PERFEX: An expert system for interpreting 3D myocardial perfusion

Introduction: Heart disease remains the leading cause of death in the United States, with the disease burden particularly high in various racial and ethnic groups. In serving an underserved population comprised largely of Hispanic and African American individuals, it is crucial for an urban public hospital to diagnose heart disease in a resource-efficient and cost-effective manner. The greater positive predictive value of cardiac CT relative to exercise stress testing presents the opportunity for such hospitals to optimize resource utilization in identifying patients with coronary artery disease (CAD). Hypothesis: The positive predictive value of cardiac CT in diagnosing CAD is greater than that of exercise stress testing in the patient population served by an urban public hospital. Methods: Patients at Harbor-UCLA Medical Center (Torrance, California) were identified for inclusion in this observational study on the basis of a positive (i.e., abnormal) exercise stress test result or a positive cardiac CT result, during the period between January 2015 and September 2019. These patients were subsequently referred for invasive coronary artery angiography, with the diagnosis of obstructive CAD established by an indication for revascularization via percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). Data were analyzed using a two-tailed Z-test for two proportions. Results: Seventy-six catheterization laboratory results were analyzed. Fifteen subjects with an abnormal exercise stress test result, out of a total of 41 (36.6%), had an indication for PCI or CABG. Twenty-five cardiac CT imaging subjects, out of a total of 35 (71.4%), had an indication for PCI or CABG. The proportion of positive cardiac CT results with an indication for PCI or CABG was significantly higher than the abnormal exercise stress test proportion (p=0.0024). Conclusions: Among urban public hospital patients who were referred for invasive coronary artery angiography, it was determined that cardiac CT provides a greater positive predictive value in the diagnosis of obstructive CAD than exercise stress testing. This result may help guide the optimal allocation of diagnostic resources in an urban public hospital.

Influence of a sensorimotor conflict on the memorization of a path traveled in virtual reality

Effective diagnosis and treatment of coronary artery disease (CAD) are key to the management of patients with diabetes. Although the use of specialized cardiac testing for CAD screening in asymptomatic patients varies widely and is the source of current controversy, evidence is emerging on the prevalence and predictors of asymptomatic ischemia in diabetic patients. Accurate diagnosis and risk stratification are essential in symptomatic patients with known or suspected CAD. Noninvasive cardiac testing has an important role in these patients, although evaluation for revascularization with cardiac catheterization is warranted in high-risk circumstances. This article reviews recent information that may help guide the clinician in the appropriate use of cardiac testing in diabetic patients.

Objective To compare low-dose dobutamine electrocardiography (ECG) stress test and echocardiography (ECHO) stress test in the diagnosis of coronary artery disease (CHD).Methods Fifty-six patients with CHD were chosen.They were given dobutamine before test in the speed of 1 μ g/(kg· min ),and gradually increased to 5 μ g/(kg·min).Low-dose dobutamine ECG stress test,ECHO stress test and coronary angiography (CAG) were performed,and the results were compared.The sensitivity,specificity and accuracy of low-dose dobutamine ECG stress test and ECHO stress test were calculated.Results CAG showed 37 cases of patients with coronary artery stenosis.The sensitivity,specificity and accuracy of low-dose dobutamine ECG stress test were 62.16％ (23/37),73.68％ (14/19) and 66.07％ (37/56).The sensitivity,specificity and accuracy of ECHO stress test were 86.49％ (32/37),52.63％ (10/19) and 75.00％ (42/56).There were significant differences in sensitivity and specificity between two test methods (P ＜0.05).Conclusions In the diagnosis of CHD, low-dose dobutamine ECG stress test has high specificity,and ECHO stress test has high sensitivity and accuracy.Combination of them has high clinical value. Key words: Dobutamine; Electrocardiography; Echocardiography; Coronary disease

