P6151Fully automated epicardial adipose tissue volume and density measured from non-contrast CT predict major adverse cardiovascular events in asymptomatic subjects

Background

Epicardial adipose tissue (EAT) volume and density has shown to correlate with standard markers of coronary artery disease (CAD) and may predict major adverse cardiovascular events (MACE).

Purpose

We aimed to evaluate the prognostic value of EAT volume and density measured by fully automated deep-learning software from non-contrast cardiac computed tomography (CT).

Methods

We assessed 2071 consecutive asymptomatic subjects (age 56±9 years, 59% male) from the EISNER (Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research) trial with long-term follow-up after coronary artery calcium (CAC) measurement. EAT volume and mean density were quantified using automated deep-learning software from non-contrast cardiac CT. MACE was defined as myocardial infarction (MI), cardiac death, late (>90 days) revascularization and acute coronary syndrome (ACS). EAT volume and density were systematically compared to CAC score and atherosclerotic cardiovascular disease (ASCVD) risk score using Cox proportional hazards regression for MACE prediction.

Results

At 14±3 years, 217 subjects suffered MACE. In age-and-gender-adjusted multivariate analysis, ASCVD risk score, CAC (two-fold increase) and EAT volume (two-fold increase) were associated with increased risk of suffering MACE [Hazard Ratio (HR) (95% CI): 1.03 (1.01–1.04); 1.25 (1.19–1.30); and 1.36 (1.08–1.70) respectively, p<0.01 for all] (Figure); the corresponding Harrell's C-statistic was 0.76. The area-under-the curve from receiver-operator characteristic analysis for MACE prediction increased significantly from 0.69 to 0.77 (p<0.0001) when EAT volume and CAC were added to the current clinical standard (ASCVD, family history and obesity measures BMI and BSA). Both in men and women, increase in EAT volume was associated with increased risk of MACE, with HR 1.14 (1.06–1.22), p<0.001 in men vs. 1.15 (1.01–1.31), p=0.03 in women, for each 20 cubic centimeter increase in volume. EAT density (HU) was independently inversely associated with MACE [HR: 0.96 (0.93–0.99), p=0.01].

MACE Prediction

Conclusions

EAT volume and density measurements improve prediction of MACE in asymptomatic populations over the current clinical standard. Fully automated EAT volume and density quantification by deep-learning from non-contrast cardiac CT can provide additional prognostic value for the asymptomatic patient.

Acknowledgement/Funding

1R01HL133616, Forschungsstiftung Medizin Universitätsklinikum Erlangen, grant from Dr Miriam and Sheldon G. Adelson Medical Research Foundation

30Machine learning to predict the long-term risk of myocardial infarction and cardiac death based on clinical risk, coronary calcium and epicardial adipose tissue: a prospective study

Background/Introduction

Machine learning (ML) allows objective integration of clinical and imaging data for the prediction of events. ML prediction of cardiovascular events in asymptomatic subjects over long-term follow-up, utilizing quantitative CT measures of coronary artery calcium (CAC) and epicardial adipose tissue (EAT) have not yet been evaluated.

Purpose

To analyze the ability of machine learning to integrate clinical parameters with coronary calcium and EAT quantification in order to improve prediction of myocardial infarction (MI) and cardiac death in asymptomatic subjects.

Methods

We assessed 2071 consecutive subjects [1230 (59%) male, age: 56.049.03] from the EISNER (Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research) trial with long-term follow-up after non-enhanced cardiac CT. CAC (Agatston) score, age-and-gender-adjusted CAC percentile, and aortic calcium scores were obtained. EAT volume and density were quantified using a fully automated deep learning method. Extreme gradient boosting, a ML algorithm, was trained using demographic variables, plasma lipid panel measurements, risk factors as well as CAC, aortic calcium and EAT measures from CAC CT scans. ML was validated using 10-fold cross validation; event prediction was evaluated using area-under-receiver operating characteristic curve (AUC) analysis and Cox proportional hazards regression. Optimal ML cut-point for risk of MI and cardiac death was determined by highest Youden's index (sensitivity + specificity – 1).

Results

At 152 years' follow-up, 76 events of MI and/or cardiac death had occurred. ML obtained a significantly higher AUC than the ASCVD risk and CAC score in predicting events (ML: 0.81; ASCVD: 0.76, p<0.05; CAC: 0.75, p<0.01, Figure A). ML performance was mostly driven by age, ASCVD risk and calcium as shown by the variable importance (Figure B); however, all variables with non-zero gain contributed to the ML performance. ML achieved a sensitivity and specificity of 77.6% and 73.5%, respectively. For an equal specificity, ASCVD and CAC scores obtained a sensitivity of 61.8% and 67.1%, respectively. High ML risk was associated with a high risk of suffering an event by Cox regression (HR: 9.25 [95% CI: 5.39–15.87], p<0.001; survival curves in Figure C). The relationships persisted when adjusted for age, gender, CAC, CAC percentile, aortic calcium score, and ASCVD risk score; with a hazard ratio of 3.42 for high ML risk (HR: 3.42 [95% CI: 1.54–7.57], p=0.002).

Conclusion(s)

Machine learning used to integrate clinical and quantitative imaging-based variables significantly improves prediction of MI and cardiac death in asymptomatic subjects undergoing CAC assessment, compared to standard risk assessment methods.

Acknowledgement/Funding

NHLBI 1R01HL13361, Bundesministerium für Bildung und Forschung (01EX1012B), Dr. Miriam and Sheldon G. Adelson Medical Research Foundation

Thyroid hormone upregulates MDM2 in rat type I fibre: Implications for skeletal muscle mass regulation

AIM

Based upon a microarray assay, we have identified that triiodothyronine (T3) upregulates MDM2 gene expression in the rat skeletal muscle. As MDM2 protein is an E3 ligase, we hypothesized that this enzyme could play a role in T3 effects on skeletal muscle mass control.

METHODS

To test our hypothesis, male rats (2 months old) were randomly assigned into the following groups: intact controls, treated with 20 physiological doses of T3 for 0.5, 1 and 7 days, or with 5, 20 and 50 physiological doses of T3 for 7 days. For in vitro experiments, myotubes and C2C12 cells were treated with T3 for 3 days.

RESULTS

After validation of the microarray finding throughout RT-PCR and confirmation that T3 induces increases in MDM2 protein expression in a dose-dependent manner, we observed that MDM2 was upregulated by T3 exclusively in fibre type I. Moreover, detailed histological evaluation showed that MDM2 overexpression distributes punctiformily along the cross section of the fibre and also inside nuclei. MDM2 colocalizes with PAX7 in control muscle and T3 downregulates this myogenic factor. Pharmacological inhibition of MDM2 in cultured myotubes caused a severe decrease in their diameter (~35%, P < .001 vs Control), enhancing the effect of T3 (from ~12% to ~35%, P < .001) alone upon myotube diameter and mRNA levels of atrogenes. Finally, we observed that FOXO3 (MDM2 target) is kept outside the nucleus under T3 stimulation.

CONCLUSION

Our results indicate that MDM2 might be involved in the pro-trophic effects of T3 in skeletal muscle.

Nanocapsules for 5-fluorouracil delivery decorated with a poly(2-ethylhexyl methacrylate-co-7-(4-trifluoromethyl)coumarin acrylamide) cross-linked wall

Nanocapsules with reverse cross-linked polymer walls containing coumarin moieties are capable of encapsulating 5-fluorouracil and accomplishing a comprehensive strategy in a drug delivery system.

