Comparison of post-exercise and post-vasodilator stress myocardial stunning as assessed by electrocardiogram-gated single-photon emission computed tomography.

BACKGROUND: Exercise gated single-photon emission computed tomography (SPECT) using technetium-99m (99mTc)-sestamibi evaluates both myocardial perfusion during stress and wall motion >30 min after the stress, which has the potential to assess not only exercise-induced myocardial ischemia but also the development of myocardial stunning. METHODS AND RESULTS: To evaluate the incidence of post-stress myocardial stunning, as well as comparing the effects of different stress methods on the development of stunning, 179 consecutive patients with known or suspected coronary artery disease (CAD) underwent (99m)Tc-sestamibi SPECT with either exercise (n=135) or adenosine triphosphate disodium (ATP) (n=44). Electrocardiogram-gated SPECT images were acquired >30 min after the stress and again 4 h later, and perfusion and wall motion were evaluated. Post-stress myocardial stunning occurred in 24 patients (13%): 22 after exercise and 2 after ATP stress. The magnitude of the transient wall motion abnormality after exercise was greater in patients with severe ischemia, compared with those with mild-to-moderate ischemia (p<0.0001). By contrast, with ATP stress, the magnitude of the transient wall motion abnormality was similar, regardless of the severity of perfusion abnormality. Furthermore, a significant correlation between summed difference score and transient wall motion abnormality was found after exercise (r=0.68, p<0.0001). With ATP, however, no such correlation was observed (r=0.28, p=NS). CONCLUSIONS: Using 99mTc-sestamibi gated SPECT, myocardial stunning is frequently observed after exercise and correlates with the severity of myocardial ischemia, but this does not occur with ATP, which is regarded as a specific marker for severe CAD.     

Postischemic Stunning Can Affect Left Ventricular Ejection Fraction and Regional Wall Motion on Post-Stress Gated Sestamibi Tomograms

Objectives. This study was designed to investigate whether left ventricular ejection fraction (LVEF) calculated from post-stress single-photon emission computed tomography (SPECT) reflects the basal value for LVEF or whether post-stress LVEF is reduced in some patients with stress-induced ischemia.

Background. Automated programs are now commercially available for assessing global left ventricular (LV) function from post-stress technetium-99m sestamibi gated SPECT performed >15 min after completion of exercise.

Methods. Eighty-one sequential patients who underwent a 2-day stress/rest sestamibi imaging protocol and showed perfusion defects on the post-stress tomogram underwent gated acquisition of the second-day rest tomogram. The post-stress and rest tomographic images were read for presence, location, severity and reversibility of defects by consensus of two to three experienced observers with the aid of circumferential count displays. Defects were scored as mild, moderate or severe and as completely or partially reversible or fixed, and a summed defect severity score was calculated. Of these 81 scans, 20 showed nonreversible perfusion defects (group 3), whereas 61 showed reversible perfusion defects. Post-stress and rest LVEF was calculated from the processed gated SPECT data. From 15 additional patients who underwent rest gated SPECT studies on separate days, serial reproducibility of LVEF values calculated from the gated SPECT data was determined to be ±5.2%. Coronary angiography was performed within 3 months of the scan without intervening events in 47 of 81 patients, including 39 of 61 with reversible perfusion defects.

Results. In 22 (36%) of 61 patients with reversible perfusion defects, post-stress LVEF was >5% lower than that at rest (group 2), whereas in the remaining 39 patients, post-stress LVEF was either ±5% or greater than that at rest (group 1). Segmental chordal shortening analysis performed in group 2 studies showed that differences in chordal shortening between rest and post-stress were significantly greater in the reversible perfusion defect territories than in the nonischemic perfusion defect territories ([mean ± SD] 0.14 ± 0.14 vs. 0.02 ± 0.09, respectively, p < 0.0001). There were no significant differences among groups for any of the following variables: age, gender, previous myocardial infarction and type of stress. Time to imaging and stress and scan variables were correlated with the change in LVEF by univariate analysis, and the two variables that correlated significantly were the summed defect reversibility score on the scan and a left anterior descending coronary artery location of the scan defect. Only summed defect reversibility score was significant on multivariate analysis.

Conclusions. When the only gated sestamibi scan is the post-stress scan, global and regional LV function will not represent basal LV function in all patients with stress-induced ischemia.     

