Usefulness of technetium-99m-MIBI and thallium-201 in tomographic imaging combined with high-dose dipyridamole and handgrip exercise for detecting coronary artery disease

High-dose dipyridamole and gated sestamibi SPECT imaging provide diagnostic resting and stress ejection fractions useful for predicting extent of coronary artery disease

A decline in ejection fraction at stress compared with rest images has been associated with increased severity of coronary artery disease (CAD) and suggests a poorer prognosis. Myocardial perfusion imaging (MPI) using high-dose dipyridamole (HDD) has been shown to more accurately detect CAD than either standard dose dipyridamole (SDD) or exercise-induced stress (EST), but has not been looked at to determine its usefulness in detecting changes in stress and rest ejection fractions. To determine the relationship between changes in left ventricular ejection fraction (LVEF) and the severity of CAD, 36 Individuals underwent gated single photon emission computed tomography (SPECT) MPI using HDD. In each case resting and stress LVEFs were determined along with MPI results. Subjects with single-vessel CAD demonstrated an increase in LVEF from 77.8% (sd +/-8.8%) to 85.6% (sd +/-8.4%) resulting in a statistically significant increase in LVEF of 7.8% (p = 0.009). Patients with two-vessel disease showed a smaller increase from 73.2% (sd + 8.3%) to 79.8% (sd + 9.8%) following HDD stress. This increase was statistically (p = 0.008) significant. Patients with triple-vessel CAD showed a reduction in LVEF from 67.4% (sd +/-14.07) to 65.1% (sd +/-16.5%) which represented a decrease in LVEF of 2.7% and approached (p = 0.25) but did not reach statistical significance. Both the resting and stress LVEFs were statistically lower (p<0.05) in patients with triple-vessel CAD. Changes in resting LVEF (REF) and HDD pharmacologically induced stress LVEF (SEF) provide a valuable diagnostic marker as to the number of significantly diseased coronary arteries and can be acquired from gated SPECT sestamibi images.

A tête-à-tête comparison of ejection fraction and regional wall motion abnormalities as measured by echocardiography and gated sestamibi SPECT

Determination of ejection fraction and regional wall motion abnormalities (RWMAs) consistent with stunned, hibernating, or infarcted myocardium can be noninvasively determined by both echocardiography and nuclear cardiac imaging. Prior comparisons between the 2 methods have been limited to Tc 99m pertechnetate or to stress images with attention to RWMAs only. To determine the relationship between results seen with echocardiography and gated single photon emission computed tomography (SPECT) using sestamibi, 26 individuals with varying degrees of coronary artery disease were prospectively studied with both techniques. Five individuals had single-vessel disease, 10 had 2-vessel disease, and 11 had triple-vessel disease. Each individual underwent 2-D, M-mode, and Doppler echocardiography (echo) as well as gated SPECT imaging using rest and stress (high-dose dipyridamole/HDD) sestamibi imaging. The results were statistically different when ejection fractions (EFs) and RWMAs were compared. There were no statistical differences between EFs determined at rest when either echo or nuclear imaging was used. However, patients with EFs <70-80% were overestimated by echo, with echo underestimating EFs >70-80% (p=0.001). There was a high correlation (r=0.76) between resting echocardiographic EFs and SPECT resting gated sestamibi images in patients with single-vessel disease, and a moderate correlation (r=0.68 and r=0.68) in patients with 2- and 3-vessel disease, respectively. Differences in the detection of RWMAs were statistically different for patients with 2-vessel disease (p=0.04) and approached significance in 3-vessel disease (p=0.56) with more RWMA being detected by resting gated SPECT imaging than by echo. Greater differences in RWMAs were seen in patients with 1-, 2-, and 3-vessel disease when resting echo was compared with HDD gated SPECT sestamibi imaging. These differences were statistically greater in 2- (p=0.0027) and 3- (p=0.0003) vessel disease. Differences between stress and resting images are expected in individuals with severe coronary artery disease. Comparison of noninvasive assessment of EFs and RWMAs by gated SPECT sestamibi and echocardiography showed different results when looking at EFs, with echo reporting greater EFs for people with EFs <70-80%. Patients with two and 3-vessel disease were statistically more likely to have RWMAs detected by gated SPECT sestamibi than by echo.

