Cold Pressor Testing and Sympathetic Nervous System Contribution to Ischemia with No Obstructive Coronary Artery Disease: Results from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction Project.

Study Objective: Cold Pressor Testing (CPT) is a known stimulus of the sympathetic nervous system (SNS). To better understand sympathetic contribution to coronary blood flow regulation in women with suspected ischemia and no obstructive coronary arteries (INOCA), we compared myocardial perfusion reserve during CPT stress cardiac magnetic resonance (CMR) imaging between women with suspected INOCA and reference subjects. Design: Prospective cohort. Setting: Academic hospital. Participants: 107 women with suspected INOCA and 21-age-matched reference women. Interventions: CPT stress CMR was performed with measurement of myocardial perfusion reserve index (MPRI), adjusted for rate pressure product (MPRIRPP). Invasive coronary function testing in a subset of INOCA women (n=42) evaluated for endothelial dysfunction in response to acetylcholine, including impaired coronary diameter response ≤0% and coronary blood flow response (ΔCBF) <50%. Main Outcome Measure: MPRIRPP. Results: Compared to reference women, the INOCA group demonstrated higher resting RPP (p=0.005) and CPT MPRIRPP (1.09±0.36 vs 0.83±0.18, p=0.002). Furthermore, INOCA women with impaired ΔCBF (n=23) had higher CPT MPRIRPP (p=0.044) compared to reference women despite lower left ventricular ejection fraction (64±7 % vs 69±2 %, p=0.005) and mass-to-volume ratio (0.79±0.15 vs 0.62±0.09, p<0.0001). These differences in CPT MPRIRPP did not persist after adjusting for age, body mass index, and history of hypertension. CPT MPRIRPP among INOCA women did not differ based on defined acetylcholine responses. Conclusions: Myocardial perfusion reserve to CPT stress is greater among women with INOCA compared to reference subjects. CPT induced a higher MPRIRPP also in women with coronary endothelial dysfunction, suggesting a greater contribution of the SNS to coronary flow than endothelial dysfunction. Further investigation in a larger cohort is needed.

Coronary computed tomography angiography for the evaluation of patients with acute chest pain.

Acute chest pain is a common presenting complaint of patients attending emergency room departments. Despite this, it can often be challenging to completely exclude a diagnosis of acute coronary syndrome following an initial standard clinical and biochemical evaluation. As a result of this, patients are often admitted to hospital until the treating clinician is satisfied that this diagnosis can be excluded. This process imparts a significant health economic burden by not only increasing hospital bed occupancy rates but also by the unnecessary layering of diagnostic investigations. With the rapid advances in coronary computed tomography angiography (CTA), there has been considerable interest in whether coronary CTA may be a viable alternative to this current standard care. We review the current literature and supporting evidence for utilising coronary CTA in the evaluation of patients presenting with acute chest pain in terms of its diagnostic accuracy, safety, cost-effectiveness and prognostic implications.

Early Permian bipedal reptile.

A 290-million-year-old reptilian skeleton from the Lower Permian (Asselian) of Germany provides evidence of abilities for cursorial bipedal locomotion, employing a parasagittal digitigrade posture. The skeleton is of a small bolosaurid, Eudibamus cursoris, gen. et sp. nov. and confirms the widespread distribution of Bolosauridae across Laurasia during this early stage of amniote evolution. E. cursoris is the oldest known representative of Parareptilia, a major clade of reptiles.

Application of conditional probability analysis to the clinical diagnosis of coronary artery disease.

