Identification of high-risk patients with left main and three-vessel coronary artery disease using stepwise discriminant analysis of clinical, exercise, and tomographic thallium data

A Validated Model to Identify Patients With Low Likelihood of High-Risk Coronary Artery Disease Anatomy

In stable coronary artery disease (CAD), revascularization improves outcomes only for patients with high-risk coronary anatomy (HRCA). We sought to derive and validate a prediction model, incorporating clinical and exercise stress test characteristics, to identify patients with HRCA. We conducted a retrospective analysis of patients undergoing exercise stress testing at Cleveland Clinic (2005 to 2014), followed by invasive coronary angiography within 3 months. We excluded patients with acute coronary syndrome, known CAD or ejection fraction <50%. HRCA was defined as left main, 3-vessel, or 2-vessel disease involving the proximal left anterior descending artery. Clinical and stress test predictors of HRCA were identified in a multivariable logistic regression model, internally validated with 1,000-fold bootstrapping. The model was then externally validated at the University of Pittsburgh Medical Center (2017 to 2019). The model was derived from 2,758 patients with complete data. HRCA was identified in 418 patients (15.2%) in the derivation cohort. The model consisted of 10 variables: age, male gender, hypertension, hypercholesterolemia, diabetes mellitus, family history of premature CAD, high-density lipoprotein, chest pain, exercise time, and Duke Treadmill Score. Bias-corrected c-statistic was 0.79 (95% confidence interval 0.77 to 0.81) with excellent calibration. In all, 762 patients (27.6%) had a predicted probability and observed prevalence of HRCA <5%. In the validation cohort, the model had a c-statistic of 0.79 (95% confidence interval 0.74 to 0.85) and 210 patients had an observed prevalence of HRCA <5% (40%). In conclusion, an externally validated prediction model, based on clinical characteristics and exercise stress test variables, can identify stable patients with CAD who have HRCA.

Very high coronary artery calcium score with normal myocardial perfusion SPECT imaging is associated with a moderate incidence of severe coronary artery disease

PURPOSE

Myocardial perfusion imaging (MPI) has limitations in the presence of balanced multivessel disease (MVD) and left main (LM) coronary artery disease, occasionally resulting in false-normal results despite the high cardiovascular risk associated with this condition. The purpose of this study was to assess the incidence of severe coronary artery disease (CAD) in the presence of a very high Agatston coronary artery calcium (CAC) score (>1,000) in stable symptomatic patients without known CAD but with normal MPI results.

METHODS

A total of 2,659 prospectively acquired consecutive patients were referred for MPI and evaluation of CAC score by CT. Of this patient population, 8 % (222/2,659) had ischemia without myocardial infarction (MI) on MPIand 11 % (298/2,659) had abnormal MPI (MI and/or ischemia). On presentation 1 % of the patients (26/2,659) were symptomatic, had a CAC score >1,000 and normal MPI results. The definition of normal MPI was strict and included a normal hemodynamic response without ischemic ECG changes and normal imaging, particularly absence of transient ischemic dilation. All of these 26 patients with a CAC score >1,000 and normal MPI findings underwent cardiac catheterization.

RESULTS

Of these 26 patients, 58 % (15/26) had severe disease (≥70 % stenosis) leading to revascularization. Of this group, 47 % (7/15) underwent percutaneous intervention, and 53 % (8/15) underwent coronary artery bypass grafting. All of these 15 patients had either MVD (14/15) or LM coronary artery disease (1/15), and represented 0.6 % (15/2,659) of all referred patients (95 % CI 0.3 - 0.9 %). The majority, 90 % (8/9), had severe CAD with typical chest pain.

CONCLUSION

A very high CAC score (>1,000) with normal MPI in a small subset of symptomatically stable patients was associated with a moderate incidence of severe CAD (95 % CI 37 - 77 %). Larger studies and/or a meta-analysis of small studies are needed to more precisely estimate the incidence of CAD in this population. This study also supports the concept that a normal MPI result in patients with severe CAD may be due to balanced MVD.

Use of discriminant analysis in assessing pulmonary function worsening in patients with sarcoidosis by a panel of inflammatory biomarkers

OBJECTIVES AND DESIGN

To date, no sufficiently sensitive and specific single marker has been found to predict the clinical course of sarcoidosis. We designed a cohort study to investigate whether a panel of biomarkers measured in bronchoalveolar lavage (BAL) and peripheral blood could help predict pulmonary function worsening during the clinical course of sarcoidosis.

METHODS

We analyzed 30 individuals with histologically proven sarcoidosis. At baseline, participants underwent pulmonary function tests (PFTs), fiberoptic bronchoscopy and radiological investigations. BAL and blood cellular profiles were obtained from all individuals and six pro-inflammatory molecules were quantified in BAL and serum. PFTs were performed at follow-up visits over a 2-year period. Using discriminant function analysis, a canonical variable was generated to optimize the accuracy of selected variables in predicting pulmonary function worsening and was validated on a subset of nine consecutive individuals with sarcoidosis.

RESULTS

A combination of 6 markers from BAL was able to predict pulmonary function worsening in 96 % of patients [95 % confidence interval (CI) 84.4-99.81]. We validated the generated formula on a group of nine patients with sarcoidosis, obtaining 77.8 % correct classification (95 % CI 45.3-93.7).

CONCLUSIONS

Our results show that a combinational approach could contribute to identifying individuals likely to experience pulmonary function worsening, thus helping to decide the correct therapeutic strategies.