Evaluation of global and regional left ventricular function obtained by quantitative gated SPECT using 99mTc-tetrofosmin for left ventricular dysfunction

OBJECTIVE: The quantitative gated SPECT (QGS) software is able to calculate LV volumes and visualize LV wall motion and perfusion throughout the cardiac cycle using an automatic edge detection algorithm of the left ventricle. We evaluated the reliability of global and regional LV function assessment derived from QGS by comparing it with the results from left ventriculo-cineangiography (LVG). PATIENTS: In 20 patients with left ventricular dysfunction who underwent ECG gated 99mTc-tetrofosmin SPECT, the end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (LVEF) were calculated. The QGS-assessed regional wall motion was determined using the cinematic display. RESULTS: QGS-derived EDV, ESV and LVEF correlated well with those by LVG (p<0.001 for each). There was a good correlation between wall motion score (WMS) derived from the QGS and the LVG (r=0.40, p<0.05). In some patients with extensive myocardial infarction, there was a discrepancy in the regional wall motion results between QGS and LVG. CONCLUSIONS: The ECG-gated SPECT using QGS is useful to evaluate global and regional LV functions in left ventricular dysfunction.     

Myocardial scintigraphy by the gated SPECT method in coronary disease patients with postischemic stunning

Gated SPECT using Tc-99m-labeled flow tracers provides simultaneous assessment of global and regional myocardial perfusion and function. The aim of this study was to evaluate whether regional wall thickening (WT) obtained after stress and at rest makes it possible to identify and analyze a subgroup of post-ischemic stunned patients. METHODS: We studied 20 patients (18 males) who underwent conventional diagnostic dual-day stress/rest Gated SPECT following injection of 925 MBq of 99mTc-tetrofosmin using a dual-head SPECT camera (Vertex ADAC). The mean age of these patients was 59 years (38-71) and 10 of them had a history of previous acute myocardial infarction (AMI). Perfusion was analyzed on ungated images using 20 segments scored on a 5-point scale (0 = normal, 4 = no uptake), while WT and motion were assessed visually on stress/rest end-systolic images using a 4-point score (0 = normal, 3 = absence of WT/motion). Left ventricular ejection fraction (LVEF) and volumes were calculated. All patients underwent coronary angiography. RESULTS: All patients showed at least one reversible defect with post-stress WT reduction and normal rest WT. The stunned group showed a significant post-stress reduction of LVEF and a statistically non-significant increase of end systolic volume (ESV). A good correlation was observed between global perfusion and WT score both at stress and rest conditions; LVEF showed a significant inverse correlation with global post-stress and rest perfusion and WT score. ESV and the global perfusion stress/rest score showed a good correlation, while end-diastolic volume did not correlate. In 44% of the segments with fixed defects, there was a normal WT and normal coronary-related vessel (false positives); 28% of reversible segments showed a post-stress pathological WT and five of them a rest pathological WT. CONCLUSIONS: The gated SPECT myocardial perfusion evaluation allowed us to analyze a subgroup of post-stress stunned coronary artery disease patients. The post-stress LVEF reduction in this population seems to be due to the increase of end-systolic volume caused by endocardial ischemia. The stunned segments showed severe perfusion defects.     

Gated technetium-99m sestamibi for simultaneous assessment of stress myocardial perfusion,postexercise regional ventricular function and myocardial viability: Correlation with echocardiography and rest thallium-201 scintigraphy

