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The aim of this study was to clarify the significance of enhanced thallium-201 (201Tl) uptake after reinjection following 4-hour redistribution imaging. Thirty-four patients with coronary artery disease (CAD) and left ventricular (LV) dysfunction (ejection fraction 32 +/- 10%) underwent exercise-redistribution (ER) 201Tl scintigraphy with rest injection, resting technetium-99m methoxy isobutyl isonitrile (MIBI) imaging, 2D-echocardiography, and coronary angiography. Wall motion (WM) was graded on echocardiographic images. A total of 510 myocardial segments were quantitatively analyzed. A total of 267 (52%) segments had normal (N) 201Tl uptake, 53 (10%) reversible (RD), and 190 (37%) irreversible (ID) 201Tl defects on ER images. Of these 190 ID, 84 (44%) showed enhanced 201Tl uptake after reinjection (Re+) and 106 (56%) remained unchanged after reinjection (Re-). MIBI uptake was significantly higher in RD compared to Re+ and Re- (both p < 0.01), and in Re+ compared to Re- (p < 0.01). The WM score was significantly lower in RD and Re+ compared to Re- (p < 0.01), while no difference was observed between RD and Re+. The severity of coronary artery stenosis was significantly lower in RD compared to Re+ and Re- (both p < 0.01), but no difference was observed between Re+ and Re-. The occurrence of collaterals was significantly higher (p < 0.01) in Re+ (69%) compared to Re- (38%). In conclusion, in patients with CAD and impaired LV function, enhanced 201Tl uptake after reinjection in myocardial segments with ID on ER images was associated with less severe WM abnormalities, higher MIBI uptake and the presence of collaterals.(ABSTRACT TRUNCATED AT 250 WORDS)

Background: We compared rest-redistribution thallium 201 and resting technetium 99m methoxyisobutyl isonitrile (MIBI) cardiac imaging in 29 men with angiographically proven coronary artery disease and regional ventricular dysfunction. Left ventricular ejection fraction at radionuclide angiography was 35% +/- 9%., Methods and Results: Regional left ventricular wall motion was assessed on gated 99mTc MIBI images according to a 3-point scale (0 = normal, 1 = hypokinetic, 2 = akinetic or dyskinetic). 201Tl and 99mTc MIBI uptake values were analyzed quantitatively. A total of 435 myocardial segments were classified on the basis of wall motion analysis into three groups: group 1 (normal wall motion; n = 201), group 2 (hypokinetic; n = 132), and group 3 (akinetic or dyskinetic; n = 102). 201Tl and 99mTc MIBI uptake values were significantly higher in groups 1 and 2 compared with group 3 (p < 0.05) and in group 1 compared with group 2 (p < 0.05). When 201Tl and 99mTc MIBI uptake values were directly compared, no significant differences in group 1 and 2 were observed. In group 3, 99mTc MIBI uptake (67% +/- 14%) was significantly lower (p < 0.001) than initial (72% +/- 11%) and delayed 201Tl uptake (73% +/- 12%)., Conclusion: Thus rest-redistribution 201Tl and resting 99mTc MIBI cardiac imaging reflect the severity of left ventricular dysfunction in coronary artery disease. However, in segments with severely impaired regional ventricular function, 201Tl uptake is significantly higher than 99mTc MIBI uptake.

The authors evaluated the clinical applications of Tc-99m methoxy isobutyl isonitrile (MIBI) in the simultaneous assessment of ventricular function and myocardial perfusion in patients with congenital heart disease. Global ventricular function was assessed by first-pass ECG gated study. Myocardial perfusion was evaluated on images performed 1 hour after the injection of the tracer. Regional wall motion and systolic thickening were assessed by gated study acquired after the perfusion study. Two young patients were studied after a surgical Glenn procedure. The first patient, with a history of transposition of the great vessels and univentricular heart, had an ejection fraction of 44%. The left ventricle was dilated and the right ventricle was not appreciable. The septal and inferoapical regions showed reduced perfusion and reduced systolic thickening. The second patient, with a history of pulmonary atresia, septal defect and left ventricular hypoplasia, had a right ventricular ejection fraction of 37%. Regional wall motion, systolic thickening, and myocardial perfusion were normal. The right ventricle was hypertrophic and larger than the left ventricle. Thus, a single injection of Tc-99m MIBI allows noninvasive simultaneous assessment of global and regional ventricular function and myocardial perfusion in young patients with complicated congenital heart disease.