Gas chromatography/mass spectrometry screening of serum metabolomic biomarkers in hepatitis B virus infected cirrhosis patients

BACKGROUND

Metabolomic studies have been applied to disease biomarkers selection. With the metabolomic technique, gas chromatography/mass spectrometry (GC/MS), human serum metabolites can be detected and identified. The purpose of this study was to investigate the serum metabolic profile of hepatitis B virus (HBV) infected cirrhosis patients and to detect disease biomarkers.

METHODS

HBV infected non-cirrhosis male subjects (n=20) and HBV infected cirrhosis male patients (n=20) participated in this experiment. Serum metabolome was detected through chemical derivatization followed by GC/MS. The high-flux metabolomic data were analyzed by stepwise discriminant analysis.

RESULTS

Out of the 41 metabolites detected in serum, we selected metabolites, including acetic acid, sorbitol, D-lactic acid, hexanoic acid, 1-naphthalenamine, butanoic acid, phosphoric acid, D-glucitol, and glucose, which in combination with each other could segregate the two groups. The error count was 0% for the non-cirrhosis group and 25% for the cirrhosis group.

CONCLUSIONS

This technique can be used to select biomarkers for hepatic cirrhosis.

Diagnostic value of left ventricular function after adenosine triphosphate loading and at rest in the detection of multi-vessel coronary artery disease using myocardial perfusion imaging

BACKGROUND

Although transient left ventricular (LV) dilation is a well-known marker for extensive coronary artery disease (CAD), few studies performed quantitative analysis of LV function of post adenosine triphosphate (ATP) stress and at rest to detect extensive CAD.

METHODS

One hundred nineteen patients with suspected CAD underwent post-stress and resting gated single-photon emission computed tomography (SPECT). Myocardial perfusion was assessed with a 20-segment model, and the changes in LV volume and function with ATP were analyzed. In addition, the stress-induced volume ratio (SIVR), defined as stress-to-rest ratios (end-systolic volume x 5 + end-diastolic volume), was calculated. All the patients underwent coronary angiography within 3 months of gated SPECT.

RESULTS

In the 62 patients with multi-vessel CAD, the summed stress score (SSS) (16.6 +/- 8.7 vs 11.5 +/- 9.1; P < .002), summed difference score (SDS) (9.6 +/- 5.8 vs 3.9 +/- 4.2; P < .0001), the post-stress increase in end-diastolic volume (EDV) (7.7 +/- 7.9 vs 2.2 +/- 5.3 mL; P < .0001), the post-stress increase in end-systolic volume (ESV) (9.4 +/- 6.0 vs 2.7 +/- 4.0 mL; P < .0001), and the (SIVR) (1.21 +/- 0.14 vs 1.06 +/- 0.10; P < .0001) were greater than in the 57 patients with insignificant or single-vessel CAD, whereas the post-stress increase in ejection fraction (EF) was less (-6.0 +/- 4.9 vs -2.0 +/- 4.4%; P < .0001). In the detection of multi-vessel CAD, an SSS of > or = 14 and an SDS of > or = 9 showed sensitivities of 57% and 52%, respectively, and specificities of 63% and 88%, respectively, while increase in EDV of > or = 6 mL, increase in ESV of > or = 6 mL, decrease in EF of > or = 5% after stress, and SIVR of > or = 1.13 demonstrated sensitivities of 60%, 81%, 60%, and 74% and specificities of 74%, 77%, 77%, and 79%, respectively. The multivariate discriminant analysis revealed that the combination of post-stress increase in ESV and the SDS best identified multi-vessel CAD, with 81% sensitivity and 77% specificity (chi(2) = 63.6), whereas the SDS alone showed 52% sensitivity and 88% specificity (chi(2) = 22.4).

CONCLUSIONS

The addition of "post-ATP stress" and "at rest" LV functional analysis using gated SPECT to conventional perfusion analysis helps to better identify patients with multi-vessel CAD.

Important parameters in the detection of left main trunk disease using stress myocardial perfusion imaging

OBJECTIVES

We sought noninvasively to diagnose left main trunk (LMT) disease using myocardial perfusion imaging (MPI).

METHODS

Five hundred and eight patients with suspected coronary artery disease (CAD) underwent both stress MPI and coronary angiography. The extent and severity of perfusion abnormalities were assessed using a 20-segment model. In addition, perfusion defects in both left anterior descending and left circumflex arterial territories were defined as a left main (LM) pattern defect, and those in 3-coronary arterial territories as a 3-vessel pattern defect.

RESULTS

In 42 patients with LMT disease, a summed stress score (19.4 ± 10.0 vs. 13.5 ± 10.0; p < 0.0001) and a summed rest score (12.1 ± 9.7 vs. 7.0 ± 7.8; p = 0.002) were greater than in 466 patients without LMT disease, while a summed difference score was similar (7.3 ± 7.7 vs. 6.5 ± 6.1; p = NS). The prevalence of an LM-pattern defect was low in both groups (12% vs. 8%; p = NS). However, a 3-vessel pattern defect (33% vs. 7%; p < 0.0001), lung uptake of radiotracers (38% vs. 11%; p < 0.0001), and transient ischemic dilation (31% vs. 13%; p = 0.003) were more frequently observed in patients with LMT disease than in those without. Logistic regression analysis showed that a 3-vessel pattern defect (OR=3.5, 95% CI = 1.4-8.8; p = 0.007), lung uptake of radiotracers (OR = 2.5, 95% CI = 1.1-5.7; p = 0.03), and previous myocardial infarction (MI) (OR = 2.4, 95% CI = 1.0-5.7; p = 0.05) were the most important parameters to detect LMT disease. After excluding 163 patients with previous MI, a repeat analysis revealed that lung uptake of radiotracers (OR = 8.2, 95% CI = 2.3-29.2; p = 0.001) and an LM-pattern defect (OR = 6.3, 95% CI = 1.4-27.2; p < 0.02) were independent predictors for LMT disease.

