Reversible Thallium Defects Research Articles

Abstract 1664: Impact of Ischemic Burden and Revascularization on Outcomes among Patients Receiving Drug Therapy Versus an Implantable Cardioverter Defibrillator in MUSTT: Evidence for Ischemia Induced Proarrhythmia

Background. ICD implantation for primary prevention of sudden death in patients with ischemic cardiomyopathy and left ventricular dysfunction is well established. However debate exists between the relationship between ischemia and the proarrhythmic state. Persistent ischemia may counter antiarrhythmic (AA) drug and/or device efficacy. Furthermore, the extent to which revascularization mitigates this influence of ischemia on efficacy is unknown. Methods . 704 patients enrolled in the MUSTT trial were studied. Ischemia was determined by the presence of angina within 6 weeks of enrollment and ≥ 2 reversible thallium defects. Revascularization was characterized as CABG or PTCA within 1 year of enrollment or the use of thrombolytics with the sentinal myocardial infarction (MI). We compared groups who were randomized to background medical treatment (BG Rx) verses those who were randomized to AA drug therapy in addition to EP testing (EP AARx). Results . 507 (81%) patients had ≤2 vessel CAD, whereas the remaining 19% had 3 vessel disease. 268 patients reported angina within 6 weeks of study enrollment. Thallium imaging revealed 0–1 defects in 458 (65%) and ≥2 in another 246 (35%). Those with ≥ 2 defects on Thallium and angina within 6 weeks of device implant had a significantly lower 5-year freedom from mortality in the EP AARx and BG Rx cohorts (Table ). Patients with EP AARx had an 8% lower mortality than those with BG Rx therapy alone if they received thrombolytics. However, if they did not receive thrombolytics, their mortality rate was 5% higher than the BG Rx group. Conclusion . Outcomes are worse in patients on antiarrhythmic therapy with ischemic factors compared to those on background therapy alone, particularly in the setting of recent angina. A proarrhythmic effect from antiarrhythmic drug therapy in patients with ischemia may underlie the higher mortality. ICD therapy mitigates the negative long-term effect of ischemia on mortality in those treated with AA therapy. Five Year Freedom from Mortality

A quantitative analysis of I-123 BMIPP uptake in the heart and surrounding tissues

Background: After an exercise-induced ischemia, recent studies have shown prolonged disturbances in myocardial fatty acid metabolism, termed “ischemic memory”, which can be successfully imaged by [ 123I] BMIPP at rest. A potential advantage of BMIPP is that it permits uncoupling of the treadmill stress from tracer injection. In this study, we determined the cardiac image quality of BMIPP by quantifying regional tracer uptake in the heart and surrounding tissues in coronal slices. The results were compared with thallium images obtained in the same patients. Methods: 13 pts with documented reversible thallium defects during exercise underwent subsequent rest BMIPP SPECT imaging within 30 hours of the thallium study. The mean thallium dose injected was 5.2 ± 0.4 mCi while the mean BMIPP dose injected was 3.6 ± 0.4 mCi. After BMIPP injection, two sets of SPECT images were acquired; a 10-minute acquisition obtained 10 minutes after BMIPP injection and a 20-minute acquisition obtained 35–60 minutes after injection. A circular region of interest (ROI) was drawn around the heart, which was then duplicated and repositioned over the lung, liver, and left upper quadrant bowel in coronal slices. Mean counts in each ROI were expressed as lung/heart, liver/heart, and bowel/heart region ratios for thallium, 10-minute BMIPP and 35–60 minute BMIPP images (table). Results: BMIPP images showed excellent cardiac tracer uptake by quantitative SPECT analysis without lung or abdominal visceral interference. The lung/heart and bowel/heart ratios were similar for thallium and BMIPP images. However, the liver/heart ratio was higher for BMIPP images than thallium. Conclusion: The cardiac imaging characteristics of BMIPP are excellent with greater tracer uptake in the heart than the surrounding tissues of lung, liver and bowel. Compared to thallium, BMIPP shows higher liver/heart but similar lung/heart and bowel/heart ratios. However, when the more favorable physical properties of I-123 are taken into consideration, [ 123I] BMIPP becomes an excellent “ischemic memory” cardiac agent. * lung/heart liver/heart bowel/heart BMIPP 10 minute .30 ± .03 .65 ± .18 .25 ± .09 BMIPP 35–60 minute .33 ± .06 .61 ± .15 .30 ± .10 thallium .23 ± .14 .22 ± .07 * .21 ± .06 * different from BMIPP (10 and 35–60 minute) p < 0.03.

