Failure to improve left ventricular function after coronary revascularization for ischemic cardiomyopathy is not associated with worse outcome.

Background-Preoperative identification of viable myocardium in patients with ischemic cardiomyopathy is considered important because CABG can result in recovery of left ventricular (LV) function. However, the hypothesis that lack of improvement of LV function after CABG is associated with poorer patient outcome is untested. Methods and Results-Outcome was compared in patients with ischemic LV dysfunction (LVEF 0.05 increase in LVEF (group A) and 36 (35%) had no significant change, or

Factors affecting uniformity in interpretation of planar thallium-201 imaging in a multicenter trial. The Multicenter Study on Silent Myocardial Ischemia (MSSMI) Thallium-201 Investigators.

OBJECTIVES: This study was designed to assess factors affecting interobserver agreement in interpretation of planar thallium-201 stress imaging in the Multicenter Study on Silent Myocardial Ischemia (MSSMI). BACKGROUND: Five hundred fifty-six planar thallium-201 images were interpreted in 24 clinical centers and in a Radionuclide Core Laboratory. The trial's Coordinating and Data Center observed that the participating clinical centers interpreted a significantly greater number of thallium-201 stress studies as abnormal (i.e., myocardial ischemia or scar) than the Core Laboratory, and overall agreement was poor (kappa 0.27). METHODS: Agreement in image interpretation between clinical centers and the Radionuclide Core Laboratory was analyzed by kappa statistics. The reproducibility of the Core Laboratory results on 41 randomly selected test studies was excellent (kappa 0.77). In contrast, the reproducibility of interpretation in the clinical centers on their own studies was at best fair (kappa 0.45). It was hypothesized that the poor agreement and reproducibility in the clinical centers were caused by lack of standardization of image display and lack of objective criteria for image interpretation. To test the effect of standardization, 13 clinical investigators interpreted the same 41 test studies using 1) uniform image display, and 2) uniform quantification of images. RESULTS: The agreement in interpretation between clinical investigators and the Radionuclide Core Laboratory improved modestly with uniformity of image display (kappa 0.57) but improved markedly (kappa 0.66) with quantitative circumferential profile analysis. CONCLUSIONS: Lack of standardization in image display and lack of objective criteria for interpretation of thallium-201 images are responsible for suboptimal reproducibility and poor interlaboratory agreement in the interpretation of thallium-201 stress imaging. The adoption of a uniformly accepted method for computer quantification of myocardial perfusion images is crucial to improve agreement in interpretation.

Relevance of increased lung thallium uptake on stress imaging in patients with unstable angina and non-Q wave myocardial infarction: results of the Thrombolysis in Myocardial Infarction (TIMI)-IIIB Study.

OBJECTIVES: This study sought to determine the significance of abnormal thallium-201 (Tl-201) lung uptake on stress imaging in the absence of perfusion abnormalities. BACKGROUND: Abnormal Tl-201 lung uptake, represented by an increased lung/heart ratio (LHR), on stress imaging is a marker of stress-induced left ventricular dysfunction and poor prognosis in patients with coronary artery disease. METHODS: We evaluate 1,271 patients from the Thrombolysis in Myocardial Infarction (TIMI)-IIIB trial (86% of TIMI-IIIB cohort) with unstable angina or non-Q wave myocardial infarction, who underwent predischarge exercise (92%) or dipyridamole stress (8%) Tl-201 imaging. An increased LHR (> or = 0.50) was related to perfusion abnormalities and adverse cardiac events at 1 year. RESULTS: Of 1,271 patients, there were 762 (60%) with and 509 (40%) without perfusion abnormalities. An increased LHR was seen in 227 patients (18%) (173 [23%] with, 54 [11%] without perfusion abnormalities). Patients with an increased LHR had a lower left ventricular ejection fraction, higher body weight, lower exercise capacity and a higher prevalence of angina on exercise than patients with a normal LHR. In the two groups with increased LHR, there was no difference in age, hypertension, previous myocardial infarction, total exercise time, frequency of angina and ST segment depression on exercise. However, the group with an increased LHR and normal myocardial perfusion had a preponderance of women (65% vs. 30%, p < 0.001). At 1-year follow-up, patients with an increased LHR had a higher cardiac event rate than those with a normal LHR (18% vs. 10%, respectively, p = 0.001) despite a higher revascularization rate (28% vs. 15%, p < 0.001). An increased LHR was associated with increased adverse cardiac events, irrespective of the presence or absence of perfusion abnormalities. CONCLUSIONS: An increased LHR continues to be associated with higher adverse cardiac events in the current era of aggressive interventional management of coronary artery disease. An increased LHR in the absence of myocardial perfusion abnormality is seen mostly in women and overweight patients. However, despite the apparent absence of perfusion abnormalities, an increased LHR in this group is also associated with a higher rate of adverse cardiac events.