CONCLUSION

In the identification of LMT disease, lung uptake of radiotracers was a single best parameter, which was independent of the presence or absence of previous MI.

Flattening of oxygen pulse during exercise may detect extensive myocardial ischemia

PURPOSE

Flattening of oxygen pulse curve during incremental cardiopulmonary exercise testing has been proposed for the improvement of diagnostic accuracy of exercise-induced myocardial ischemia. In this study, we compare the oxygen pulse response to incremental treadmill exercise in patients with and without ischemia as detected by myocardial perfusion scintigraphy.

METHODS

Eighty-seven patients referred to exercise myocardial perfusion scintigraphy were also evaluated with incremental treadmill cardiopulmonary exercise testing. One investigator prospectively identified patients who presented transient exercise-induced perfusion defects on 99mTc sestamibi myocardial scintigraphies. Another investigator evaluated the response of oxygen pulse to incremental exercise testing without knowledge of electrocardiographic response or scintigraphic findings.

RESULTS

Exercise myocardial perfusion scintigraphy detected transient perfusion defects in 36% of the patients. Compared with patients with normal perfusion studies, patients with exercise-induced ischemia presented similar peak double product, peak oxygen uptake, and anaerobic threshold. Oxygen pulse at 25% of peak (ischemia: 9.7 +/- 2 mL per beat; no ischemia: 9.3 +/- 2 mL per beat), 50% of peak (11.2 +/- 3 vs 10.8 +/- 3 mL per beat), 75% of peak (12.5 +/- 3 vs 11.9 +/- 3 mL per beat), and at peak exercise (13 +/- 4 vs 13 +/- 4 mL per beat) were not different in exercise-induced ischemia and normal groups, respectively. However, patients who presented extensive transient perfusion defects during exercise had a lower peak oxygen pulse (12.8 +/- 3.8 vs 16.4 +/- 4.6 mL per beat; P < 0.05).

CONCLUSION

The analysis of the oxygen pulse response to incremental exercise test does not identify mild myocardial ischemia. Flattening of oxygen pulse response during incremental exercise might be present only with extensive myocardial ischemia.

Identification of advanced coronary artery disease with exercise myocardial perfusion imaging: the clinical value of a novel approach for assessing lung thallium-201 uptake

INTRODUCTION

The precise clinical utility of lung 201Tl uptake in exercise SPECT myocardial perfusion imaging remains open to research. This study validates an optimal index for lung 201Tl uptake measurement and assesses its value in the prediction of higher-risk coronary artery disease (CAD).

METHOD

Three hundred and ninety-eight patients underwent exercise SPECT myocardial perfusion imaging. They were separated into derivation (n = 217) and validation (n = 186) groups, both including sub-populations of lower- and higher-risk CAD, according to coronary angiography. Another 56 individuals with a low probability of CAD comprised the control group. From a planar, anterior, post-exercise acquisition, the lung (L) to heart (H) maximal (L/H(max)), total (L/H(mean)) and background-subtracted total (L/H(net)) ratios were calculated. These were also adjusted for confounding variables, as assessed from the control group. ROC analysis was used to compare the L/H ratios and define thresholds of abnormality. The performance of the optimal index was assessed in the derivation group and was then tested in the validation population. Subsequently, it was compared with other scintigraphic, exercise electrocardiography and clinical variables.

RESULTS

In the derivation group L/H(net) was a better discriminator for higher-risk CAD than both L/H(max) and L/H(mean). Similarly, the adjusted L/H(net) was a better discriminator than both the adjusted L/H(max) and the adjusted L/H(mean). No significant difference was attained between L/H(net) and the adjusted L/H(net). At the upper defined threshold of abnormality, sensitivity and specificity of L/H(net) in the detection of higher-risk CAD in the derivation and the validation cohorts were 52% and 92% versus 47% and 94%, respectively (p = ns). The results were similar at other defined thresholds. Moreover, L/H(net) was found to be a significant predictor of higher-risk CAD, superior to myocardial perfusion images, transient ventricular dilation measurements, and clinical and exercise testing variables (ROC analysis and logistic regression). By raising the threshold of abnormality of L/H(net), specificity and positive predictive value increased, whereas sensitivity and negative predictive value decreased.

CONCLUSION

Lung 201Tl assessment assists substantially in the identification of higher-risk CAD in exercise SPECT myocardial perfusion imaging and this is best achieved by L/H(net). This index is a significant predictor of higher-risk CAD, superior to myocardial perfusion images, and its value is associated with the probability of a disease state.

Significance of extension of exercise-induced ischemia toward apex of left ventricle

BACKGROUND

The aim of this study was to evaluate the significance of extension of exercise-induced ischemia toward apex of left ventricle.

METHODS

After injections of technetium-99m tetrofosmin at peak ergometer exercise and thallium-201 at 3 min post-exercise, dual-isotope single photon emission computed tomography (SPECT) images were obtained simultaneously with cross-talk compensation using triple-energy window in 70 patients (65.8+/-9.5 years) with angiographically proven ischemic heart disease. The left ventricle was divided into a total of 18 areas in 3 levels of apical, middle, basal, and the extent and localization of ischemia to long axis of left ventricle were measured at peak exercise and 3 min into the recovery.

RESULTS

Of 57 patients with exercise-induced reversible ischemia, in 25 patients with the ischemia in 2 levels to long axis of left ventricle, the ischemia extended mainly to the middle and basal levels (p<0.0001) and was localized during recovery mainly in the basal level (p<0.0005). In 21 patients with the ischemia in all 3 levels, the ischemia was localized during recovery mainly to the middle and basal levels (p<0.05). The persistence of ischemia in apex at post-exercise reflected the delay of recovery from ischemia on the whole of left ventricle and was related to the enlargement of resting end-diastolic volume of left ventricle as compared to the quick recovery of ischemia in apex (p<0.0005 and p<0.05, respectively).