Objectives. This study compares technetium-99m sestamibi (sestamibi) electrocardiographic (ECG) gated single-photon emission computed tomography (gated SPECT) and echocardiography for the evaluation of myocardial function and assesses the feasibility of single-injection, single-acquisition stress perfusion/rest function technetium-99m sestamibi-gated SPECT as an alternative to conventional stress/rest imaging for assessment of myocardial perfusion and viability.Background. Simultaneous assessment of stress perfusion and rest function is possible with gated SPECT acquisition of stress-injected technetium-99m sestamibi.Methods. Rest thallium-201 SPECT followed by stress sestamibigated SPECT (acquired 0.5 to 1 h after sestamibi injection) was performed in 58 patients. Echocardiography was performed immediately after or before gated SPECT in 43 of the patients. All studies were analyzed by semiquantitative visual scoring. Sestamibi-gated SPECT studies were read for stress perfusion and rest wall motion and thickening. Reversibility on sestamibi-gated SPECT was defined as the presence of a definite stress defect with normal or mildly impaired wall motion or thickening on gated SPECT.Results. There was high segmental score agreement between gated SPECT and echocardiography for wall motion (91%, kappa = 0.68, p < 0.001) and thickening (90%, kappa = 0.62, p < 0.001). Correlation for global wall motion (r = 0.9S, p < 0.001) and thickening (r = 0.96, p < 0.001) scores between the two modalities was excellent. In 32 patients without previous myocardial infarction, there was excellent agreement for reversibility between stress sestamibi-gated SPECT and rest thallium-201/stress sestamibi (98%, kappa = 0.93, p < 0.01). However, in 26 patients with previous infarction, discordance between the two approaches was frequent, with 26% (20 of 78) of nonreversible defects by stress sestamibi-gated SPECT being reversible by rest thallium-201/stress sestamibi and 21% (23 of 112) of reversible defects by stress sestamibi-gated SPECT being nonreversible by rest thallium-201/stress sestamibi.Conclusions. Gated SPECT of stress-injected sestamibi correlates well with echocardiographic assessment of regional function and thus adds information to perfusion SPECT. In patients without previous myocardial infarction, a single-injection stress perfusion/rest function approach using sestamibi-gated SPECT can substitute for conventional stress/rest myocardial perfusion imaging, adding a rest perfusion study only if there are nonreversible defects or consideration of attenuation artifacts. In patients with previous myocardial infarction, the gated SPECT approach does not replace the need for a rest perfusion study.     

Assessment of left ventricular function by electrocardiogram-gated myocardial single photon emission computed tomography using quantitative gated single photon emission computed tomography software]

Electrocardiogram (ECG)-gated myocardial single photon emission computed tomography (SPECT) can assess left ventricular (LV) perfusion and function easily using quantitative gated SPECT (QGS) software. ECG-gated SPECT was performed in 44 patients with coronary artery disease under post-stress and resting conditions to assess the values of LV functional parameters, by comparison to LV ejection fraction derived from gated blood pool scan and myocardial characteristics. A good correlation was obtained between ejection fraction using QGS and that using cardiac blood pool scan (r = 0.812). Some patients with myocardial ischemia had lower ejection fraction under post-stress compared to resting conditions, indicating post-stress LV dysfunction. LV wall motion and wall thickening were significantly impaired in ischemic and infarcted myocardium, and the degree of abnormality in the infarcted areas was greater than in the ischemic area. LV functional parameters derived using QGS were useful to assess post-stress LV dysfunction and myocardial viability. In conclusion, ECG-gated myocardial SPECT permits simultaneous quantitative assessment of myocardial perfusion and function.     

Left ventricular function assessed by gated spet after an exercise-augmented adenosine infusion. Correlation with myocardial ischaemia

BACKGROUND. Gated single photon emission tomography (SPET) may simultaneously assess perfusion and function of the myocardium. AIM. To evaluate the relationship between the presence of ischaemia during an adenosine stress test and the changes in left ventricular (LV) function obtained after stress and at rest with gated SPET by using adenosine same-day stress and rest protocol. METHODS. The study population consisted of twenty eight patients. The gated SPET acquisition was performed both after adenosine vasodilatation and at rest with a protocol as follows: 300 MBq of Tc-99m Myoview at stress, 700 MBq reinjection at rest and double head gamma camera. Global left ventricular ejection fraction (LVEF) and end-diastolic and end-systolic volumes (EDV, ESV) as well as the regional wall motion reversibility from post-stress and resting scan were analysed. RESULTS. Wall motion disturbances were present in the stress study in 15 patients with subsequent improvement in 14 cases on the rest scans. An independent evaluation of the perfusion data revealed significant reversible myocardial ischaemia in 18 patients and negative result in 10. There was a significant difference between EDV change in patients with or without ischaemia (p<0.02). The post-stress LVEF and ESV were significantly different from those measured at rest. Reversible regional wall motion impairment indicated the presence of significant reversible myocardial ischaemia with an 88% positive predictive value (70% and 75% for sensitivity and specificity, respectively). CONCLUSIONS. The post-stress LVEF with gated SPET may not reflect true resting measurements. The qualitative assessment of regional wall motion reversibility shows better correlation with the ischaemic scan pattern than the difference in the LVEF and may be helpful in assessing the significance of reversible myocardial ischaemia.     