Silent left ventricular dysfunction during routine activity after thrombolytic therapy for acute myocardial infarction.

To investigate prospectively the occurrence and significance of postinfarction transient left ventricular dysfunction, 33 ambulatory patients who underwent thrombolytic therapy after myocardial infarction were monitored continuously for 187 +/- 56 min during normal activity with a radionuclide left ventricular function detector at the time of hospital discharge. Twelve patients demonstrated 19 episodes of transient left ventricular dysfunction (greater than 0.05 decrease in ejection fraction, lasting greater than or equal to 1 min), with no change in heart rate. Only two episodes in one patient were associated with chest pain and electrocardiographic changes. The baseline ejection fraction was 0.52 +/- 0.12 in patients with transient left ventricular dysfunction and 0.51 +/- 0.13 in patients without dysfunction (p = NS). At follow-up study (19.2 +/- 5.4 months), cardiac events (unstable angina, myocardial infarction or death) occurred in 8 of 12 patients with but in only 3 of 21 patients without transient left ventricular dysfunction (p less than 0.01). During submaximal supine bicycle exercise, only two patients demonstrated a decrease in ejection fraction greater than or equal to 0.05 at peak exercise; neither had a subsequent cardiac event. These data suggest that transient episodes of silent left ventricular dysfunction at hospital discharge in patients treated with thrombolysis after myocardial infarction are common and associated with a poor outcome. Continuous left ventricular function monitoring during normal activity may provide prognostic information not available from submaximal exercise test results.

Prognostic significance of normal quantitative planar thallium-201 stress scintigraphy in patients with chest pain.

The prognostic significance of normal quantitative planar thallium-201 stress scintigraphy was evaluated in patients with a chest pain syndrome. The prevalence of cardiac events during follow-up was related to the pretest (that is, before stress scintigraphy) likelihood of coronary artery disease determined on the basis of symptoms, age, sex and stress electrocardiography. In a consecutive series of 344 patients who had adequate thallium-201 stress scintigrams, 95 had unequivocally normal studies by quantitative analysis. The pretest likelihood of coronary artery disease in the 95 patients had a bimodal distribution. During a mean follow-up period of 22 +/- 3 months, no patient died. Three patients (3%) had a cardiac event: two of these patients (pretest likelihood of coronary artery disease 54 and 94%) had a nonfatal myocardial infarction 8 and 22 months, respectively, after stress scintigraphy, and one patient (pretest likelihood 98%) underwent percutaneous transluminal coronary angioplasty 16 months after stress scintigraphy for persisting anginal complaints. Three patients were lost to follow-up; all three had a low pretest likelihood of coronary artery disease. It is concluded that patients with chest pain and normal findings on quantitative thallium-201 scintigraphy have an excellent prognosis. Cardiac events are rare (infarction rate 1% per year) and occur in patients with a moderate to high pretest likelihood of coronary artery disease.

Thallium-201 for assessment of myocardial viability: quantitative comparison of 24-hour redistribution imaging with imaging after reinjection at rest.

Redistribution thallium-201 imaging 2 to 4 h after exercise may be incomplete and therefore may be inadequate to fully assess myocardial variability. Late redistribution imaging 24 h after exercise has been proposed to overcome this limitation of thallium stress imaging. However, because of poor count density the image quality on these studies is often suboptimal. In the present study the diagnostic information on 24-h planar thallium redistribution images was compared with that on images obtained after a reinjection of thallium at rest. Eighty-four patients with a stress thallium-201 defect had delayed redistribution imaging after 2 to 4 h and 24 h later, and again after an injection of thallium at rest. Defect reversibility on 24-h redistribution images was compared quantitatively with that on images after injection of thallium at rest. The quality of thallium images at rest was consistently better than that of 24-h redistribution images. Poor quality studies occurred in 13% of 24-h redistribution images compared with 0.4% of the studies at rest. Significantly more defect reversibility was detected on images after the reinjection at rest. Of 41 patients who appeared to have a fixed defect at 2- to 4-h redistribution imaging, 11 (27%) had a reversible defect by 24-h redistribution imaging compared with 29 (71%) after thallium-201 reinjection. No clinical variables at the time of stress testing were predictive of late defect reversibility. It is concluded that in patients with fixed a thallium defect at 2 to 4 h after exercise, reimaging after a reinjection at rest provides better diagnostic information than does 24-h late redistribution imaging.