SPECT/PET myocardial perfusion imaging versus coronary CT angiography in patients with known or suspected CAD

Stress SPECT myocardial perfusion imaging (MPI) is the most commonly utilized stress imaging technique for patients with suspected or known coronary artery disease (CAD) and has a robust evidence base including the support of numerous clinical guidelines. Gated SPECT is a well-established noninvasive imaging modalities that is a core element in evaluation of patients with both acute and stable chest pain syndromes. Over the past decade, PET has become increasingly used for the same applications. By comparison, cardiac computed tomography (CT) is a more recently developed method, providing non-invasive approaches for imaging coronary atherosclerosis and coronary artery stenosis. Non-contrast CT for imaging the extent of coronary artery calcification (CAC), in clinical use since the mid-1990's, has a very extensive evidence base supporting its use in CAD prevention. While contrast-enhanced CT for noninvasive CT coronary angiography (CCTA) is relatively new, it has already developed an extensive base of evidence regarding diagnosing obstructive CAD and more recently evidence has emerged regarding its prognostic value. It is likely that non-contrast CT or CCTA for assessment of extent of atherosclerosis will become an increasing part of mainstream cardiovascular imaging practices as a first line test. In some patients, further ischemia testing with MPI will be required. Similarly, MPI will continue to be widely used as a first-line test, and in some patients, further anatomic definition of atherosclerosis with CT will also be appropriate. This review will provide a synopsis of the available literature on imaging that integrates both CT and MPI in strategies for the assessment of asymptomatic patients for their atherosclerotic coronary disease burden and risk as well as symptomatic patients for diagnosis and guiding management. We propose possible strategies through which imaging might be used to identify asymptomatic candidates for more intensive prevention and risk factor modification strategies as well as symptomatic patients who would benefit from referral to invasive coronary angiography for consideration of revascularization.

Peripheral arterial responses to treadmill exercise among healthy subjects and atherosclerotic patients

BACKGROUND-Peripheral cutaneous vascular beds, such as the fingertips, contain a high concentration of arteriovenous anastomoses, richly innervated by a-adrenergic nerve fibers, to control heat regulation. Nevertheless, for a variety of technical reasons, finger blood flow responses to exercise have not been well studied in health and disease. Hence, we compared finger pulse-wave amplitude (PWA) responses to exercise among 50 normal volunteers and 57 patients with atherosclerotic coronary artery disease (CAD) using a robust, modified form of volume plethysmography.

METHODS AND RESULTS

PWA was quantified for each minute of exercise as a ratio relative to baseline. Exercise PWA responses were compared with clinical, hemodynamic, ECG, and myocardial single photon emission computed tomography parameters. Among normal subjects, 38 (76%) manifested vasodilation throughout exercise and 12 (24%) manifested initial vasodilation followed by vasoconstriction at high heart rate thresholds. None manifested vasoconstriction throughout exercise. By contrast, 20 CAD patients (35%) manifested progressive vasoconstriction from the onset of exercise, and 10 others (18%) manifested vasoconstriction at low heart rate thresholds (P < 0.001 versus normals) after initial vasodilation with exercise. Patients exhibiting vasodilation versus vasoconstriction during exercise had similar clinical and exercise profiles, except for a greater use of ACE inhibitors and a greater level of achieved metabolic equivalents among the former (P<0.05 for both).

CONCLUSIONS

Half of our CAD patients manifested diminution in PWA that was consistent with peripheral arterial vasoconstriction during the early phases of treadmill exercise. Such paradoxical vasoconstrictive responses were not observed in normal subjects and, therefore, they may represent generalized vascular pathology secondary to atherosclerosis.

Stress radionuclide imaging versus stress echocardiography: a framework for comparisons

Comparisons of stress-imaging procedures require analyses based on their 2 principal applications: diagnostic and prognostic assessments. Besides comparing results reported in the literature--in which differences have been reported in the ability of stress nuclear versus stress echocardiographic imaging to predict a low risk of cardiac events-other factors often not reported may be important in discerning the relative efficacy of these tests. These include consideration of how these tests perform in specific, individualized patient scenarios; the effect of on-going technical advances on test usefulness; and evaluation of test worthiness according to such factors as cost-effectiveness and the magnitude of incremental test information that is provided. Furthermore, it is important to distinguish between a test's efficacy (ie, its intrinsic accuracy) and its effectiveness (ie, how it performs in the real world of clinical practice).

Principles for combining radionuclide and echocardiographic stress imaging into a single clinical laboratory service

Physicians who supervise stress-imaging procedures, whether they be stress nuclear or stress echocardiography tests, are increasingly required to incorporate important principles in the interpretation of the test results. Important guiding principles, common to these tests, are reviewed in this article. The principles include the following: avoiding categorical interpretation of test results; identifying equivocal test responses; combining diagnostic and prognostic information in rendering information to referring physicians; integrating the stress test results with other clinical data and using Bayesian analysis as a decision-aid; reporting one's confidence in the interpretation of the results of testing; characterizing both the extent and severity of any induced myocardial ischemia; and analyzing the test results in a blinded fashion, without prior knowledge of patient clinical history

Principal uses of myocardial perfusion scintigraphy in the management of patients with known or suspected coronary artery disease

The use of myocardial perfusion single photon emission computed tomography (SPECT) has undergone considerable expansion and evolution over the past 2 decades. Although myocardial perfusion imaging was first conceived as a noninvasive diagnostic tool for determining the presence or absence of coronary artery disease, its prognostic value is now well established. Thus, identification of patients at risk for future cardiac events has become a primary objective in the noninvasive evaluation of patients with chest pain syndromes and among patients with known coronary artery disease. In particular, the ability of myocardial perfusion SPECT to identify patients at low (< 1%), intermediate (1% to 5%) or high (> 5%) risk for future cardiac events is essential to patient management decisions. Moreover, previous studies have conclusively shown the incremental prognostic value of myocardial perfusion SPECT over clinical and treadmill exercise data in predicting future cardiac events. This report addresses the current role and new developments, with respect to the use of myocardial perfusion imaging, in determining patient risk for cardiac events and the cost-effective integration of such information into patient management decisions.

Postexercise left ventricular function: a comparative assessment by different noninvasive imaging modalities

The variety of noninvasive imaging modalities now available permits assessment of different aspects of left ventricular function in the postexercise state. Some of these modalities, such as first-pass radionuclide ventriculography, permit a nearly instantaneous assessment of left ventricular function in the early postexercise state. These modalities indicate that most exercise-induced left ventricular wall motion abnormalities resolve quickly after exercise. Resting wall motion abnormalities may also improve in the postexercise period; this response indicates the presence of hibernating myocardium capable of improving in response to myocardial revascularization procedures. On the other hand, all imaging techniques indicate that a certain percentage of exercise-induced wall motion abnormalities may persist into the postexercise period, and this finding signifies that severe coronary disease subtends the region of persisting wall motion abnormality. Further, if there is increased left ventricular size after exercise, both extensive and severe coronary disease are present. A conceptual framework for unifying these disparate findings is provided. These results underscore the importance of postexercise imaging in enhancing clinical assessment and imply that there are important technical considerations to contemplate when performing certain tests such as postexercise echocardiography.

Development and application of normal limits for left ventricular ejection fraction and volume measurements from 99mTc-sestamibi myocardial perfusion gates SPECT

Gated SPECT is a reproducible method for assessing left ventricular volume (LVV) and left ventricular ejection fraction (LVEF) from 99mTc-sestamibi myocardial perfusion imaging studies. LVV and LVEF measurements by this approach correlate well with those obtained from other cardiovascular imaging techniques. Nevertheless, the lack of criteria for abnormal test findings has limited the potential clinical application of this new imaging technique.

METHODS

Gated SPECT measurements were evaluated for 214 patients with a low Bayesian likelihood (< 10%) of coronary artery disease (CAD) before performance of 99mTc-sestamibi stress-rest myocardial perfusion SPECT. The patients were grouped into normotensive patients (n = 98), hypertensive patients without left ventricular hypertrophy (LVH) (n = 80), and hypertensive patients with LVH on resting electrocardiography (n = 36). Gated SPECT measurements for left ventricular end-diastolic volume (LVEDV) index, left ventricular end-systolic volume (LVESV) index, and LVEF were obtained according to a published method, using a modified Simpson's rule technique.