Reversible regional wall motion abnormalities on exercise technetium-99m-gated cardiac single photon emission computed tomography predict high-grade angiographic stenoses

OBJECTIVES: We sought to determine the level of angiographic stenosis at which reversible regional wall motion abnormalities (RWMA) are present on exercise stress technetium-99m (Tc-99m)- gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), and whether assessments of stress and rest RWMA add incremental diagnostic information. BACKGROUND: Stress and rest gated SPECT MPI enables the detection of post-exercise stunning. Although some studies have correlated RWMA to the severity of MPI defects, only one previous study correlated RWMA on gated MPI to angiographic findings. However, this correlation excluded patients with rest perfusion defects and did not involve gating of rest images. METHODS: One hundred patients undergoing angiography within six months of exercise stress Tc-99m (sestamibi)-gated SPECT MPI (in the absence of interim cardiac events or revascularization) were recruited. Images were acquired 15 to 30 min after stress and interpreted without knowledge of the Duke treadmill score, left ventricular ejection fraction and angiographic data. RESULTS: The sensitivity of reversible RWMA for angiographic stenoses >70% was 53%, with a specificity of 100%. The presence of reversible RWMA was able to stratify patients with angiographic stenoses of 50% to 79% and 80% to 99% with a high positive predictive value. A good correlation was noted between the presence of reversible RWMA and the coronary artery jeopardy score (R = 0.49, p < 0.0001). Multivariate analysis showed that the post-stress RWMA, Duke treadmill and reversible RWMA scores were significant predictors of angiographic severity. CONCLUSIONS: Post-stress and reversible RWMA, as shown by exercise stress Tc-99m-gated SPECT MPI, are significant predictors of angiographic disease and add incremental value to MPI for the assessment of angiographic severity.     

Gated single-photon emission computed tomographic myocardial imaging: a new tool in clinical cardiology

BACKGROUND: Gated single-photon emission computed tomography (gated SPECT) myocardial perfusion imaging allows the analysis of left ventricular (LV) perfusion and function during the same acquisition. RESULTS: Gated SPECT provides additional information to myocardial perfusion, which improves test specificity in patients with known or suspected coronary artery disease and hence diminishes the amount of borderline diagnosis. Because gated SPECT provides reliable information on LV ejection fraction and LV volumes, it is also a valuable tool in risk stratification. In addition, from gated SPECT, images can be reconstructed from which wall motion can be assessed showing a good correlation with wall motion assessed by accepted imaging modalities as echocardiography, magnetic resonance imaging, and contrast angiography. In the future wall motion analysis from gated SPECT may also be used for revascularization stratification. CONCLUSIONS: Gated SPECT gives important additional information beyond myocardial perfusion imaging alone, which could have major clinical implications for optimal patient management.     

Comparison of gated single-photon emission computed tomography with magnetic resonance imaging for evaluation of left ventricular function in ischemic cardiomyopathy

To perform a head-to-head comparison between magnetic resonance imaging (MRI) and gated single-photon emission computed tomography (SPECT) for the evaluation of left ventricular (LV) function (LV ejection fraction [LVEF], LV volumes, and regional wall motion) in patients with ischemic cardiomyopathy, we studied 22 patients with chronic coronary artery disease and LV dysfunction. Multislice, multiphase echoplanar MRI was performed with Philips Gyroscan ACS-NT15. Image analysis was performed using the MASS software package to determine LV end-systolic volume, LV end-diastolic volume, and LVEF. The same parameters were calculated using quantitative gated SPECT software (QGS, Cedars-Sinai Medical Center). The different parameters were compared using linear regression, and correlation coefficients were calculated. Regional wall motion was also determined from both techniques, according to a 13-segment model and a 3-point scoring system (from 1 = normokinesia to 3 = akinesia or dyskinesia). A summed wall motion score was also calculated for MRI and gated SPECT. Good correlations were found between MRI and gated SPECT for all parameters: (1) summed wall motion score^MRI versus summed wall motion score^SPECT: Y = 0.74x + 8.0, R = 0.88, p <0.01; (2) LV end-systolic volume^MRI versus LV end-systolic volume^SPECT: Y = 0.94x − 12.3, R = 0.87, p <0.01; (3) LV end-diastolic volume^MRI versus LV end-diastolic volume^SPECT: Y = 0.93x − 18.4, R = 0.84, p <0.01; and (4) LVEF^MRI versus LVEF^SPECT: Y = 0.97x + 0.68, R = 0.90, p <0.01. For regional wall motion, an exact agreement of 83% was found, with a kappa statistic of 0.77 (95% confidence intervals 0.71 to 0.83, SE 0.03), indicating essentially excellent agreement. Thus, close and significant correlations were observed for assessment of LVEF, LV volumes, and regional wall motion by MRI and gated SPECT in patients with ischemic cardiomyopathy.     

