Visual patterns of breast attenuation artifacts in women and men with an upright and supine cadmiun-zinc-telluride camera.

BACKGROUND: Breast attenuation artifacts occurring with upright cadmium-zinc-telluride (CZT) cardiac imaging systems have not been well characterized. METHODS: 216 consecutive patients with Single Photon Emission Computerized Tomography myocardial perfusion imaging and no angiographically significant obstructive coronary artery disease were identified. All upright and supine SPECT images as well as coronary angiograms were reviewed and analyzed in blinded fashion. RESULTS: In women imaged upright, more visual false positive defects were noted in the inferior wall compared to the anterior wall (26 vs. 10 at rest, p = 0.006, and 33 vs. 13 at stress, p < 0.001). Visual inferior wall defects were more common in the upright than supine position at stress (33 vs. 23, p = 0.018) and rest (26 vs. 14, p = 0.011), and most apparent in non-obese women (13 vs. 8, at stress, p = 0.059 and 11 vs. 5, at rest, p = 0.014). CONCLUSIONS: With upright CZT myocardial perfusion imaging, women often have visible inferior wall attenuation artifact defects, likely from pendant breast tissue. These inferior wall attenuation artifacts may be seen in non-obese female patients.

Effects of gender and defect reversibility on detection of coronary disease with an upright and supine cadmium-zinc-telluride camera.

BACKGROUND: Limited data address the roles of gender, perfusion defect reversibility, and imaging position in interpretation of images acquired on an upright/supine cadmium-zinc-telluride (CZT) cardiac imaging system. METHODS AND RESULTS: From a consecutive cohort of patients imaged on an upright/supine CZT camera, 260 patients with coronary angiograms were studied. Multivariable models identified gender as a significant effect modifier for imaging variables of CAD. For males, a supine summed stress score (SSS) ≥ 3 provided high accuracy (sensitivity 70.7%, specificity 72.2%), and highest contribution to multivariable models. In females, supine SSS ≥ 2 provided the best cut-off for defect size and severity (sensitivity 90%, specificity 35.9%), but specificity was improved substantially to 53.3% with decrease in sensitivity to 80% by also requiring quantitative identification of perfusion defect reversibility in the supine position. Eight variables, accurate for predicting coronary disease, were more accurate with supine than upright imaging. CONCLUSIONS: Perfusion defect reversibility improved specificity in female patients for detection of coronary disease compared to perfusion defect size and extent alone. Supine images provided superior accuracy for detection of coronary disease compared to upright images.

Sympathetic drive stimulating diastolic dysfunction?

Diastolic heart failure accounts for half of the heart failure population and its pathophysiology remains an area of active research. The renin angiotensin and aldosterone axis has been the focus of clinical trials to treat patients with heart failure with preserved ejection fraction, however with limited yield in terms of clinical success. Sympathetic activity has been considered a plausible cause for the molecular changes that lead to diastolic dysfunction. Based on this understanding the study by Gimelli et al uses MIBG to evaluate for association between diastolic dysfunction and sympathetic denervation. The results of this study set the stage for a follow up study for evaluation of sympathetic denervation in isolated diastolic dysfunction.

Feasibility and safety of exercise stress testing using an anti-gravity treadmill with Tc-99m tetrofosmin single-photon emission computed tomography (SPECT) myocardial perfusion imaging: A pilot non-randomized controlled study.

BACKGROUND: Exercise is the AHA/ACC guideline-recommended stress modality for myocardial perfusion imaging, but many patients are unable to exercise to target heart rate on a conventional treadmill. We examined the feasibility and safety of stress imaging using an anti-gravity treadmill in patients with perceived poor exercise capacity. METHODS AND RESULTS: 49 patients were recruited for stress testing by anti-gravity treadmill (n = 29) or to a regadenoson control group (n = 20). Seventeen anti-gravity test patients (59%) reached target heart rate obviating the need for a pharmacologic stress agent. Adverse effects of the anti-gravity treadmill were limited to minor muscle aches in 5 subjects. Stress myocardial perfusion image quality judged by 3 blinded readers on a 5-point scale was comparable for the anti-gravity treadmill (4.30 ± SD 0.87) vs pharmacologic stress (4.28 ± SD 0.66). CONCLUSION: Stress testing using an anti-gravity treadmill is feasible and may help some patients safely achieve target heart rate.

Analysis of stress-only imaging, comparing upright and supine CZT camera acquisition to conventional gamma camera images with and without attenuation correction, with coronary angiography as a reference.