RESULTS

Similar results were obtained for mean LVV and LVEF measurements between normotensive patients and hypertensive patients without LVH. Hence, these groups were combined (as group 1). By contrast, hypertensive patients with LVH (group 2), had significantly lower LVEF values (P = 0.01) and higher mean LVESV index values than normotensive patients (P = 0.03). Sex differences were marked: women had significantly higher mean resting LVEF values than men (P < 0.0001) and significantly lower mean resting LVEDV index values (P < 0.0001). A significant relationship was seen between LVEDV index and LVEF (r = -0.60; P < 0.0001) and between LVEDV index and heart rate (r = -0.26; P < 0.001). The normal limits were LVEF > or = 41% in men and > or = 49% in women, LVEDV index < or = 76 mL/m2 in men and < or = 57 mL/m2 in women, and LVESV index < or 38 mL/m2 in men and < or =26 mL/m2 in women. Among hypertensive patients, 22% with LVH had an abnormally low LVEF and 19% had an increased LVEDV index according to these test criteria. By contrast, no hypertensive patients without LVH had an abnormally low LVEF, and only 6% had volume abnormalities.

CONCLUSION

Using a cohort of low-likelihood patients, we generated sex-specific normal limits for LVV and LVEF for myocardial perfusion gated SPECT. Application of these findings resulted in the detection of occult left ventricular dysfunction in approximately one fifth of hypertensive patients for whom concomitant LVH was found through resting electrocardiography. These normal limits can now be evaluated prospectively for their potential clinical value.

Echocardiographic validation of gated SPECT ventricular function measurements

Left ventricular (LV) volumes are valuable prognostic indicators in the management of coronary artery disease and traditionally have been obtained by x-ray contrast angiography or echocardiography. There now are several scintigraphic methods to compute volumes that are based on different LV modeling assumptions. Both the reasons that calculations from different nuclear techniques can disagree with one another and the relationship of these values to the more conventional echocardiographic measurements must be investigated thoroughly for calculations to be interpretable for individual patients.

METHODS

Echocardiographic volumes were determined in 33 retrospective subjects with coronary artery disease (mean age, 61 +/- 12 y; 42% men; 70% with abnormal perfusion and 58% with abnormal segmental wall motion) using the modified Simpson's rule technique applied to digitized apical 4-chamber and apical 2-chamber views of 4 averaged heartbeats. These volumes were compared with those from 3 gated SPECT methods based on Simpson's rule LV modeling similar to standard echocardiographic algorithms (SPECT EF from St. Luke's-Roosevelt Hospital) (method 1), Gaussian myocardial count profile curve fitting (QGS from Cedars-Sinai Medical Center) (method 2), and an endocardial model based on perfusion sampling and count-based thickening (Cardiac Toolbox from Emory University) (method 3).

RESULTS

By ANOVA, there were no significant differences among ejection fractions (EFs), but there were for volumes. Paired t test analysis showed volumes from methods 2 and 3 to be significantly larger than echocardiographic volumes and larger than those of method 1. Linear regression analysis comparing gated SPECT and echocardiographic volumes showed a nearly identical strong correlation (r = 0.92; P < 0.000001) for all 3 methods. Excellent correlation also was found among gated SPECT volumes from the 3 methods (r = 0.94). Bland-Altman analysis and t tests showed that method 1 volumes (70 +/- 61 mL) were the same as for echocardiography (77 +/- 55 mL), but volumes were overestimated by method 2 (105 +/- 74 mL) and method 3 (127 +/- 92 mL), particularly for larger volumes. Pearson coefficients for EFs compared with echocardiography were r = 0.82, 0.75, and 0.72 for methods 1-3, respectively. EFs correlated strongly among the 3 gated SPECT methods (r = 0.86-0.92). The Fisher z test showed no differences among these methods for any of the volume or EF linear correlation analyses.

CONCLUSION

All gated SPECT parameters correlated well with echocardiographic values. However, the gated SPECT method for which underlying assumptions most closely resembled those commonly used in echocardiography produced mean volume values closest in agreement with echocardiographic measurements.

Prognostic value of mental stress testing in coronary artery disease

This study assesses the prognostic value of mental stress-induced ischemic left ventricular wall motion abnormalities and hemodynamic responses in patients with stable coronary artery disease (CAD). Seventy-nine patients (76 men and 3 women) with prior positive exercise test results were exposed to mental arithmetic and a simulated public speech stress in 2 prior studies. Ischemic wall motion abnormalities were monitored using echocardiography or radionuclide ventriculography (RNV). During mental stress testing, new or worsened ischemic wall motion abnormalities to mental stress and exercise were ascertained, as were peak changes in blood pressure and heart rate to mental stress. The occurrence of subsequent cardiac events (including cardiac death, nonfatal myocardial infarction, or revascularization procedures) was ascertained. New cardiac events were observed in 28 of 79 patients (35%) after a median follow-up duration of 3.5 years (range 2.7 to 7.3). Survival analysis indicated that 20 of 45 patients with mental stress ischemia (44%) experienced new cardiac events more frequently than those without mental stress ischemia (8 of 34; 23%; p = 0.048). Type of cardiac event did not differ between mental stress-positive and stress-negative patients. After controlling for baseline blood pressure and study group status (echocardiography vs RNV), there was a significantly higher relative risk of subsequent events for patients with high versus low peak stress-induced diastolic blood pressure responses (RR = 2.4, confidence interval 1.1 to 5.2; p = 0.03). These results demonstrate that ischemic and hemodynamic measures obtained from mental stress testing may be useful in assessing prognosis in CAD patients with prior positive exercise test results.

Influence of arrhythmias on gated SPECT myocardial perfusion and function quantification

Despite the importance of R-wave gating myocardial perfusion tomography for ventricular function assessment, neither prevalence of gating errors nor their influence on quantified cardiac parameters has been studied.

METHODS

Arrhythmia-induced anomalies in curves of counts versus projection angle for each R-wave segment were detected visually and algorithmically. Arrhythmia prevalence was tabulated for 379 patients (group 1) with prospective coronary artery disease (mean age 63+/-13 y, 47% male). Myocardial counts were analyzed from all reconstructed cinematic midventricular slices to assess arrhythmia effects on percentage of systolic count increase, generally assumed to equal percentage of wall thickening. In a separate retrospective analysis of 41 patients (group 2), with coronary artery disease (mean age 64+/-12 y, 68% male) having no significant arrhythmias, 36 of whom also underwent equilibrium radionuclide angiography, original projection data were altered to simulate arrhythmia-induced aberrant count patterns to evaluate effects on ventricular function and perfusion measurements.

RESULTS

Group 1 patients consisted of 26% without gating errors, 32% with count losses only in the last R-wave interval due to inconsistent transient increase of heart rate, 24% with count decreases in several late intervals due to consistently variable rates, 8% with early interval count increases paired with late interval count decreases due to ectopic beats and 9% with erratic count changes due to atrial fibrillation. Observed count patterns were strongly associated (P < 10(-3)) with arrhythmias detected by electrocardiogram monitoring. In group 2 simulations, ventricular volumes changed by only 2%+/-9% and ejection fraction (EF) by only 1%+/-4% from control values and correlated linearly (r> or = 0.96) with control values for all simulated arrhythmias. SPECT and equilibrium radionuclide angiography EFs correlated similarly (r = 0.85-0.89) for control and all simulations. Percentage changes from control in perfusion defect extent and severity were larger than processing reproducibility limits, the largest change being for atrial fibrillation. Control wall thickening was 38%+/-17%, significantly lower (P < 10(-6)) than for simulated arrhythmias, reflecting similar observations for group 1 patients.

CONCLUSION

Even though ventricular volumes and EFs were affected minimally by arrhythmias, both perfusion analysis and wall thickening were compromised. Consequently, quality assurance of gating may be critically important for obtaining accurate quantified parameters.

Comparison of Tc-99m sestamibi and Tl-201 gated perfusion SPECT

BACKGROUND

To determine the interpretability of gated thallium-201 perfusion SPECT compared with that performed by use of technetium-99m sestamibi (MIBI), 33 patients with prior myocardial infarction were studied. Patients received 22 to 30 mCi (814 to 1110 MBq) MIBI at peak stress, and a 15-minute gated SPECT acquisition was begun 30 to 40 minutes thereafter. On a subsequent day gated Tl-201 SPECT was acquired for 15 minutes, 4 hours after a resting 3.5 mCi (130 MBq) injection. SPECT was performed over a 180-degree arc by use of a 90-degree angled 2-detector camera.