Identification of severe and extensive coronary artery disease by postexercise regional wall motion abnormalities in Tc-99m sestamibi gated single-photon emission computed tomography

Postexercise wall motion abnormality (WMA) in patients with normal resting myocardial perfusion may represent prolonged postischemic stunning, and may be related to the presence of severe angiographic coronary artery disease (CAD). This study assesses the diagnostic value of postexercise WMA by technetium-99m (Tc-99m) sestamibi gated single-photon emission computed tomography (SPECT) in patients with normal resting perfusion. Ninety-nine patients underwent exercise gated Tc-99m sestamibi/resting thallium-201 SPECT and coronary angiography within 90 days of nuclear testing. All patients had normal perfusion at rest. Multivariate logistic regression analysis demonstrated an incremental value of wall motion and perfusion over perfusion data alone in identifying severe and extensive CAD. Sensitivity for identifying any severely stenosed coronary artery by WMA was significantly higher than by severe perfusion defect (78% vs 49%, p <0.0001). Overall specificities of severe perfusion defect and WMA were 91% and 85%, respectively (p = NS). Thus, postexercise WMA detected by gated Tc-99m sestamibi SPECT in patients with normal resting perfusion is a sensitive marker of severe and extensive CAD.     

Good correlation between gated single photon emission computed myocardial tomography and contrast ventriculography in the assessment of global and regional left ventricular function

Purpose: The purpose of this study was to determine the reliability of the measured left ventricular ejection fraction (LVEF) and wall motion analysis by the recently introduced quantitative electrocardiographically (ECG)-gated myocardial perfusion single-photon emission computed myocardial tomography technique (gated SPECT) (QGS). Materials and methods: We compared technetium-99 m tetrofosmin gated SPECT imaging and contrast ventriculography in the assessment of global and regional left ventricular function in 74 patients with undiagnosed chest pain of whom 27 sustained a previous myocardial infarction. Results: Linear regression analysis demonstrated that gated SPECT determined LVEF correlated well with LVEF determined from contrast ventriculography (y = 0.95x + 1.9, r ² = 0.84, p < 0.0001). Bland–Altman plot analysis showed no systematic difference between the two sets of values derived from the two imaging approaches over a wide range of LVEF values. Exact agreement of segmental wall motion scores was 460 of 518 (89%) segments with a kappa value of 0.76 (p < 0.0001). Conclusion: We conclude that gated SPECT imaging is an accurate and reliable clinical tool to accurately measure global and regional left ventricular function.     

Usefulness of electrocardiographic-gated stress technetium-99m sestamibi single-photon emission computed tomography to differentiate ischemic from nonischemic cardiomyopathy