Analysis of multiple noninvasive tests offers the promise of more accurate diagnosis of coronary artery disease, but discordant test responses can occur frequently and, when observed, result in diagnostic uncertainty. Accordingly, 43 patients undergoing diagnostic coronary angiography were evaluated by noninvasive testing and the results subjected to analysis using Bayes' theorem of conditional probability. The procedures used included electrocardiographic stress testing for detection of exercise-induced ST segment depression, cardiokymographic stress testing for detection of exercise-induced precordial dyskinesis, myocardial perfusion scintigraphy for detection of exercise-induced relative regional hypoperfusion, and cardiac fluoroscopy for detection of coronary artery calcification. The probability for coronary artery disease was estimated by Bayes' theorem from each patient's age, sex, and symptom classification, and from the observed test responses. This analysis revealed a significant linear correlation between the predicted probability for coronary artery disease and the observed prevalence of angiographic disease over the entire range of probability from 0 to 100% (P less than 0.001 by linear regression). The 12 patients without angiographic disease had a mean posttest likelihood of only 7.0 +/- 2.6% despite the fact that 13 of the 60 historical and test responses were falsely "positive." In contrast, the mean posttest likelihood was 94.1 +/- 2.8% in the 31 patients with angiographic coronary artery disease, although 45 of the 155 historical and test responses were falsely "negative." In 8 of the 12 normal patients, the final posttest likelihood was under 10% and in 26 of the 31 coronary artery disease patients, it was over 90%. These estimates also correlated well with the pooled clinical judgment of five experienced cardiologists (P less than 0.001 by linear regression). The observed change in probability for disease for each of the 15 different test combinations correlated with their information content predicted according to Shannon's theorem (P less than 0.001 by linear regression). These results support the use of probability analysis in the clinical diagnosis of coronary artery disease and provide a formal basis for comparing the relative diagnostic effectiveness and cost-effectiveness of different test combinations.

Incremental prognostic value of rest-redistribution (201)Tl single-photon emission computed tomography.

BACKGROUND: The incremental prognostic value of rest-redistribution (201)Tl compared with stress and rest perfusion abnormalities has not been defined. METHODS AND RESULTS: We identified 458 patients who underwent rest (201)Tl /stress (exercise or adenosine) (99m)Tc sestamibi single-photon emission computed tomography (SPECT) and had late (18 to 24 hours) (201)Tl imaging, were not revascularized within 60 days of SPECT, and were followed up at >1 year. SPECT images were visually analyzed with the use of a 20-segment model on a scale of 0 to 4. Thirty-seven cardiac deaths (CDs) and 17 nonfatal myocardial infarctions occurred. Univariate Cox proportional hazards analysis showed that the presence of a large amount of rest (201)Tl reversibility (rest-late summed difference score [SDS] of >8) was a significant predictor of CD (chi(2) = 5.77, P = 0.02) and CD or myocardial infarction (chi(2) = 5.3, P = 0.02). The CD rate was 9.3% y(-1) in patients with rest-late SDS of >8 compared with 3.6% y(-1) in patients with a mild/moderate amount of rest reversibility (rest-late SDS 3 to 8) and 3.4% y(-1) in patients with no rest reversibility (rest-late SDS <3) (P = 0.029). Kaplan-Meier survival analysis demonstrated significantly lower cumulative survival rates in patients with rest-late SDS of >8 (P = 0.01). Multivariate Cox proportional hazards analysis demonstrated that the presence of a large amount of resting reversibility was an independent and incremental predictor of CD after adjustment for stress and rest perfusion information. Multivariate logistic regression analysis demonstrated that resting reversibility was not an independent predictor of referral to coronary angiography and revascularization. CONCLUSIONS: The identification of a large amount of resting (201)Tl reversibility is an independent predictor of CD over stress and rest perfusion abnormalities.

Multicenter clinical trial to evaluate the efficacy of correction for photon attenuation and scatter in SPECT myocardial perfusion imaging.

BACKGROUND: Soft tissue attenuation is a prominent cause of single-photon emission computed tomography (SPECT) imaging artifacts, which may result in reduced diagnostic accuracy of myocardial perfusion imaging. A method incorporating simultaneously acquired transmission data permits nonuniform attenuation correction and when incorporating scatter correction and resolution compensation may substantially reduce interpretive errors. METHODS AND RESULTS: A prospective multicenter trial was performed recruiting patients with angiographically documented coronary disease (n=96) and group of subjects with a low likelihood of disease (n=88). The uncorrected and attenuation/scatter corrected images were read independently, without knowledge of the patient's clinical data. The detection of >/=50% stenosis was similar using uncorrected perfusion data or with attenuation/scatter correction and resolution compensation (visual or visual plus quantitative analysis), 76% versus 75% versus 78%, respectively (P=NS). The normalcy rate, however, was significantly improved with this new methodology, using either the corrected images (86% vs 96%; P=0.011) or with the corrected data and quantitative analysis (86% vs 97%; P=0.007). The receiver operator characteristic curves were also found to be marginally but not significantly higher with attenuation/scatter correction than with tradition SPECT imaging. However, the ability to detect multivessel disease was reduced with attenuation/scatter correction. Regional differences were also noted, with reduced sensitivity but improved specificity for right coronary lesions using attenuation/scatter correction methodology. CONCLUSIONS: This multicenter trial demonstrates the initial clinical results of a new SPECT perfusion imaging modality incorporating attenuation and scatter correction in conjunction with 99mTc sestamibi perfusion imaging. Significant improvements in the normalcy rate were noted without a decline in overall sensitivity but with a reduction in detection of extensive coronary disease.