RESULTS

Gated studies were interpreted independently by 4 experienced physicians. Study quality was graded (0 = uninterpretable to 4 = excellent). Wall motion (0 = normal to 2 = akinetic/dyskinetic) and wall thickening (0 = normal to 2 = absent) were graded for each of 10 segments viewed in orthogonal planes. Left ventricular ejection fraction (LVEF) was calculated by use of software thus far validated only for MIBI. The average count density of mid-ventricular end-diastolic short axis tomograms with sestamibi was 3.47 times greater than with thallium. Mean study quality was 3.4 for MIBI and 1.8 for thallium (P < 10(-6)). No gated MIBI SPECTs, but 2 gated thallium studies (6%) were judged uninterpretable. Among interpretable scans, interobserver agreement (Kendall statistic) in assessing wall motion was 0.73 for MIBI and 0.66 for thallium (P = .01). For assessing wall thickening, the Kendall statistic was 0.73 for MIBI and 0.69 for thallium (P = .05). Correlation (r) of LVEFs was 0.91, SEE = 6.4.

CONCLUSIONS

We conclude that gated thallium SPECT is inferior to MIBI because of much poorer image quality and somewhat poorer interobserver agreement among experienced physicians. However, LVEF can be determined reliably from gated thallium SPECT.

Impact of psychological factors on the pathogenesis of cardiovascular disease and implications for therapy

Recent studies provide clear and convincing evidence that psychosocial factors contribute significantly to the pathogenesis and expression of coronary artery disease (CAD). This evidence is composed largely of data relating CAD risk to 5 specific psychosocial domains: (1) depression, (2) anxiety, (3) personality factors and character traits, (4) social isolation, and (5) chronic life stress. Pathophysiological mechanisms underlying the relationship between these entities and CAD can be divided into behavioral mechanisms, whereby psychosocial conditions contribute to a higher frequency of adverse health behaviors, such as poor diet and smoking, and direct pathophysiological mechanisms, such as neuroendocrine and platelet activation. An extensive body of evidence from animal models (especially the cynomolgus monkey, Macaca fascicularis) reveals that chronic psychosocial stress can lead, probably via a mechanism involving excessive sympathetic nervous system activation, to exacerbation of coronary artery atherosclerosis as well as to transient endothelial dysfunction and even necrosis. Evidence from monkeys also indicates that psychosocial stress reliably induces ovarian dysfunction, hypercortisolemia, and excessive adrenergic activation in premenopausal females, leading to accelerated atherosclerosis. Also reviewed are data relating CAD to acute stress and individual differences in sympathetic nervous system responsivity. New technologies and research from animal models demonstrate that acute stress triggers myocardial ischemia, promotes arrhythmogenesis, stimulates platelet function, and increases blood viscosity through hemoconcentration. In the presence of underlying atherosclerosis (eg, in CAD patients), acute stress also causes coronary vasoconstriction. Recent data indicate that the foregoing effects result, at least in part, from the endothelial dysfunction and injury induced by acute stress. Hyperresponsivity of the sympathetic nervous system, manifested by exaggerated heart rate and blood pressure responses to psychological stimuli, is an intrinsic characteristic among some individuals. Current data link sympathetic nervous system hyperresponsivity to accelerated development of carotid atherosclerosis in human subjects and to exacerbated coronary and carotid atherosclerosis in monkeys. Thus far, intervention trials designed to reduce psychosocial stress have been limited in size and number. Specific suggestions to improve the assessment of behavioral interventions include more complete delineation of the physiological mechanisms by which such interventions might work; increased use of new, more convenient "alternative" end points for behavioral intervention trials; development of specifically targeted behavioral interventions (based on profiling of patient factors); and evaluation of previously developed models of predicting behavioral change. The importance of maximizing the efficacy of behavioral interventions is underscored by the recognition that psychosocial stresses tend to cluster together. When they do so, the resultant risk for cardiac events is often substantially elevated, equaling that associated with previously established risk factors for CAD, such as hypertension and hypercholesterolemia.

Do patient data ever exceed the partial volume limit in gated SPECT studies?

BACKGROUND

Some single photon emission computed tomography (SPECT) methods to detect percent myocardial wall thickening (%WT) assume a linear relationship to changes in maximum myocardial counts, predicated on myocardial walls never exceeding the SPECT camera's partial volume limit. Recent studies have challenged such assumptions, reporting that systolic count changes underestimate wall thickening as measured by echocardiography and magnetic resonance imaging.

METHODS AND RESULTS

To test whether clinical data ever are observed to exceed the partial volume limit, we examined gated tomograms of 75 patients selected at random and of an additional 25 patients known to have hypertension with electrocardiographic evidence of left ventricular hypertrophy. Image transformations were performed such that for every cinematic frame, radial counts at every angle were automatically normalized to the same maximum count. If no patient's myocardium ever exceeded the partial volume limit, thickness quantified from transformed images would always be the same throughout the cardiac cycle and would just correspond to the camera's line spread function. Thickness was measured by Gaussian fitting of transformed myocardial counts in the epicardial direction only to exclude cavitary count contamination. % WT was computed from thickness differences from diastole to systole. % WT values were assessed from clinical data at lateral, inferior, septal, anterior, and apical territories. Resulting %WT distributions were tested against the null hypothesis of %WT = 0 by the Z-test. Although some distributions were not actually Gaussian, the maximum mean %WT was only +3% +/-5% for the septal wall, in agreement with an observer's impressions of no detectable wall thickening. Thus mean %WT values were trivial compared with expected physiologic normal values of 30% to 50%.

CONCLUSION

No convincing evidence was found of thickness above the partial volume limit in this large sample of 75 normotensive and 25 hypertensive patients. Therefore it is likely that relations between myocardial count increases and wall thickening are similar throughout the cardiac cycle, even in patients with left ventricular hypertrophy.

Reliability of enhanced gated SPECT in assessing wall motion of severely hypoperfused myocardium: echocardiographic validation

BACKGROUND

A method has been described for improving myocardial visibility on 99mTc-labeled sestamibi gated tomograms, even in the presence of severe hypoperfusion. It is essential to verify that images transformed in this manner truly depict the myocardium and do not contain image artifacts. This is especially important if transformed images are to be used to aid in the discernment of regional wall-motion abnormalities.

METHODS AND RESULTS

All radially detected maximum counts were mapped automatically to the same brightness level for each cinematic frame. This produced tomographic cine images strongly suggestive of myocardium that appeared to translate but not to brighten from diastole to systole. Transformed scintigrams were compared with echocardiographic cine images of horizontal long axis and short axis views for 40 patients. Echocardiograms were of sufficient quality to allow comparison of radial distances from left ventricular center to midmyocardium for 15 short axis images and 25 horizontal long axis images. Readings were graded independently for 10 territories on a five-point scale (normal, mild-to-moderate hypokinesis, severe hypokinesis, akinesis, dyskinesis) of regional wall motion of original and enhanced scintigrams and echocardiograms. Comparison of echocardiographic and single photon emission computed tomographic (SPECT) locations of midmyocardial horizontal long axis points yielded a root-mean-square error value of 1.5+/-0.6 pixels (average absolute error, 11%+/-5%). SPECT versus echocardiographic wall-motion readings were compared by means of contingency table analysis. The log-likelihood ratio (G2) was 109.3 (n = 364; df = 16) with probability of no association <10(-6). Although readings of unenhanced SPECT cine images agreed well with those of echocardiograms (G2 = 94.3; n = 350; df = 16; P < 10(-6), Pearson-corrected contingency coefficients indicated stronger association with echocardiograms of transformed tomograms than with readings of original scintigrams (0.57 versus 0.51). The McNemar chi2 test indicated this improvement to be significant. The strongest associations were found between readings of unenhanced and enhanced scintigrams. Overall, similar results were obtained for horizontal long axis and short axis territories when analyzed separately. Linear regression analysis indicated strong correlations (r = .80 to r = .92) of ejection fractions from unenhanced gated SPECT images, enhanced gated SPECT images, echocardiograms, and first-pass radionuclide angiograms with no significant differences among correlations.