Peak filling rate normalized to mitral stroke volume: a new Doppler echocardiographic filling index validated by radionuclide angiographic techniques.

The noninvasive measurement of left ventricular filling has relied predominantly on radionuclide-derived peak filling rate normalized to end-diastolic volume. Doppler echocardiography also has the ability to measure peak filling rate, but wide application of this technique has been limited by technical errors involved in quantitative echocardiographic determination of mitral anulus cross-sectional area and ventricular volumes. For Doppler echocardiography, normalization of peak filling rate to mitral stroke volume rather than end-diastolic volume permits the derivation of a diastolic filling index that is relatively free of errors caused by geometric assumptions, diameter measurements and sample volume positioning. This normalization process can be achieved by simply dividing early peak filling velocity by the time velocity integral of mitral inflow. To validate this new Doppler echocardiographic filling index, Doppler echocardiographic and radionuclide-derived peak filling rate, both normalized to mitral stroke volume, were compared in 30 patients; there was an excellent correlation (r = 0.91, SEE = 0.88). This variable was not influenced by the position of the sample volume in relation to the mitral apparatus in contrast to early filling velocity, which increased 37%, and early/late filling (E/A) ratio, which increased 43% as the sample volume was moved from the anulus to the tips of the mitral leaflets. In a cohort of 22 normal patients, the mean peak filling rate normalized to mitral stroke volume (SV) was 5.25 +/- 1.47 SV/s. The mean peak filling rate for a subgroup of eight normal patients aged 57 to 89 years (mean 71 +/- 9) was 3.9 +/- 1 SV/s.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of mental stress on left ventricular and peripheral vascular performance in patients with coronary artery disease.

OBJECTIVES: We sought to investigate the mechanism of a mental stress-induced fall in left ventricular ejection fraction (LVEF) in patients with coronary artery disease. BACKGROUND: Mental stress induces a fall in LVEF in a significant proportion of patients with coronary artery disease. This is accompanied by an increase in heart rate, blood pressure and rate-pressure product. Whether the mental stress-induced fall in LVEF is due to myocardial ischemia, altered loading conditions or a combination of both is not clear. METHODS: Left ventricular (LV) function was studied noninvasively by serial equilibrium radionuclide angiocardiography and simultaneous measurement of peak power, a relatively afterload-independent index of LV contractility, in 21 patients with coronary artery disease (17 men, 4 women) and 9 normal subjects (6 men, 3 women) at baseline, during mental stress and during exercise. Peripheral vascular resistance (PVR), cardiac output (CO), arterial and end-systolic ventricular elastance (Ea, Ees,) and ventriculoarterial coupling (V/AC) were also calculated. Patients underwent two types of mental stress-mental arithmetic and anger recall-as well as symptom-limited semisupine bicycle exercise. RESULTS: Nine patients (43%) had an absolute fall in LVEF of > or = 5% (Group I) in response to at least one of the mental stressors, whereas the remaining patients did not (Group II). Group I and Group II patients were similar in terms of baseline characteristics. Both groups showed a significant but comparable increase in systolic blood pressure (15+/-7 vs. 9+/-10 mm Hg, p=0.12) and a slight increase in heart rate (7+/-4 vs. 8+/-7 beats/min, p=0.6) and a comparable increase in rate-pressure product (2.2+/-0.9 vs. 1.9+/-1.2 beats/min x mm Hg, p=0.6) with mental stress. However, PVR increased in Group I and decreased in Group II (252+/-205 vs. -42+/-230 dynes x s x cm(-5), p=0.006), and CO decreased in Group I and increased in Group II (-0.2+/-0.4 vs. 0.6+/-0.7 liters/min, p=0.02) with mental stress. There was no difference in the change in peak power (p=0.4) with mental stress. With exercise, an increase in systolic blood pressure, heart rate, rate-pressure product and CO and a fall in PVR were similar in both groups. Of the two mental stressors, anger recall resulted in a greater fall in LVEF and a greater increase in diastolic blood pressure. Exercise resulted in a fall in LVEF in 7 patients (33%). However, exercise-induced changes in LVEF and hemodynamic variables were not predictive of mental stress-induced changes in LVEF and hemodynamic variables. Conclusions. Abnormal PVR and Ea responses to mental stress and exercise are observed in patients with a mental stress-induced fall in LVEF. Peripheral vasoconstrictive responses to mental stress contribute significantly toward a mental stress-induced fall in LVEF.