Incremental prognostic value of post-stress left ventricular ejection fraction and volume by gated myocardial perfusion single photon emission computed tomography.

BACKGROUND: The incremental prognostic value of post-stress left ventricular ejection fraction (EF) and volume over perfusion has not been investigated. METHODS AND RESULTS: We identified 1680 consecutive patients who underwent rest Tl-201/stress Tc-99m sestamibi gated single photon emission computed tomography (SPECT) and who were followed-up for 569+/-106 days. Receiver-operator characteristics analysis defined an EF<45%, an end-systolic volume (ESV) >70 mL, and an end-diastolic volume >120 mL as optimal thresholds, yielding moderate sensitivity and high specificity in the prediction of cardiac death. Patients with an EF> or = 45% had mortality rates <1%/year, despite severe perfusion abnormalities, whereas patients with an EF<45% had high mortality rates, even with only mild/moderate perfusion abnormalities (9.2%/year; P<0.00001). Similarly, an ESV< or = 70 mL was related to a low cardiac death rate (<1.2%/year), even for patients with severe perfusion abnormalities, whereas patients with an ESV>70 mL and only mild/moderate perfusion abnormalities had high death rates (8.2%/year; P<0.00001). Patients with an EF<45% and an ESV< or = 70 mL had low cardiac death rates (1.7%/year); those with an EF<45% but an ESV>70 mL had high death rates (7.9%/year; P<0.02). Multivariate Cox proportional hazards regression showed that perfusion variables and ESV were independent predictors of overall coronary events, whereas EF and ESV demonstrated incremental prognostic values over prescan and perfusion information in predicting cardiac death and cardiac death or myocardial infarction. CONCLUSIONS: Post-stress EF and ESV by gated-SPECT have incremental prognostic values over prescan and perfusion information in predicting cardiac death, and they provide clinically useful risk stratification.

Long-term outcome of patients with intermediate-risk exercise electrocardiograms who do not have myocardial perfusion defects on radionuclide imaging.

BACKGROUND: The appropriate management of patients with intermediate-risk Duke treadmill scores is not established. The purpose of this study was to determine the long-term risk of subsequent cardiovascular events in patients with an intermediate-risk treadmill score who do not have myocardial perfusion defects on radionuclide imaging. METHODS AND RESULTS: The existing databases of the nuclear cardiology laboratories of 4 academic institutions were searched retrospectively. A total of 4649 patients were identified who had intermediate-risk Duke treadmill scores (-10 to 4), normal or near-normal exercise single photon-emission computed tomographic myocardial perfusion images using either thallium-201 or technetium-99m sestamibi, and no previous coronary revascularization. Follow-up was 95% complete. Cardiovascular survival was 99.8% at 1 year, 99.0% at 5 years, and 98.5% at 7 years. Cardiac survival free of myocardial infarction was similarly high at 96.6% at 7 years. Cardiac survival free of myocardial infarction or revascularization was 87.1% at 7 years. Near-normal scans and cardiac enlargement were independent predictors of time to cardiac death. Seven-year cardiac survival was still high at 97.0% in the 357 patients with near-normal scans and normal cardiac size and somewhat lower, at 89.0%, in the 167 patients with cardiac enlargement. CONCLUSIONS: Patients with an intermediate-risk treadmill score but with normal or near-normal exercise myocardial perfusion images and normal cardiac sizes are at low risk for subsequent cardiac death and can be safely managed medically until their symptoms warrant revascularization. The appropriate management of patients with cardiac enlargement will remain a matter of clinical judgment.