Prognostic value of thallium-201 single-photon emission computed tomography for patients with multivessel coronary artery disease after revascularization (the Emory Angioplasty versus Surgery Trial [EAST

The aim of this study was to investigate the relation between reversible thallium single-photon emission computed tomography (SPECT) myocardial perfusion defects at 1-year after revascularization and quantitative indexes in Emory Angioplasty versus Surgery Trial (EAST) and outcomes 3 years after revascularization in 336 patients. EAST was a randomized controlled trial assessing cardiac outcomes for angioplasty versus bypass surgery for patients with multivessel coronary artery disease. During this prospective trial, a substudy included the evaluation of the prognostic value of reversible defects on quantitative thallium SPECT. At 1-year after revascularization, 336 patients underwent SPECT thallium-201 stress myocardial perfusion and 3-hour delayed imaging. Subsequent events, percutaneous transluminal coronary angioplasty, coronary artery bypass graft surgery, myocardial infarction, and death, were recorded at 3 years. A stress-induced reversible thallium-201 defect was defined using a quantitative index of a reversibility score >30% and severity score >500. Reversible defects were observed more frequently in the percutaneous transluminal coronary angioplasty than in the coronary artery bypass graft surgery treatment groups (46% vs 27%, p <0.001). A total of 123 patients had stress-induced, reversible thallium defects and more events than patients with other perfusion results (freedom from all events was 81.3% vs 94% [p <0.001], and freedom from myocardial infarction and death 88.3% vs 95.5% [p = 0.031]). Quantitative thallium SPECT at 1 year after revascularization risk stratifies patients as to their likelihood of major cardiac outcomes.

Comparison of dobutamine echocardiography, dobutamine sestamibi, and rest-redistribution thallium-201 single-photon emission computed tomography for determining contractile reserve and myocardial ischemia in ischemic cardiomyopathy

Both dobutamine stress echocardiography (DSE) and myocardial perfusion scintigraphy are used to assess myocardial viability. Few studies have compared the data on myocardial viability and ischemia by low and peak dose DSE and myocardial perfusion imaging in the same patients. Fifty-four patients (45 men and 9 women aged 65 ± 9 years) with ischemic cardiomyopathy (mean ejection fraction 24 ± 9%) underwent rest 4-hour redistribution thallium-201 single-photon emission computed tomography (SPECT), low and peak dose DSE, and dobutamine sestamibi SPECT. A total of 864 segments were analyzed (16 segments/patient). Wall motion abnormality was present in 796 segments (92%), and contractile reserve during dobutamine infusion was seen in 400 of these segments (50%). Contractile reserve was seen in 331 of 509 hypokinetic segments (65%) and 69 of 287 akinetic/dyskinetic segments (24%) (p <0.001). Contractile reserve was more frequent in segments with normal thallium uptake (64%), reversible thallium defects (42%), or mild to moderate fixed thallium defects (48%) than severely fixed defects (22%) (p <0.05 each). Concordant information about viability by thallium imaging and DSE was obtained in 62% of segments. Dobutamine sestamibi ischemia was seen in 518 of 796 segments (65%) compared with 265 segments (33%) by DSE (p <0.001). Scintigraphic ischemia was noted in 126 of 195 segments (65%) demonstrating biphasic response, 129 of 205 segments (63%) showing sustained improvement, 42 of 70 segments (60%) deteriorating during dobutamine infusion, and 221 of 326 (68%) demonstrating no change (p = NS). Thus, in patients with ischemic cardiomyopathy, contractile reserve is more frequent in hypokinetic segments than akinetic/dyskinetic segments. The number of segments with normal or near-normal thallium uptake or with scintigraphic ischemia is significantly greater than the number of those capable of increasing contractile function or demonstrating an ischemic response during dobutamine echocardiography.

Long-term prognostic value of preoperative dipyridamole thallium imaging and clinical indexes in patients with diabetes mellitus undergoing peripheral vascular surgery