Value of radionuclide rest and exercise left ventricular ejection fraction in assessing survival of patients after thrombolytic therapy for acute myocardial infarction: results of Thrombolysis in Myocardial Infarction (TIMI) phase II study. The TIMI Study Group.

OBJECTIVES: This study sought to determine the prognostic value of rest and exercise left ventricular ejection fraction in patients receiving thrombolytic therapy as part of the Thrombolysis in Myocardial Infarction (TIMI) trial. BACKGROUND: In the prethrombolytic era, ejection fraction at rest as well as during exercise was an important prognostic index in patients recovering from acute myocardial infarction. The prognostic value of these measurements in the thrombolytic era is not clear. METHODS: As part of the TIMI II protocol, we obtained radionuclide left ventricular ejection fraction at rest and during symptom-limited submaximal supine exercise. Measurements were related to 1-year all-cause as well as cardiac mortality. In addition, the relation between ejection fraction obtained at rest and 1-year cardiac mortality in this study was compared with the relation established previously in the prethrombolytic era by the Multicenter Postinfarction Research Group. RESULTS: A distinct relation was noted between left ventricular ejection fraction at rest and all-cause mortality. The highest mortality rate (9.9%) was noted in patients with an ejection fraction < 30%. Those not undergoing a study had a 1-year mortality rate of 6.2%. Peak exercise ejection fraction provided prognostic information similar to that of rest ejection fraction. Likewise, change in ejection fraction from rest to exercise did not appreciably improve prognostic impact. CONCLUSIONS: Rest left ventricular ejection fraction is an important prognostic index in patients receiving thrombolytic therapy. Peak exercise ejection fraction and the change in ejection fraction from rest to exercise do not provide appreciable prognostic data beyond those obtained at rest. Patients unable to exercise or those not having a rest study have a poor prognosis. When compared with the Multicenter Postinfarction Research Group data, there was strong evidence of a difference in survival in the two studies. At any level of ejection fraction, mortality was lower in TIMI II patients than in patients in the prethrombolytic era.

Electrophysiologic effects of thrombolytic therapy in patients with a transmural anterior myocardial infarction complicated by left ventricular aneurysm formation.

To assess the effects of early thrombolytic therapy on the incidence of clinical and induced ventricular arrhythmias in high risk postmyocardial infarction patients, 32 patients with a transmural anterior myocardial infarction complicated by left ventricular aneurysm formation were prospectively evaluated. Sixteen patients (Group A) received routine care because of contraindication to thrombolytic therapy or other factors and 16 (Group B) received either tissue plasminogen activator or streptokinase within 6 h of the onset of chest pain. The two groups were similar in left ventricular ejection fraction (mean +/- SD, 28 +/- 9% [Group A] versus 30 +/- 8% [Group B]) and occurrence of spontaneous nonsustained ventricular tachycardia, new bundle branch block and congestive heart failure. Group B patients had higher peak creatine kinase MB levels (446 +/- 336 versus 205 +/- 120 IU; p = 0.017) and earlier time to peak creatine kinase values (13.4 +/- 6.6 versus 19.1 +/- 6.1 h; p = 0.006). Twenty patients who had no clinical sustained ventricular arrhythmias underwent electrophysiologic study 13 +/- 6 days after infarction. Ventricular tachycardia was induced during the study in 7 (88%) of 8 Group A patients, but in only 1 (8%) of 12 Group B patients given thrombolytic therapy (p = 0.0008). During a mean follow-up period of 11 +/- 8 months, eight Group A patients (50%) died suddenly or were resuscitated from sustained ventricular tachycardia; all Group B patients are alive and have had no clinical arrhythmic events (p = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Serial quantitative planar technetium-99m isonitrile imaging in acute myocardial infarction: efficacy for noninvasive assessment of thrombolytic therapy.