Comparison of physiologic ejection fraction responses to activities of daily living: implications for clinical testing.

The recent development of the VEST, an ambulatory radionuclide detector, to measure left ventricular ejection fraction may enhance the detection of ischemia during daily activities in patients with coronary artery disease. The normal range and determinants of ejection fraction responses to stimuli other than physical exercise, however, are not adequately characterized. Therefore, ejection fraction responses to various activities were measured in 18 normal subjects utilizing the VEST. Uniform increases (greater than 5%) in ejection fraction were seen during physical exercise, uniform decreases were seen during cold pressor testing and modest changes (including decreases greater than 5%) were seen in ejection fraction during mental stress, micturition and hyperventilation. Different forms of stress produced significantly different changes in ejection fraction, even when values were controlled for changes in heart rate. Ventricular loading conditions in the form of enhanced blood pressure responses during mental stress may have contributed to the relatively smaller changes in ejection fraction compared with those during exercise. Subjects demonstrating a decrease in ejection fraction during mental stress did not differ from other subjects in hemodynamic reactivity during mental testing but did have evidence of increased parasympathetic tone during cold pressor and bicycle exercise testing. The results reveal that normal ejection fraction response differs among varying physiologic stimuli. These changes are in part related to changes in heart rate and blood pressure; however, other factors, such as neurohumoral regulation, may also play a role. These findings indicate that the patient's activity and the setting in which it occurs must be considered when interpreting ambulatory ejection fraction responses.

Automatic quantitation of regional myocardial wall motion and thickening from gated technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography.

OBJECTIVES: We developed an automatic quantitative algorithm for the measurement of regional myocardial wall motion and wall thickening from three-dimensional gated technetium-99m sestamibi myocardial perfusion single-photon emission computed tomographic images. BACKGROUND: The algorithm measures the motion of the three-dimensional endocardial surface using a modification of the centerline method, as well as wall thickening using both geometry (gaussian fit) and partial volume (counts). METHODS: The algorithm was tested using a "variable thickness" heart phantom, and the quantitative results were compared with visual segmental assessment of myocardial motion and thickening in 79 clinical patients with a wide range of ejection fractions (6% to 87%). RESULTS: Phantom measurements of simulated motion and thickening were accurate regardless of the camera used (dual or triple detector), the angular span of reconstructed data (180 degrees or 360 degrees), the amount of motion (3 or 6 mm) or the amount of thickening (33%, 50% or 100%). Quantitative measurements of segmental motion and thickening in the patients were correlated with visual scores (r = 0.668, exact agreement 72.6%, kappa 0.433 and r = 0.550, exact agreement 74.7%, kappa 0.408, respectively). Significant inverse linear relations exist between the global (summed) visual motion score and the average quantitative motion, and between the global (summed) visual thickening score and the average quantitative thickening. Automatic quantitative ejection fraction measurements correlated extremely well with average quantitative motion (r = 0.929) and thickening (r = 0.959). CONCLUSIONS: Our algorithm is accurate and may be the first automatic technique for the quantitative three-dimensional assessment of regional ventricular function in cardiology.

Adenosine technetium-99m sestamibi myocardial perfusion SPECT in women: diagnostic efficacy in detection of coronary artery disease.