CONCLUSIONS

Although the ischemia recovers earliest in the peripheral apical level within exercise-induced ischemic territory, the delay of recovery from the ischemia in the apical level may be related to the development of heart failure, independent of intensity of occurred ischemia during exercise.

[Clinical predictors of the presence of perfusion defects in more than than one territory in myocardial scintigraphy with GATED-SPECT]

BACKGROUND AND OBJECTIVE

Extension of perfusion defects is associated with outcome in patients undergoing myocardial scintigraphy. The study aimed to identify the clinical characteristics that can predict the existence of perfusion defects in more than one territory in patients referred for myocardial scintigraphy with GATED-SPECT.

PATIENTS AND METHODS

A total of 193 patients undergoing myocardial scintigraphy with GATED-SPECT (99mTc-tetrofosmine) were studied. Clinical variables and scintigraphy results were studied to determine what clinical variables are associated with perfusion defects in more than one territory.

RESULTS

The number of territories with perfusion defects per patient was 1.1 0.8 and 29% had perfusion defects in > 1 territory. Patients with greater probability of having perfusion defects in > 1 territory were those with previous myocardial infarction (44% vs 21%, p = 0.030) and males (33% vs 10%, p = 0.006). In addition, patients with > 2 coronary risk factors had a statistical tendency to have defects in > 1 territory (47% vs 20%, p = 0.057). Only 15% of the patients with one of these three characteristics had perfusion defects in > 1 territory in comparison with 45% and 83% in those with 2 or 3 factors, respectively.

CONCLUSION

Considering 3 simple clinical characteristics (male gender, previous infarction and existence of > 2 coronary risk factors), it is possible to predict which patients are more likely to show perfusion defects in > 1 territory during GATED-SPECT myocardial scintigraphy.

Significance of ST-segment morphology noted on electrocardiography during the recovery phase after exercise in patients with ischemic heart disease as analyzed with simultaneous dual-isotope single photon emission tomography

BACKGROUND

The significance of differences in electrocardiographic morphology that occur during the recovery phase after exercise has not been clarified. We investigated the relationship between postexercise electrocardiographic morphology and the pattern of residual ischemia measured at that time.

METHODS

Exercise dual-isotope single photon emission computed tomography was performed on 171 consecutive patients with chest pain syndrome. After injection of technetium-99m tetrofosmin at peak exercise and thallium-201 at 3 minutes after exercise, dual-isotope single photon emission computed tomographic images were obtained simultaneously. After cross-talk compensation, the extent of ischemia and its localization were measured at both peak exercise and after exercise.

RESULTS

When 64 patients with angiographically and scintigraphically proven ischemic heart disease were grouped by morphology of ST-segment depressions at 3 minutes after exercise, 38 patients with the downsloping type had ischemia localized mainly to the middle and basal levels as compared with the more rapid resolution of ischemia in 12 patients with horizontal type and 14 patients with no ischemic electrocardiographic response (apical level 18.4% [7/38], 8.3% [1/12], and 0% [0/14], P = not significant, middle level 47.4% [18/38], 16.7% [2/12], and 7.1% [1/14], P <.01, basal level 57.9% [22/38], 33.3% [4/12], and 14.3% [2/14], P <.02, respectively) independent of the extent or localization of any ischemia noted during exercise (all levels, P = not significant).

CONCLUSION

Electrocardiographic morphology during the recovery phase of exercise reflects the extent and localization of residual ischemia at that time independent of ischemic changes noted during exercise.

Risk stratification post-myocardial infarction: is early coronary angiography the more effective strategy?

The primary management strategy for the post-myocardial infarction patient continues to be controversial despite published guidelines. In part, this is the consequence of study designs that are not directly applicable to individual patients, but also to the rapidly changing pharmacological and mechanical device armamentarium that rapidly renders clinical trial results obsolete within a few years. This review attempts to highlight those areas where there is consensus as well as to explicate those situations where common clinical practice appears to be in conflict with accepted guidelines.

Predictive potential of noninvasive methods, inclusive of exercise SPECT Tc99m MIBI imaging, in recognition of high-risk patients with left main coronary artery stenosis

The aim of the present study was to determine which clinical, exercise and perfusion variables can be instrumental in the identification of left main coronary artery. A multivariate model for prediction of left main disease was developed, based on a number of clinical, exercise and MIBI perfusion variables in two groups of patients. Group I consisted of 38 patients (30 men and eight women) with angiographically proven left main stenosis, while group II consisted of 41 patients (27 men and 14 women) with multivessel coronary artery diseases. A multivariate logistic regression analysis demonstrated that clinical variables including diabetes, hypertension, together with history of typical angina were the only independent predictors of left main stenosis. It was found that p value was 0.05 for hypertension, 0.01 for diabetes as well as 0.01 for the history of typical angina in clinical examination. No exercise or perfusion variables may be instrumental in prediction of left main stenosis, when considered in isolation. Myocardial perfusion by itself is therefore not deemed sufficiently specific to attempt its positive identification. High-risk patients with left main disease can be identified noninvasively by exercise perfusion imaging using a model based on the proposed logistic regression analysis with clinical variables.

Improved detection of left main coronary artery disease with attenuation-corrected SPECT

BACKGROUND

Myocardial perfusion imaging has demonstrated a limited sensitivity as a means of accurately identifying left main (LM) coronary disease. Because regional quantitative perfusion biases are eliminated with attenuation corrected (AC) single photon emission computed tomography (SPECT), as compared with uncorrected (NC) SPECT, we hypothesized that AC SPECT would demonstrate increased diagnostic accuracy for the detection of significant LM coronary stenosis.