CONCLUSIONS

Regional image enhancement succeeded in revealing shapes that genuinely represented myocardium in this population with hypoperfusion. Wall-motion conclusions were similar whether drawn from original or enhanced scintigrams, although enhancement significantly improved agreement with echocardiographic readings. Enhanced SPECT cine images allowed sensitive discrimination of regional wall-motion abnormalities, even in areas of severely hypoperfused myocardium, in excellent agreement with visual echocardiographic assessment for which myocardial visualization is independent of perfusion.

Relationship of gated SPECT ventricular function parameters to angiographic measurements

OBJECTIVES

Left ventricular volumes and ejection fractions constitute important information in the diagnosis of cardiac disease. This investigation examined the relations of functional parameters computed with a recently published scintigraphic gated tomographic method with those from angiography, analyzing discrepancies arising from differences involved in modeling the left ventricle.

BACKGROUND

While left ventricular ejection fractions obtained from myocardial perfusion gated single-photon emission computed tomography (SPECT) have demonstrated accurate comparisons with other imaging modalities, validations of volumes have not been examined as extensively, and some recent studies have reported a wide range of angiographic correlation. It is important to know how volumes obtained by a new class of methods compare with those from older, well-established techniques in order to interpret individual patients' results, particularly when scintigraphic images are severely hypoperfused.

METHODS AND RESULTS

Tc-99m sestamibi myocardial perfusion gated SPECT data were processed retrospectively for 58 patients studied by single-plane angiography. Endocardial borders were generated automatically on paired vertical and horizontal long-axis Tc-99m sestamibi gated tomograms for computing ventricular volume using a Simpson's rule summation of elliptical slices. Linear regression and paired t tests were used to compare SPECT with angiographic parameters for all patients and for groups identified on the basis of tomogram visual examination as hypoperfused, ischemic or nonischemic, with the latter category further subgrouped as to fixed defects or normal perfusion. Linear regression analysis demonstrated Pearson correlation coefficients of 0.87 for end-diastolic volumes, 0.91 for end-systolic volumes, and 0.86 for ejection fraction; paired t test analysis showed end-systolic volumes to be nearly identical (p > 0.99) to angiographic values. However, paired t tests also revealed gated SPECT end-diastolic volumes and ejection fractions were significantly lower (p < 10(-4)) than angiography. Correlations and trends were essentially the same for all subgroups except for the small sample (n = 10) of patients with normal perfusion.

CONCLUSIONS

Gated SPECT provides ventricular volumes and ejection fractions that correlate well with angiography, even in hypoperfused and ischemic populations. However, gated SPECT end-diastolic volumes and ejection fractions are significantly lower than angiographic measurements, partly because of inclusion of greater outflow tract amounts in standard angiographic models. Because myocyte concentration decreases rapidly at the ventricular base, it is likely that most gated SPECT methods will produce endocardial borders encompassing less of the outflow tract than do angiographic outlines.

Cardiovascular stress response and coronary artery disease: evidence of an adverse postmenopausal effect in women

OBJECTIVES

To test the hypothesis that postmenopausal women demonstrate greater vascular instability, measured by enhanced cardiovascular stress responses during mental stress, compared with men and premenopausal women.

BACKGROUND

Recent data suggest that estrogen plays a role in regulating vascular tone. The possible consequences of estrogen deficiency during menopause on systemic vascular reactivity is largely unexplored.

METHODS

One hundred subjects (84 men and 16 women) underwent mental stress testing with radionuclide ventriculo graphy. Study subjects included 19 normal volunteers, 23 control subjects with chest pain syndromes or hypertension but without coronary artery disease, and 58 coronary artery disease subjects. The subjects performed a series of three mental stress tasks, during which hemodynamic data and radionuclide ventriculograms were obtained.

RESULTS

Overall, women demonstrated greater hemodynamic responses during mental stress measured by changes in heart rate, systolic and diastolic blood pressure, and double product compared with those of men (all p < 0.05). Women with coronary artery disease demonstrated greater heart rate, diastolic blood pressure, and double product stress responses than their male counterparts (all p < 0.05). Women of postmenopausal age demonstrated significantly greater systolic blood pressure reactivity than men or premenopausal women (p < 0.05).

CONCLUSIONS

Women of postmenopausal age have greater cardiovascular responses to stress than men or premenopausal women. These findings suggest an additional mechanism by which estrogen deficiency conveys a poor prognosis in female patients with coronary artery disease.

The differing prognostic utility of exercise radionuclide ventriculography in coronary artery disease patients with and without prior myocardial infarction

Previous studies have documented the prognostic utility of left ventricular ejection fraction response to exercise primarily in populations without prior myocardial infarction. We undertook a study to assess the prognostic utility of exercise left ventricular ejection fraction and segmental wall motion response during exercise radionuclide ventriculography in coronary artery disease patients with and without prior myocardial infarction.

METHODS

We examined the comparative prognostic utility of left ventricular ejection fraction and segmental wall motion response during upright bicycle exercise radionuclide ventriculography in 419 coronary artery disease patients with (n = 217) and without (n = 202) prior myocardial infarction using univariate and multivariate hierarchical regression analyses.

RESULTS

During an average followup period of 61 months, 96 patients (23%) suffered cardiac events, including 55/217 (25%) of the patients with prior myocardial infarction and 41/200 (21%) of the patients without prior myocardial infarction (p = ns). Both cumulative Kaplan-Meier survival analyses and stepwise hierarchical Cox survival analyses demonstrated that peak left ventricular ejection fraction < 55% was a significant predictor of cardiac events in patients without prior myocardial infarction (p = 0.04), whereas an exercise wall motion worsening score > or = 2 was a significant predictor in patients with a prior myocardial infarction (p = 0.0001).

CONCLUSIONS

The prognostic utility of exercise radionuclide ventriculography variables differ according to the presence or absence of prior myocardial infarction. Global function, assessed by peak left ventricular ejection fraction, adds the greatest prognostic information in patients without prior myocardial infarction, whereas regional function, assessed by exercise wall motion worsening, is the best predictor among patients with prior myocardial infarction.

Image enhancement of severely hypoperfused myocardia for computation of tomographic ejection fraction

Ejection fractions computed from 99mTc-sestamibi myocardial perfusion gated tomograms have demonstrated a high degree of accuracy and reproducibility. Although automated algorithms appear to provide reasonable endocardial outlines for patients over a broad spectrum of cardiac diseases, in cases of severe hypoperfusion, it is necessary to manually adjust contrast and brightness to judge whether borders are correct or must be altered.

METHODS

Midventricular horizontal and vertical long axis gated tomograms were generated for 116 studies chosen on the basis of extensive, severe myocardial perfusion defects. Automated software transformed cinematic tomograms into images demonstrating uniform appearance of the myocardium throughout the cardiac cycle. Transformed images were introduced to edge detection algorithms for subsequent calculation of ventricular volumes and ejection fractions.

RESULTS

Linear regression analysis demonstrated excellent intraobserver reproducibility for ejection fractions (r = 0.95) and volumes (r = 0.98). There was also good agreement of ejection fractions (r = 0.86) and volumes (r = 0.94) with values derived from an expert's manual drawings. In a subgroup of 22 patients, automated ejection fractions from transformed images demonstrated better agreement with independent first-pass values (r = 0.90) than did manual measurements derived from original data (r = 0.85).

CONCLUSION

Image enhancement algorithms succeeded in providing accurate, reproducible gated SPECT ejection fractions in the most difficult class of patients exhibiting severe hypoperfusion.

The secondary prevention of coronary artery disease

Randomized clinical trials demonstrate the efficacy of medical secondary prevention in coronary disease patients. The magnitude of risk reduction with exercise, diet, lipid modification, and smoking cessation is similar to other medical therapies for coronary disease such as aspirin, beta blockers, as well as coronary bypass surgery, (Table VI) In contrast to these therapies, however, secondary prevention stabilizes angiographic progression in about 50% of patients and induces regression in about 25% of patients. Both symptoms and perceived quality of life also are beneficially altered by secondary prevention programs, although possibly not by the magnitude reported for bypass surgery. These clinical trial results have led the American Heart Association, and the American College of Cardiology to strongly endorse secondary prevention. A reasonable projection based on these clinical trial data is that widespread use of these recommendations in the 12 million established coronary disease patients would significantly reduce coronary mortality and morbidity.