OBJECTIVES: This study sought to assess the diagnostic efficacy of adenosine technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography (SPECT) in a consecutive series of female patients. BACKGROUND: The utility of adenosine myocardial perfusion SPECT for the detection of coronary artery disease is not well defined in women because most studies have described a predominantly male population with a high prevalence of coronary artery disease. METHODS: Of the 201 consecutive female patients in the study group who had undergone adenosine Tc-99m sestamibi myocardial perfusion SPECT, 130 had coronary angiography within 2 months of the nuclear test, and the other 71 had a low likelihood (<10%, mean [+/-SD] 5 +/- 3%) of coronary artery disease. The SPECT protocol used separate acquisition of rest thallium-201 and adenosine Tc-99m sestamibi and was visually analyzed in 20 segments with a semiquantitative five-point scoring system (0=normal; 4=absent uptake). RESULTS: The normalcy rate in patients with a low likelihood of coronary artery disease was 93% (66 of 71). Among the catheterized group, the overall sensitivity, specificity and predictive accuracy of adenosine sestamibi SPECT for detecting coronary artery disease (> or = to 50% diameter stenosis) were 93% (87 of 94), 78% (28 of 36) and 88% (115 of 130), respectively. In the 103 patients without a prior myocardial infarction, the sensitivity, specificity and predictive accuracy were 91% (61 of 67), 78% (28 of 36) and 86% (89 of 103), respectively, for detecting > or = to 50% diameter stenosis. Of particular interest, the sensitivity and specificity were as high in patients with nonanginal symptoms (93% and 69%, respectively) as in patients with angina (92% and 83%, respectively, p=NS). The sensitivity and specificity among patients with a relatively low (<25%), intermediate (between 25% and 75%) or high prescan likelihood of coronary artery disease (>75%) were similar: 82% and 82%, 93% and 73%, and 95% and 100%, respectively. The sensitivity and specificity for detecting individual diseased vessels (> or = to 50% diameter stenosis) were, respectively, 76% and 81% for the left anterior descending coronary artery, 44% and 90% for the left circumflex coronary artery and 75% and 77% for the right coronary artery. CONCLUSIONS: Adenosine Tc-99m sestamibi SPECT is an efficient protocol with high sensitivity and specificity for the detection of coronary artery disease in women irrespective of presenting symptoms or pretest likelihood of coronary artery disease and a high normalcy rate. These findings are of particular clinical relevance because chest pain, anginal or otherwise, has been shown to be a frequent but a less specific marker for coronary artery disease among female patients.

Adenosine pharmacologic stress myocardial perfusion tomographic imaging in patients with significant aortic stenosis. Diagnostic efficacy and comparison of clinical, hemodynamic and electrocardiographic variables with 100 age-matched control subjects.

OBJECTIVES: This study assessed the safety and diagnostic accuracy of adenosine stress myocardial perfusion scintigraphy for the detection of coronary artery disease using single-photon emission computed tomography (SPECT) in patients with significant aortic stenosis. BACKGROUND: Exercise cardiac stress testing in patients with significant aortic stenosis is generally avoided because of concerns for safety. In addition, those studies that have analyzed the utility of exercise testing both with and without myocardial thallium-201 scintigraphy for the diagnosis of coronary artery disease have yielded low specificity. Currently, no safe and accurate means exists to noninvasively assess the presence, extent and severity of coronary artery disease in patients with significant aortic stenosis. METHODS: The study included 35 patients with moderate to severe aortic stenosis (mean [+/- SD] aortic valve area 0.84 +/- 0.16 cm2, range 0.5 to 1.2; mean maximal instantaneous aortic valve gradient 44.4 +/- 15.9 mm Hg, range 20 to 84). All patients underwent a 6-min adenosine infusion (140 micrograms/kg body weight per min) protocol and either separate acquisition rest thallium-201/stress technetium-99m sestamibi or stress and 4-h redistribution thallium-201 SPECT: Visual 20-segment SPECT analysis used a standard five-point scoring system from 0 (normal tracer uptake) to 4 (absent uptake). The SPECT results were considered abnormal if more than two segments had a stress score > or = 2. Hemodynamic, electrocardiographic and clinical responses were compared with those in a reference group of 100 consecutive age-matched patients undergoing adenosine SPECT who did not have aortic stenosis. RESULTS: Hemodynamic responses during adenosine stress testing between the study and control patients demonstrated no significant difference in the net change in systolic blood pressure (18% of baseline vs. 14%, patients with aortic stenosis vs. control subjects), heart rate (21% vs. 19%), rate-pressure product (0% vs. 2%) or incidence of chest pain (23% vs. 35%) or transient second-(9% vs. 9%) or third-degree atrioventricular block (3% vs. 1%). In the 20 patients who had coronary angiography, sensitivity for detection of coronary artery disease was 92% (12 of 13) and specificity was 71% (5 of 7). CONCLUSIONS: In this preliminary study, adenosine was found to be well tolerated and diagnostically accurate in patients with moderate to severe aortic stenosis.

Effect of beta-blockade on low heart rate-related ischemia during mental stress.