Exercise supplementation to dipyridamole prevents hypotension, improves electrocardiogram sensitivity, and increases heart-to-liver activity ratio on Tc-99m sestamibi imaging

BACKGROUND

Myocardial perfusion imaging with dipyridamole is an alternative with which to evaluate patients who are unable to exercise. Many patients who undergo dipyridamole testing are limited in their ability, but are not completely unable, to exercise. There are benefits from adding low workload exercise to dipyridamole testing, including a reduction of thallium 201 concentration in the liver, leading to a higher heart-to-liver activity ratio and better image quality. This prospective study was designed to evaluate a protocol of exercise supplementation during dipyridamole technetium 99m sestamibi imaging and to verify whether a higher heart-to-liver activity ratio could be obtained. We also evaluated the potential of this combined protocol to prevent hypotension and induce ischemic changes on the electrocardiogram (ECG).

METHODS AND RESULTS

Ninety consecutive patients who were not completely disabled for exercise underwent dipyridamole Tc-99m sestamibi cardiac single photon emission computed tomography with a protocol of exercise supplementation (DipEx). The heart-to-liver activity ratio, hemodynamics, and electrocardiographic changes were studied. The findings were compared with those of a control group (Dip) composed of 99 patients who underwent dipyridamole infusion alone. Patients with left bundle branch block, pacemaker, and atrial fibrillation were excluded. The DipEx patients tolerated the protocol, exercising 4.2 +/- 1.3 minutes on the treadmill (Bruce protocol). Compared with Dip, patients in the DipEx group had a higher heart-to-liver activity ratio (1.3 +/- 0.4 vs 1.6 +/- 0.5, respectively; P =.00001), had no incidence of hypotension (6% vs 0%, respectively; P =.03), and had a higher sensitivity of the ECG to detect ischemia (6% vs 34%, respectively; P =.003). The increase in sensitivity seen in the DipEx group was accompanied by a significant decrease in specificity compared with the Dip group (67% vs 100%, P =.000001).

CONCLUSIONS

Our data show that the addition of limited exercise to dipyridamole results in benefits during Tc-99m sestamibi imaging, increasing heart-to-liver activity ratio, preventing vasodilator-induced hypotension, and improving ECG sensitivity for the detection of ischemia. Furthermore, this protocol also provides an estimation of the patient's physical capacity and could be used as an alternative for patients undergoing dipyridamole infusion who are not completely unable to exercise.

SPECT attenuation artifacts in normal and overweight persons: insights from a retrospective comparison of Rb-82 positron emission tomography and TI-201 SPECT myocardial perfusion imaging

PURPOSE

Myocardial perfusion imaging can be performed using SPECT or positron emission tomography (PET). SPECT has lower specificity than PET, largely as a result of attenuation artifacts; however, it is more widely available. The authors describe a study of the effect of sex and body weight on the incidence of SPECT attenuation artifacts using a retrospective comparison of TI-201 SPECT and Rb PET.

METHODS

One hundred sixty-one persons (101 men, 60 women; 81 normal weight, 80 overweight) underwent TI-201 SPECT and Rb PET. The incidence of observed perfusion defects was studied in territories of the three major coronary arteries. SPECT and PET results were also compared with those of angiography in a subset of 75 patients.

RESULTS

One hundred fourteen defects were reported on Rb PET compared with 176 defects with TI-201 SPECT. Excess TI-201 SPECT defects occurred in male and female, normal-weight and overweight persons. The average specificity was 64% for TI-201 SPECT and 84% for Rb PET, reflecting this difference.

CONCLUSIONS

Attenuation artifacts in TI-201 SPECT occur frequently and are not confined to easily identifiable subgroups of patients. Therefore, measures to improve specificity of SPECT (e.g., prone or gated imaging) or alternative imaging techniques such as PET have potential advantages for everyone, not simply for obese patients and women with large breasts. In addition, awareness of the prevalence of SPECT attenuation artifacts, in both sexes and all weight categories, may contribute to improved accuracy of interpretation.

Dobutamine-atropine stress echocardiography and dipyridamole sestamibi scintigraphy for the detection of coronary artery disease: limitations and concordance

OBJECTIVES

We sought to compare dobutamine-atropine stress echocardiography (DASE) and dipyridamole Technetium 99-m (Tc-99m) sestamibi single photon emission computed tomography (SPECT) scintigraphy (DMIBI) for detecting coronary artery disease (CAD).

