Linda A. Taillon

Left ventricular function in patients with coronary artery disease assessed by gated tomographic myocardial perfusion images. Comparison with assessment by contrast ventriculography and first-pass radionuclide angiography.

OBJECTIVES This study evaluated the use of gated single-photon emission computed tomographic (SPECT) myocardial perfusion images for determination of left ventricular ejection fraction. BACKGROUND Gated SPECT has expanded the applications of myocardial perfusion imaging to include the evaluation of left ventricular size, regional wall motion and regional systolic thickening. Accurate automated or semi-automated methods for quantitation of left ventricular ejection fraction from tomographic perfusion images would provide additional valuable clinical information. METHODS Rest gated SPECT was performed on the stress distribution of technetium-99m sestamibi, using eight frames per cardiac cycle. Mid-horizontal long-axis and vertical long-axis gated tomographic perfusion images were analyzed after digital matrix inversion, which enhances edge detection, for ejection fraction determination. These ejection fractions were compared with those determined by contrast ventriculography (n = 54, including 45 biplane and 9 single plane) and first-pass radionuclide angiography (n = 38) in patients with coronary artery disease. RESULTS Myocardial perfusion SPECT image inversion-derived ejection fractions were slightly lower (2.7 ejection fraction units, p < 0.01), and first-pass ejection fractions were much lower (8.0 ejection fraction units, p < 0.001) than those obtained with contrast ventriculography. There was excellent correlation between SPECT and contrast ventriculographic ejection fractions (r = 0.93) over a wide range of ejection fractions (14% to 89%). Good correlation was also observed between first-pass radionuclide angiography and both contrast ventriculography (r = 0.83) and SPECT (r = 0.87). Reproducibility of SPECT image inversion ejection fractions was excellent (intraobserver r = 0.99, interobserver r = 0.93). CONCLUSIONS Semiautomated ejection fractions can be obtained from gated SPECT technetium-99m sestamibi perfusion images using the image inversion technique. These results are reproducible and correlate well with results of first-pass radionuclide angiography but are closer in value to those obtained with contrast ventriculography.

The association between erectile dysfunction and peripheral arterial disease as determined by screening ankle-brachial index testing

BACKGROUND Peripheral arterial disease (PAD) is a potent marker of adverse cardiovascular prognosis, yet PAD frequently remains asymptomatic or undiagnosed. Erectile dysfunction (ED) has been associated with atherosclerosis, but whether ED is an independent predictor of PAD is unknown. We hypothesized that ED is a marker for previously undiagnosed PAD, and thus ED may identify men who would benefit from screening ankle-brachial index (ABI). METHODS 690 male patients (pts) who had been referred for stress testing, and were without known PAD were prospectively screened for ED and PAD, using the International Index of Erectile Function (IIEF) questionnaire, and ABI, respectively. ED was defined by a score of <or=25 on the ED domain of the IIEF, PAD was defined as an ABI<or=0.9. RESULTS ED was present in 45% of pts and PAD was present in 23%. Of pts found to have PAD, 66% reported no lower extremity symptoms. Men with ED were found to have significantly more PAD than men without ED (32% vs. 16%, p<0.01), and there was a stepwise increase in the prevalence of PAD with increasing ED severity (28% of men with mild ED, 33% with moderate ED, 40% with severe ED, p<0.001). On multivariate logistic regression analysis ED (OR 1.97, 95% CI 1.32-2.94, p=0.002), was an independent predictor of PAD. CONCLUSIONS In men referred for stress testing, erectile dysfunction is an independent predictor of PAD as determined by screening ABI examination, and increasing severity of ED is associated with increasing prevalence of PAD. These results suggest that men with ED might be targeted for screening ABI evaluation.

