fast and standard protocols for identifying individuals with and without coronary artery disease were equivalent. Accuracy was 76% for the fast protocol and 73% for the standard protocol in individuals with at least one coronary stenosis > or = 70%. The accuracies of the two protocols for identifying individual coronary arteries with stenoses > or = 70% also were equivalent. Accuracy was 77% for the fast protocol and 74% for the standard protocol. CONCLUSIONS: SPECT myocardial images may be acquired in as little as 5 to 10 minutes using Tc-99m sestamibi and a 1-day rest/stress protocol. Accuracy is equivalent to that attained in studies with longer imaging times.     

Radiosurgical activities

In order to quantitatively assess the extent and severity of myocardial ischemia by Tc-99m sestamibi exercise myocardial scintigraphy, we developed a new method of change rate (CR) mapping and examined its efficiency. CR was calculated to divide the counts per pixel in the stress polar map by that in the rest polar map at each corresponding pixel. The CR map showed the CR values at each pixel. To correct the differences between the stress and rest images for the dose of Tc-99m sestamibi administered, the mean counts per pixel in the stress polar map and the rest map were adjusted to the same level. Regarding the regions in which the CR value was less than 1 as ischemia, we compared the abilities of the CR map and the polar map to detect coronary artery stenosis in 5 patients with angina pectoris. The sensitivity for coronary artery stenosis was 80% in the CR map, and 40% in the polar map. The specificity for both was 75%. We concluded that the CR map was effective in assessing the extent and severity of myocardial ischemia in Tc-99m sestamibi exercise myocardial scintigraphy.     

Lipopolysaccharide-neutralizing antibody reduces hepatocyte injury from acute hepatotoxin administration

OBJECTIVES: This study investigated the role of nitrate technetium-99m sestamibi imaging in predicting the postrevascularization outcome of chronically hypoperfused asynergic territories. BACKGROUND: Rest technetium-99m sestamibi myocardial scintigraphy underestimates the presence of viable myocardium in asynergic territories. Stimulation that improves coronary blood flow could increase tracer uptake in hibernating territories. METHODS: Nineteen patients with a previous myocardial infarction and left ventricular dysfunction scheduled for revascularization underwent quantitative technetium-99m sestamibi tomography under baseline conditions and during isosorbide dinitrate infusion. Global and regional function were assessed, respectively, before and after revascularization by radionuclide angiocardiography and two-dimensional echocardiography. RESULTS: Seven patients (group A) showed postrevascularization regional function recovery, and 12 (group B) showed no significant changes. In group A, nitrate infusion induced a decrease in the extent of the global uptake defect ([mean +/- SD] -37.4 +/- 21.6% of baseline value); in group B, no change or a slight increase was observed (+5.8 +/- 8.4%, p < 0.0005 vs. group A). The nitrate-induced changes in the extent of uptake defect correlated with postrevascularization changes in ejection fraction (r = -0.94, SEE 7.6). After revascularization, 11 asynergic vascular territories showed improvement (hibernating), and 34 remained unchanged (fibrotic). With administration of nitrates, 10 hibernating territories had a decrease in the extent of uptake defect, whereas only 4 of 34 of the fibrotic territories showed a nitrate-induced uptake improvement. CONCLUSIONS: Short-term administration of isosorbide dinitrate immediately before injection of technetium-99m sestamibi increases tracer uptake in some chronically hypoperfused asynergic territories. This finding correlates with the observation of post-revascularization functional recovery. Nitrate technetium-99m sestamibi myocardial scintigraphy could be a promising method for the noninvasive detection of viable hibernating myocardium.     

Power Doppler imaging findings in multilocular giant parathyroid adenoma which caused hypercalcaemic crisis

Radiological findings including ultrasonography, computed tomography (CT) and Tc-99m sestamibi scintigraphy of a patient with multilocular giant parathyroid adenoma which caused hypercalcaemic crisis are presented. The location of the tumour by grey scale sonography, CT and Tc-99m sestamibi scintigraphy was not certain because the tumour was uncommon in shape, location, size and internal structure. Whereas, increased flow in the solid portion of the mass was demonstrated on power Doppler sonography, which proved to reflect abundant vessels in the adenoma in pathological findings.     