BACKGROUND

Both DASE and DMIBI are effective for evaluating patients for CAD, but their concordance and limitations have not been directly compared.

METHODS

To investigate these aims, patients underwent multistage DASE, DMIBI and coronary angiography within three months. Dobutamine-atropine stress echocardiography and stress-rest DMIBI were performed according to standard techniques and analyzed for their accuracy in predicting the extent of CAD. Segments were assigned to vascular territories according to standard models. Angiography was performed using the Judkin's technique.

RESULTS

The 183 patients (mean age: 60 +/- 11 years, including 50 women) consisted of 64 patients with no coronary disease and 61 with single-, 40 with two- and 18 with three-vessel coronary disease. Dobutamine-atropine stress echocardiography and DMIBI were similarly sensitive (87%, 104/119 and 80%, 95/119, respectively) for the detection of CAD, but DASE was more specific (91%, 58/64 vs. 73%, 47/64, p < 0.01). Sensitivity was similar for the detection of CAD in patients with single-vessel disease (84%, 51/61 vs. 74%, 45/61, respectively) and multivessel disease (91%, 53/58 vs. 86%, 50/58, respectively). Multiple wall motion abnormalities and perfusion defects were similarly sensitive for multivessel disease (72%, 42/58 vs. 66%, 38/53, respectively), but, again, DASE was more specific than DMIBI (95%, 119/125 vs. 76%, 95/125, respectively, p < 0.01). Dobutamine-atropine stress echocardiography and DMIBI were moderately concordant for the detection and extent of CAD (Kappa 0.47, p < 0.0001) but were only fairly (Kappa 0.35, p < 0.001) concordant for the type of abnormalities (normal, fixed, ischemia or mixed).

CONCLUSIONS

Dobutamine-atropine stress echocardiography and DMIBI were comparable tests for the detection of CAD. Both were very sensitive for the detection of CAD and moderately sensitive for the extent of disease. The only advantage of DASE was greater specificity, especially for multivessel disease. Dobutamine-atropine stress echocardiography may be advantageous in patients with lower probabilities of CAD.

Nonlimited exercise test combined with high-dose dipyridamole for thallium-201 myocardial single-photon emission computed tomography in coronary artery disease

Clinical, electrocardiographic, and thallium-201 single-photon emission computed tomography data were evaluated in 397 consecutive patients divided into 3 groups according to coronary hyperemic stimulation: 186 patients (group I; Ex) had maximal symptom-limited exercise ergometric stress testing, 93 patients (group II; Dip) had intravenous dipyridamole (0.7 to 0.8 mg/kg) stress testing, and 118 patients (group III; Dip+Ex) had dipyridamole (0.7 to 0.8 mg/kg) plus nonlimited (i.e., symptom-limited) exercise stress testing, achieving a maximal workload (mean +/- SD) of 102 +/- 37 W. Clinical tolerance was higher in Ex than in Dip groups (p < 0.01), and tended to be higher in Dip+Ex than in Dip groups (p = NS). Image quality--as judged by signal-to-noise ratios--was superior in Ex and Dip+Ex groups when compared with the Dip group (p < 0.01). Chest pain and electrocardiographic positivity were more frequent in the Dip+Ex group than in the Dip group (p < 0.05), despite more extensive coronary artery disease (CAD) in the Dip group; and reversible scintigraphic defects were more frequent in Dip+Ex versus Dip (p < 0.01) and in Ex versus Dip groups (p < 0.05) in patients with established CAD, as well as for the whole group. We conclude that, in patients unable to achieve 85% of their maximal predicted heart rate, the combination of high-dose dipyridamole plus nonlimited exercise stress testing is superior to dipyridamole stress testing alone, and comparable to maximal exercise testing.