Technetium-99m isonitrile is a new myocardial perfusion imaging agent that accumulates according to the distribution of myocardial blood flow. However, unlike thallium-201, it does not redistribute over time. This imaging agent was used with serial quantitative planar imaging to assess the initial risk area of infarction, its change over time and the relation to infarct-related artery patency in 30 patients with a first acute myocardial infarction. Twenty-three of 30 patients were treated with recombinant tissue-type plasminogen activator (rt-PA) within 4 h after the onset of chest pain. Seven patients were treated in the conventional manner without thrombolytic therapy. Technetium-99m isonitrile was injected before or at the initiation of thrombolytic therapy, and imaging was performed several hours later. These initial images demonstrated the area at risk. Repeat imaging was performed 18 to 48 h later and at 6 to 14 days after the onset of myocardial infarction to visualize the ultimate extent of infarction. The initial area at risk varied greatly (range defect integral 2 to 61) both in patients treated with rt-PA and in those who received conventional treatment. For the total group, the initial imaging defect decreased in size in 20 patients and was unchanged or larger in 10 patients. Patients with a patent infarct-related artery had a significantly greater decrease in defect size than did patients with persistent coronary occlusion (-51 +/- 38% versus -1 +/- 26%, p = 0.0001). All patients with a decrease in defect size greater than 30% had a patent infarct-related artery. In 12 patients who also had predischarge quantitative exercise thallium-201 imaging, good agreement existed between the extent and severity of myocardial perfusion defect on the last technetium-99m isonitrile study before discharge and that noted on delayed thallium-201 imaging. It is concluded that serial planar technetium-99m isonitrile myocardial imaging in patients with acute myocardial infarction undergoing thrombolytic therapy offers a new quantitative noninvasive approach for assessment of the initial risk zone as well as the success of reperfusion.

Quantitative radionuclide assessment of regional ventricular function after thrombolytic therapy for acute myocardial infarction: results of phase I Thrombolysis in Myocardial Infarction (TIMI) trial.

In Thrombolysis in Myocardial Infarction (TIMI) Phase I,290 patients with acute myocardial infarction were randomized to either intravenous recombinant tissue-type plasminogen activator (rt-PA) or intravenous streptokinase. Two hundred twenty-nine patients had radionuclide ventriculograms at discharge for assessment of global and regional left ventricular ejection fraction. Among these 229 patients 185 had totally occluded infarct-related arteries, and angiographic reperfusion of the infarct-related artery occurred in 69% of patients treated with rt-PA and 28% of patients treated with streptokinase (p less than 0.001). Mean global left ventricular ejection fraction was not different for rt-PA-treated patients compared with streptokinase-treated patients (0.46 versus 0.45). However, the average regional ejection fraction of the regions subtended by the infarct-related artery showed a trend toward better average infarct region ejection fraction in patients treated with rt-PA than in patients treated with streptokinase (0.40 versus 0.36; 0.05 less than p less than 0.06). Analysis of data according to perfusion status of the infarct-related artery showed no difference in mean global left ventricular ejection fraction between patients with sustained versus nonsustained reperfusion (0.47 versus 0.44). However, there was better average regional ejection fraction of the region subtended by the infarct-related artery in patients with sustained reperfusion (0.40 versus 0.36; p less than 0.01). Thus, quantitation of regional left ventricular function by radionuclide techniques provides a noninvasive means for evaluating the effects of thrombolysis. This study suggests a direct relation between improvement of regional left ventricular function and the greater infarct-related artery patency rate achieved by rt-PA compared with streptokinase.

Short-term effects of early intravenous treatment with a beta-adrenergic blocking agent or a specific bradycardiac agent in patients with acute myocardial infarction receiving thrombolytic therapy.

OBJECTIVES: This study was conducted to explore mechanisms that could explain the possible clinical benefit of early administration of a beta 1-selective adrenoreceptor blocking agent or a bradycardiac drug as adjunct to thrombolysis in acute myocardial infarction. BACKGROUND: The effects of beta-blockers given concomitantly with thrombolytic therapy in patients with acute myocardial infarction have not been fully examined. The potential role of specific bradycardiac agents lacking negative inotropism as an alternative to beta-blockers in this setting has never been studied in humans. METHODS: In a double-blind study, we examined the effects of early intravenous and continued oral administration of a beta-blocker (atenolol), a specific bradycardiac agent (alinidine) or placebo on left ventricular function, late coronary artery patency, infarct size, exercise capacity and incidence of arrhythmias. RESULTS: A total of 292 patients with acute myocardial infarction of < or = 5 h duration and without contraindications to thrombolytic or beta-blocker therapy were studied. Of these, 100 were allocated to treatment with atenolol (5 to 10 mg intravenously followed by 25 to 50 mg orally every 12 h), 98 to alinidine (20 to 40 mg intravenously followed by 20 to 40 mg orally every 8 h) and 94 to placebo. All patients received 100 mg of alteplase over 3 h and full intravenous heparinization. No significant differences in coronary artery patency, global ejection fraction or regional wall motion were observed at 10 to 14 days among the three groups. Likewise, enzymatic and scintigraphic infarct size were also very similar. Neither atenolol nor alinidine was associated with a significant reduction in the incidence of arrhythmias during the 1st 24 h. No significant differences in clinical events were observed, with the exception of a greater incidence of nonfatal pulmonary edema in the atenolol group (6% vs. 1% in the alinidine group and 0% in the placebo group, p = 0.021). CONCLUSIONS: In the absence of contraindications, the administration of a beta-blocker or a specific bradycardiac agent together with thrombolytic therapy was safe. In this limited number of patients, these agents did not appear to enhance myocardial salvage or preservation of left ventricular function or to reduce the incidence of major arrhythmias in the early phase of infarction.