Ambulatory monitoring (VEST) of left ventricular (LV) function has been shown to be accurate and repeatable. The aim of this study was to assess VEST repeatability in the evaluation of haemodynamic responses to different cardiac stimulations. Twelve patients (all men, mean age 59 +/- 8 years) underwent two separate VEST studies 5-day apart. In both studies, LV function was continuously monitored at rest and during different cardiac stimulations: 1) changing position from supine to upright (tilt); 2) sustained isometric exercise (handgrip); and 3) sublingual administration of 5 mg of nitroglycerin (NTG). Changes from baseline to peak response (delta) in the heart rate, ejection fraction, end-diastolic volume, end-systolic volume, stroke volume and cardiac output were evaluated. Reproducibility was assessed by computing, the coefficient of repeatability. In addition, the differences between the delta values obtained with the two VEST studies were plotted against their mean. This plot allowed us to detect whether there was any relationship between the error in the measurements and the best estimate of the "true value". No statistically significant differences between the two VEST studies were found in the haemodynamic changes in heart rate, ejection fraction, end-diastolic volume, end-systolic volume, stroke volume and cardiac output induced by handgrip, tilt and NTG. For each parameter the mean difference was not significantly different from zero and no significant relationship between the error and the "true value" was observed. Our results demonstrate that VEST has a good repeatability in measuring cardiac haemodynamic responses to different types of stimulations.

We studied 19 patients with angiographically proven coronary artery disease and left ventricular dysfunction (ejection fraction 33% +/- 8%) by resting technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) and rest-redistribution thallium-201 cardiac imaging. Thallium and 99mTc-MIBI studies were visually analysed. Of 285 segments, 203 (71%) had normal thallium uptake, 48 (17%) showed reversible thallium defects and 34 (12%) showed irreversible thallium defects. Of these 34 irreversible thallium defects, 19 (56%) were moderate and 15 (44%) were severe. Of the corresponding 285 segments, 200 (70%) had normal 99mTc-MIBI uptake, while 37 (13%) showed moderate and 48 (17%) showed severe reduction of 99mTc-MIBI uptake. Myocardial segmental agreement for regional uptake score between initial thallium and resting 99mTc-MIBI images was 90% (kappa = 0.78). Segmental agreement between delayed thallium and resting 99mTc-MIBI images was 77% (kappa = 0.44). In particular, in 26 (9%) segments 99mTc-MIBI uptake was severely reduced while delayed thallium uptake was normal or only moderately reduced. These data suggest that although rest-redistribution thallium and resting 99mTc-MIBI cardiac imaging provide concordant results in the majority of myocardial segments, some segments with severely reduced resting 99mTc-MIBI uptake may contain viable but hypoperfused myocardium. Thus, conclusions on myocardial viability based on 99mTc-MIBI uptake should be made with caution in chronic coronary artery disease.

We studied 25 male patients, with coronary artery disease, mean age 56 +/- 8 yr. All underwent 201Tl rest-redistribution and resting 99mTc methoxyisobutyl isonitrile (MIBI) cardiac imaging. Regional 201Tl and MIBI uptake were quantitatively analyzed. Regional left ventricular wall motion (WM) was visually assessed on MIBI gated images using a three-point scale (0 = normal, 1 = hypokinetic, 2 = a/dyskinetic). Two patterns of reverse redistribution (RR) were identified: RR-A when 201Tl uptake was normal on rest images and abnormal on redistribution images, and RR-B when 201Tl uptake was abnormal on rest images and a significant decrease in uptake was observed on redistribution images. Of the total 375 myocardial segments analyzed, 229 were classified as normal (Nl), 40 as reversible defect (RD), 74 as irreversible defect (ID); 26 showed RR-A while 6 myocardial segments had RR-B. Myocardial segments with RR-A differed from NI in the degree of coronary artery stenosis (81% +/- 33% versus 57% +/- 39%, respectively, p < 0.05), in WM score (1.1 +/- 0.7 versus 0.5 +/- 0.6, respectively, p < 0.01), and in MIBI uptake (81% +/- 10% versus 92% +/- 9%, respectively, p < 0.0001). Moreover, the percent of myocardial segments supplied by a totally occluded coronary artery was significantly higher (p < 0.05) in myocardial segments with RR-A (46%) than in NI (22%). Segments with RR-B did not show any significant difference either from RD and ID. These results suggest that myocardial segments with RR-A on resting 201Tl images have impaired function and are supplied by severely stenosed coronary arteries and should not be considered normal.