From eradication to resistance: five continuing concerns about pediculosis

Myocardial scintigraphy was performed three times in a 55-year-old woman with left bundle branch block (LBBB). A significant LAD stenosis had been excluded by coronary angiography. The first scintigraphy was performed with Tc-99m sestamibi after submaximal bicycle exercise and revealed a septal perfusion deficit. This deficit could not be reproduced in the following examinations after pharmacological stress testing with dipyridamole using both Tl-201 and Tc-99m sestamibi. Perfusion at rest assessed with Tl-201 was normal in all studies. It is concluded that pharmacological stress testing with dipyridamole is to be preferred in patients with LBBB. With respect to the accuracy of myocardial perfusion imaging the choice of the radiopharmaceutical plays a less important role.     

Technetium-99m sestamibi tomographic evaluation of residual ischemia after anterior myocardial infarction

OBJECTIVES: This study investigated the value of sestamibi scintigraphy in assessing residual ischemia after anterior myocardial infarction. BACKGROUND: Serial imaging with sestamibi, the uptake and retention of which correlate with regional myocardial blood flow and viability, has been used to estimate salvaged myocardium and risk area after acute infarction. We recently documented that recovery of perfusion and contraction in the infarcted area may continue well after the subacute phase, suggesting myocardial hibernation. Some underestimation of viability in the setting of hibernating myocardium by sestamibi imaging has been reported. METHODS: We studied 58 patients in stable condition after Q wave anterior infarction. Regional perfusion and function were quantitatively assessed by sestamibi tomography and two-dimensional echocardiography at 4 to 6 weeks and at 7 months after infarction. In sestamibi polar maps, abnormal areas with tracer uptake > 2.5 SD below our reference values were computed at rest and after symptom-limited exercise. On two-dimensional echocardiography the ejection fraction and extent of rest wall motion abnormalities were assessed by a computerized system. All patients had coronary angiography between the two studies. RESULTS: At 7 months the extent of rest sestamibi defect was significantly reduced in 40 patients (69%, group 1) and unchanged in 18 (31%, group 2). Rest wall motion abnormalities and ventricular ejection fraction significantly improved in group 1 but not in group 2. Underlying coronary disease, patency of the infarct-related vessel and rest sestamibi defect extent at 5 weeks were comparable between the two groups. At 7 months, an increase in the reversible (stress-rest defect) tracer defect was observed in group 1 (p < 0.05) despite a smaller stress-induced hypoperfusion (p < 0.05). Reversible sestamibi defects and stress hypoperfusion were unchanged in group 2. In 38 (95%) of 40 group 1 patients, the area showing reversible sestamibi defects at 7 months matched the area showing fixed hypoperfusion at 5 weeks. CONCLUSIONS: The reduction in the rest tracer uptake defect that can occur late after infarction may affect the assessment of ischemic burden by sestamibi imaging early after anterior myocardial infarction.     

Angiographic evidence of hemorrhagic myocardial infarction after intracoronary thrombolysis with streptokinase

The reperfusion of acutely ischemic myocardium by intracoronary streptokinase thrombolysis is an exciting new therapy for acute myocardial infarction (MI). It appears that successful thrombolysis and reperfusion in the first few hours after acute coronary occlusion may salvage myocardium and possibly improve prognosis. A potential adverse effect of reperfusion is the production of hemorrhage in the area of myocardial necrosis. We report on a patient with prompt, successful coronary thrombolysis by streptokinase infusion who showed angiographic evidence of a hemorrhagic MI.     