Myocardial risk area defined by technetium-99m sestamibi imaging during percutaneous transluminal coronary angioplasty: comparison with coronary angiography.

OBJECTIVES: The purpose of this study was to compare the assessment of myocardial area at risk in patients with coronary artery stenosis by coronary angiography and quantitative myocardial perfusion imaging with technetium-99m sestamibi. BACKGROUND: Decisions concerning patient management frequently rely on semiquantitative angiographic estimation of the myocardial area at risk, although this approach has not been well validated. Technetium-99m sestamibi is a perfusion imaging agent with little redistribution after initial myocardial uptake. This characteristic allows for injection during angioplasty and later imaging for visualization and quantitation of the nonperfused area at risk. METHODS: Thirty-nine patients referred for coronary angioplasty were studied. Technetium-99m sestamibi was injected intravenously during angioplasty balloon inflation. Planar (33 patients) or tomographic (6 patients) imaging was performed after completion of angioplasty. Imaging was repeated 24 to 48 h later. Myocardial risk area (perfusion defect on angioplasty image) was quantified as an integral using circumferential count distribution profiles and normal reference. Angiographic risk area was assessed using five scoring methods. RESULTS: The scintigraphic risk area was 14 +/- 15 on planar images and 39 +/- 16 on tomography. Scintigraphic risk area of patients with infarction was larger than in patients without (22 +/- 17 versus 7 +/- 8, p = 0.003). The left anterior descending coronary artery had a larger mean risk area than other vessels (22 +/- 15 versus 7 +/- 11, p = 0.002). The presence of angiographic collateral channels was associated with smaller risk areas. Angiographic risk scores correlated only moderately with the technetium-99m sestamibi risk area (r = 0.54 to 0.65), with considerable spread of data. CONCLUSIONS: Area at risk estimated from coronary angiography does not correlate well with that from quantitative myocardial perfusion imaging with technetium-99m sestamibi. These findings emphasize that the functional significance of coronary artery disease is not predicted by coronary anatomy alone.

Gold-195m for serial first pass radionuclide angiocardiography during upright exercise in patients with coronary artery disease.

Sequential first pass radionuclide angiocardiography can be performed in rapid succession using gold-195m because of its low radiation dose and short half-life (30.5 seconds). In 25 patients with known or suspected coronary artery disease, first pass studies with gold-195m were obtained using a computerized multicrystal gamma camera at rest (n = 29), at the end of each 3 minute stage of exercise (n = 25) and immediately after exercise (n = 23). In 13 patients, assessment of left ventricular function during exercise with gold-195m was combined with thallium-201 stress scintigraphy. Left ventricular ejection fraction at rest assessed with technetium-99m and gold-195m correlated well (r = 0.93). In addition, repeat left ventricular ejection fractions at rest with gold-195m correlated closely (r = 0.96). Comparing peak exercise left ventricular ejection fraction with ejection fraction at rest, abnormal left ventricular reserve was found in 20 of 25 patients. Various abnormal patterns of left ventricular ejection fraction response were noted, showing the diagnostic potential of serial exercise angiocardiography. Thallium-201 myocardial images, obtained on a single crystal gamma camera after multiple gold-195m injections, were all of good diagnostic quality and were abnormal in 10 of 13 patients. Thus, multiple high count rate first pass studies can be obtained with gold-195m during and after exercise, allowing serial study of physiologic changes in left ventricular function during exercise. Thallium-201 myocardial imaging can be performed using the same exercise test, providing direct comparison of myocardial function and perfusion.

Ejection fraction by radionuclide ventriculography and contrast left ventriculogram. A tale of two techniques. SAVE Investigators. Survival and Ventricular Enlargement.