The purpose of this study was to evaluate the diagnostic accuracy of сoronary сomputed tomography angiography (CCTA) in the diagnosis of stable coronary artery disease (CAD) in patients aged ≥70 years. The study included 390 patients aged ≥70 years with symptoms suggested stable CAD which underwent elective coronary artery angiography (CAG). Initially the prevalence of angiographically significant CAD was estimated according to the gender and chest pain character, and identifications of patients in whom CCTA was appropriate. After that diagnostic accuracy and сost-efficiency of CCTA in the diagnosis of stable CAD in 82 patients with atypical angina and non-anginal chest pain were evaluated. The prevalence of obstructive CAD in patients with typical angina was very high and they were excluded from the final analysis. Among 82 patients with atypical angina and non-anginal pain which underwent CCTA 48 (59%) patients had obstructive CAD. CСTA data matched with results of CAG in all cases. Among 34 patients that had non-obstructive CAD the results of CCTA and CAG matched in 88% cases. CCTA has sensitivity, specificity, positive predictive value, negative predictive value of 100%, 88%, 92% and 100% respectively. The likelihood ratio for positive result was 8.3, likelihood ratio for negative result was 0.3. Positive result increased post-test probabilityof obstructive CAD from 42% to 86%, negative result reduced post-test probabilityof obstructive CAD to 0%. negative CCTA result in patients aged 70 years and older with atypical angina and non-anginal pain allows to exclude the presence of obstructive CAD. The likelihood ratio for positive result indicates a moderately difference between the pre-test and post-test probability of the presence of obstructive CAD. In patients aged ≥70 years with atypical angina or non-anginal chest pain which have inconclusive results of functional testing or unable undergo functional testing CCTA allows to increase diagnostic yield of CAG and reduce the frequency of minor complications and diagnostic evaluation costs.

This chapter presents some of the major issues and dichotomies found in the literature and use them to discuss the role that visual processing and visual memory might play. In many of these debates, the evidence is not decisive, but it does speak to the critical questions in the field. Visual mapping theories of spatial memory have suggested the most direct link between vision and spatial representations. The dominance of vision over other modalities can be seen in studies that put visual and nonvisual information in competition. When visual information and nonvisual information are providing incongruent information about the location of a single stimulus, participants will localize the stimulus to the visual source. Visual capture for locations across modalities extends beyond just the immediate resolution of a conflict. A similar type of coding has been identified in nonhuman primates, in the form of spatial view cells.

ObjectiveTo improve current knowledge of coronary flow reserve and non-obstructive coronary artery disease in terms of definition, features and clinical implications of measurement of coronary flow reserve (CFR), is an integrated measure of focal, diffuse, and small vessel coronary artery disease, can also be explained as a calculated ratio of hyperaemic to rest absolute myocardial blood flow. Non-obstructive coronary artery disease is defined as atherosclerotic plaque that does not obstruct blood flow or result in anginal symptoms. We also aimed at knowing the significance of PET in diagnosing coronary microvascular disease.ResultsIn our study 92% were between 41 and 60 years. 83% were males and 17% females, more patients had hypertension about 50%, few had diabetes mellitus about 16%, while those with both hypertension and diabetes mellitus were 17%. About 83% had ST segment and T wave changes on ECG. All patients and controls had normal coronaries on coronary angiography TIMI 3 flow. On further investigation by Positron emission tomography/CT we found out 58% had abnormal CFR and 42% had normal coronary flow reserve. Our findings indicate PET/CT coronary flow reserve concept provides a platform for the diagnosis of non-obstructive coronary artery disease in patients with signs and symptoms of ischemia without angiographic obstructive CAD.