Effect of dipyridamole on myocardial perfusion and function using technetium-99m MIBI

Myocardial perfusion imaging with dipyridamole is an accepted method for diagnosing coronary artery disease. However, the simultaneous effect of dipyridamole on perfusion and function in the detection of coronary artery disease has not been studied extensively. The aim of this study was to investigate this effect using technetium-99m methoxy isobutyl isonitrile (Tc-MIBI) imaging. Twenty-eight patients with proven coronary artery disease participated in a 2-day protocol (rest and then 0.56 mg/kg dipyridamole i.v.) using Tc-MIBI for first-pass radionuclide ventriculography followed by SPECT imaging. Fifteen patients (54%) demonstrated a decrease in left ventricular ejection fraction from rest to dipyridamole and/or wall motion abnormality, while 21 patients (75%) showed abnormal perfusion by dipyridamole MIBI SPECT imaging. Concordance between perfusion and function was 65%. Correlation for one-, two- and three-vessel disease (coronary angiography) to perfusion versus function were: 54% vs. 38%, 80% vs. 60% and 80% vs. 80%, respectively. Left ventricular dysfunction using dipyridamole was noted in patients with multivessel disease, and with multi-reversible perfusion filling defects. We conclude that dipyridamole in combination with Tc-MIBI for assessment of perfusion and function serves as a valuable tool to identify patients with multivessel disease and a high amount of myocardium at risk.

Prevalence, characteristics, and risk stratification of electrocardiographic and symptomatic silence of myocardial ischemia despite scintigraphically evidenced ischemia in symptomatic patients presenting with severe coronary artery stenosis

Symptoms of angina pectoris and transient ST-segment depression are most commonly used to evidence acute myocardial ischemia during exercise testing. However, the diagnostic accuracy of either or both criteria in relation to clinical characteristics and the patient's exercise response has been a subject of controversy. The prevalence and severity of symptoms of angina pectoris and/or ST-segment depression were studied prospectively in 147 consecutive patients with a history of daily angina pectoris, scintigraphic evidence of exercise-induced myocardial ischemia, and coronary artery stenosis > 75%. Logistic regression analysis was applied to determine absence of any or both criteria by the clinical characteristics or exercise response of the patient. During exercise testing, ST-segment response failed to prove scintigraphically evidenced myocardial ischemia in 14/147 patients (10%) and 35/147 patients (24%) when ST-segment depression > or = 0.1 in either > or = 1 or > or = 2 ECG leads was chosen. Symptoms of angina pectoris were found to be absent in 69/147 patients (47%). Only 58 patients (40%) suffered from angina and met the ECG criterion at the time of scintigraphic myocardial ischemia. Absence of ST-segment depression was best predicted by clinical variables such as large myocardial infarction (increase: 2.6 times, p = 0.007), number of stenoses < or = 2 (2.0 times, p = 0.023), and presence of diabetes mellitus (4.3 times, p = 0.035). Painless myocardial ischemia was determined by blood response to exercising. Thus, a double product > 23 increased the risk of painless myocardial ischemia by 1.5 times (p = 0.017).(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacologic stress dual-isotope myocardial perfusion single-photon emission computed tomography

Separate-acquisition rest thallium-201/exercise technetium-99m sestamibi (sestamibi) dual-isotope single-photon emission computed tomography (SPECT) has been shown to be effective for assessment of myocardial perfusion and viability. The present study was designed to validate the dual-isotope approach when used in conjunction with pharmacologic stress. All patients had rest 201TI SPECT followed immediately by adenosine (n = 82) or dipyridamole (n = 50) infusion and sestamibi injection. Sestamibi SPECT was performed 1 hour later. The entire study lasted < 2.5 hours. The patient population was categorized into three groups: 51 consecutive patients with coronary angiography and no previous myocardial infarction (group I), 58 consecutive patients with a low prescintigraphic test likelihood of coronary artery disease (group II), and 23 consecutive catheterized patients with remote Q-wave myocardial infarction (group III). For group I patients, the sensitivity and specificity for dual-isotope SPECT were 92% (35 of 38) and 85% (11 of 13), respectively, when > or = 50% coronary artery narrowing was considered significant and were 97% (34 of 35) and 81% (13 of 16) respectively, when > or = 70% narrowing was considered significant. The normalcy rate among the 58 patients of group II was 96%. Comparisons for pattern of stress-defect reversibility demonstrated that of the 97 stress defects within the infarct zones (group III), 15% were reversible and 85% were nonreversible. In contrast, of the 227 stress defects within the diseased (> or = 50% stenosis) vessel zones of the group I patients, 93% were reversible and 7% were noreversible (p < 0.001 vs group III). In conclusion, separate acquisition rest 201-TI/pharmacologic stress sestamibi dual-isotope SPECT is an efficient myocardial perfusion imaging protocol with high accuracy for detection and assessment of angiographically significant coronary artery disease.