OBJECTIVES: We assessed the abilities of two methods to measure ejection fraction (EF)-radionuclide ventriculography (RVG) and contrast left ventriculography (Cath-EFa) to predict cardiovascular events. BACKGROUND: Both RVG and Cath-EFa are commonly used methods to measure left ventricular performance and assess prognosis. Their comparative abilities to predict clinical events have not been reported. METHODS: Both RVG EF and Cath-EFa were measured within 16 days of myocardial infarction (MI) in 688 patients. The results were divided into terciles. Prognosis by terciles was assessed for each technique. A multivariate analysis was performed to determine which EF measurement was a better predictor of prognosis. RESULTS: Average RVG-EF was 32%+/-7, while Cath-EFa was 42%+/-10. Both RVG and Cath-EFa were poorly correlated (R=0.42). Event rate declined across terciles with increasing EF for both techniques (events in lowest to highest tercile of Cath-EFa 40.7%, 25.9%, 11.6%, p < 0.001; and RVG-EF 39.9%, 26.1%, 15.6%, p < 0.001). There was concordance of terciles in 303 of 688 patients (44%). When patients in the highest RVG terciles were in the highest Cath-EFa tercile, the event rate was 7%. However, when patients in the highest RVG terciles were in the lowest Cath-EFa tercile, the event rate was 19%. Both Cath-EFa (p < 0.001) and RVG-EF (p < 0.001) were independent predictors of cardiovascular events. CONCLUSIONS: Ejection fraction measured by RVG or during catheterization is a valuable tool in the risk stratification of postinfarct patients. When disagreement is present between clinical impression and measurement by either method, the use of an alternative measurement is warranted and complementary.

Prognostic value of noninvasive testing one year after orthotopic cardiac transplantation.

OBJECTIVES: We sought to evaluate the prognostic value of routine noninvasive testing--stress thallium-201 imaging, rest two-dimensional echocardiography and rest equilibrium radionuclide angiography--1 year after cardiac transplantation. BACKGROUND: Coronary artery vasculopathy is the most important cause of late death after orthotopic cardiac transplantation. Several clinical variables have been identified as risk factors for development of coronary vasculopathy. Traditional noninvasive diagnostic testing has been shown to be relatively insensitive for identifying patients with angiographic vasculopathy. METHODS: Results of prospectively acquired noninvasive testing in 47 consecutive transplant recipients alive 1 year after transplantation were related to subsequent survival. Other clinical variables previously shown to be associated with the development of coronary artery vasculopathy were also included in the analysis. RESULTS: The 5-year survival rate after cardiac transplantation was 81%. By univariate analysis, echocardiography (chi-square 9.21) and stress thallium-201 myocardial perfusion imaging (chi-square 16.76) were predictive for survival, whereas rest equilibrium radionuclide angiography was not. Clinical contributors to survival were donor age (chi-square 4.56), number of human leukocyte antigen mismatches (chi-square 3.06) and cold ischemic time (chi-square 3.23). By multivariate analysis, stress myocardial imaging remained the only significant predictor of survival (risk ratio 0.27; 95% confidence interval 0.06 to 0.89). CONCLUSIONS: Normal thallium-201 stress myocardial perfusion imaging 1 year after cardiac transplantation is an important predictor of 5-year survival.

Left ventricular inotropic reserve and right ventricular function predict increase of left ventricular ejection fraction after beta-blocker therapy in nonischemic cardiomyopathy.

OBJECTIVES: The purpose of this study was to determine whether higher left ventricular inotropic reserve, defined as the increase in left ventricular ejection fraction (LVEF) in response to intravenous dobutamine infusion, or other ventriculographic variables predict the increase in LVEF after beta-blocker therapy in patients with nonischemic cardiomyopathy (NICM). BACKGROUND: Long-term beta-blocker therapy increases LVEF in some patients with NICM. Other than dose, there are no definite predictors of LVEF increase. METHODS: Thirty patients with LVEF < or = 0.35 and NICM underwent assessment of LVEF at rest and after a 10-min intravenous infusion of dobutamine at 10 microg/kg/min, using equilibrium radionuclide ventriculography. Age was 49 +/- 11 years, 33% women, functional class 2.6 +/- 0.5, duration of chronic heart failure 3.2 +/- 2.9 years, LVEF 0.21 +/- 0.07, left ventricular end-diastolic volume index 180 +/- 64 ml/m2. Right ventricular ejection fraction (RVEF) was abnormal in 37%. Mean dobutamine-induced augmentation of LVEF (DoALVEF) was 0.12 +/- 0.08. Patients were started on one of three beta-blockers (carvedilol, bucindolol or metoprolol) and the dose was advanced to the maximum tolerated. RESULTS: Left ventricular ejection fraction, reassessed 7.4 +/- 5.9 months after maximum beta-blocker dose was reached, increased to 0.34 +/- 0.13 (p = 0.0006). The following baseline variables correlated with improvement of LVEF: DoALVEF (p = 0.001), RVEF (p = 0.005), systolic blood pressure at end of dobutamine infusion (p = 0.02) and dose of beta-blocker (p = 0.07). In a multivariate analysis, only DoALVEF (p = 0.0003) and RVEF (p = 0.002) were predictive of the increase in LVEF. CONCLUSIONS: Patients with nonischemic cardiomyopathy who have higher left ventricular inotropic reserve and normal RVEF derive higher increase in LVEF from beta-blocker therapy.