To explore the effect of beta-adrenergic blockade on low heart rate-related (mental stress) ischemia, 19 patients with coronary artery disease were randomized into a double-blind crossover trial of metoprolol, 100 mg twice daily, and underwent serial mental stress/bicycle exercise studies. Mental stress-induced wall motion abnormalities occurred at a lower heart rate than exercise-induced wall motion abnormalities during placebo administration (81 +/- 16 vs. 123 +/- 20 beats/min, p less than 0.05). Metoprolol reduced the mean magnitude of exercise-induced wall motion abnormalities (2.8 +/- 2.0 vs. 1.6 +/- 2.4, p = 0.003); improvement was related to the magnitude of hemodynamic beta-blockade effect. Metoprolol did not significantly reduce the mean magnitude of mental stress-induced wall motion abnormalities (3.0 +/- 2.2 vs. 2.6 +/- 2.2), although individual responses predominantly either improved (50%) or worsened (29%). Unlike exercise, the magnitude of hemodynamic beta-blockade did not predict mental stress response and metoprolol did not block mental stress-induced blood pressure elevations. Patients with abolition of exercise-induced ischemia were more likely to have reduction of mental stress-induced ischemia. Patients whose ischemia worsened with metoprolol during mental stress had more easily inducible ischemia, as assessed by exercise-induced placebo wall motion abnormality, chest pain and prior myocardial infarction. Beta-blockade was associated with a lowering of ischemia-related hemodynamic thresholds compared with placebo. These results suggest that beta-blockade has a variable effect on low heart rate-related ischemia that may be due to a lack of effect on mental stress-induced blood pressure elevation in patients with easily induced ischemia or to effects on coronary vasomotor tone, or both.

Late reversibility of tomographic myocardial thallium-201 defects: an accurate marker of myocardial viability.

Twenty-one patients were studied who underwent thallium-201 stress-redistribution single photon emission computed tomography (SPECT) both before and after coronary artery bypass grafting (n = 15) or transluminal coronary angioplasty (n = 6). All patients underwent thallium imaging 15 min, 4 h and late (18 to 72 h) after stress as part of the preintervention thallium-201 scintigram. In a total of 201 tomographic myocardial segments with definite post-stress thallium-201 perfusion defects in which the relevant coronary arteries were subsequently successfully reperfused, the 4 h redistribution images did not predict the postintervention scintigraphic improvement: 67 (85%) of the 79 4 h reversible as well as 88 (72%) of the 122 4 h nonreversible segments improved (p = NS). The 18 to 72 h late redistribution images effectively subcategorized the 4 h nonreversible segments with respect to postintervention scintigraphic improvement: 70 (95%) of the 74 late reversible segments improved after intervention, whereas only 18 (37%) of the 48 late nonreversible segments improved (p less than 0.0001). The frequency of late reversible defects and the frequency of postrevascularization improvement of late nonreversible defects are probably overestimated by this study because of referral biases. The cardiac counts and target to background ratios from late redistribution studies resulted in satisfactory cardiac images for visual interpretation. For optimal assessment of the extent of viable myocardium by thallium-201 scintigraphic studies, late redistribution imaging should be performed when nonreversible defects are observed on 4 h redistribution images.

Scintigraphically detected predominant right ventricular dysfunction in acute myocardial infarction: clinical and hemodynamic correlates and implications for therapy and prognosis.

To determine the clinical and hemodynamic correlates as well as therapeutic and prognostic implications of predominant right ventricular dysfunction complicating acute myocardial infarction, 43 consecutive patients with scintigraphic evidence of right ventricular dyssynergy and a depressed right ventricular ejection fraction (less than 0.39) in association with normal or near normal left ventricular ejection fraction (greater than or equal to 0.45) were prospectively evaluated. All 43 patients had acute inferior infarction, forming 40% of patients with acute inferior infarction, and only eight (24%) had elevated jugular venous pressure on admission. On hemodynamic monitoring, 74% of patients had a depressed cardiac index (less than or equal to 2.5 liters/min per m2), averaging 2.0 +/- 0.05 for the group. Of these, 30% did not demonstrate previously described hemodynamic criteria of predominant right ventricular infarction (right atrial pressure greater than or equal to 10 mm Hg or right atrial to pulmonary capillary wedge pressure ratio greater than or equal to 0.8, or both). The left ventricular end-diastolic volume was reduced to 49 +/- 11 ml/m2 (n = 22) and correlated significantly with the stroke volume index (r = 0.82; p less than 0.0001) and cardiac index (r = 0.57; p = 0.005). The follow-up right ventricular ejection fraction, determined in 33 patients, showed an increase of 10% or greater in 26 (79%), increasing from a mean value of 0.30 +/- 0.06 to 0.40 +/- 0.09 (p less than 0.0001) without a significant overall change in the mean left ventricular ejection fraction (0.56 +/- 0.10 to 0.56 +/- 0.11, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Reversal of rest myocardial asynergy during exercise: a radionuclide scintigraphic study.