The objective of this study is to assess the prognostic impact of preoperative dipyridamole thallium imaging and clinical variables on the long-term outcome of diabetic patients undergoing peripheral vascular surgery. Complete follow-up was obtained in 101 consecutive patients with diabetes mellitus undergoing routine dipyridamole thallium scintigraphy before vascular surgery (mean 4.2 ± 3.2 years, range 1 month to 11 years). Low risk was defined by diabetes alone with a normal resting electrocardiogram. High risk was defined as a history of angina, myocardial infarction, congestive heart failure, or resting electrocardiogram abnormalities. There were 71 deaths in 98 patients discharged alive from the hospital (median survival 4.4 years). Age, the presence of resting electrocardiogram abnormalities, and an abnormal thallium scan were independent predictors of late death. After adjusting for age >70 years and thallium abnormalities, high-risk patients had a death rate 4.8 times (95% confidence interval 1.7 to 13.4, p <0.002) greater than low-risk patients. The presence of >2 reversible thallium defects was useful in further risk stratification of both low- and high-risk patients. Low-risk patients with >2 reversible defects had a median survival of 4.0 years compared with 9.4 years in those with ≤2 reversible defects (p <0.001). Similarly, high-risk patients with ≤2 reversible defects had an intermediate median survival rate of 4.7 years compared with 1.8 years in the group with >2 reversible defects (p <0.001). Therefore, advanced age and the presence of resting electrocardiographic or thallium abnormalities identifies a subset of diabetic patients with a poor long-term outcome after vascular surgery. Combined clinical and thallium variables may identify a population in whom intensive medical or surgical interventions may be warranted to reduce both perioperative and late cardiac events.

Prognostic value of dipyridamole thallium imaging after acute myocardial infarction in older patients.

To assess the utility of intravenous dipyridamole thallium testing for predicting major cardiac events following acute myocardial infarction in older patients. Prospective cohort study with a median follow-up of 18 months. A university teaching hospital. 73 patients aged 65 years and older with enzymatically confirmed acute myocardial infarction (mean age 75 years, 56% male, 71% white). All patients underwent a detailed clinical assessment, an echocardiogram, and an intravenous dipyridamole thallium stress test before hospital discharge. The study endpoint was death or nonfatal reinfarction during the follow-up period. Overall, 24 patients (33%) died or developed recurrent myocardial infarction during follow-up. Among 44 patients with a reversible thallium defect, 19 (43%) reached the study endpoint, compared with only five of 29 patients (17%) without reversible ischemia (P = .04). On multivariate analysis, independent prognostic variables included non-use of aspirin at hospital discharge (P = .002), decreased left ventricular systolic function (P = .009), non-use of a beta-blocker at hospital discharge (P = .013), and reversible ischemia on thallium scintigraphy (P = .025). The relative risks for death or reinfarction associated with non-use of aspirin, non-use of a beta-blocker, left ventricular dysfunction, and reversible ischemia were 2.65, 2.39, 2.01, and 2.51, respectively. Patients with three or four of these risk factors had an 83% probability of death or reinfarction, compared with 41% in patients with two risk factors and 6% in patients with one or no risk factor (P < .001). Intravenous dipyridamole thallium imaging provides independent prognostic information in older patients with acute myocardial infarction. Moreover, the combination of clinical, echocardiographic, and dipyridamole thallium variables effectively stratifies older postinfarction patients into high-, intermediate-, and low-risk categories for death or recurrent myocardial infarction.

Stress-induced reversible and mild-to-moderate irreversible thallium defects: are they equally accurate for predicting recovery of regional left ventricular function after revascularization?

In patients with coronary artery disease, stress-redistribution-reinjection thallium scintigraphy provides important information regarding myocardial ischemia and viability. Although both reversible and mild-to-moderate irreversible thallium defects retain metabolically active, viable myocardium, we hypothesized that stress-induced reversible thallium defects may better differentiate reversible from irreversible regional left ventricular dysfunction after revascularization. Twenty-four patients with chronic coronary artery disease underwent prerevascularization and postrevascularization exercise-redistribution-reinjection thallium single photon emission CT, gated MRI, and radionuclide angiography. After revascularization, mean left ventricular ejection fraction increased from 30+/-9% to 37+/-13% at rest (P<0.001). Before revascularization, abnormal contraction at rest was observed in 56 of 110 reversible and 20 of 37 mild-to-moderate irreversible thallium defects (51% and 54%, respectively). After revascularization, regional contraction improved in 44 of 56 reversible compared with 6 of 20 mild-to-moderate irreversible thallium defects (79% and 30%, respectively; P<0.001). The final thallium content (maximum tracer uptake on redistribution-reinjection images) was significantly higher in regions with reversible defects that improved than in those that did not improve after revascularization (86+/-16% versus 66+/-9%, P<0.001). In contrast, final thallium content was similar in regions with mild-to-moderate irreversible defects that improved and in those that did not improve after revascularization (69+/-9% versus 65+/-10%, P=NS). Furthermore, when asynergic regions were grouped according to the final thallium content, at 60% threshold value, functional recovery was observed in 83% of regions with reversible defects compared with 33% of regions with mild-to-moderate irreversible defects (P<0.001). These findings suggest that although both reversible and mild-to-moderate irreversible thallium defects after stress retain viable myocardium, the identification of reversible thallium defect on stress in an asynergic region more accurately predicts recovery of function after revascularization. Even at a similar mass of viable myocardial tissue (as reflected by the final thallium content), the presence of inducible ischemia is associated with an increased likelihood of functional recovery.