Limited usefulness of exercise testing and thallium scintigraphy in evaluation of ambulatory patients several months after recovery from an acute coronary event: implications for management of stable coronary heart disease. Multicenter Myocardial Ischemia Research Group.

OBJECTIVES: This study evaluated the value of noninvasive testing to predict cardiac events in patients with stable coronary disease after hospital admission (and risk stratification) for an acute coronary event. BACKGROUND: Exercise testing with thallium perfusion imaging identifies patients with obstructive coronary artery disease and has been used to stratify patients after myocardial infarction. Its usefulness for predicting cardiac events in patients with stable coronary disease after recovery from an acute coronary event was explored. METHODS: Nine hundred thirty-six patients were enrolled 1 to 6 months after hospital admission for a coronary event. Patients underwent exercise treadmill testing with planar thallium-201 scintigraphy and were followed up for an average of 23 months (range 6 to 43). End points were 1) unstable angina requiring hospital admission, nonfatal myocardial infarction or cardiac death; 2) nonfatal infarction or cardiac death; or 3) cardiac death alone. RESULTS: Twelve patients died of cardiac causes (1.2%); 32 had a nonfatal myocardial infarction (3.4%); and 79 patients (8.4%) developed unstable angina in the first year. Exercise testing improved proportional hazards models constructed from clinical variables for all three end points (p < 0.05). The perfusion scan further improved models for the end points (nonfatal infarction or cardiac death and cardiac death alone, p < 0.05). However, the exercise test with or without thallium added little to the overall prediction of primary events (area under the receiver operating curve increased from 0.649 to 0.663), and only 2% to 13% of patients with abnormal results either had a nonfatal infarction or died. CONCLUSIONS: Thallium-201 scintigraphy and exercise testing variables identify patients at risk for subsequent cardiac events. However, the poor predictive performance of these tests in this group of patients with stable coronary disease severely limits their usefulness. These results suggest a limited role for exercise and thallium testing in predicting cardiac events in patients with known coronary disease.

Clinical value of acute rest technetium-99m tetrofosmin tomographic myocardial perfusion imaging in patients with acute chest pain and nondiagnostic electrocardiograms.

OBJECTIVES: We sought to evaluate the clinical use and cost-analysis of acute rest technetium-99m (Tc-99m) tetrofosmin single-photon emission computed tomographic (SPECT) myocardial perfusion imaging in patients with chest pain and a normal electrocardiogram (ECG). BACKGROUND: Current approaches used in emergency departments (EDs) for treating patients presenting with chest pain and a nondiagnostic ECG result in poor resource utilization. METHODS: Three hundred fifty-seven patients presenting to six centers with symptoms suggestive of myocardial ischemia and a nondiagnostic ECG underwent Tc-99m tetrofosmin SPECT during or within 6 h of symptoms. Follow-up evaluation was performed during the hospital period and 30 days after discharge. All entry ECGs, SPECT images and cardiac events were reviewed in blinded manner and were not available to the admitting physicians. RESULTS: By consensus interpretation, 204 images (57%) were normal, and 153 were abnormal (43%). Of 20 patients (6%) with an acute myocardial infarction (MI) during the hospital period, 18 had abnormal images (sensitivity 90%), whereas only 2 had normal images (negative predictive value 99%). Multiple logistic regression analysis demonstrated abnormal SPECT imaging to be the best predictor of MI and significantly better than clinical data. Using a normal SPECT image as a criterion not to admit patients would result in a 57% reduction in hospital admissions, with a mean cost savings per patient of $4,258. CONCLUSIONS: Abnormal rest Tc-99m tetrofosmin SPECT imaging accurately predicts acute MI in patients with symptoms and a nondiagnostic ECG, whereas a normal study is associated with a very low cardiac event rate. The use of acute rest SPECT imaging in the ED can substantially and safely reduce the number of unnecessary hospital admissions.