First-pass radionuclide angiocardiography with single-crystal gamma cameras

Both multicrystal and single-crystal detectors have been in use for more than 25 years for measurement of ejection fraction by analysis of images collected during the first-pass transit of radionuclides through the heart. Originally, multicrystal cameras were preferred, because they provided higher count rates than Anger cameras; however, over the years improvements in count rate capability and collimator design have enabled Anger cameras to perform equally well. This has become an important issue now that readily available 99mTc agents, such as sestamibi, enable evaluation of both myocardial function and perfusion from a single injection. The technical abilities of a particular camera determine which acquisition protocols are most likely to provide clinically useable images for the widest spectrum of patients. Electrocardiographic-gated list mode collection is highly desirable for first-pass imaging, providing the greatest flexibility of data review, rebinning, and analysis. Attention to quality control issues of data characterization and processing is important to ensure accuracy and precision of all measurements. Accurate determinations of ejection fraction of the left ventricle are possible routinely and, under favorable circumstances, of the right ventricle as well.

Automation of gated tomographic left ventricular ejection fraction

BACKGROUND

The feasibility of determining left ventricular (LV) ejection fraction (EF) from 99mTc-labeled sestamibi gated tomography (GSPECT) is well established. To improve precision of measurement, rules used by observers in processing tomograms were encoded for automation.

METHODS AND RESULTS

LV centers were estimated from activity centroids of time-difference images exceeding 50% of maximum counts. End diastole and end systole were defined by time-varying maximum count extremes. Endocardial borders were generated by fitting maximum locations with fifth-order two-dimensional harmonics, searching inward to predetermined thresholds, and reconciling endocardial with valve plane points. Regression analysis of GSPECT EF yielded r = 0.87 versus equilibrium gated blood pool in 75 patients and r = 0.87 versus gated first pass in 65 patients. GSPECT EF interobserver variability was r = 0.92 and intraobserver automatic versus manual linear correlation was r = 0.94. A subgroup of 25 studies was analyzed by six independent observers, for whom EF agreement with the core laboratory ranged from r = 0.93 to r = 0.96. Experienced observers judged it necessary to alter end-diastolic or end-systolic frames in 7% of patients, endocardial borders in 14%, and LV centers in 28%.

CONCLUSION

Results of automated GSPECT LV EF correlated well with those of manual GSPECT and gated first-pass and equilibrium blood pool values and were highly reproducible.

Heart rate variability reproducibility and stability using commercially available equipment in coronary artery disease with daily life myocardial ischemia

Heart rate variability (HRV) appears to be a strong predictor of death. The reproducibility of HRV measurements in patients with stable coronary artery disease (CAD) who have daily life myocardial ischemia, however, is unknown. Thirty patients with stable CAD (25 men and 5 women; aged 62 +/- 8 years) with daily life ischemia were studied with 2 consecutive 24-hour Holter monitoring recordings. Intra- and interobserver reproducibility of the HRV measures was high, with correlations ranging from 0.990 to 0.999 (p < 0.0001). Strong correlations between time and frequency domain HRV measures were observed (range 0.912 to 0.963; p < 0.0001). Both the frequency and duration of ischemia, measured by ST change, varied significantly by day for each patient (s = 155.5; p < 0.0001; s = 232.5, p < 0.0001, respectively). Correlations for HRV measurements between days remained high (range 0.871 to 0.983; p < 0.0001), despite stratification by magnitude of daily ischemia. Thus, 24-hour HRV measurements are stable in CAD patients with daily life myocardial ischemia over a short period, despite varying magnitudes of daily ischemia. These results support the use of HRV as a clinical tool and an outcome measure in future CAD intervention studies using commercially available equipment.

Gender-related differences in exercise ventricular function among healthy subjects and patients

Increasing numbers of women are undergoing noninvasive stress testing for coronary artery disease evaluation. Limited information is available regarding the presence, magnitude, and importance of gender-related differences in exercise ventriculography among the heterogeneous population of patients referred for noninvasive stress testing. Patients referred for exercise radionuclide ventriculography between 1979 and 1986 were evaluated, including 175 patients with a likelihood of coronary artery disease, 59 patients with angiographically normal coronary arteries, and 419 patients with coronary artery disease. Overall, women demonstrated higher resting left ventricular ejection fraction and lower delta left ventricular ejection fraction response to exercise compared with men. Although left ventricular response to exercise correlated with the underlying severity of coronary artery disease in both women and men, fewer women demonstrated a delta left ventricular ejection fraction >5 percent despite a lower prevalence of multivessel coronary artery disease compared with men. We conclude that gender-related differences in left ventricular response to exercise are present in a wide range of patients referred for testing.

Circadian variation of ambulatory myocardial ischemia. Triggering by daily activities and evidence for an endogenous circadian component

BACKGROUND

The morning peak in myocardial ischemia has been related to diurnal variations in physical and mental activities and to postural changes upon awakening. This study assesses (1) the effects of exogenous activity triggers at different times of the day and (2) the contribution of an endogenous (ie, activity- and posture-independent) circadian vulnerability for ambulatory ischemia.

METHODS AND RESULTS

Sixty-three stable coronary artery disease patients underwent ambulatory ECG monitoring and completed a structured diary assessing physical and mental activities. During 2519 hours of observation, a morning increase in ischemia coincided with increases in physical and mental activities, and an evening decrease in ischemia coincided with a decline in activities. During the morning, ischemic versus ischemia-free periods were more likely to occur with high levels of physical activity (P < .001). High physical activity triggered ischemia to a lesser but still significant extent (P < .05) in the afternoon but not in the evening (P = NS). High levels of mental activity triggered ischemia significantly during the morning (P < .04) and evening (P < .04) but not in the afternoon. When a residualized score procedure was used to correct ischemic time for each patient's simultaneously measured activities, for hourly heart rates, or for activity-related heart rate fluctuations, the circadian variation in ischemia was still observed (P < .001), with a peak at 6 AM. A significant increase in ischemia occurred immediately after awakening (P < .05), but activity-adjusted increases in morning ischemia persisted (P < .05) for 2 hours after awakening.

CONCLUSIONS

Exogenous factors (physical and mental activities) are most potent as triggers of ischemia during the morning hours, and the postural change after awakening contributes to the morning increase in ischemia. There is also evidence for an endogenous, activity-independent circadian influence on ischemic susceptibility that is independent of exogenous factors and that sustains the increase in ischemia upon awakening.

Triggers of myocardial ischemia during daily life in patients with coronary artery disease: physical and mental activities, anger and smoking

OBJECTIVES

This study assessed the potency of physical and mental activities and emotions (anger and anxiety) and smoking and other substance use as proximate triggers of ischemia in patients with coronary artery disease during daily life.

BACKGROUND

Myocardial ischemia occurs during a wide variety of activities in patients with coronary artery disease, but frequency and relative potency of physical and mental activities, smoking and use of caffeine and alcohol as triggers of ischemia during daily life have not been established.

METHODS

Patients (n = 63) with coronary artery disease and evidence of out-of-hospital ischemia kept a validated structured diary of physical and mental activities and psychologic states while undergoing ambulatory electrocardiographic monitoring for 24 to 48 h.

RESULTS

Ischemia occurred most frequently during moderately intense physical and mental activities. Patients spent the largest proportion of time engaged in low intensity physical and mental activities (p < 0.05), but the likelihood of ischemia was greatest during intense physical (p < 0.0001) and stressful mental activities (p < 0.03). The percentage of time in ischemia was elevated and approximately equivalent for high intensity physical and high intensity mental activities (5%) compared with 0.2% when patients were engaged in low intensity activities. Strenuous physical activity (e.g., effortful walking, p < 0.05) and the experience of intense anger were potent ischemic triggers, and heart rates at onset of ischemia increased with the intensity of physical and mental activity and with anger. Among smokers, ischemia was more than five times as likely when patients smoked than when they did not (during 24% vs. 5% of diary entries, p < 0.0001). Coffee and alcohol consumption were also related to ischemia (p < 0.05), but this association disappeared after controlling for concurrent cigarette smoking.