One-year prognosis of patients with normal planar or single-photon emission computed tomographic technetium 99m-labeled sestamibi exercise imaging

BACKGROUND

The favorable prognostic significance of normal 201Tl stress perfusion images, even in the presence of known coronary artery disease, has been well documented. Relatively few data are available with regard to the prognostic significance of normal planar and single-photon emission computed tomographic (SPECT) stress 99mTc-labeled sestamibi (99mTc-sestamibi) images.

METHODS AND RESULTS

The prognostic significance of normal exercise 99mTc-sestamibi myocardial perfusion imaging was evaluated in 208 consecutive patients. All patients were referred for evaluation of chest pain syndrome. One hundred eight patients (52%) underwent SPECT imaging, 79 patients (38%) underwent planar imaging, and 21 patients (10%) underwent both planar and SPECT imaging. One hundred seventy-five patients (84%) had a normal or nondiagnostic exercise electrocardiogram, and 33 patients (16%) had a positive exercise electrocardiogram. Follow-up was 13.5 +/- 2 months and was complete in 99.5% of patients. No patient died of cardiac causes during follow-up. One patient (0.5%) had a nonfatal myocardial infarction and four patients (2%) had unstable angina necessitating revascularization. There was no difference in rate of cardiac events between men and women or whether SPECT or planar imaging was used. However, 33 patients with normal 99mTc-sestamibi imaging and a positive exercise electrocardiogram had a significantly higher cardiac event rate than had patients with negative exercise electrocardiograms (9% vs 1%, p < 0.025).

CONCLUSION

Patients with normal 99mTc-sestamibi exercise SPECT or planar imaging results and a normal or nondiagnostic exercise electrocardiogram have a favorable 1-year prognosis. Patients with normal 99mTc-sestamibi images and a positive stress electrocardiogram have a less favorable outcome.

Dipyridamole technetium 99m sestamibi myocardial tomography as an independent predictor of cardiac event-free survival after acute ischemic events

BACKGROUND

A total of 137 consecutive patients with recent uncomplicated myocardial infarction (n = 31) or unstable angina (n = 106) were studied to determine the relative prognostic value of predischarge clinical risk stratification and intravenous dipyridamole stress sestamibi (MIBI) myocardial tomography in patients unable to exercise maximally after an acute ischemic coronary event.

METHODS AND RESULTS

Patients were followed up after the index study for 10 +/- 5 months (range 1 to 23 months) to ascertain cardiac events that occurred in 20 patients (15%): nonfatal myocardial infarction (n = 5) or cardiac death (n = 15). Cardiac event rates were 35% in patients with a recent myocardial infarction and 8% in the group with unstable angina (p < 0.001). Patients with these cardiac events had more frequent abnormal MIBI study results, fixed defects, and reversible plus fixed (combined) defects (all p < 0.05). The univariate relative risk of death or myocardial infarction associated with an abnormal MIBI study was 6.0 (95% confidence limits 0.8 to 44.7). Multivariate stepwise logistic regression models identified an abnormal MIBI study and either fixed or reversible MIBI defects as being predictive of death or myocardial infarction (all p < 0.05). The Mantel-Haentzel 1-year cardiac event-free survival rate was excellent in 27 patients with a normal MIBI single-photon computed emission tomographic scan (100%) but significantly reduced in the 110 patients with an abnormal MIBI study (80%; p < 0.05 vs normal subjects). The presence of combined MIBI defects was associated with the poorest event-free survival rate (66%; difference not significant vs fixed or reversible defects only).

CONCLUSION

We conclude that predischarge dipyridamole MIBI tomography provided independent prognostic information in this population of patients who were unable to exercise after a recent acute ischemic coronary event.