Long-term prognosis of young patients after myocardial infarction in the thrombolytic era

BACKGROUND: Myocardial infarction (MI) in young adults is a rare event. In the Framingham study, the 10-year incidence rate of MI per 1,000 was 12.9 in men 30-34 years old. Overall, 4-8% of patients with acute MI are < or = 40 years old. HYPOTHESIS: It was the purpose of this study to assess the in-hospital and long-term morbidity and mortality in patients < or = 40 years old with acute myocardial infarction compared with older patients in the thrombolytic era. METHODS: A consecutive series of 75 patients aged < or = 40 years (mean 35.0 +/- 4.8) with acute myocardial infarction was compared with an equally sized group of patients aged > 40 years (mean 65.1 +/- 9.8). RESULTS: Thrombolysis or direct percutaneous transluminal coronary angioplasty was performed in 52 versus 24% (p = 0.0004) and 5.3 versus 2.7% (p = NS) in younger and older patients, respectively. Significantly fewer young patients had multivessel disease (28 vs. 64%, p < 0.004). No in-hospital mortality was observed in patients with reperfusion therapy irrespective of age. After a mean followup time of 47 +/- 35 months, cardiac mortality was 0 and 11% (p < 0.03), respectively, in young and older patients with, and 3 versus 24% (p < 0.02) without reperfusion therapy, respectively. In addition, significantly fewer patients in the younger age group developed recurrent angina pectoris (12 vs. 39%, p = 0.0004) or congestive heart failure (9 vs. 34%, p = 0.0005) irrespective of reperfusion therapy. CONCLUSION: Our observations demonstrate that long-term prognosis after myocardial infarction in young patients is excellent in the thrombolytic era.     

Improved cardiac iodine-123 metaiodobenzylguanidine accumulation after drug therapy in a patient with Parkinson's disease

A 72-year-old woman with Parkinson's disease and autonomic dysfunction underwent I-123 MIBG cardiac imaging to study sympathetic neuronal integrity. This revealed a defect in the infero-posterior wall. Tc-99m sestamibi myocardial perfusion imaging revealed no abnormalities. On follow-up I-123 MIBG SPECT, the defect was less prominent and the parkinsonian symptoms were ameliorated by drug therapy. Cardiac I-123 MIBG imaging may be a promising new method for evaluating drug therapy in patients with Parkinson's disease.     

Hypertension and retinopathy, arteriolar narrowing, and arteriovenous nicking in a population

OBJECTIVES: The purpose of this study was to determine the relative value of single-photon emission computed tomographic (SPECT) imaging at rest using technetium-99m methoxyisobutyl isonitrile (technetium-99m sestamibi) with positron emission tomography for detection of viable myocardium. BACKGROUND: Recent studies comparing positron emission tomography and thallium-201 reinjection with rest technetium-99m sestamibi imaging have suggested that the latter technique underestimates myocardial viability. METHODS: Twenty patients with a previous myocardial infarction underwent rest technetium-99m sestamibi imaging and positron emission tomography using fluorine (F)-18 deoxyglucose and nitrogen (N)-13 ammonia. In each patient, circumferential profile analysis was used to determine technetium-99m sestamibi, F-18 deoxyglucose and N-13 ammonia activity (expressed as percent of peak activity) in nine cardiac segments and in the perfusion defect defined by the area having technetium-99m sestamibi activity < 60%. Technetium-99m sestamibi defects were graded as moderate (50% to 59% of peak activity) and severe (< 50% of peak activity). Estimates of perfusion defect size were compared between technetium-99m sestamibi and N-13 ammonia. RESULTS: Sixteen (53%) of 30 segments with moderate defects and 16 (47%) of 34 segments with severe defects had > or = 60% F-18 deoxyglucose activity considered indicative of viability. Fluorine-18 deoxyglucose evidence of viability was still present in 50% of segments with technetium-99m sestamibi activity < 40%. There was no significant difference in the mean (+/- SD) technetium-99m sestamibi activity in segments with viable (40 +/- 7%) and nonviable segments (49 +/- 7%, p = 0.84). Of the 18 patients who had adequate F-18 deoxyglucose studies, the area of the technetium-99m sestamibi defect was viable in 5 (28%). In 16 patients (80%), perfusion defect size determined by technetium-99m sestamibi exceeded that measured by N-13 ammonia. The difference in defect size between technetium-99m sestamibi and N-13 ammonia was significantly greater in patients with viable (21 +/- 9%) versus nonviable segments (7 +/- 9%, p = 0.007). CONCLUSIONS: Moderate and severe rest technetium-99m sestamibi defects frequently have metabolic evidence of viability. Technetium-99m sestamibi SPECT yields larger perfusion defects than does N-13 ammonia positron emission tomography when the same threshold values are used.