Shunichi Yoda

Diagnosis of anomalous origin of the right coronary artery using multislice computed tomography: evaluation of possible causes of myocardial ischemia.

Anomalous origin of the right coronary artery (RCA) is a rare condition, but may cause myocardial ischemia and sudden death. Multislice computed tomography, which allows three-dimensional visualization of the coronary artery with high spatial resolution, may be the most promising imaging modality for diagnosing this anomaly. We describe a patient with anomalous origin of the RCA arising from the left sinus of Valsalva. Volume rendering, and axial and curved multiplanar images showed stenosis in the proximal portion of the RCA that coursed between the aorta and the pulmonary artery, and an acute angled take-off of the RCA from the aorta. Three-dimensional virtual angioscopic images showed a hypoplastic RCA orifice and luminal narrowing in the proximal portion of the RCA. Multislice computed tomography was thought to be useful for detecting anomalous origin of the RCA and for evaluating possible causes of myocardial ischemia.

Risk stratification of cardiovascular events in patients at all stages of chronic kidney disease using myocardial perfusion SPECT

BACKGROUND Cardiovascular disease is the leading cause of death among patients with chronic kidney disease (CKD). Therefore, stratification of the prognostic risk of cardiovascular events is useful for their clinical management. We evaluated the ability of electrocardiogram (ECG)-gated myocardial perfusion single photon emission computed tomography (SPECT) to predict cardiac events among Japanese patients at all stages of CKD including those on hemodialysis. METHODS Patients with CKD undergoing ECG-gated myocardial perfusion SPECT to investigate suspected ischemic heart disease were followed up to monitor retrospectively major cardiac events including cardiac death, non-fatal myocardial infarction, and unstable angina pectoris. Summed stress score, summed rest score, and summed difference score were estimated with a 20 segment 5-point scoring model. The severity of CKD was divided into five levels based on estimated glomerular filtration rate (eGFR) revised for the Japanese population. RESULTS The follow-up period was 25.8 ± 11.0 months. Sixty-two major cardiac events (cardiac death, n=30; non-fatal myocardial infarction, n=13; unstable angina pectoris, n=19) developed in 2243 patients during the first year of follow-up. The findings of multivariate Cox proportional hazards regression analysis indicated that diabetes, eGFR, the summed difference score, and summed stress score were significant independent predictors of cardiac events. The major cardiac event rate at one year increased in proportion to the progression of CKD stage. The major cardiac event-free survival rate decreased steeply over time in patients with CKD stage 5 compared with those who had CKD stages 4 or less. CONCLUSION Myocardial perfusion SPECT can contribute to the prediction of cardiac events and survival in patients at all stages of CKD including those on hemodialysis.

Regression of an atherosclerotic coronary artery plaque demonstrated by multislice spiral computed tomography in a patient with stable angina pectoris.

Multislice spiral computed tomography (MSCT) permits direct visualization of not only coronary artery stenosis but also atherosclerotic plaques in patients with coronary artery disease. In this report, we describe a patient with stable angina in whom the regression of the plaque was documented by serial MSCT examinations. In the patient, a 46-year-old man with stable angina, MSCT revealed a stenotic lesion at the proximal portion of the left anterior descending artery. Axial, curved multiplanar reconstruction and cross-sectional images consistently depicted a protruding computed tomography low-signal mass suggesting an atherosclerotic plaque. Intracoronary ultrasound (ICUS) also documented an eccentric soft plaque with an echo-lucent mass suggesting a lipid core. Lipid-lowering therapy with pravastatin was started. Follow-up MSCT performed 7 months later documented an increase in the luminal area while the external vessel area remained unchanged. The regression of the plaque was also confirmed by a follow-up ICUS study. MSCT was thought to be feasible for serial evaluation of the plaque size and texture.

Development of Human‐Like Advanced Coronary Plaques in Low‐Density Lipoprotein Receptor Knockout Pigs and Justification for Statin Treatment Before Formation of Atherosclerotic Plaques

Background Although clinical trials have proved that statin can be used prophylactically against cardiovascular events, the direct effects of statin on plaque development are not well understood. We generated low‐density lipoprotein receptor knockout (LDLR −/−) pigs to study the effects of early statin administration on development of atherosclerotic plaques, especially advanced plaques. Methods and Results LDLR −/− pigs were generated by targeted deletion of exon 4 of the LDLR gene. Given a standard chow diet, LDLR −/− pigs showed atherosclerotic lesions starting at 6 months of age. When 3‐month‐old LDLR −/− pigs were fed a high‐cholesterol, high‐fat (HCHF) diet for 4 months (HCHF group), human‐like advanced coronary plaques developed. We also fed 3‐month‐old LDLR −/− pigs an HCHF diet with pitavastatin for 4 months (Statin Prophylaxis Group). Although serum cholesterol concentrations did not differ significantly between the 2 groups, intravascular ultrasound revealed 52% reduced plaque volume in statin‐treated pigs. Pathological examination revealed most lesions (87%) in the statin prophylaxis group were early‐stage lesions, versus 45% in the HCHF diet group (P<0.01). Thin‐cap fibroatheroma characterized 40% of the plaques in the HCHF diet group versus 8% in the statin prophylaxis group (P<0.01), intraplaque hemorrhage characterized 11% versus 1% (P<0.01), and calcification characterized 22% versus 1% (P<0.01). Conclusions Results of our large animal experiment support statin prophylaxis before the occurrence of atherosclerosis. Early statin treatment appears to retard development of coronary artery atherosclerosis and ensure lesion stability. In addition, the LDLR −/− pigs we developed represent a large animal model of human‐like advanced coronary plaque suitable for translational research.