METHODS AND RESULTS

We studied 28 patients (23 men, 5 women; mean age, 66+/-9 years) with significant LM stenoses (> or =50%) and 34 control patients (27 men, 7 women; mean age, 65+/-11 years) with 2-vessel coronary disease. Rest thallium-201 and stress technetium 99m sestamibi SPECT imaging with and without AC were performed, as described earlier. Both AC and NC images were analyzed visually and quantitatively in comparison with corresponding normal databases. A greater sensitivity for detection of an LM defect pattern (64% vs. 7%, P = .0009) with equivalent specificity (94% vs. 100%, P = not significant) was demonstrated by means of visual analysis of AC SPECT images. More disease was demonstrated in a greater number of territories with AC SPECT images than with NC images (2.14+/-0.97 for AC images vs. 1.43+/-0.84 for NC images, P = .0001). Similar improvement in the detection of LM disease was shown by means of automated quantitative analysis (57% for AC SPECT vs 14% for NC SPECT, P = .0005), again with no loss in specificity.

CONCLUSIONS

AC SPECT with the University of Michigan method in consecutive patients with LM stenoses and a select control population with severity matched multivessel coronary disease significantly improved the diagnostic accuracy of myocardial perfusion imaging for the identification of LM coronary disease, compared with uncorrected SPECT.

[Nuclear cardiology: technical bases and clinical applications]

Although the role of nuclear cardiology is currently well consolidated, the addition of new radiotracers and modern techniques makes it necessary to continuously update the requirements, equipment and clinical applications of these isotopic tests. The characteristics of the radioisotopic drugs and examinations presently used are explained in the first part of this text. In the second, the indications of them in diagnostic and prognostic evaluation of the different coronary diseases are presented.

Identification of severe coronary artery disease in patients with a single abnormal coronary territory on exercise thallium-201 imaging: the importance of clinical and exercise variables

OBJECTIVES

The aim of this study was to determine which clinical, exercise and thallium variables can aid in the identification of three-vessel or left main coronary artery disease (3VLMD) in patients with one abnormal coronary territory (either a reversible or fixed defect) on exercise thallium testing and to test the prognostic value of these variables.

BACKGROUND

Although the sensitivity of detection of coronary artery disease by thallium-201 imaging is high, the actual detection of 3VLMD by thallium tomographic images alone is not optimal.

METHODS

A multivariate model for prediction of 3VLMD was developed from several clinical, exercise and thallium-201 variables in a training population of 264 patients who had one abnormal coronary artery territory on exercise thallium testing and had undergone coronary angiography. Using this model, patients were stratified into risk groups for prediction of 3VLMD. A separate validation cohort of 474 consecutive patients who were treated initially with medical therapy and who had one abnormal coronary territory were divided into identical risk groupings by the variables derived from the training population, and they were followed for a median of 7.0 years to evaluate the prognostic value of this model.

RESULTS

The prevalence of 3VLMD was 26% in the training population despite one abnormal thallium coronary territory. Four clinical and exercise variables--diabetes, hypertension, magnitude of ST segment depression, and exercise rate-pressure product-were found to be independent predictors of 3VLMD. In the training population, the prevalence of 3VLMD in low-, intermediate- and high-risk groups was 15%, 22% and 51%, respectively. When the multivariate model was applied to the validation population, the eight-year overall survival rates in the low-, intermediate- and high-risk groups were 89%, 73% and 75%, respectively (p < 0.001).

CONCLUSIONS

A substantial proportion of patients with one abnormal thallium coronary territory have 3VLMD with subsequent divergent outcomes based upon risk stratification by clinical and exercise variables. Consequently, the finding of only a single abnormal coronary territory by thallium-201 perfusion imaging does not necessarily confer a benign prognosis in the absence of consideration of nonimaging variables.

Increased stress right ventricular activity on dual isotope perfusion SPECT: a sign of multivessel and/or left main coronary artery disease

OBJECTIVES

This study sought to determine the anatomic and physiologic correlates of increased right ventricular (RV) activity on exercise single-photon emission computed tomography (SPECT) perfusion imaging in patients with coronary artery disease (CAD).

BACKGROUND

Because SPECT perfusion imaging delineates relative myocardial blood flow, patients with global left ventricular (LV) hypoperfusion but normal RV perfusion may have increased relative RV tracer uptake as an indicator of multivessel CAD.

METHODS

Rest thallium-201 and exercise 99mTc-sestamibi or 99mTc-tetrofosmin SPECT perfusion images were analyzed for peak RV and LV activity (RV:LV index) in 315 patients, including 240 patients with documented CAD, 39 patients with no significant CAD on arteriography, and a "normalcy" group of 36 patients with a low pre- and posttest probability of CAD.

RESULTS

Resting RV:LV perfusion index ranged from 0.32 to 0.34 in each group, increasing to 0.36 with exercise in control and normalcy groups. CAD patients with the highest exercise RV:LV were those with severe left main CAD (or "left main equivalent"), with a lesser degree of proximal right CAD (0.51, n = 14, p < 0.001 vs. other groups). An exercise RV:LV >0.42 with a exercise:rest ratio >1.2 was present in 93% patients with this pattern of CAD, but was absent in 97% of the normalcy group, 92% of patients without significant angiographic CAD, and 100% of patients with proximal right CAD tighter than stenoses in the left system.

CONCLUSIONS

Increased RV:LV activity exercise may occur in patients with acute RV strain, but is otherwise an indicator of exercise-induced RV:LV perfusion imbalance associated with severe CAD, particularly high-grade left main with less severe proximal right CAD.