The noninvasive differentiation between ischemic and nonischemic cardiomyopathy is frequently difficult. We examined the clinical value of stress electrocardiographic gated (ECG-gated) single-photon emission computed tomography (SPECT) to identify ischemic cardiomyopathy and detect coronary artery disease (CAD) in 164 patients without known CAD, ejection fraction < or =40% by ECG-gated SPECT, and subsequent coronary angiography. Summed stress, rest, and difference scores were measured from the SPECT studies, and regional wall motion variance was calculated from the ECG-gated images. Sensitivity and 95% confidence intervals for the diagnosis of ischemic cardiomyopathy and for detection of any CAD (>50% diameter stenosis) were estimated using previously defined cutoffs for summed stress score and regional wall motion variance. For the diagnosis of ischemic cardiomyopathy, sensitivity of stress SPECT (summed stress score >8) was 87% (95% confidence interval [CI] 78 to 95), with a specificity of 63% (95% CI 60 to 82). The addition of wall motion information (summed stress score >8 or regional wall motion variance >0.114) increased sensitivity to 88% (95% CI 80 to 96) and decreased specificity to 45% (95% CI 35 to 55). If reversibility was also taken into account (summed stress score >8, regional wall motion variance >0.114, or summed difference score >0), sensitivity further increased to 94% (95% CI 88 to 100) and specificity decreased to 32% (95% CI 23 to 41). For detection of any CAD, the combined approach using stress perfusion, reversibility, and region of wall motion had a sensitivity of 94% (95% CI 89 to 99) and a specificity of 45% (95% CI 35 to 57). Therefore, ECG-gated SPECT is very sensitive for detection of ischemic cardiomyopathy and CAD among patients with moderate to severe systolic dysfunction.     

再注射201铊心肌显像检测冬眠心肌的价值

目的探讨再注射２０１铊（Ｔｌ）心肌单光子发射计算机断层显像检测冬眠心肌的价值。方法对２２例冠心病心肌梗塞患者进行了运动再分布再注射２０１Ｔｌ心肌显像、心血池显像、冠状动脉（冠脉）造影及冠脉血运重建术，术后复查心血池及运动再分布２０１Ｔｌ心肌显像。结果１８个（４５％）在运动再分布影像上呈不可逆缺损节段在再注射影像上有再分布。再注射２０１Ｔｌ心肌显像预测冬眠心肌血运重建术后血流灌注与功能改善的阳性预测值为８８．９％和８３．３％，阴性预测值为７７．３％和８１８％，两者符合率为８４８％。术后患者运动耐量及左室射血分数改善。结论再注射２０１Ｔｌ心肌显像是检测冬眠心肌较可靠和实用的方法     

99mTc-MIBI门电路SPECT对冠心病的诊断和心肌存活性评价的作用

为进一步评价99m锝-甲氧基异睛(99mTc-MIBI)门电路和非门电路单光子发射断层显像(SPECT)对冠心病的诊断价值及硝酸甘油介入诊断试验在心肌存活状态评价中的作用,对40例进行运动心肌灌注断层显象,并与冠状动脉(冠脉)造影比较.结果32例冠脉造影显示冠脉有意义狭窄.门电路断层显象对冠心病诊断总的敏感和特异性分别为93.8%和87.5%;非门电路断层显象分别为84.4%和87.5%,两相比较,无显著性差异(P＞0.05).对冠脉病变支数诊断敏感性门电路方法优于非门电路方法(分别为73.8%和62.3%,P＜0.05).特异性均为96.6%.20例进行含服硝酸甘油后静态心肌灌注断层显象,16例心肌梗死病人中有3例为部分可逆性心肌灌注缺损,4例慢性心肌缺血病人,全部有可逆性心肌灌注.表明硝酸甘油介入诊断试验有助于心肌灌注异常可逆性的评估;99mTc-MIBI门电路SPECT和硝酸甘油介入诊断试验是有效的对冠心病无创性诊断和心肌存活状态评价方法.     

Regional wall-motion abnormalities on post-stress electrocardiographic-gated technetium-99m sestamibi single-photon emission computed tomography imaging predict cardiac events.

BACKGROUND: The global left-ventricular (LV) ejection fraction (EF) is a powerful predictor of cardiac death (CD). There are limited data on the prognostic value of regional LV function. We examined the role of visually assessed regional wall motion in risk stratification for future cardiac events. METHODS AND RESULTS: A prospectively gathered database of 10,336 patients who underwent technetium (Tc)-99m sestamibi-gated single-photon emission computed tomography (SPECT) was analyzed. The summed stress score (SSS) and summed wall-motion score (SWMS) were calculated using a standard 17-segment model. The post-stress EF was generated using QGS software. The follow-up was 90.2% complete over 28.6 +/- 16 months. Patients with early (or=5) was an independent predictor of cardiac death (odds ratio = 1.78, 95% confidence interval = 1.11 to 2.85, P = .016). Among patients with an EF >or=45%, abnormal wall motion was the only gated SPECT variable that independently predicted cardiac death (odds ratio = 1.69, 95% confidence interval = 1.06 to 2.7, P = .028). In patients with an EF >or=45% and reversible perfusion defects, abnormal wall motion predicted an intermediate (2.2%/year) risk for CD, and a high (4.2%/year) risk for the combined endpoint of cardiac death and nonfatal MI. CONCLUSIONS: Regional LV function data from gated SPECT provide important prognostic information, and may identify a subgroup of patients with preserved EF and ischemia who are at significant risk for future cardiac events.     