99Tcm-sestamibi uptake in the leg muscles and in the myocardium in patients with intermittent claudication

99Tcm-Sestamibi has now replaced 201Tl as a cardiac imaging agent. In addition to the myocardial uptake there is also a considerable uptake in the striated muscle, which may be used for analyzing the muscular perfusion. Sixteen patients with intermittent claudication were investigated with 99Tcm-Sestamibi-SPECT (single photon emission computerized tomography) in order to visualize coronary ischemic disease. After the registration of the myocardial perfusion they were also studied regarding their leg muscle perfusion. This was done at rest and during standardized stress test using a bicycle ergometer. In 10 of the patients there was an increase in the isotope uptake in the myocardium from work to rest > 10% reflecting pronounced myocardial ischemia, which, however, was symptomatic in only 4 of the patients. The muscular uptake in the myocardium of 99Tcm-Sestamibi in the thigh increased significantly from rest to exercise (P < 0.01), while it remained unchanged in the calf muscle. There were no significant correlations at rest between the ratio of the right and left systolic blood pressure in the ankles and the ratio between the right and left isotope uptake in the calves, but the increase in the isotope uptake from rest to work correlated with the blood pressure ratio at r = 0.79, P < 0.01 (anterior projection) and r = 0.71, P < 0.01 (posterior projection).

Identification of hemodynamically significant coronary artery stenoses by dipyridamole-magnetic resonance imaging and 99mTc-methoxyisobutyl-isonitrile-SPECT

Magnetic resonance imaging (MRI) has been used in conjunction with dipyridamole induced wall motion abnormalities for the noninvasive detection of coronary artery disease (CAD). To assess the clinical usefulness of dipyridamole-MRI for the localization of CAD and to evaluate the relation between dipyridamole induced wall motion abnormalities and myocardial perfusion 33 patients with severe CAD (> 70% diameter reduction) underwent MRI at rest and after dipyridamole infusion (0.75 mg dipyridamole/kg over a period of 10 minutes). All patients performed exercise stress testing and 20 patients of the study group additionally had rest and exercise stress 99mTc-methoxyisobutyl-isonitrile-SPECT (MIBI-SPECT). Two patients (6%) could not be evaluated due to severe motion artifacts during dipyridamole MRI. Segmental wall motion and perfusion of corresponding short axis planes were related to the major coronary arteries using a standardized segmental coronary artery perfusion pattern. Detection of wall motion abnormalities or perfusion defects by 2 blinded observers in consensus was the criterion for grading a segment normal or pathologic. For localization of CAD, segmental gradings were related to the presumed coronary artery territories. Stress-ECG was pathologic in 19/31 patients yielding a sensitivity of 61% and dipyridamole induced angina was present in 68% (21/31) of patients. Dipyridamole-MRI detected coronary artery disease with a sensitivity of 84% (26/31 patients) and all patients with new wall motion abnormalities also had dipyridamole induced angina. For the subgroup of 20 patients with MIBI-SPECT images, CAD was detected by both MIBI-SPECT and Dipyridamole-MRI in 90% (18/20) of patients. Dipyridamole-MRI and MIBI-SPECT gradings agreed in 55/60 (92%) coronary artery perfusion territories. There were no significant differences with respect to the sensitivities of Dipyridamole-MRI/MIBI-SPECT for the localization of individual coronary artery stenoses yielding 81%/78% for left anterior descending, 80%/80% for left circumflex and 92%/89% for right coronary artery stenoses. However, specificity of Dipyridamole-MRI (89%) for the detection of RCA stenoses was slightly better than for MIBI-SPECT (80%).

Preoperative diagnosis of coronary artery disease in patients with valvular heart disease using technetium-99m isonitrile tomographic imaging together with high-dose dipyridamole and handgrip exercise

Forty-seven consecutive patients (mean age 61 +/- 8 years) referred for cardiac catheterization due to moderate to severe aortic (n = 30) or mitral (n = 17) valvular heart disease were examined by technetium-99m isonitrile tomography together with a high-dose dipyridamole infusion (0.7 mg/kg) and handgrip stress. Tomography did not identify coronary artery disease (CAD) in 3 of the 21 patients with angiographically proven disease (sensitivity 86%) and suggested false positive results in 5 of the 26 without the disease (specificity 81% and negative predictive accuracy 88%). No patient without angina pectoris and with negative scintigraphy (n = 14) had angiographically significant (greater than or equal to 50% diameter stenosis) CAD. Overall vessel sensitivity was 63%, and specificity was 92%. The frequency of side effects during the dipyridamole-handgrip test was only 7%. No serious complications occurred during stress tests. Thus, technetium-99m isonitrile tomographic imaging, together with high-dose dipyridamole and handgrip exercise, is a useful noninvasive method in excluding significant CAD in patients with valvular heart disease.