DOES AGE AFFECT THE PREDICTIVE VALUE OF THE MAGNITUDE OF EXERCISE-RELATED ST DEPRESSION FOR THALLIUM RESULTS

1428 The incidence of coronary artery disease is higher in an older population, which by Bayesian analysis would be expected to affect the predictive value of exercise parameters. In this study, the SPECT Th-201 scans of 148 men with≥1mm ST depression (horizontal/downsloping) during symptom-limited exercise(treadmill) thallium testing were reviewed to determine how age affects the usefulness of the magnitude of exercise-related ST depression for predicting thallium results. Patients with baseline ST-T changes or a prior abnormal exercise test as a reason for referral were excluded. The group was stratified based on age (above or below 65 years) and the degree of ST depression (1-2 mm vs >2 mm). The incidence of reversible thallium defects (ThPOS) was then determined for each group. TableTableFor the entire group, 1-2 mm ST depression and >2 mm ST depression showed the same predictive value for ThPOS. Men >65 years had a sig higher%ThPOS than men <65 years (69% vs 48%, P=.01), and the predictive value of 1-2 mm was sig higher in men >65 years than men <65 years(P=.01). However, within each age group there was no sig difference in predictive value for ThPOS between patients with 1-2 mm ST depression and patients with >2 mm ST depression. Conclusion: In men with an abnormal exercise EKG, increased magnitude of ST depression (1-2 mm vs >2 mm) does not result in sig additional predictive value for thallium results. The increased incidence of ThPOS associated with increased age does not affect the relative predictive value of different magnitudes of ST depression for thallium results.

Chest pain during daily life in patients with hypertrophic cardiomyopathy: an ambulatory electrocardiographic study.

Patients with hypertrophic cardiomyopathy frequently complain of chest pain during daily activities. ST-segment depression is described in association with sudden death and pacing, but its prevalence during ambulatory electrocardiographic monitoring is unknown. The aim of this study was to determine the relation of ambulatory ST-segment depression to clinical characteristics, risk factors for sudden death and thallium-201 perfusion in patients with hypertrophic cardiomyopathy. Continuous 48 h ambulatory electrocardiographic monitoring was performed in 113 patients (age 38 +/- 14 years) with hypertrophic cardiomyopathy. Ninety-four (83%) recordings were suitable for ST-segment analysis. A total of 109 episodes of ST-segment depression (> or = 1 mm from baseline) were recorded in 25 (27%) patients (mean 4 +/- 5). In patients < or = 30 years of age (but not > 30) there was an association between ST-segment depression and a history of exertional chest pain (seven of 12 vs one of 20; P = 0.001), and dyspnoea NYHA class II/III (seven of 15 vs one of 17; P = 0.008). There was no association between ST-segment depression and risk markers for sudden death, i.e. family history of sudden death, syncope and non-sustained ventricular tachycardia, in any group. Reversible thallium-201 defects occurred in 27 (29%) of the 94 patients with analysed recordings but were not associated with symptoms, risk factors for sudden death or ambulatory ST-segment depression. In young patients with hypertrophic cardiomyopathy, ischaemia-like ST-segment depression is common and is associated with a history of typical angina and dyspnoea. Reversible thallium-201 perfusion defects are associated with neither symptomatic status nor ambulatory ST-segment depression.

Relation between contractile response of akinetic segments during dobutamine stress echocardiography and myocardial ischemia assessed by simultaneous thallium-201 single-photon emission computed tomography