Impact of stress single-photon emission computed tomography perfusion imaging on downstream resource utilization

This study shows that in patients with intermediate pretest probability of coronary artery disease stress single-photon emission computed tomography perfusion imaging decreases the rate of coronary angiography and coronary revascularization and is economically a superior strategy to routine coronary angiography.

Clinical review of attenuation-corrected cardiac SPECT

Rather than the introduction of a heralded technologic advancement in cardiac SPECT imaging challenging the accuracy of PET perfusion imaging, the commercial introduction of attenuation correction has been met with at least as many negative as positive reports. Some studies have reported significant improvements in specificity or specificity and sensitivity, especially for high-risk patterns of coronary artery disease; others have reported no improvement or a decrease in accuracy resulting from the introduction of troublesome artifacts. Although this review has attempted to emphasize the positive aspects of attenuation-corrected cardiac SPECT perfusion imaging and the potential for improved patient care it may provide, several negative reports continue to appear. Still there has been sufficient positive data reported to suggest that with fully developed, accurate, and robust correction methods, significant gains in SPECT assessments of the presence and extent of CHD, patient risk, and myocardial viability can be anticipated. Ultimately attenuation correction for cardiac SPECT should have a positive impact on the management of patients with coronary artery disease with important savings in lives and health care dollars.

[Stress myocardial gammatomography in the diagnosis of multivessel coronary disease]

OBJECTIVE

The aim of the study was to evaluate the diagnostic yield of 99m-Technetium-methoxy-isobutyl-isonitrile (MIBI) SPET for identification of individual coronary artery disease and in the prediction of multivessel involvement.

METHODS

Stress/rest myocardial SPET and coronary arteriography were evaluated in 231 consecutive patients (age 58 +/- 10 years, 26% women) without prior myocardial infarction. 149 patients had coronary narrowing > 50%: 104 with multivessel disease and 45 with one vessel disease. Tomographic stress defect score was obtained by semiquantitative analysis (maximal score 65). Univariate and multivariate analysis was performed to identify discriminant parameters between one vessel and multivessel patients.

RESULTS

The sensitivity and specificity for the identification of individual artery disease was 74% and 85% for left anterior descending artery, 79% and 85% for right coronary and 45% and 96% for circumflex artery. In the prediction of multivessel involvement the sensitivity was 65%, specificity 87%, positive predictive value 81% and negative predictive value 76%. In the bivariate analysis, four parameters differed significantly between one vessel and multivessel disease patients: ST downslope > 1 mm (p = 0.01), ST downslope/heart rate corrected (p = 0.005), reversible defects in two or more regions (p = 0.009) and SPET score (p = 0.002). In the multivariate analysis the probability of multivessel disease was 90% when ST depression > 1 mm and SPET score > 20 were associated and the probability was lowered to 16% when these criteria were not present.

CONCLUSION

Myocardial SPET with MIBI offers an accurate localization of individual coronary artery disease, mainly in left anterior descending artery and right coronary artery lesions. Combined evaluation of ST depression and extension of myocardial stress defects improved prediction of multivessel involvement.

Identification of severe or extensive coronary artery disease in women by adenosine technetium-99m sestamibi SPECT

To assess the ability of adenosine technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography (SPECT) to identify high-risk women with severe or extensive coronary artery disease (CAD), we studied 130 consecutive women who underwent adenosine sestamibi myocardial perfusion SPECT and catheterization within 2 months. Severe (> or = 50% stenosis of left main coronary artery, > or = 90% stenosis in the proximal left anterior descending or in > or = 2 coronary arteries) or extensive (> or = 70% stenosis in 3 vessels) CAD was present in 54 patients, whereas 76 had no CAD or mild to moderate CAD. Semiquantitative visual SPECT analysis used 20 segments and a 5-point scoring system (0 = normal, 4 = absent uptake). Among the clinical, hemodynamic and nuclear variables analyzed, univariate predictors of severe or extensive CAD included a higher prescan likelihood of CAD, history of myocardial infarction, a higher heart rate at rest, a lower increase in heart rate during adenosine infusion, a higher summed stress score, summed reversibility score, and multivessel scan abnormality. Multivariate logistic analysis of the most predictive clinical (prescan likelihood of CAD), hemodynamic (increase in heart rate during adenosine infusion), and scan variables (summed stress score) revealed summed stress score (chi-square = 32; p <0.0001) and prescan likelihood of CAD (chi-square = 6.4; p <0.05) as the only independent predictors of severe or extensive CAD. Based on these logistic models, we determined the probability for the presence of severe or extensive CAD in patients with low, intermediate, and high prescan likelihood of CAD across the range of values of a summed stress score. This revealed that there were incremental increases in the probability for severe or extensive CAD both as a function of prescan likelihood of CAD and summed stress score. A severely abnormal scan (summed stress score > 8) during adenosine technetium-99m sestamibi myocardial perfusion SPECT had a high sensitivity of 91% and a moderately high specificity of 70% for identifying high-risk women with severe or extensive CAD. These results coupled with the previously defined prognostic significance of these findings suggest this test to be a useful diagnostic tool for the evaluation of CAD in women.