Myocardial ischemic reduction evidenced by gated myocardial perfusion imaging after treatment results in good prognosis in patients with coronary artery disease

BACKGROUND There are no nuclear cardiology reports indicating the prediction of prognosis based on ischemic reduction after revascularization in Japanese patients with coronary artery disease (CAD). We aimed to evaluate quantitatively ischemia using myocardial perfusion single photon emission computed tomography (SPECT) before and after treatment such as revascularization and to determine a relationship between the ischemic reduction and the incidence of major cardiac events (MCEs) after the treatment in patients with CAD. METHODS We retrospectively investigated 513 patients who underwent rest (201)Tl and stress (99m)Tc-tetrofosmin myocardial perfusion SPECT between October 2004 and March 2011 and who had a significant stenosis with 75% or greater narrowing of the coronary arterial diameter detected by coronary angiography performed after confirmation of ≥5% ischemia with SPECT. The patients underwent the treatment including revascularization and medication and thereafter were re-evaluated with SPECT during a chronic phase and followed up to confirm prognosis for ≥1 year. The follow-up period was 33.4±16.4 months. The endpoint was the incidence of the MCEs consisting of cardiac death, non-fatal myocardial infarction, and unstable angina pectoris. RESULTS During the follow-up, 45 patients experienced MCEs comprising cardiac death (n=13), non-fatal myocardial infarction (n=3), and unstable angina pectoris (n=29). The multivariate Cox proportional hazards regression model analysis for the risk of the MCEs showed the changes in the summed difference score % (p=0.0102) and the stress left ventricular ejection fraction after the treatment (p=0.0146) as significant independent variables. The incidence of the MCEs significantly decreased in the patients with ≥5% ischemic reduction than in the patients without ≥5% ischemic reduction and in the patients without residual ischemia than in the patients with the residual ischemia. CONCLUSION Myocardial ischemic reduction detected by nuclear cardiology leads to a decrease in MCE rates after treatment in Japanese patients with CAD.

Left ventricular aneurysm associated with isolated noncompaction of the ventricular myocardium

A 66-year-old woman was admitted to our hospital because of left ventricular failure and nonsustained ventricular tachycardia. Two-dimensional echocardiography demonstrated prominent trabeculations and deep intertrabecular recesses, findings consistent with noncompaction of the ventricular myocardium. Myocardial perfusion scintigraphy demonstrated a defect in the anterobasal left ventricular segment. Coronary angiogram was normal, but the left ventriculogram showed an aneurysm in the anterior myocardial segments. This is the first reported case with isolated noncompaction of the ventricular myocardium associated with left ventricular aneurysm.

Validation of automated quantification of nuclear cardiology in Japanese patients using total perfusion deficits: Comparison with visual assessment

BACKGROUND Automated quantitative assessment based on a total perfusion deficit (TPD) has been recognized to be useful for detection of coronary artery disease (CAD). We, therefore, aimed to validate reproducibility of the automated quantification with the TPD on myocardial perfusion single photon emission computed tomography (SPECT) images in Japanese patients with history of stable CAD. METHODS Patients (n=47, age 67 ± 10) underwent rest (201)Tl and stress (99m)Tc-tetrofosmin myocardial perfusion SPECT on two separate occasions with the same protocol within 3-26 months. They had abnormal findings on the first SPECT imaging by visual analysis and had no changes in symptoms, cardiac medications, coronary risk factors, and electrocardiogram findings at the time of the second imaging. They had no intervening coronary revascularization and myocardial infarction between the first and second imaging. The TPD was automatically derived from SPECT images through quantitative perfusion SPECT software with the Japanese normal database. A visual summed stress score (SSS) was estimated with the 5-point visual scoring model for 20 segments of SPECT images by independent expert interpreters. Abnormal criteria for the stress TPD and SSS were defined as ≥5% and ≥4, respectively. RESULTS The stress TPD determined by the quantitative analysis well correlated between the first and second imaging (r=0.985) as well as the SSS by the visual analysis showed good correlation (r=0.978). The correlation coefficients were similar between the visual and quantitative analyses. Bland-Altman analyses indicated extremely good reproducibility in both assessments. CONCLUSION The TPD is evidently a quantitative index having high reproducibility and the automated quantification with it provides comparable results to the visual assessment by experienced interpreters. The automated quantification with the TPD is highly significant for clinical assessment of CAD, and allows easily performing myocardial perfusion SPECT imaging without expert interpreters.