There are no standard criteria for the diagnosis of myocardial ischemia in akinetic segments during dobutamine stress echocardiography (DSE). The aim of the study was to assess the relation between different responses of akinetic segments during DSE and ischemia assessed by thallium-201 single-photon emission computed tomography (SPECT). Dobutamine-atropine stress echocardiography with simultaneous stress-reinjection thallium-201 SPECT was performed in 67 patients with old myocardial infarction significant and coronary artery stenosis. Fourteen myocardial segments were matched for both DSE and SPECT. Ischemia on SPECT was defined as reversible thallium defects. In 257 akinetic segments, 4 patterns during DSE were identified: (1) biphasic response in 41 segments (16%), defined as improvement at low dose (5 to 10 μg/kg/min) followed by worsening at high dose; (2) persistent akinesia in 155 segments (60%); (3) akinesia becoming dyskinesia in 39 segments (15%); and (4) sustained improvement in 22 segments (9%). Reversible thallium defects were detected in 21 segments (51%) in group 1, in 20 segments (13%) in group 2, none in group 3, and in 2 segments in group 4 (9%). The prevalence of reversible defects in biphasic segments was higher compared with other patterns (p < 0.00001 vs groups 2 and 3, p < 0.005 vs group 4). The ischemic perfusion defect score was significantly higher in group 1 than group 2. The positive predictive value of biphasic response for reversible thallium defects was similar to that of stress-induced dyssynergia in normal segments at rest (51% vs 58%). It is concluded that of the various responses of akinetic segments to dobutamine infusion, the biphasic response is associated with the highest prevalence and greatest severity of ischemia on thallium SPECT. Observation of contractile response at both low- and high-dose DSE is a valuable approach for the diagnosis of myocardial ischemia in akinetic segments.

Prediction of outcome after revascularization in patients with poor left ventricular function

In patients with poor left ventricular function, the determinants of outcome after revascularization are unknown. We studied prospectively 57 patients with stable coronary artery disease and poor left ventricular function (left ventricular ejection fraction, 0.28 +/- 0.04) who underwent coronary artery bypass grafting. Clinical variables were assessed as predictors of outcome in all patients, and preoperative stress thallium-201 scintigraphic data were analysed in 37 patients. The operative mortality was 1.7%. At 12 months after operation, 46 of the 49 survivors were angina-free and 35 had fewer heart failure symptoms, but postoperative left ventricular ejection fraction (0.30 +/- 0.09) did not change significantly. Eighteen survivors had left ventricular ejection fraction improved by 0.05 or more (0.30 +/- 0.03 preoperatively, 0.40 +/- 0.05 postoperatively; p = 0.0001). The adjusted odds ratio of large reversible thallium-201 defects in predicting such outcome was 15 (95% confidence interval, 1.6 to 140), whereas other clinical variables had no predictive value. The transplantation-free 5-year survival was 73%. In patients with poor left ventricular function, surgical revascularization can be performed safely, with good symptomatic relief and long-term survival. One-year survival and improvement in left ventricular function is better in patients with large reversible defects on preoperative stress thallium-201 scintigraphy.

The QRS score: a promising new exercise score for detecting coronary artery disease based on exercise-induced changes of Q-, R- and S-waves: a relationship with myocardial ischaemia.

Recently, a new exercise test criterion diagnosing coronary artery disease was proposed, based on a composite of changes in Q-, R- and S-waves: the QRS score. We compared this new criterion with conventional ST-segment depression and other compositions of Q-, R- and S-wave changes in patients and normals and related the QRS score to reversible thallium-201 scintigraphic defects and ST-segment depression as markers for ischaemia. The influence of beta-blockade on the QRS score was also studied. The study population consisted of 155 persons with 53 normals (group I) and 102 patients with documented coronary artery disease (group II). Another 20 patients (group III) with proven coronary artery disease and a positive exercise test by ST-segment criteria were studied for the influence of beta-blockade on the QRS score. A symptom-limited exercise protocol according to the modified Bruce protocol was used. For the QRS score, Q-, R- and S-wave amplitudes which could be recovered immediately were subtracted from pretest values: delta Q, delta R, delta S respectively. The score was calculated by the formula: (delta R - delta Q - delta S)AVF + (delta R - delta Q - delta S)V5. Using a cut-off point of > 5 as normal, the QRS score resulted in a sensitivity of 88.2%, a specificity of 84.8% and a predictive accuracy of 87.1%. For ST-segment depression these values were 54.9%, 83% and 64.5% respectively (P < 0.001 compared to the QRS score). Predictive accuracies of changes in Q-, R- and S-waves in leads AVF and V5 separately, combinations of changes and combining the two leads, resulted-with the exception of solitary S-wave changes-in predictive accuracies higher than those of ST-segment depression, but all were lower than the QRS score. We found a significant correlation between the QRS score, the summed ST-segment depression (P < 0.004) and the extent of reversible thallium-201 defects (P < 0.001). Applying Bayes' theorem, the combination of an abnormal QRS score and ST-segment depression resulted in the highest post-test risk for coronary artery disease and a normal QRS score without ST-segment depression in the lowest post-test risk. The QRS score and the maximal ST-segment depression changed significantly under the influence of beta-blockade (P < 0.02 and P < 0.001 respectively). Our data suggest that an abnormal QRS score reflects myocardial ischaemia. Furthermore, for the interpretation of the exercise test, the combined analysis of ST-segments and the QRS score is of value for the prediction of the presence or absence of coronary artery disease and its follow-up.