UNLABELLED: While exercise-induced segmental left ventricular wall motion abnormalities are well described, the phenomenon of improvement in certain asynergic segments during exercise in some patients remains a curiosity. To assess this unexpected finding, results were analyzed in 85 patients with wall motion abnormalities at rest who underwent two view (45 degrees left anterior oblique and anterior) exercise radionuclide ventriculography and exercise thallium-201 myocardial perfusion imaging. Wall motion was scored with a 5 point system (from 3 [normal] to - 1 [dyskinesia]); normalization or increase of 2 or more points with exercise signified improvement. Forty-eight patients (56%) had no change or further deterioration of wall motion at peak exercise, 15 (18%) showed both improvement of wall motion and deterioration and 22 (26%) showed only improvement of wall motion. Wall motion improvement during exercise was found in 57 (20%) of 279 segments with asynergy at rest. Of these 57 segments improving with exercise, 45 (79%) showed mild and 12 (21%) showed severe asynergy at rest. Only seven segments (12%) were associated with pathologic Q waves. Thallium-201 perfusion was normal in 44 segments (77%) while only 6 segments (11%) had reversible and only 7 (12%) had nonreversible thallium-201 defects. IN CONCLUSION: 1) wall motion that is abnormal at rest can sometimes improve with exercise; 2) this phenomenon generally occurs in zones without a Q wave or nonreversible thallium-201 defect. Hence, segments with abnormal wall motion at rest that show improvement with exercise appear to represent viable nonischemic segments.

Comprehensive noninvasive evaluation of left atrial myxomas using cardiac cine-computed tomography.

This report describes the first clinical experience with ultrafast (cine) computed tomography for evaluating intracardiac masses. Two patients had a left atrial myxoma that was comprehensively described (size, location, site of attachment and relation to the mitral valve) preoperatively by cine-computed tomography. The information content of the studies exceeded that of two-dimensional echocardiography, and both patients were operated on without invasive cardiac catheterization. This early experience with a new minimally invasive high temporal and spatial resolution technology suggests that cine-computed tomography may be uniquely suited for precise evaluation of intraatrial masses.

Noninvasive identification of left main and triple vessel coronary artery disease: improved accuracy using quantitative analysis of regional myocardial stress distribution and washout of thallium-201.

The capabilities of visual and quantitative analysis of stress redistribution thallium-201 scintigrams, exercise electrocardiography and exercise blood pressure response were compared for correct identification of extensive coronary disease, defined as left main or triple vessel coronary artery disease, or both (50% or more luminal diameter coronary narrowing), in 105 consecutive patients with suspected coronary artery disease. Extensive disease was present in 56 patients and the remaining 49 had either less extensive coronary artery disease (n = 34) or normal coronary arteriograms (n = 15). Although exercise blood pressure response, exercise electrocardiography and visual thallium-201 analysis were highly specific (98, 88 and 96%, respectively), they were insensitive for identification of patients with extensive disease (14, 45 and 16%, respectively). Quantitative thallium-201 analysis significantly improved the sensitivity of visual thallium-201 analysis for identification of patients with extensive disease (from 16 to 63%, p less than 0.001) without a significant loss of specificity (96 versus 86%, p = NS). Eighteen (64%) of the 28 patients who were misclassified by visual analysis as having less extensive disease were correctly classified as having extensive disease by virtue of quantitative analysis of regional myocardial thallium-201 washout. When the results of quantitative thallium-201 analysis were combined with those of blood pressure and electrocardiographic response to exercise, the sensitivity and specificity for identification of patients with extensive disease was 86 and 76%, respectively, and the highest overall accuracy (0.82) was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

A new approach to the assessment of tomographic thallium-201 scintigraphy in patients with left bundle branch block.