Diagnostic value of automated quantification of nuclear cardiology in Japanese patients with single vessel coronary artery disease: comparison between Japanese and American normal databases.

BACKGROUND The Japanese diagnostic assessment of nuclear cardiology has usually been based on semi-quantitative visual analyses but not on automated quantification with a total perfusion deficit (TPD). We, therefore, aimed to determine whether automated TPD quantification is useful to detect coronary artery disease (CAD) in Japanese patients in comparison with conventional visual segmental analysis, and to compare results from the automated assessment between the Japanese and American normal databases (NDBs). METHODS Patients with suspected CAD underwent rest (201)Tl and stress (99m)Tc-tetrofosmin myocardial perfusion single photon emission computed tomography (SPECT) and coronary angiography within three months. The TPD was automatically derived from the SPECT image through quantitative perfusion SPECT software with the Japanese and American NDBs. The visual summed stress scores (SSS) were estimated with the 5-point visual scoring model for 20 segments of SPECT images. An abnormal criteria for the stress TPD and SSS were defined as ≥ 5% and ≥ 4, respectively. RESULTS Detection sensitivity of CAD was 87% with the stress TPD score derived from the Japanese NDB and 85% with the SSS in visual analysis. In contrast, the detection sensitivity with the stress TPD score derived from the American NDB was 75%, which was significantly lower than that with the Japanese TPD (p=0.0004). Specificity of the automated Japanese TPD assessment was similar to that of the visual SSS assessment (87% vs. 80%). Thus, sensitivity and specificity of the automated quantitative assessment based on the TPD scores derived from the Japanese NDB were consistent with that of visual quantification based on the segmental defect scores. CONCLUSION The automated quantitative assessment with the Japanese NDB is useful for the detection of CAD when experts in visual interpretation of a myocardial perfusion SPECT image were absent in a clinical setting.

Clinical Feasibility of Simultaneous Acquisition Rest (99m)Tc/Stress (201)Tl Dual-Isotope Myocardial Perfusion Single-Photon Emission Computed Tomography With Semiconductor Camera.

BACKGROUND The aim of this study was to evaluate the clinical feasibility of simultaneous acquisition of rest (99m)Tc-tetrofosmin/stress (201)Tl dual-isotope single-photon emission computed tomography with a semiconductor gamma camera. METHODSANDRESULTS Ninety-four patients with known or suspected coronary artery disease (CAD) were enrolled in the study. First, patients were injected with (99m)Tc-tetrofosmin (296 MBq) for rest imaging, followed by (201)Tl (74 MBq) injection during 6 min of vasodilator stress test. Immediately after the stress test, the patients underwent the first electrocardiogram (ECG)-gated simultaneous acquisition including rest and stress perfusion scans. Patients were brought back for the second simultaneous acquisition for the comparison of ECG-gated wall motion between stress and rest scan 30 min later. Coronary angiography was performed in all the patients within 3 months of this protocol. Sensitivity, specificity and accuracy on a per patient basis to detect significant coronary artery stenosis (≥75%) were 88.6%, 79.2% and 86.2%, respectively. Per coronary vessel, sensitivity, specificity and accuracy were as follows: 84.9%, 80.5% and 83% in the left anterior descending coronary artery; 75%, 93.1% and 86.2% in the left circumflex coronary artery; and 74.2%, 85.7% and 81.9% in the right coronary artery. CONCLUSIONS Simultaneous acquisition of rest (99m)Tc-tetrofosmin/stress (201)Tl dual-isotope protocol had high diagnostic accuracy for significant CAD. (Circ J 2016; 80: 689-695).

Mid-Ventricular Obstructive Hypertrophic Cardiomyopathy Associated with an Apical Aneurysm: Evaluation of Possible Causes of Aneurysm Formation

Mid-ventricular obstructive hypertrophic cardiomyopathy (MVOHCM) is a rare type of cardiomyopathy, associated with apical aneurysm formation in some cases. We report a patient presenting with ventricular fibrillation, an ECG with an above normal ST segment, and elevated levels of cardiac enzymes but normal coronary arteries. Left ventriculography revealed a left ventricular obstruction without apical aneurysm. There was a significant pressure gradient between the apical and basal sites of the left ventricle. Cine magnetic resonance imaging (MRI), performed on the 10th hospital day, showed asymmetric septal hypertrophy, mid-ventricular obstruction, and an apical aneurysm with a thrombus. The first evaluation by contrast-enhanced imaging showed a subendocardial perfusion defect and delayed enhancement. It was speculated that the intraventricular pressure gradient, due to mid-ventricular obstruction, triggered myocardial infarction, which subsequently resulted in apical aneurysm formation.