Impaired fatty acid uptake in ischemic but viable myocardium identified by thallium-201 reinjection

Iodine 123—labeled 15-iodophenyl-3-methyl-pentadecanoic acid (BMIPP) has been proposed as a potential myocardial fatty acid probe. We studied BMIPP uptake in ischemic myocardium identified by thallium reinjection. Fifty-five patients with coronary artery disease who had persistent defects on standard exercise-redistribution thallium imaging were investigated. Patients underwent exercise-redistribution-reinjection thallium and resting BMIPP imaging. BMIPP uptake less than that seen with thallium on reinjection imaging was observed in 105 (82%) of 128 myocardial segments with new fill-in after thallium reinjection and 87 (37%) of 238 segments with reversible thallium defects. In contrast, only 32 (19%) of 166 segments with no fill-in showed discordantly decreased BMIPP uptake. Quantitative analysis showed reduction in BMIPP activity compared with differential uptake of thallium, an index of resting myocardial perfusion, especially in the area of fill-in (53.5% ± 15.0% vs 76.0% ± 12.1% of peak; p < 0.01). These observations are consistent with impaired fatty acid uptake in ischemic myocardium, particularly in the area of fill-in after thallium reinjection.

Meta-analysis of intravenous dipyridamole-thallium-201 imaging (1985 to 1994) and dobutamine echocardiography (1991 to 1994) for risk stratification before vascular surgery

Objectives. This study evaluated the prognostic value of abnormal test results with pharmacologic stress with regard to perioperative and long-term outcomes in a large population of candidates for vascular surgery.Background. Although numerous studies have demonstrated the prognostic value of dipyridamole-thallium-201 myocardial perfusion and dobutamine echocardiography in vascular surgery candidates, a synopsis of predictive estimates is different because of individual study variability in pretest clinical risk, sample size and study design.Methods. A systematic review of published reports on preoperative pharmacologic stress risk stratification from the MEDLINE data base (1985 to 1994) identified 10 reports on dipyridamole-thallium-201 myocardial perfusion (1,994 patients) and 5 on dobutamine stress echocardiography (445 patients). Random effects models were used to calculate summary odds ratios and 95% confidence intervals.Results. Summary odds ratios for death or myocardial infarction and secondary cardiac end points were greater for dobutamine echocardiographic dysynergy (14- to 27-fold) than for dipyridamole-thallium-201 redistribution (4-fold); wider confidence intervals were noted with dobutamine echocardiography. Pretest coronary disease probability was correlated with the positive predictive value of a reversible thallium-201 defect (r = 0.70). Increasing sixfold from low to high risk patients subsets. Cardiac event rates were low in patients without a history of coronary artery disease (1% in 176 patients) compared with patients with coronary disease and a normal or fixed-defect pattern (4.8% in 83 patients) and one or more thallium-201 redistribution abnormality (18.6% in 97 patients, p = 0.0001).Conclusions. Meta-analysis of 15 studies demonstrated that the prognostic value of noninvasive stress imaging abnormalities for perioperative ischemic events is comparable between available t techniques but that the accuracy varies with coronary artery disease prevalence.

Additive value of thallium single-photon emission computed tomography myocardial imaging for prediction of perioperative events in clinically selected high cardiac risk patients having abdominal aortic surgery

The present study was designed to prospectively evaluate whether reinjection mallium-201 single-photon emission computed tomography (SPECT) has a significant additive predictive value for occurrence of perioperative cardiac events in clinically selected patients at high cardiac risk undergoing abdominal aortic surgery. Of a group of 517 consecutive patients referred, 134 had ≥2 of the following clinical or electrocardiographic cardiac risk variables: age >70 years; history of myocardial infarction, angina, or congestive heart failure; diabetes mellitus; hypertension with severe left ventricular hypertrophy; and Q waves or ischemic ST-segment abnormalities on electrocardiogram at rest. Operation was performed after thallium SPECT study. Twelve patients (9%) had major perioperative events (cardiac death or nonfatal myocardial infarction) and 18 patients had other cardiac events (unstable angina, congestive heart failure, or severe ventricular tachyarrhythmia). Variables correlated with the occurrence of major events were history of myocardial infarction (p < 0.05) and the presence (p < 0.001) and number of segments with thallium reversible defects (p < 0.001). In multivariate analysis, history of myocardial infarction (p < 0.05) and the number of segments with reversible thallium defects (p < 0.001) were independent predictors. When all the cardiac events were taken into consideration, all the previous variables, as well as Q waves and ischemic ST abnormalities on the electrocardiogram, showed significant predictive value in both univariate and multivariate analyses. Furthermore, thallium SPECT imaging has an additive predictive value for major cardiac events over clinical and electrocardiographic risk factors. When performed on clinically selected patients at high cardiac risk undergoing abdominal aortic surgery, thallium SPECT demonstrates significant prognostic value for cardiac events over that provided by clinical variables alone.