Evaluation of response to chemotherapy in patients affected with non-small cell lung cancer by means of three tumour markers elaborated by discriminant analysis

Chemotherapy is the most effective treatment for inoperable patients (70%) affected with non-small cell lung cancer (NSCLC). The early detection of tumour progression is mandative in order to promptly shift these patients towards salvage or supportive therapy. The present authors investigated the clinical value of a panel of tumour markers, elaborated by means of discriminant analysis, as a follow-up indicator for the detection of tumour progression. The serum levels of tissue polypeptide antigen (TPA), CYFRA-21.1, neuron-specific enolase (NSE) and carcino-embryonic antigen (CEA) were determined before chemotherapy and after three cycles of treatment. Discriminant analysis generated a formula (canonic variable) which correctly classified the 87.8% of the 74 subjects (86.1% of the 36 progressive diseases and 89.5% of 38 non-progressive diseases). This approach produces an algorithm able to calculate a progression score in NSCLC patients which can be helpful for following-up care and therapy control of these patients.

Quantification of left ventricular size on exercise thallium-201 single-photon emission tomography

The purposes of this study were to determine whether quantification of the left ventricular size on exercise thallium-201 single-photon emission tomography (SPET) correlates with echocardiographic measurements, whether the quantification reflects the severity of coronary artery disease, and whether it can provide supplementary information regarding the severity of coronary artery disease. In 42 control subjects and 110 patients who underwent coronary angiography, we performed exercise 201Tl SPET and quantified six non-regional markers: lung 201Tl uptake on an initial planar image (Lung/Heart), left ventricular width on a tomogram (Width), change in the Width from the initial to delayed tomograms (DeltaWidth), count ratio of the left ventricular cavity to the myocardium (C/M), count ratio of the lung to the myocardium (L/M), and count ratio of the lung to the left ventricular cavity (L/C). In 76 patients, furthermore, the Width was compared with echocardiographic measurements. The Width correlated with echocardiographic measurements (P<0.001). The Width and DeltaWidth were significantly different among zero-, one-, two- and three-vessel disease (P<0.001). However, the Width and DeltaWidth could not improve the power of discrimination for multi-vessel disease derived from the Lung/Heart. The six non-regional markers correlated with each other (P<0.001). Among the six markers, the Lung/Heart was only the independent discriminator for multi-vessel disease. In conclusion, quantification of the left ventricular size on exercise 201Tl SPET correlated with echocardiographic measurements and reflected the severity of coronary artery disease, but may be replaced with quantitation of the lung 201Tl uptake.

Additional value of thallium-201 SPECT to a conventional exercise test for the identification of severe coronary lesions after an episode of unstable coronary artery disease

The additional value of thallium-201 SPECT to a conventional exercise test for the identification of patients with severe coronary lesions was evaluated in 170 men, one month after an episode of unstable coronary artery disease. Severe coronary lesions at coronary angiography--defined as three vessel disease, left main stenosis or proximal left anterior descending artery stenosis as part of two vessel disease--were observed in 45.9%. In the SPECT image, the left ventricular myocardium was divided into nine segments and each segment was classified as either normal (= 0), reduced uptake (= 1) or uptake defect (= 2). The sum of gradings in all segments post-exercise was denoted "SPECT score". The patients were divided into nine different groups regarding ST-depression during exercise (no ST-depression, ST-depression in 1-2 leads or > or = 3 leads) and "SPECT score" (no SPECT score, 1-3 scores or > or = 4 scores). Severe coronary lesions were, in 68% identified by SPECT score > or = 4 and in 65% by ST-depression in > or = 1 lead at exercise test. The specificity for identification of severe coronary lesions was, for both tests, 65%. SPECT score > or = 4 and/or ST-depression in > or = 3 leads identified 82% of the patients with severe coronary lesions with a specificity of 63%. Furthermore, SPECT score > or = 3 identified more patients with isolated proximal left anterior descending artery stenosis than ST-depression alone at exercise test.

Comparison of thallium-201 single-photon emission computed tomography and electrocardiographic response during exercise in patients with normal rest electrocardiographic results

OBJECTIVES

This study compared the diagnostic accuracy of exercise thallium-201 single-photon emission computed tomography (SPECT) with the exercise electrocardiographic (ECG) response in patients with normal baseline ECG results.

BACKGROUND

Previous studies comparing exercise thallium imaging with exercise electrocardiography have included patients with abnormal rest ECG results that may have biased the results in favor of thallium imaging.

METHODS

Of 321 patients with a pretest likelihood of coronary artery disease of 70 +/- 29% (mean +/- SD) who underwent exercise stress testing and coronary angiography, 68 had no coronary artery disease; 94 had one-vessel disease; 79 had two-vessel disease; and 80 had three-vessel or left main coronary artery disease.

RESULTS

The diagnostic accuracy of SPECT was higher than that of the ECG response (79% vs. 49%, p < 0.0001). Patients with extensive (left main or three-vessel) coronary artery disease were older and had a lower work load, lower heart rate, greater ST segment depression and more extensive perfusion abnormalities than patients with no disease or one- or two-vessel disease. Multivariate discriminant analysis of exercise and thallium variables identified multivessel thallium abnormalities (F = 35), exercise heart rate (F = 18) and extent of ST segment depression (F = 6) as independent predictors of extensive disease. Of the 80 patients with left main or three-vessel disease, 37 (46%) had > or = 2-mm ST segment depression, 44 (55%) had multivessel SPECT abnormalities, and 61 (76%) had either > or = 2-mm ST depression or multivessel SPECT abnormalities (p = 0.0005 vs. the ECG response; p = 0.01 vs. SPECT).

CONCLUSIONS

In patients with an intermediate to high pretest probability of coronary artery disease and normal baseline ECG results, SPECT is superior to the ECG response in detecting coronary disease. Further, SPECT provides incremental power in identifying patients with extensive (left main or three-vessel) coronary disease.

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

OBJECTIVES

This study evaluated the value of noninvasive testing to predict cardiac events in patients with stable coronary disease after hospital admission (and risk stratification) for an acute coronary event.