CONCLUSIONS

Triggers of ischemia in patients with coronary artery disease during daily life include not only strenuous exercise, but also activities involving low levels of exertion, such as anger and smoking. Mental activities appear to be as potent as physical activities in triggering daily life ischemia. Coffee and alcohol consumption are related to ischemia only by virtue of their associations with smoking.

The limited efficacy of exercise radionuclide ventriculography in assessing prognosis of women with coronary artery disease

Increasing numbers of women are undergoing stress testing for coronary artery disease evaluation. Limited study is available as to its efficacy in women. Four hundred nineteen patients with coronary artery disease (74 women and 345 men) referred for exercise radionuclide ventriculography between 1979 and 1986 were evaluated in a prospective cohort evaluation with 5-year follow-up. Exercise radionuclide ventriculographic variables were analyzed and compared between women and men. The prognostic efficacy of exercise radionuclide ventriculography was assessed separately for women and men among patients with coronary artery disease by Kaplan-Meier cumulative survival curves, univariate Cox regression analyses, and hierarchical stepwise Cox regression analyses. Overall, women demonstrated higher resting and peak left ventricular ejection fraction response to exercise than men. Ninety-six of 419 patients (23%) had cardiac events at 5-year follow-up. Although left ventricular response to exercise conveyed prognostic information in the combined and male populations (multivariate hierarchical analyses chi-square 11, p = 0.001 for delta left ventricular ejection fraction and chi-square 10, p = 0.002 for worsening exercise wall motion score), these variables were not found to be prognostically useful in women. Women with coronary artery disease demonstrated a worsened functional status, evidenced by greater compromise of exercise capacity, despite having less extensive anatomic disease than their male counterparts. We conclude that sex-related differences in left ventricular response to exercise limit the prognostic utility of exercise ventriculography in women with coronary artery disease.

Defensive hostility: relationship to multiple markers of cardiac ischemia in patients with coronary disease

Three studies assessed whether the combined traits of hostility and defensiveness identify a group of hostile individuals with functionally severe coronary artery disease (CAD). CAD patients completed the Cook-Medley Hostility Inventory (Ho) and the Marlowe-Crowne Social Desirability Scale (MC). Patients were classified into 4 groups: defensive hostile (DH: high Ho, high MC), low hostile (LH: low Ho, low MC), high hostile (HH: high Ho, low MC), and defensive (Def: low Ho, high MC). DH in comparison to HH, LH, and Def CAD patients demonstrate the greatest perfusion defects as measured by exercise thallium scintigraphy; DH patients exhibit the most frequent ischemic episodes during ambulatory electrocardiographic monitoring; and in a laboratory study, DH patients exhibit the most severe mental stress-induced ischemia assessed by echocardiography. Thus, the combination of high hostility and high defensiveness are associated with more functionally severe CAD and may predispose CAD patients to a more adverse prognosis.

Using gated technetium-99m-sestamibi SPECT to characterize fixed myocardial defects as infarct or artifact

Perfusion-scan fixed defects may result from soft tissue attenuation, decreasing test specificity for coronary disease and myocardial infarction (MI). Gated 99mTc-sestamibi SPECT may help differentiate MI from artifact since fixed defects with decreased function (wall motion and thickening) probably represent MI, whereas attenuation artifacts either have normal function or at least do not demonstrate markedly reduced function.

METHODS

Ungated resting and gated stress 99mTc-sestamibi SPECT was performed in 551 consecutive patients referred for evaluation of coronary disease. From resting and summed gated stress images, 180 patients (33%) were identified with isolated fixed defects. Function of the defects was assessed subjectively from gated stress images and results were correlated with clinical (history and/or ECG Q-waves) evidence of MI.

RESULTS

Of 102 patients with fixed defects and clinical MI, 98 (96%) had abnormal defect function. Of 78 patients with no clinical MI, 18 (23%) had decreased function of the defect, possibly indicating silent MI. In 60 of the 78 patients (77%) with no clinical MI, defect function was normal. Because most (91%) of fixed defects with normal systolic function occurred in women with anterior fixed defects (48%) or men with inferior fixed defects (43%), these were most likely attenuation artifacts. By reclassifying patients with fixed defects and normal function as normal, patients with unexplained fixed defects (no clinical MI) decreased from 14% to 3%.

CONCLUSION

Gating provides a valuable adjunct to 99mTc-sestamibi SPECT in characterizing fixed defects and potentially improving test specificity.

Defensive hostility: relationship to multiple markers of cardiac ischemia in patients with coronary disease

Three studies assessed whether the combined traits of hostility and defensiveness identify a group of hostile individuals with functionally severe coronary artery disease (CAD). CAD patients completed the Cook-Medley Hostility Inventory (Ho) and the Marlowe-Crowne Social Desirability Scale (MC). Patients were classified into 4 groups: defensive hostile (DH: high Ho, high MC), low hostile (LH: low Ho, low MC), high hostile (HH: high Ho, low MC), and defensive (Def: low Ho, high MC). DH in comparison to HH, LH, and Def CAD patients demonstrate the greatest perfusion defects as measured by exercise thallium scintigraphy; DH patients exhibit the most frequent ischemic episodes during ambulatory electrocardiographic monitoring; and in a laboratory study, DH patients exhibit the most severe mental stress-induced ischemia assessed by echocardiography. Thus, the combination of high hostility and high defensiveness are associated with more functionally severe CAD and may predispose CAD patients to a more adverse prognosis.

Induction of silent myocardial ischemia with mental stress testing: relation to the triggers of ischemia during daily life activities and to ischemic functional severity

OBJECTIVES

This study examined the relations among the triggers of ischemia during the activities of daily life, mental stress-induced ischemia in the laboratory and functional severity of ischemia on exercise testing.

BACKGROUND

Myocardial ischemia is readily induced with exercise testing, but most episodes of ischemia in daily life occur during relatively sedentary activities. Although mental and emotional arousal are known to trigger myocardial ischemia, mental stress testing induces ischemia in only approximately 50% of patients with active coronary disease. It is not known whether such patients are particularly susceptible to nonexertional ischemia during daily activity.

METHODS

We studied 45 men (mean age +/- SD 58 +/- 9 years) with coronary artery disease by means of 48-h Holter ambulatory electrocardiography for ST segment analysis and quantification of physical and mental activity with a structured diary system. These data were cross-tabulated with new left ventricular dyssynchrony (detected on two-dimensional echocardiography) induced by two mental stressors and by bicycle exercise.

RESULTS

During mental stress testing, 24 patients (53%) (Group I) had a new wall motion abnormality; the other 21 patients (Group II) did not. The average wall motion dyssynchrony score increased from 1.20 +/- 0.29 to 1.34 +/- 0.36 (p = 0.001), but the increase was less than that with exercise stress (1.52 +/- 0.41, p = 0.001). The total duration of ischemia during sedentary activities was greater in Group I (22.9 +/- 24.5 min) than in Group II (3.6 +/- 3.9 min, p = 0.025). Group I had more ischemic events while sedentary (23 of 290 diary entries) than did Group II (8 of 256 diary entries, p = 0.015). The magnitude of dyssynchrony with mental stress and the number of mental stressors capable of triggering ischemia were related to severity of ischemia with exercise.

CONCLUSIONS

Patients with ischemia during mental stress testing also have increased ischemia during sedentary activities in daily life. This finding may reflect greater functional severity of coronary artery disease or a propensity toward coronary vasoconstriction while sedentary.