Reversible ischemia in severe stress technetium 99m-labeled sestamibi perfusion defects assessed from gated single-photon emission computed tomographic polar map fourier analysis

BackgroundDetection of reversible ischemia and regional viability by inference from the presence of preserved resting myocardial thickening on dynamic electrocardiographic-gated tomographic (GSPECT) images obtained after stress injection could potentially obviate the need for a separate resting injection. This would decrease the cost, effort, duration, and radiation exposure of diagnostic myocardial perfusion imaging. The aim of this study was to determine whether functional images derived from GSPECT stress myocardial perfusion images, which represent indices of regional wall thickening, could predict the pattern of reversibility of perfusion defects in myocardial segments with severe perfusion defects on stress 99mTc-labeled sestamibi (99mTc-sestamibi) images.Methods and ResultsReversible ischemia in myocardial segments with severe hypoperfusion (≤50% of normal activity) on stress 99mTc-sestamibi images was assessed with GSPECT indexes of myocardial thickening, as reflected by an increase in regional count density during systole. GSPECT bullseye plots were generated for each of eight frames acquired after stress 99mTc-sestamibi injection in 44 patients with coronary artery disease and at least one severe perfusion defect on summed (ungated) SPECT images. With first harmonic Fourier amplitude (AMP) and AMP/perfusion ratio (APR) images, regional myocardial systolic thickening was assessed according to a nine-segment model as absent, markedly reduced, mildly reduced, or normal thickening. These data were compared on a regional basis with defect reversibility determined with resting sestamibi images. Of 124 severe stress defects, 32 showed absent, 53 minimal, 35 partial, and four complete reversibility on resting images. AMP and APR scores had 75% and 82% agreement on the presence or absence of reversibility on resting images, respectively (both p≤0.00005), and both had significant agreement (p=0.0072 and p≤0.00005, respectively) with resting reversibility grades by kappa analysis. AMP correctly identified 83% of the defects that were reversible on resting images, whereas the APR identified 96% (p=0.0014 for sensitivity of APR vs AMP). On analysis of the triad of segment scores, the AMP slightly underestimated the degree of resting reversibility (p=0.0002), whereas APR images indicated more reversibility than did resting images (p≤0.00005). AMP and APR indicated a greater degree of reversibility than did resting images in at least one myocardial segment in 13 (30%) and 27 (61%) of the 44 patients, respectively.ConclusionsThe presence and degree of reversible ischemia in severe stress sestamibi perfusion defects seen on resting images can be detected reliably by the pattern of regional myocardial thickening demonstrated by Fourier analysis of GSPECT polar maps. When indexed for degree of perfusion, the APR images predict a greater degree of reversibility than do resting images.

Quantitative planar imaging of glucose metabolic activity in myocardial segments with exercise thallium-201 perfusion defects in patients with myocardial infarction: comparison with late (24-hour) redistribution thallium imaging for detection of reversible ischemia.

Exercise thallium-201 24-hour redistribution imaging and myocardial glucose metabolism with F-18-deoxyglucose were used to identify reversible ischemia in 30 patients with previous myocardial infarction. Metabolic images were obtained using a planar gamma camera fitted with a rotating tungsten collimator. Of 184 exercise thallium perfusion defects, late redistribution occurred in 88. Metabolic evidence for reversibility (metabolism-perfusion mismatch) was identified in 91% of these 24-hour reversible segments. However, 72% of the segments with fixed perfusion defects also had residual ischemia by F-18-deoxyglucose. Out of 26 fixed severe thallium defects, 69% had F-18-deoxyglucose evidence for residual ischemia. A subset of 14 patients underwent serial exercise thallium scintigraphy or gated equilibrium radionuclide angiography after revascularization or medical therapy. Out of 46 fixed thallium defects in these patients, 30 demonstrated serial scintigraphic improvement. F-18-deoxyglucose-thallium mismatch was present in 81% of these segments, but was absent in the majority of the unimproved segments. Thus quantitative planar imaging of myocardial glucose metabolism with F-18-deoxyglucose using a well-collimated gamma camera can detect clinically important reversible ischemia in segments with fixed thallium defects at late redistribution imaging.

Comparison of Findings on Stress Myocardial Perfusion Imaging in Men With Versus Without Erectile Dysfunction and Without Prior Heart Disease

Erectile dysfunction (ED) has been associated with a future risk of myocardial infarction, yet the findings on stress testing in men with ED and without previous coronary artery disease are unknown. Stress myocardial perfusion single-photon emission computed tomographic imaging (MPI) allows detection of coronary artery disease and predicts cardiovascular prognosis. Our goal was to determine the association between ED and findings at stress MPI testing in men without previous coronary artery disease. Five hundred seventy-five men without previous coronary artery disease referred for stress MPI were prospectively screened for ED with the validated International Index of Erectile Function. ED was present in 46% of subjects, and ED was associated with more mild (summed stress score >or=4) and severe (summed stress score >8) coronary artery disease and with more composite high-risk stress MPI findings (summed stress score >8, left ventricular ejection fraction <40%, transient ischemic dilation). In patients referred for exercise, ED was associated with a lower Duke treadmill score. On multivariate analysis, ED was found to be an independent predictor of a summed stress score >or=4, a summed stress score >8, and composite high-risk MPI findings. In conclusion, in men without known coronary artery disease referred for stress MPI testing, ED is associated with adverse prognostic indicators at MPI testing including coronary artery disease and high-risk MPI findings.