Poststress left ventricular function in patients with coronary artery disease measured by Tl-201 ECG-gated SPECT

BACKGROUND:

The phenomenon of reversible impairment in left ventricular function has been well described and is known as myocardial stunning.

OBJECTIVE:

To assess myocardial stunning in patients with stress-induced ischemia by the use of Tl-201 myocardial perfusion-gated single-photon emission computed tomography (SPECT).

PATIENTS AND METHODS:

Fifty-six patients (63±11 years old) with coronary artery disease participated in the study. All patients underwent exercise thallium scintigraphy. Electrocardiographically gated SPECT was obtained after stress (10 min after the injection of 111 MBq of thallium at the time of peak exercise) and at rest (after 180 min). The left ventricular ejection fraction (LVEF) and end systolic and end diastolic (EDV) volumes were determined using a quantitative gated SPECT (QGS) program. Patients were angiographically classified into three groups: one-vessel disease (n=38), two-vessel disease (n=9) and three-vessel disease (n=9). In 56 patients, resting left ventricular parameters determined by QGS were compared with those obtained by contrast left ventriculography (LVG) to investigate the feasibility of using thallium-gated SPECT to evaluate left ventricular function.

RESULTS:

Good correlation was obtained between LVEF measured by QGS and LVEF measured by LVG (r=0.893, P<0.01). EDV measured by QGS correlated well with EDV measured by LVG (r=0.067, P<0.001). There was a significant difference between poststress LVEF and resting LVEF in patients with three-vessel disease (P<0.05); the difference was not significant in either of the other groups. The magnitude of the depression of LVEF after stress relative to that at rest correlated with the severity of ischemia (P<0.05).

CONCLUSION:

Thallium-gated SPECT determines left ventricular function as well as perfusion does. Impaired poststress LVEF was detected using thallium-gated SPECT in patients with three-vessel disease. Poststress functional data would provide further diagnostic information in patients with coronary artery disease.     

Usefulness of dobutamine Tc-99m sestamibi-gated single-photon emission computed tomography for prediction of left ventricular ejection fraction outcome after coronary revascularization for ischemic cardiomyopathy

Gated single-photon emission computed tomography (SPECT) imaging allows analysis of myocardial perfusion and assessment of baseline global and regional left ventricular (LV) function and their changes during low-dose dobutamine infusion. The study examined whether the changes in LV ejection fraction induced by dobutamine and evaluated using technetium-99m sestamibi- gated SPECT predict the evolution of ejection fraction after revascularization in patients with ischemic cardiomyopathy. Thirty-seven patients underwent resting and dobutamine nitrate-enhanced sestamibi-gated SPECT before revascularization and baseline-resting sestamibi gated SPECT after intervention to assess global functional changes. A postrevascularization improvement in ejection fraction > or =5 U was defined as significant. At follow-up, ejection fraction increased significantly in 19 patients. According to receiver-operating characteristic curve analysis, an increase in ejection fraction > or =5 U during dobutamine was the optimal cutoff value for predicting a significant postrevascularization improvement, with 79% sensitivity, 78% specificity, and 78% accuracy. A significant correlation was found between dobutamine and postrevascularization ejection fraction (r = 0.85; p <0.0001). The increase in ejection fraction during dobutamine is a good predictor of an improvement in ejection fraction after revascularization. This represents another important diagnostic contribution obtained using gated SPECT imaging for the assessment of myocardial viability in patients with ischemic cardiomyopathy.     

Diagnostic value of left ventricular function after stress and at rest in the detection of multivessel coronary artery disease as assessed by electrocardiogram-gated SPECT.