BACKGROUND: Diagnostic performance of stress-only imaging using a Cadmium-Zinc-Telluride (CZT) camera has not been directly compared in the same patients to stress-only attenuation-corrected conventional Anger camera images. METHODS: 112 subjects with correlative coronary angiographic data and 40 subjects with <5% pre-test likelihood of coronary disease completed attenuation-corrected stress-only images on a conventional Anger camera and uncorrected upright and supine stress images on a CZT camera. Two readers provided independent, blinded interpretations of stress-only images. RESULTS: Upright and supine stress-only CZT images and attenuation-corrected Anger camera images provided similar positive (reader 1/reader 2, 50.0%/44.1% vs 46.4%/51.9%) and negative (66.7%/64.0% vs 67.9%/67.7%) predictive values (all P = NS) for obstructive coronary artery disease; however, the sensitivity was higher (81.3% vs 58.3%, P = .05), specificity lower (29.7% vs 50.0%, P = .005), and normalcy rate lower (87.5% vs 100%, P = .025) with attenuation-corrected Anger camera images for the first reader with no significant differences between cameras for the second reader. CONCLUSIONS: Stress-only upright and supine CZT imaging was non-inferior statistically to attenuation-corrected stress-only Anger camera imaging. Nevertheless, stress-only CZT imaging may be associated with reduced diagnostic sensitivity for some readers compared to attenuation-corrected Anger camera images, which may be less acceptable clinically compared to stress plus rest images.

Cardiac autonomic innervation.

The autonomic nervous system plays a key role in regulating changes in the cardiovascular system and its adaptation to various human body functions. The sympathetic arm of the autonomic nervous system is associated with the fight and flight response, while the parasympathetic division is responsible for the restorative effects on heart rate, blood pressure, and contractility. Disorders involving these two divisions can lead to, and are seen as, a manifestation of most common cardiovascular disorders. Over the last few decades, extensive research has been performed establishing imaging techniques to quantify the autonomic dysfunction associated with various cardiovascular disorders. Additionally, several techniques have been tested with variable success in modulating the cardiac autonomic nervous system as treatment for these disorders. In this review, we summarize basic anatomy, physiology, and pathophysiology of the cardiac autonomic nervous system including adrenergic receptors. We have also discussed several imaging modalities available to aid in diagnosis of cardiac autonomic dysfunction and autonomic modulation techniques, including pharmacologic and device-based therapies, that have been or are being tested currently.

Computer derived transient ischemic dilation ratio for identifying extensive coronary artery disease using a CZT camera and imaging in the upright position.

BACKGROUND: Transient ischemic dilation (TID) of the left ventricle (LV) has not been validated as a marker of extensive coronary artery disease (CAD) for studies using a cadmium-zinc-telluride (CZT) camera with upright imaging. METHODS: TID ratios were obtained from upright stress and rest images on a CZT camera. Separate cut-off values were determined for exercise and for regadenoson stress. The cutoffs were then applied to 28 patients with extensive CAD and 101 patients without extensive CAD. RESULTS: With treadmill exercise, an upright TID ratio ≥1.16 provided a positive predictive value of 50% and a negative predictive value of 85.4% for the identification of extensive CAD. In the regadenoson group, an upright TID ratio of 1.29 provided a positive predictive value of 20% and a negative predictive value of 75.9%. Although not an independent predictor of extensive CAD in all subjects, in subjects with a normal upright LVEF, it provided a predictive value by receiver operating characteristics comparable to the SSS. CONCLUSIONS: Increased upright TID measurements on a CZT camera are associated with extensive CAD. The upright TID measurements can serve in an adjunctive role to SSS, and may be most effective in patients with a normal upright exercise LVEF.

Significance of I-123 metaiodobenzylguanidine (¹²³I-MIBG) lung activity in subjects with heart failure in comparison to healthy control subjects.

BACKGROUND: Little is known concerning the significance of lung activity of the sympathetic neuronal imaging agent (123)I-MIBG in heart failure patients and healthy subjects. METHODS: (123)I-MIBG activity was assessed in lung, heart, and mediastinum regions of interest on early and late planar images in 951 heart failure patients and 94 controls. Cox regression analyses were performed to identify factors associated with outcome events during a median 17 month follow-up. RESULTS: Heart failure subjects with pulmonary disease had significantly reduced late lung-to-mediastinum (L/M) ratios compared to heart failure subjects without pulmonary disease. Late L/M ratio was greater in heart failure subjects without outcome events than either subjects with events or healthy controls. L/M ratio was an independent predictor of all-cause mortality. Subjects with combined favorable prognosis L/M ratio ≥ 1.7 and heart-to-mediastinum ratio (H/M) ≥ 1.6 had a significantly lower 2-year mortality (2.0%) than subjects with unfavorable L/M ratio < 1.7 and H/M ratio < 1.6 (17.7% 2-year mortality, P < .0008). CONCLUSIONS: Increased (123)I-MIBG lung activity in heart failure subjects, compared to controls, is associated with a relatively low risk of adverse events, including all-cause mortality. L/M ratio may, therefore, be useful to provide incremental prognostic information on (123)I-MIBG imaging.