Gated planar technetium 99m-labeled sestamibi myocardial perfusion image inversion for quantitative scintigraphic assessment of left ventricular function.

BackgroundQuantitative assessment of left ventricular systolic performance in conjunction with myocardial perfusion scintigraphy would significantly expand the clinical information obtained from these studies.Methods and ResultsLeft ventricular function was evaluated in 264 patients in whom planar 99mTc-labeled sestamibi myocardial perfusion images were obtained in the best septal left anterior oblique projection. Digital inversion of these perfusion images allows semiautomated designed for equilibrium blood pool imaging. In this study, ejection fractions derived from this technique were compared with those obtained from a myocardial perfusion phantom, first-pass radionuclide angiography, and contrast ventriculography. In vitro validation demonstrated that the myocardial perfusion image inversion ejection fractions correlated linearly with those obtained from a double-chamber phantom (r=0.999). In vivo, there was good linear correlation between image inversion and first-pass (r=0.88; image inversion =0.98·first-pass +0.11), with 95% agreement on the presence or absence of significant left ventricular systolic dysfunction. There was also very good correlation between image inversion and contrast ventriculographic ejection fractions (n=35; r=0.85; image inversion =0.8 · contrast +0.05). Intraobserver and interobserver variability of the image inversion ejection fractions was very small (mean difference of 0.4±0.8 and 2.8±4.7 units, respectively).ConclusionGated 99mTc-labeled sestamibi myocardial perfusion image inversion allows evaluation of the dynamics of the left ventricular chamber changes during the cardiac cycle, providing a method for evaluation of systolic function during myocardial perfusion imaging, with highly reproducible results that correlate well with established techniques.

Usefulness of abnormal heart rate recovery on exercise stress testing to predict high-risk findings on single-photon emission computed tomography myocardial perfusion imaging in men.

Abnormal heart rate recovery (HRR) after maximal exercise treadmill testing predicts adverse cardiac outcomes, although whether abnormal HRR on exercise treadmill testing should prompt further diagnostic cardiac testing is unknown. The aim of this study was to determine the prevalence of high-risk stress single-photon emission computed tomography myocardial perfusion imaging (MPI) findings in patients with abnormal HRR. A total of 509 men who had been referred for exercise stress MPI and were without other abnormal exercise treadmill testing findings (ischemic electrocardiographic changes or exercise treadmill testing-induced angina) were included in this study. Abnormal HRR was defined as a decrease in heart rate <or=12 beats at 1 minute after maximal exercise. Overall, 11% had abnormal HRR. Patients with abnormal HRR had significantly more mild or greater coronary heart disease (summed stress score [SSS] >or=4, 49% vs 27%; p = 0.001), severe coronary heart disease (SSS >8, 36% vs 7%; p <0.001), left ventricular (LV) dysfunction (LV ejection fraction <50%; 25% vs 6%; p <0.001), and composite high-risk MPI findings (SSS >8 or LV ejection fraction <40%; 40% vs 9%; p <0.001) compared with those without abnormal HRR. On multivariate logistic regression analysis, abnormal HRR was found to be an independent predictor of mild or greater coronary heart disease (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.4 to 4.3, p = 0.003), severe coronary heart disease (OR 5.5, 95% CI 2.7 to 11.0, p <0.001), and composite high-risk MPI findings (OR 4.3, 95% CI 2.1 to 8.6, p <0.001). In conclusion, abnormal HRR on exercise treadmill testing was associated with a high prevalence of abnormal and high-risk stress MPI findings, even in patients without other exercise treadmill testing findings that traditionally would prompt further testing. These findings suggest that further testing with stress MPI should be considered in patients with abnormal HRR on routine exercise treadmill testing.