BACKGROUND: Although transient left ventricular (LV) dilation is a well-known marker for extensive coronary artery disease (CAD), few studies have performed quantitative analysis of LV function after stress and at rest to detect extensive CAD. METHODS AND RESULTS: Poststress and resting gated single photon emission computed tomography (SPECT) was performed in 175 patients with suspected CAD. All of the patients underwent coronary angiography within 3 months of gated SPECT. In the 83 patients with multivessel CAD, the summed difference score was greater (9.2 +/- 7.0 vs 3.3 +/- 4.0, P < .0001), the poststress increase in end-systolic volume (ESV) was larger (7.0 +/- 8.0 mL vs -0.8 +/- 4.7 mL, P < .0001), and the poststress increase in ejection fraction (EF) was less (-4.7% +/- 5.4% vs -0.4% +/- 4.5%, P < .0001) than in the 92 patients with insignificant or single-vessel CAD. In the detection of multivessel CAD, a summed difference score of 9 or greater showed a sensitivity of 46% and specificity of 90%, whereas an increase in ESV of 5 mL or greater and a decrease in EF of 5% or greater after exercise had a sensitivity of 66% and 52%, respectively, and specificity of 87% and 83%, respectively. The multivariate discriminant analysis revealed that the combination of poststress increase in ESV, summed difference score, and diabetes mellitus best identified multivessel CAD, with a sensitivity of 72% and specificity of 84% (chi(2), 81.7). CONCLUSIONS: The addition of poststress and at-rest LV functional analysis by use of gated SPECT to conventional perfusion analysis helps to better identify patients with multivessel CAD.     

Additive value of low-dose dobutamine to technetium-99m sestamibi-gated single-photon emission computed tomography for prediction of wall motion improvement in patients undergoing coronary artery bypass graft

BACKGROUND: The two most useful methods for myocardial viability assessment are perfusion imaging and dobutamine echocardiography. HYPOTHESIS: The present study investigated the additive value of a new method, dobutamine technetium 99m (99mTc)-sestamibi-gated single-photon emission computed tomography (SPECT), which combines these two modalities, to the prediction of wall motion improvement after revascularization. METHODS: Fifty-five consecutive patients with ischemic cardiomyopathy, who were referred for viability evaluation, underwent resting and dobutamine (dose, 5-10 microkg/kg/min) gated SPECT with 99mTc-sestamibi. Of these patients, 36 underwent coronary artery bypass graft (CABG) within 1 month of the study and 32 had repeat resting gated SPECT within 1 year. Global and regional wall motion, wall thickness, and perfusion were simultaneously analyzed at rest and after dobutamine using the 20-segment model; the sestamibi uptake and wall motion response to dobutamine of each segment were rated quantitatively. Based on these findings, the segments were categorized as normal, viable, or nonviable. The predictive values for wall motion improvement were assessed by perfusion, using cutoffs of 50 and 60% of sestamibi uptake, and thereafter by the addition of dobutamine response in the segments that were rated nonviable. RESULTS: Of the 1,080 myocardial segments studied, 906 (84%) had abnormal wall motion and were analyzed for viability. Concordance between perfusion and wall motion response to dobutamine was 60% with the 50% cutoff of sestamibi uptake, and increased to 65% with the 60% sestamibi cutoff (p < 0.04). The respective predictive values of wall motion improvement using the 50 and 60% cutoff points were as follows: sensitivity 93 and 70%, respectively, (p < 0.01); specificity 59 and 86% (p < 0.001), respectively; accuracy 77% for both. The addition of the wall motion response to dobutamine to the assessment of the nonviable segments by perfusion (60% cutoff) increased the sensitivity from 70 to 85% (p = 0.001) and the negative predictive value from 70 to 81% (p = 0.009); the positive predictive value remained high (86 vs. 82%). No additive value of wall motion response to dobutamine was demonstrated for nonviable segments by perfusion with a 50% cutoff. CONCLUSION: Dobutamine sestamibi-gated SPECT is a feasible method for the analysis of myocardial perfusion, function, and contractile reserve of individual myocardial segments in patients with ischemic cardiomyopathy. Viability assessment based on a threshold of 60% uptake of sestamibi, with the addition of the wall motion response to dobutamine in the nonviable segments, seems to yield better predictive values for wall motion improvement after CABG.