Assessment of myocardial viability by dynamic tomographic iodine 123 iodophenylpentadecanoic acid imaging: Comparison with rest-redistribution thallium 201 imaging

This study examined the ability of dynamic 123I-labeled iodophenylpentadecanoic acid (IPPA) imaging to detect myocardial viability in patients with left ventricular (LV) dysfunction caused by coronary artery disease. Serial 180-degree single-photon emission computed tomographic (SPECT) images (five sets, 8 minutes each) were obtained starting 4 minutes after injection of 2 to 6 mCi 123I at rest in 21 patients with LV dysfunction (ejection fraction [EF] 34% +/- 11%). The segmental uptake was compared with that of rest-redistribution 201Tl images (20 segments/study). The number of perfusion defects (reversible and fixed) was similar by IPPA and thallium (11 +/- 5 vs 10 +/- 5 segments/patient; difference not significant). There was agreement between IPPA and thallium for presence or absence (kappa = 0.78 +/- 0.03) and nature (reversible, mild fixed, or severe fixed) of perfusion defects (kappa = 0.54 +/- 0.04). However, there were more reversible IPPA defects than reversible thallium defects (7 +/- 4 vs 3 +/- 4 segments/patient; p = 0.001). In 14 patients the EF (by gated pool imaging) improved after coronary revascularization from 33% +/- 11% to 39% +/- 12% (p = 0.002). The number of reversible IPPA defects was greater in the seven patients who had improvement in EF than in the patients without such improvement (10 +/- 4 vs 5 +/- 4 segments/patient; p = 0.075). 123I-labeled IPPA SPECT imaging is a promising new technique for assessment of viability. Reversible defects predict recovery of LV dysfunction after coronary revascularization.

Independent and incremental prognostic value of exercise thallium single-photon emission computed tomographic imaging in women

This study examined the independent and incremental prognostic value of exercise thallium single-photon emission computed tomographic imaging in 212 women who also underwent coronary angiography. The left ventricular ejection fraction was normal (65% +/- 15%). During a mean follow-up of 40 months, 27 women had events (cardiac death or nonfatal myocardial infarction). Univariate Cox survival analysis showed several variables to be different between patients with events and those without events: age, exercise heart rate, the extent of coronary artery disease, reversible thallium defects, number of segments with reversible abnormality, and size of perfusion abnormality. Multivariate survival analysis showed that a large perfusion abnormality and age were the independent predictors of events. Actuarial life-table analysis showed that women with a large thallium abnormality (> or = 15% of the myocardium) had significantly worse event-free survival rates than had women with no or small abnormalities (Mantel-Cox statistic = 16; p = 0.0001). Thus exercise thallium-201 single-photon emission computed tomographic imaging provides independent and incremental prognostic information to clinical, exercise, and coronary angiographic results in women. The presence of a larger thallium abnormality identifies women at high risk of cardiac events.

Emory angioplasty versus surgery trial (EAST): Design, recruitment, and baseline description of patients

In patients with multivessel coronary artery disease who require revascularization there is uncertainty as to the selection of the appropriate patients for percutaneous transluminal coronary angioplasty (PTCA) as opposed to coronary artery bypass grafting (CABG). To define the relative roles of PTCA and CABG for multivessel disease, 392 patients were randomly assigned to revascularization by PTCA or CABG and followed for 3 years. This is a single-center randomized study in which individual group assignment was known but grouped data remained blinded until a full 3 years of follow-up was complete on all patients. The patients were randomized in 4 strata: (1) 2-vessel disease with 1 lesion per vessel; (2) 2-vessel disease with multiple lesions in at least 1 vessel; (3) 3-vessel disease with 1 lesion per vessel; and (4) 3-vessel disease with multiple lesions in at least 1 vessel. All data were collected on study-specific forms and sent to an independent biostatistical coordinating center for entry into a computerized database. All data will be analyzed by intention-to-treat. The primary endpoint of the trial is the composite of death of any cause, Q-wave myocardial infarction within 3 years, or a large reversible thallium defect at 3 years. Multiple secondary endpoints will include each of the components of the primary endpoint, the need for additional procedures, angiographic status at 1 and 3 years measured by an independent quantitative coronary arteriography laboratory, and measures of quality of life. A total of 5,118 patients were screened, of whom 3,371 were excluded for angiographic reasons, 191 because the angioplasty operators or surgeons believed that the patients were anatomically unsuitable, and 714 for clinical exclusions, leaving 842 eligible patients, of whom 392 were randomized. Of these, 40% had triple-vessel disease and 60% had double-vessel disease. There was no baseline difference between the 2 treatment arms for any clinical or major angiographic variable. This randomized trial will permit an in-depth comparison of coronary angioplasty and coronary surgery in comparable patients suitable for either procedure. Clinical, angiographic, and quality-of-life comparisons will be made and should be helpful in medical decision making between the 2 procedures.