BACKGROUND

Exercise testing with thallium perfusion imaging identifies patients with obstructive coronary artery disease and has been used to stratify patients after myocardial infarction. Its usefulness for predicting cardiac events in patients with stable coronary disease after recovery from an acute coronary event was explored.

METHODS

Nine hundred thirty-six patients were enrolled 1 to 6 months after hospital admission for a coronary event. Patients underwent exercise treadmill testing with planar thallium-201 scintigraphy and were followed up for an average of 23 months (range 6 to 43). End points were 1) unstable angina requiring hospital admission, nonfatal myocardial infarction or cardiac death; 2) nonfatal infarction or cardiac death; or 3) cardiac death alone.

RESULTS

Twelve patients died of cardiac causes (1.2%); 32 had a nonfatal myocardial infarction (3.4%); and 79 patients (8.4%) developed unstable angina in the first year. Exercise testing improved proportional hazards models constructed from clinical variables for all three end points (p < 0.05). The perfusion scan further improved models for the end points (nonfatal infarction or cardiac death and cardiac death alone, p < 0.05). However, the exercise test with or without thallium added little to the overall prediction of primary events (area under the receiver operating curve increased from 0.649 to 0.663), and only 2% to 13% of patients with abnormal results either had a nonfatal infarction or died.

CONCLUSIONS

Thallium-201 scintigraphy and exercise testing variables identify patients at risk for subsequent cardiac events. However, the poor predictive performance of these tests in this group of patients with stable coronary disease severely limits their usefulness. These results suggest a limited role for exercise and thallium testing in predicting cardiac events in patients with known coronary disease.

Comparison of the treadmill exercise score and single-photon emission computed tomographic thallium imaging in risk assessment

BACKGROUND

This study compared the prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging with that of treadmill exercise score in medically treated patients with coronary artery disease (CAD).

METHODS AND RESULTS

The treadmill exercise score was derived from exercise duration, degree of ST segment depression, and the treadmill anginal index. There were 121 patients with no CAD and 316 patients with angiographically defined CAD (> or = 50% diameter stenosis of one or more vessels). During a mean follow-up of 29 months, there were 35 cardiac deaths or nonfatal myocardial infarctions. Multivariate Cox survival analysis showed the extent of thallium imaging abnormality and CAD to be independent predictors of prognosis. On the other hand, the treadmill exercise score was not a significant predictor even on univariate analysis. The results of thallium uptake were the strongest independent predictors of prognosis and in addition provided incremental prognostic power to coronary angiography (chi 2 = 29 for SPECT, 27 for coronary angiography, and 37 for both).

CONCLUSIONS

Thus exercise SPECT thallium imaging is significantly better than the treadmill exercise score in risk assessment. The size of the perfusion abnormality is an important predicator of prognosis.

Independent and incremental prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging in coronary artery disease

OBJECTIVES

The objective of this study was to examine the independent and incremental prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging in patients with angiographically defined coronary artery disease.

BACKGROUND

Previous studies showed the importance of exercise thallium-201 in risk stratification. However, most of these studies used planar imaging techniques.

METHODS

Follow-up data were obtained in 316 medically treated patients with coronary artery disease. Cox proportional hazards regression models were used to examine the independent and incremental prognostic values of clinical, exercise, thallium and cardiac catheterization data.

RESULTS

There were 35 events (cardiac death or nonfatal myocardial infarction) at a mean follow-up time of 28 months. Univariate analysis showed that gender (chi-square = 5.1), exercise work load (chi-square = 3.1), extent of coronary artery disease and left ventricular ejection fraction (chi-square = 14.8) and thallium variables (chi-square = 22.7) were prognostically important. The thallium data provided incremental prognostic value to catheterization data (chi-square = 33.7, p < 0.01). The extent of the perfusion abnormality was the single best predictor of prognosis (chi-square = 14). Patients with a large perfusion abnormality had a worse prognosis than that of patients with a mild or no abnormality (Mantel-Cox statistics = 10.6, p < 0.001).

CONCLUSIONS

In medically treated patients with coronary artery disease, exercise SPECT thallium imaging provides independent and incremental prognostic information even when catheterization data are available. The extent of the perfusion abnormality is the single most important prognostic predictor.

Identification of extensive coronary artery disease in women by exercise single-photon emission computed tomographic (SPECT) thallium imaging

OBJECTIVES

The aim of this study was to examine the ability of exercise single-photon emission computed tomographic (SPECT) thallium imaging to identify high risk women with left main or three-vessel coronary artery disease using a stepwise discriminant analysis.

BACKGROUND

Previous studies have used statistical methods to identify high risk men with coronary artery disease. Only limited data are available in women.

METHODS

Exercise SPECT thallium imaging and coronary arteriography were performed for evaluation of chest pain in 243 women. Group 1 comprised 58 women with left main or three-vessel coronary disease and group 2 comprised 185 women with no or one- or two-vessel disease. Stepwise discriminant analysis was used to determine predictors of left main or three-vessel disease.

RESULTS

On univariate analysis, women in group 1 were older (p < 0.03) and had a lower exercise work load (p < 0.02), lower exercise heart rate (p < 0.004), higher prevalence rate of diabetes mellitus (p < 0.0003) and more multivessel thallium abnormality (p < 0.0001) compared with women in group 2. On multivariate analysis, only multivessel thallium abnormality (F = 43) and exercise heart rate (F = 6) were independent predictors of left main or three-vessel coronary disease. A model based on these two variables separated the women into three risk groups: 99 patients with 9%, 70 patients with 23% and 74 patients with 45% prevalence of left main or three-vessel disease (p < 0.0001).

CONCLUSIONS

High risk women with left main or three-vessel coronary disease can be identified by exercise SPECT thallium imaging.