To determine whether a new approach to interpretation could improve the accuracy of thallium-201 single photon emission computed tomography (SPECT) for detection of left anterior descending coronary artery disease in patients with left bundle branch block, 69 patients were evaluated. Forty-four had angiographically proved coronary artery disease; the remaining 25 were considered to have a "low" (mean 13.5 +/- 6.4%, range 3.4% to 24.9%) likelihood of disease before thallium-201 scintigraphy. The conventional scintigraphic criterion for detection of left anterior descending artery disease (septal, anterior or apical defects) was compared with a new criterion that required the apex to be abnormal to indicate left anterior descending disease. The normalcy rates in the low likelihood patient group were significantly improved by using the new approach, from 16% to 80% (p less than 0.0001) by visual analysis and from 24% to 64% (p = 0.003) by quantitative SPECT polar map analysis. The sensitivity for left anterior descending disease was similar for the conventional and the new method by visual (100% vs. 94%) and quantitative (100% vs. 83%) analyses. In contrast, the specificity was significantly improved by using the new approach, from 14% to 79% (p = 0.0006) by visual analysis and 14% to 64% (p = 0.007) by quantitative analysis. In conclusion, septal and anterior thallium-201 SPECT defects are common in patients with left bundle branch block without coronary artery disease, resulting in low specificity for left anterior descending artery disease. The normalcy rates and accuracy for detection of left anterior descending coronary artery disease were significantly better when an apical defect was used as the criterion for disease.

Arbutamine stress thallium-201 single-photon emission computed tomography using a computerized closed-loop delivery system. Multicenter trial for evaluation of safety and diagnostic accuracy. The International Arbutamine Study Group.

OBJECTIVES: This study sought to evaluate the efficacy and safety of arbutamine when used in conjunction with thallium-201 single-photon emission computed tomography (SPECT) in a multicenter trial and to compare arbutamine stress and treadmill exercise thallium-201 SPECT for diagnostic sensitivity and myocardial perfusion pattern. BACKGROUND: Arbutamine is a potent beta-agonist developed specifically for pharmacologic stress testing. METHODS: Arbutamine was administered by a novel computerized closed-loop device that measures heart rate and adjusts arbutamine infusion to achieve a selected rate of heart rate increase toward a predetermined limit. The cohort included 184 patients who underwent arbutamine stress testing, of whom 122 (catheterization group) had angiographically defined coronary artery disease ( > or = 50% diameter stenosis of a major coronary artery), and 62 had a low pretest likelihood of coronary artery disease (low likelihood group). A subset of 69 patients from the catheterization group underwent both arbutamine and exercise stress testing. RESULTS: Hemodynamic responses during arbutamine and exercise stress testing demonstrated no significant difference in percent increase in heart rate (81% vs. 76%) or systolic blood pressure (26% vs. 30%). The sensitivity for detecting coronary artery disease ( > or = 50% stenosis) using arbutamine thallium-201 SPECT was 87% (95% for detecting > or = 70% stenoses), and the normalcy rate in the low likelihood group was 90%. In patients completing both arbutamine and exercise stress testing, thallium-201 SPECT sensitivity for detecting coronary artery disease ( > or = 50% stenosis) was 94% and 97% (p = NS), respectively Furthermore, SPECT segmental visual score agreement (defect vs. no defect) showed a concordance of 92% between arbutamine and exercise results (kappa 0.80, p < 0.001). The stress thallium-201 SPECT segmental scores showed 83% exact agreement (kappa 0.69, p < 0.001), and analysis of the reversibility of segments with stress perfusion defects demonstrated 86% exact agreement (kappa 0.68, p < 0.001). In general, side effects associated with arbutamine were well tolerated and resolved with discontinuation of infusion. CONCLUSIONS: Arbutamine, administered by a closed-loop feed-back system was shown to be a safe and effective pharmacologic stress agent. Arbutamine stress thallium-201 SPECT appears to be accurate for the diagnosis of coronary artery disease with a diagnostic efficacy similar to that of treadmill exercise thallium-201 studies.