Pathophysiologic factors governing the variability of ischemic responses to treadmill and bicycle exercise

Ischemic responses may vary considerably when patients with coronary artery disease (CAD) are tested serially, but the pathophysiologic mechanisms that govern this variability have not been well evaluated. We thus evaluated whether clinical, hemodynamic, physiologic, and anatomic factors influenced the variability in ischemic responses among 140 patients (mean age 54 +/- 11 years) subjected to both bicycle and treadmill exercise electrocardiography. Radionuclide ventriculography was obtained during bicycle exercise in each patient. The population included 77 patients with CAD, 21 patients with normal coronary arteriograms, and 42 patients with < 5% likelihood of CAD. Bicycle exercise evoked higher systolic blood pressure (p < 0.001) and double-product (p < 0.001) responses compared with treadmill exercise in the patients with CAD and in the normal subjects, and it evoked a lower frequency of chest pain (12% vs 41%, p < 0.001) in the 34 patients with CAD who had ST-segment depression during both exercise tests. There was a high frequency of variability in ischemic responses during treadmill versus bicycle exercise: 22 (39%) of the 56 CAD patients who had exercise-induced ST-segment depression manifested this response during one stress test only. This variability was strongly related to the functional and anatomic magnitude of disease. Ischemic variability decreased progressively as the response of left ventricular ejection fraction (LVEF) to exercise worsened progressively (p = 0.003 by analysis of variance), from 83% in those with an LVEF increase of > 10% with exercise to only 13% in those with an LVEF fall of > or = 5% with exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Triggers of angina and ST-segment depression in ambulatory patients with coronary artery disease: evidence for an uncoupling of angina and ischemia

This study evaluated daily-life physical and mental triggers of painful and painless myocardial ischemia and of anginal pain in patients with coronary artery disease (CAD) by using ambulatory electrocardiographic monitoring and a structured diary. Eighty-five percent of ambulant ischemic episodes occurred without chest pain; 66% of anginal pain reports were made in the absence of ischemic ST-segment depression. Chest pain reports in the absence of ischemia could not be attributed to "borderline" ST-segment changes. Compared with silent ischemia, painful ischemia was triggered at higher levels of physical activity (p < 0.05) and at higher levels of self-rated effort and negative emotion (p < 0.05). Painful episodes were associated with greater-magnitude ST depression (p < 0.02), but a substantial percentage of episodes with > or = 2 mm and > or = 3 mm ST depression were silent. These results reveal an uncoupling of anginal symptoms from ambulatory ischemic episodes in patients with CAD during daily life. In addition, specific activities and emotions correlate with the presence or absence of anginal symptoms as much as does the presence of ischemic ST depression. These results may have implications for antiischemic and antianginal treatment strategies.

Is 'silent' myocardial ischemia really as severe as symptomatic ischemia? The analytical effect of patient selection biases

BACKGROUND

The clinical significance of exercise-induced chest pain remains controversial, as reflected by sharply discordant clinical results within the medical literature. Thus, we developed a prospective study to compare the functional significance of silent versus symptomatic ischemia and to evaluate whether patient selection biases influence this analysis.

METHODS AND RESULTS

We evaluated 117 patients (mean age, 63 +/- 9 years) with ischemic ST-segment depression during treadmill testing. Each patient underwent Tl-201 myocardial perfusion single-photon emission computed tomography (SPECT) after exercise followed by 24-ambulatory ECG monitoring. Patients were divided into silent versus symptomatic cohorts and were compared for the degree of hemodynamic, exercise and ambulatory ECG, and thallium abnormalities during stress testing. Analyses were repeated as the patient population became increasingly restricted. Compared with the silent patients, patients with chest pain during exercise had a shorter exercise duration (P < .009), lower peak heart rate (P = .009) and double product (P = .005), lower heart rate threshold for ST depression (P < .05), more episodes of ambulatory ST-segment depression (P < .05), a higher frequency of ischemia abnormalities during Tl-201 SPECT (P = .02), and higher summed Tl reversibility scores (P = .002). As the population became increasingly restricted, the relative magnitude of differences in silent versus symptomatic cohorts diminished, whereas the absolute magnitude of ischemic abnormalities progressively increased in both cohorts. For example, within the restricted group having ischemia on both exercise and ambulatory ECG, 50% of the silent cohort had severe ischemia on Tl SPECT (five or more reversible defects) and more than one third demonstrated the ominous finding of transient left ventricular dilation after exercise.

CONCLUSIONS

The induction of chest pain is associated with substantially more functional abnormalities when it is analyzed in a relatively "broad-spectrum" coronary artery disease population; by contrast, chest pain tends to lose its apparent value as a clinical test parameter when its analysis is restricted to coronary artery disease populations with a greater a priori likelihood of manifesting inducible ischemia. These findings may help resolve some of the previous discordant literature reports.

Effect of motion on thallium-201 SPECT studies: a simulation and clinical study

Although patient motion on 201Tl SPECT studies has been reported as a source of artifacts, systematic studies on motion patterns and resultant artifacts are lacking. Accordingly, we simulated 74 motion patterns upon a normal study. The tomograms were assessed for presence of defects: The "motion pixel area index" ranged from 1 to 83; 26 of 30 (87%) simulations with an index > or = 21 had defects, whereas 38 of 44 (86%) simulations with an index < 21 were normal. Defect location was dependent on motion direction; defect intensity was dependent on its magnitude and timing. Review of data acquisition in 164 recent normal patient studies revealed motion in 42 (26%). Motion was generally minimal and caused defects in only seven (4%). Thus, mild motion is unlikely to produce defects. In our laboratory, motion is now an infrequent source of artifacts; severe motion produces recognizable patterns that depend on its direction, magnitude and timing.

Prevalence and functional significance of transient ST-segment depression during daily life activity: comparisons of ambulatory ECG with stress redistribution thallium 201 single-photon emission computed tomographic imaging

To assess the prevalence and functional significance of ischemic ambulatory ECG responses, we prospectively performed ambulatory ECG monitoring in 244 patients (mean age 61 +/- 10 years) referred for stress redistribution thallium 201 myocardial perfusion scintigraphy. The prevalence of ST-segment depression during ambulatory ECG was 33% among patients with a positive exercise ECG, but prevalence varied in selected patient subgroups. Among three groups with coronary artery disease (CAD), the group with ambulatory ECG ischemia (group 1) had a greater frequency of ischemic thallium responses (p = 0.07), a greater median number of reversible thallium defects (p < 0.05), and a greater summed thallium "reversibility" score (p < 0.05) than did the group with a positive exercise ECG but negative ambulatory ECG response (group 2) or that with negative exercise and ambulatory ECG responses (group 3). Exercise ST depression in group 1 versus group 2 was significantly greater (p = 0.002), occurred at a lower heart rate threshold (p = 0.002), and lasted longer after exercise (p = 0.001). Notably, one third of group 1 patients also manifested evidence of transient ischemic dilation of the left ventricle after exercise (p < 0.01 vs groups 2 and 3), a sign of severe ischemia. However, although functionally less "sick" than group 1 patients, 66% of group 2 patients and 50% of group 3 patients still had an ischemic thallium response, which was sometimes severe. Thus transient ischemia during ambulatory ECG monitoring identifies a functionally sicker cohort of patients with CAD and occurs in approximately one third of CAD patients with positive results of exercise tests. A negative ambulatory ECG response, however, does not exclude functionally significant disease among CAD patients. These results imply that caution should be applied in the interpretation of a negative ambulatory ECG response for the purpose of patient risk stratification.

Hostility and myocardial ischemia in coronary artery disease patients: evaluation by gender and ischemic index

Two studies assess relationships of hostility to extent and severity of exercise-induced cardiac ischemia and daily life ischemia in patients with coronary artery disease (CAD). CAD patients (N = 80) who underwent exercise tomographic thallium testing to assess myocardial perfusion completed the Cook-Medley Hostility Inventory (Ho). A Composite Hostility (Chost) score obtained from the Ho scale was also used. Statistically controlling for the effects of gender in the full sample (N = 80), Chost was positively correlated with severity of perfusion defects (r = 0.22, p < 0.05). This relationship was nonsignificant in the 63 male patients, but was significant among women (N = 17, r = 0.42, p < 0.05) and among middle-aged men (less than 60 years, N = 17, r = 0.55, p < 0.05). In an overlapping sample of 42 CAD patients with ischemia (ST-segment depression > or = 1 mm) during 24 to 48 hours of ambulatory electrocardiographic monitoring, after controlling for gender, both Ho and Chost were positively correlated with total minutes of ischemia (r = 0.28 and r = 0.29, respectively, p < 0.05). In addition, there was a significant gender x hostility interaction, with stronger relationships with hostility evident for women. Results from these two studies indicate that in patients with coronary artery disease, hostility traits are significantly correlated with extent of daily life ischemia and with severity of exercise-induced myocardial ischemia. These relationships appear to be significant among female and middle aged male patients, but may be less evident among older male patients.