The accuracy of an ambulatory radionuclide detector (VEST) for left ventricular systolic (ejection fraction, EF) and diastolic (peak filling rate, PFR) measurements was assessed at different time averaging of the nuclear and electrocardiographic data. Fifty-one patients, in a total of 67 studies, underwent equilibrium radionuclide angiography (RNA) immediately before a VEST study. VEST data were analyzed using single-beat analysis and different time averaging of 5, 10, 15, 30 and 60 sec. Agreement between VEST and RNA in estimating EF and PFR was evaluated by computing limits of agreement (LA). These were computed as 1.96 times the s.d. of the mean differences between the two methods, expressed in the same unit as EF and PFR. Differences between the two methods were plotted against their mean, allowing investigation of any possible relationship between measurement error and the true value (whose best estimate is the mean between the two methods). The entire statistical analysis was repeated at each different time averaging. LAs for EF measurement by VEST were -10.4:8.8 (single-beat analysis), -11.2:9.9 (5-sec averaging), -5.4:4.8 (10-sec averaging), -4.9:4.5 (15-sec averaging), -6.2:5.6 (30-sec averaging), -6.9:4.5 (60-sec averaging). Results indicate good agreement between VEST and RNA in measuring EF, at least for time averaging > or = 10 sec. LAs for PFR ranged from -0.6:0.6 (single beat) to -1.0:0.6 (60-sec averaging), which was considered a clinically acceptable agreement between VEST and RNA. No relationship between measurement error and true value was found either for EF and PFR.

Background: This study evaluates the incremental prognostic value of qualitative thallium-201 imaging and coronary angiography in patients with suspected or known coronary artery disease., Methods: Within 1 month, 150 patients underwent diagnostic symptom-limited ECG stress test, thallium imaging, and coronary angiography. The incremental power of sequentially performed tests was evaluated by the overall likelihood ratio statistic., Results: At 3-year follow-up, 16 patients had died from a cardiac cause, 12 had suffered a nonfatal myocardial infarction, and 34 had undergone revascularization procedures more than 60 days after testing. Considering hard events, thallium imaging did not improve the prognostic information provided by clinical exercise stress test data, while coronary angiography increased the predictive power of the combined, exercise stress test, and scintigraphic data (P < 0.001). Moreover, when thallium results were added to clinical, exercise, and coronary angiographic data, the predictive power was unchanged. When the analysis was repeated including the occurrence of late revascularization procedures, each test showed additional prognostic information to that obtained by the other combined tests (P < 0.001)., Conclusions: This study demonstrates that in patients with a symptom-limited ECG stress test, coronary angiography adds prognostic information to combined clinical, exercise ECG, and thallium imaging data. The incremental prognostic value of qualitative thallium imaging is demonstrable only when late revascularization procedures are included as events.

To compare rest-injected thallium-201 (Tl) redistribution and resting technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) myocardial uptake in chronic coronary artery disease (CAD), 15 patients with angiographically proven CAD and left ventricular (LV) dysfunction (ejection fraction 34% +/- 9%) were studied. All patients underwent rest-redistribution Tl and resting 99mTc-MIBI cardiac imaging. Gated 99mTc-MIBI images were also acquired to assess regional LV wall motion (WM). Myocardial segments (n = 225) were divided into three groups on the basis of the degree of coronary artery stenosis: group 1 (total occlusion, n = 82), group 2 (50%-99% of stenosis, n = 84) and group 3 (< 50% of stenosis, n = 59). WM was significantly worse in groups 1 and 2 compared to group 3 (P < 0.001), but no difference was observed between groups 1 and 2. Tl and 99mTc-MIBI uptake were significantly lower in groups 1 and 2 compared to group 3 (P < 0.001), and in group 1 compared to group 2 (P < 0.001). When Tl and 99mTc-MIBI uptake were directly compared. Tl uptake was higher than 99mTc-MIBI uptake in group 1 (P < 0.001), while no significant difference was observed in groups 2 and 3. Thus, both rest-injected Tl redistribution and resting 99mTc-MIBI uptake reflected the severity of coronary artery stenosis in CAD. However, in myocardial segments with total coronary occlusion Tl uptake was significantly higher than 99mTc-MIBI uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

The recent development of new radionuclide detectors allows noninvasive outpatient monitoring of left ventricular function. This study was aimed at describing a new radionuclide technique useful to monitor cardiac function and at evaluating its potential clinical applications. We studied 14 normal subjects, 30 patients with coronary artery disease and 25 patients with dilated cardiomyopathy. Left ventricular function was continuously monitored in control conditions at rest, during daily physical activity of different intensity (walking on a level surface and climbing stairs), and during bicycle exercise. Left ventricular ejection fraction (EF) variability during recording in control conditions at rest was 0.2 +/- 1.8%. A significant relationship between outpatient EF at rest and conventional equilibrium radionuclide angiography was observed (r = 0.97, n = 69, p less than 0.001). In normal subjects both daily physical activity and exercise stress test induced an increase in heart rate and EF. In patients with coronary artery disease and in patients with dilated cardiomyopathy a heterogeneous EF response was observed during physical activity and exercise stress test. Our results demonstrate that this technique can be used for the ambulatory monitoring of left ventricular function in both normal subjects and patients with different types of cardiomyopathies.