Conventional echocardiography is widely used and well documented in evaluation of patients with stable and unstable coronary artery disease (Mollema et al., 2009). In particular, assessment of left ventricular function, volumes and ejection fraction adds important prognostic information in individual patients. In addition, echocardiography may detect any concomitant valvular heart disease as well as acute complications in unstable coronary syndromes. Stress echocardiography has through several studies established its role in diagnosis of stable coronary artery disease and assessment of myocardial viability (Sicari et al., 2008). However, introduction of ultrasound contrast agents and contrast specific imaging modalities have significantly improved the usefulness of echocardiography in diagnosis and assessment of coronary artery disease (Dijkmans et al., 2006). Indications for use of ultrasound contrast are implemented in guidelines for assessment of left ventricular function at rest and during stress echocardiography (Senior et al., 2009; Mulvagh et al., 2008). Ultrasound contrast is recommended for assessing left ventricular ejection fraction at rest when image quality is suboptimal and for stress echocardiography when the endocardial boarder is not visualized in 2 or more left ventricular segments (Senior et al., 2009; Mulvagh et al., 2008). In contrast echocardiography regional myocardial function and perfusion may be assessed simultaneously, thereby optimizing the non-invasive diagnostics of coronary artery disease. The incremental value of assessing myocardial perfusion in diagnosing coronary artery disease is emphasised by the ischemic cascade (Fig. 1), demonstrating that hypoperfusion precedes functional impairment, ECG changes, symptoms and myocardial necrosis as depicted in Fig.1. (Crossman, 2004; Leong-Poi et al., 2002). Diagnosing distribution and extent of myocardial ischemia by contrast echocardiography can give information on the total ischemic burden and has become a supplemental tool in evaluation of the physiological impact of an angiographic coronary artery stenosis. Consequently, myocardial perfusion assessment by contrast echocardiography may also be used for risk prediction in patients with known coronary artery disease and in prioritizing the need for urgent revascularization among patients with acute coronary syndromes (Jeetley et al., 2007; Rinkevich et al., 2005; Lonnebakken et al., 2011). It has the potential to become a future tool to tailor and evaluate the effect of treatment on myocardial perfusion in patients with different clinical syndromes of coronary artery disease. Furthermore,

Myocardial Perfusion by CT Versus Hybrid Imaging

Global and regional left ventricular (LV) systolic dysfunction is a marker of coronary artery disease (CAD), which is conventionally assessed using two-dimensional echocardiography. Tissue Doppler imaging (TDI) has emerged as an adjunct tool in the diagnosis of regional wall motion abnormalities from CAD. We performed a systematic review and meta-analysis to assess the efficacy of TDI indices in the diagnosis of CAD. We searched MEDLINE and the Cochrane Library for controlled studies comparing TDI measurements in those with and without CAD as confirmed by coronary angiography. Meta-analyses of mean differences in TDI velocities between these populations were performed. Screening of titles and abstracts followed by full-text screening identified 8 studies. At rest, TDI was associated with a significant decrease in the pooled maximum systolic velocity among CAD patients compared to those without CAD [mean difference (MD): -0.66; 95% confidence interval (CI): -0.98 to −0.34]. There were no significant differences in maximum early and late diastolic velocities. Post-stress, TDI was associated with a significant decrease in maximum early diastolic velocity (MD: -1.91; 95% CI: -2.74 to −1.09) and maximum late diastolic velocity (MD: -1.57; 95% CI: -2.95 to −0.18) among CAD patients compared to those without CAD. There was no significant difference in maximum systolic velocity post-stress. Our results suggest that TDI may have a role in the evaluation of CAD. Future studies should evaluate the incremental value of TDI velocities over LV ejection fraction and two dimensional wall motion analysis in the detection of CAD and assessment of its severity. (Word Count: 249)