Doppler guide wire flow-velocity indexes measured distal to coronary stenoses associated with reversible thallium perfusion defects

A Doppler guide wire was used to measure phasic coronary blood flow velocity distal to coronary stenoses in 17 symptomatic patients with corresponding positive exercise or adenosine thallium scintigrams. Distal average peak velocity and diastolic/systolic flow-velocity ratio were obtained in 16 vessels with stenoses (55% to 85% diameter stenosis) and a corresponding reversible thallium defect and in 11 control vessels with no stenosis or thallium defect. Coronary flow-velocity reserve was obtained with intracoronary adenosine. Coronary flow reserve (2.3 ± 0.4 vs 1.2 ± 0.3, p < 0.01) and diastolic/systolic flow-velocity ratio (1.95 ± 0.56 vs 1.44 ± 0.59, p < 0.04) were significantly different between normal vessels and distal to stenoses, respectively. Excellent concordance between distal coronary flow reserve and diastolic/systolic flow-velocity ratio to thallium scintigraphy was noted. A coronary flow reserve of <1.8 and a diastolic/systolic flow-velocity ratio of <1.7 predicted a reversible thallium perfusion scintigram (concordance 96% and 88%, respectively). Distal coronary flow velocity indexes may provide an alternative means of physiologic assessment of lesion severity during coronary angiography.

738–5 Three-year Frequency of New Lesions in Native Vessels in EAST

The Emory Angioplasty vs. Surgery Trial (EAST) randomized pts with multivessel disease to an initial strategy of PTCA or CABG. Of 298 pts who completed 3-year angiographic follow-up (F/U), 53 (18%) had at least one new lesion (N-Les) in their native vessels. The definitions for N-Les were: (1) percent stenosis (%S) at baseline was &lt;50%S, measured by quantitative arteriography, (2) increased by at least 10%5 to become ≥50%5 during the 3-year F/U. N-Les were located either in a non-procedure native vessel (Tp. A) or in procedure vessel, distal to the direct effects of PTCA or CABG (Tp. B). “Instrumented” N-Les possibly due to balloon injury and “hemdynamic” N-Les proximal to, or at, the CABG sites were excluded from this analysis. PTCA and CABG were compared in terms of proportion of pts with N-Les (any, Tp. A or Tp. B) or whose N-Les caused Q-wave infarction (MI), or a large reversible thallium defect (TL), or required additional procedure(s) (AddP), and of %S of these N-Les at baseline (%SB) and when N-Les were first seen (%SN-Les). The occurrence of N-Les, per pt, was correlated with 30 common risk variables. Comparison of Frequency of N-Les between PTCA and CABGPts with:N-lesTp.ATp.BMITIAddP%SB%SN-LesPTCA (152)23101413631 ± 1371 ± 11CABG (146)30141723832 ± 1168 ± 11 Comparison of Frequency of N-Les between PTCA and CABG None of these comparisons is statistically significant.Correlation Analysis·Significant FindingsEmpty CellLDL/HDLDiabeHBPCholST ↓ ≥ 0.1 mvchest painSys BPRadioF/UHxHxF/UBase ETTF/U ETTBaser0.190.160.160.160.160.140.13p0.0030.0050.0050.010.0060.020.03 Correlation Analysis·Significant Findings There were no differences between PTCA and CABG in terms of the frequency of N-Les, and the frequency of ischemic evidence due to N-Les over the 3 years. Of 136 pts who completed 3-year angiographic F/U and had MI or TL or AddP, only 19 (14%) were due to N-Les. As expected, both PTCA and CABG pts with atherogenic risk profiles were more likely to develop N-Les.