Ventricular Tachycardia or Fibrillation Storm in Coronavirus Disease.

Ventricular tachycardia (VT) or ventricular fibrillation (VF) storm associated with severe acute respiratory syndrome coronavirus 2 infection is a potentially fatal complication; the correlation of these 2 disorders, however, has not been well studied. This retrospective case series examined outcomes of 2 patients who were admitted for repeated implantable cardioverter-defibrillator shocks with or without syncope and observed to have VT/VF storms with COVID-19. Mechanisms of VT/VF storms in COVID-19 are multifactorial including myocarditis, systemic inflammation, hyperadrenergic state, hemodynamic instability, hypoxia, acidosis, and proarrhythmic drugs. A higher incidence of VT/VF storm is observed in patients with comorbidities and those requiring critical care, with some studies reporting increased mortality. In our cohort, 1 of the 2 patients succumbed to the complications from COVID-19, and the other patient was discharged to home in stable condition. Monitoring of life-threatening arrhythmias in the setting of COVID-19 may need to be adopted to prevent morbidity and mortality.

Enterococcus faecalis Endocarditis After Endoscopic Mucosal Resection of a Large Sessile Colonic Polyp.

A 71-year-old man with mitral regurgitation and apical cardiomyopathy underwent endoscopic mucosal resection of a 22-mm transverse colon tubulovillous adenoma with high-grade dysplasia. Six weeks later, he presented with fever, valvular vegetations, and positive blood cultures for Enterococcus faecalis. To our knowledge, this is the first reported case of endocarditis involving native heart valves after endoscopic mucosal resection.

Resting radionuclide myocardial perfusion imaging in a chest pain center including an overnight delayed image acquisition protocol.

UNLABELLED: Emergency department (ED) patients with chest pain (CP) and a nondiagnostic electrocardiogram (ECG) present difficult management decisions. The purpose of this study was to investigate the utility of resting radionuclide SPECT myocardial perfusion imaging (SPECT MPI)-including an overnight delayed image acquisition protocol-in identifying patients presenting to the ED with CP at risk for cardiac events. METHODS: Patients presenting to the ED with CP and a nondiagnostic ECG were prospectively enrolled and underwent chest pain center evaluation. All patients also underwent resting gated SPECT MPI using (99m)Tc-tetrofosmin tracer. Patients presenting on weeknights between 12 am and 6 am had tracer injection in the ED with image acquisition delayed until later in the morning. Patients were monitored for a 30-d occurrence of cardiac events. RESULTS: Over a 16-mo period, 479 patients were enrolled and completed follow-up. For the prediction of 30-d cardiac events, resting SPECT MPI demonstrated a sensitivity and a specificity of 76.9% and 92.4%, respectively. Positive and negative predictive values were 22.2% and 99.3%, respectively. Among the 3 patients with a normal perfusion scan who suffered cardiac events, all had tracer injection several hours after resolution of CP. The overnight delayed image acquisition protocol provided a negative predictive value of 100% for the 44 patients whose image acquisition was delayed until the following morning. CONCLUSION: A normal resting SPECT MPI in ED patients presenting with CP predicts a very low occurrence of 30-d cardiac events. A delayed image acquisition protocol did not decrease the accuracy of SPECT MPI. Such a protocol may be useful in increasing the availability of this imaging modality.

Meta-Analysis of Prognostic Implications of Exercise-Induced Ventricular Premature Complexes in the General Population.

Ventricular premature complexes (VPCs) during stress testing in the general population are commonly seen in clinical practice, but their prognostic value is not well understood. A comprehensive literature search of MEDLINE, Embase, and the Cochrane Library from January 1970 to May 2015 was conducted. Observational cohort studies on general populations evaluating the association between exercise-induced VPCs and all-cause or cardiovascular mortality were included in the analysis. Nine studies comprising 62,488 participants comparing clinical outcomes of patients with and without exercise-induced VPCs were included. The overall combined relative risks (RRs) for all-cause mortality and cardiovascular mortality in patients with exercise-induced VPCs were 1.41 (95% CI 1.23 to 1.61) and 1.86 (95% CI 1.51 to 2.30), respectively. In subgroup analysis, both frequent VPCs (RR 1.35, 95% CI 1.14 to 1.60) and infrequent VPCs (RR 1.57, 95% CI 1.13 to 2.18) were associated with an adverse outcome. VPCs during recovery were associated with an increased risk of death (RR 1.55, 95% CI 1.22 to 1.96). VPCs during exercise did not achieve statistical significance (RR 1.14, 95% CI 0.96 to 1.34), but only a few studies were included in the analysis. In conclusion, our meta-analysis suggests that exercise-induced VPCs in the general population significantly increase the risk of total mortality and cardiovascular mortality. Our study calls for further studies to assess the prognostic significance of exercise-induced VPCs and the utility of efforts to reduce the VPC burden to improve the clinical outcome.