Background: Abnormalities in the velocity and pattern of myocardial shortening on tissue Doppler imaging (TDI) have been pro- posed to aid in the noninvasive diagnosis of coronary artery disease (CAD). Objectives: We investigated the diagnostic value of post-systolic shortening (PSS), a delayed ejection velocity of the myocardium after the closure of the aortic valve, on TDI in the diagnosis of CAD among patients with chest pain and normal resting wall motion on standard 2D echocardiography. Methods: Eighty consecutive patients (49% female) with typical ischemic chest pain but without prior myocardial infarction, coro- nary revascularization, arrhythmia, or heart failure, who had no regional wall motion abnormalities on resting echocardiography and who were scheduled to undergo coronary angiography, were selected. TDI was performed in each patient before coronary an- giography at 2 levels (basal and mid left ventricle (LV)) in each of the 4 LV walls (i.e., septal, anterior, inferior, and lateral). Coronary angiography was performed and interpreted per standard clinical protocols. Results: Compared to the patients with normal coronaries, those with angiographic CAD showed significantly increased myocar- dial isovolumic relaxation time (IVRT) velocity (P 4.0 m/sec, a positive PSS velocity had about 65% sensitivity and 85% specificity with a positive predictive value > 90% in predicting angiographic CAD. Conclusions: Among patients with chest pain and normal LV wall motion on 2D echocardiography, a prominent and prolonged IVRT on TDI may help predict the presence of significant CAD.

Background: Exercise is commonly used as a physiological test to determine cardiovascular disorders not appearing at rest and to assess the functional status of the heart. It is a widely used non-invasive test for assessment of suspicious or proved cardiovascular disorders. It is mainly performed to clarify the prognosis and to assess the functional capacity, the possibility and severity of coronary artery disease (CAD), and the efficacy of treatment. Coronary angiograprhy is the standard method for diagnosis of coronary artery disease (CAD), and it determins the type of therapy according to severity of coronary involvement wether by medical therapy, percutanous coronary intervention (PCI), or coronary artery bypass grafting (CABG) surgery in patients with CAD. Aim: To estimate the sensitivity, specificity, positive and negative predictive values and accuracy of exercise treadmill test in diagnosis of coronary artery disease. Methods: Exercise treadmill test and coronary angiography were performed on 77 consecutive patients (men and women), age range between 30-70 years, they were evaluated at Basrah Cardiac Center (February-June-2012). Both examinations were performed primarily for diagnostic reasons. All clinical data and results of ECG and exercise treadmill test were collected before coronary angiography. Results: The total number of patients included in the study was 77; mean age was 56.9 ± 8.9 years. The mean age for men was 57.0 ± 8.7 years (n= 53), women had a mean age of 56.0 ± 9.5 years (n=24), 90.9% of patients had CAD risk factors. Hypertension was the frequent risk factor present in 72% of patients. Exercise test was positive in 75.3%, negative in 20.8%, pseudonormalization in 3.9%. The sensitivity and positive predictive value of the test were 88% and 79% respectively, while its specificity, negative predictive value and accuracy were 46%, 63% and 75% respectively. Conclusion: Exercise test is a relatively safe, non- invasive and valuable test in the diagnosis of CAD in patients with signs and symptoms of this disease, but still considered below the coronary angiography (which is the gold standard method) for the diagnosis of CAD. The sensitivity of the test increases as the number of diseased coronary arteries increases as in left main and three vessel diseases. ST depression in women with abnormal resting ECGs is probably of less diagnostic value than in men, false positive and false negative tests were more common in women than men.

Left ventricular dysfunction after vasodilator stress is more accurate than perfusion for diagnosis of coronary artery disease

Magnetic resonance (MR) imaging is widely recognized for its ability to provide accurate and reliable assessments of the function and anatomy of the heart and great vessels. With the recent development of more specialized cardiovascular MR scanners, cardiac MR applications have expanded and are now utilized on a routine basis. In this chapter, the technical aspects of MR scanning of the cardiovascular system are outlined followed by brief discussions of its applications to several diseases involving the heart in adults. A separate chapter in this volume specifically covers the use of cardiac MR for the diagnosis of coronary artery disease.

229 Non invasive diagnosis of coronary artery disease in patients with heart failure and systolic dysfunction of uncertain etiology, using gadolinium cardiovascular magnetic resonance