Background: The recent development of an ambulatory radionuclide detector (VEST) to assess left ventricular (LV) function may enhance the detection of ischemia during routine daily activities in patients with coronary artery disease (CAD). The aim of this study was to evaluate the usefulness of VEST in monitoring LV ejection fraction (EF) responses to daily activities and sustained handgrip test (HG) in patients with CAD., Methods: 13 patients (12 men and 1 woman) with angiographically proven coronary artery disease were studied by VEST (mean 162 min, range 120 to 250 min). LV responses to different daily activities (walking and climbing stairs) and to HG were evaluated., Results: Walking on a level surface and climbing stairs did not induce significant change in mean LVEF. However, a transient decrease in EF was observed in 4 (31%) and in 5 (38%) of the 13 patients during walking and climbing stairs, respectively. HG induced a significant (p < 0.01) reduction in mean EF. In particular, during HG, EF decreased > or = 5% in 11 (85%) of the 13 patients. A transient spontaneous decrease in LVEF lasting > or = 1 min was observed on 18 occasions in 11 patients with CAD; 5 episodes were symptomatic and 13 asymptomatic. ECG ST segment depression was recorded in 4 of the 5 symptomatic and in 5 of the 13 asymptomatic episodes., Conclusions: These results suggest that simultaneous monitoring of LV function and ECG may permit a better understanding of the incidence and severity of ischemic symptomatic and asymptomatic episodes.

The accuracy and repeatability of a new ambulatory radionuclide detector (VEST) for left ventricular systolic (ejection fraction) and diastolic (peak filling rate) measurements were assessed. Seventeen patients underwent equilibrium radionuclide angiography immediately before and immediately after a VEST study. The accuracy was evaluated at the beginning and at the end of the VEST studies. Limits of agreement for the ejection fraction were -1%:2% at the beginning of the VEST study and -4%:4% at the end. Limits of agreement for the peak filling rate were -0.6:0.6 at the beginning of the VEST study and -0.7:0.5 at the end. For both measurements the limits of agreement were well within the clinical range. Repeatability was evaluated in a second group of 11 patients who underwent VEST studies in 2 separate days. The coefficient of repeatability (twice the standard deviation of the differences between the 2 studies) was 13 for the ejection fraction and 0.4 for the peak filling rate. Thus, the VEST is an accurate and repeatable method to measure both the ejection fraction and peak filling rate.

In this study we compared the results of exercise and trans-oesophageal atrial pacing (TAP) technetium-99m methoxyisobutyl isonitrile (99mTc-SESTAMIBI) cardiac imaging in the evaluation of left ventricular (LV) function and myocardial perfusion in patients with angiographically proven coronary artery disease. Ten patients (8 men and 2 women, mean age 59 +/- 6 years) were submitted to 3 separate injections of 99mTc-SESTAMIBI, one under control conditions, one after exercise and one after TAP. LV ejection fraction, as measured by electrocardiogram (ECG) gated first pass, decreased from 49 +/- 5% under control conditions to 42 +/- 6% during exercise (P less than 0.05 versus control) and to 43 +/- 8% during TAP (P less than 0.05 versus control and insignificant change versus exercise). Segmental myocardial perfusion analysis was performed on a total of 150 myocardial segments. On both exercise and TAP 99mTc-SESTAMIBI studies, 103 segments (69% of the total) were normal, 32 (21%) had reversible, and 15 (10%) irreversible, perfusion defects. Relative regional tracer uptake was not statistically different between exercise and TAP in normal regions (91.1 +/- 9.1% versus 90.7 +/- 8.5%, respectively), in regions with reversible (61.9 +/- 12% versus 62.4 +/- 10.4%, respectively) and irreversible perfusion defects (55.8 +/- 7.8% versus 58.8 +/- 9.5%, respectively). Our results demonstrated that 99mTc-SESTAMIBI TAP cardiac imaging shows similar results to 99mTc-SESTAMIBI exercise myocardial scintigraphy in the assessment of LV function and myocardial perfusion in patients with coronary artery disease.

Technetium-99m methoxy-isobutyl-isonitrile (MIBI) myocardial scintigraphy has been proposed as an alternative to Thallium 201 myocardial imaging in the evaluation of patients with coronary artery diseases. We studied 39 patients (37 men, mean age 56 +/- 9 years) with suspected coronary artery disease. All patients underwent 99mTc MIBI myocardial scintigraphy after stress and at rest. Coronary arteriography, performed within 1 month, showed significant (greater than or equal to 50%) stenosis of at least 1 epicardial coronary artery in 36 subjects. 99mTc MIBI myocardial scintigraphy exhibited 94% sensitivity (34/36 patients) and 100% specificity (3/3 subjects with normal coronary arteries). Sensitivity for individual vessel stenosis was 81% (96% for the left anterior descending artery, 65% for the circumflex artery and 79% for the right artery). Our data show that 99mTc MIBI myocardial scintigraphy is capable of evaluating patients with coronary artery diseases.