Diagnostic performance of a semiconductor gamma-camera system as studied by multicenter registry.

BACKGROUND: Despite the introduction of the novel cadmium-zinc-telluride (CZT) single-photon emission computed tomography (SPECT) in Japan; its diagnostic value in clinical practice remains largely unknown. METHODS: The Semiconductor SPECT Study group is a multicenter Japanese registry which registered 1000 patients to evaluate the diagnostic utility of the CZT camera system (Discovery NM530c; GE Healthcare, Haifa, Israel). The patients underwent stress myocardial SPECT and coronary angiography within a 3-month interval. A significant stenosis was defined as ≥75% diameter narrowing based on the American Heart Association classification. RESULTS: Technetium (99mTc) radiotracer (555-1110MBq) was used in 71% and thallium-201 (201Tl) (74-148MBq) in 29%. The scan times with 99mTc-radiotracer were 5-10min for stress and 3-10min for rest, whereas those with 201Tl were 5-9min for stress and 8-10min for rest. To detect individual coronary stenosis, the respective sensitivities, specificities, and accuracies were 74%, 85%, and 81% for left anterior descending coronary artery (LAD) stenosis, 76%, 89%, and 85% for left circumflex stenosis, and 72%, 86%, and 82% for right coronary artery stenosis. However, 66% sensitivity and 91% specificity for LAD stenosis were observed with 99mTc-radiotracer, whereas 88% sensitivity and 63% specificity were found with 201Tl. CONCLUSIONS: The novel CZT SPECT system facilitated a short scan time with reduced radiotracer dose, yielding an acceptable diagnostic performance for angiographical coronary artery disease, although the low sensitivity for LAD detection with 99mTc-radiotracer needs to be refined.

Factors influencing trough and 90-minute plasma dabigatran etexilate concentrations among patients with non-valvular atrial fibrillation.

INTRODUCTION: Dabigatran etexilate, a direct oral anti-coagulation agent, is used in the prevention of thromboembolism in patients with non-valvular atrial fibrillation (NVAF). However, for reasons that are not fully understood, plasma dabigatran etexilate concentrations (PDC) vary significantly among patients. METHODS: We measured trough and 90min PDC in 98 patients with NVAF. To elucidate the cause of variations in PDC, we determined correlations between PDC and various factors including renal function, co-administration of a P-glycoprotein inhibitor, and the effects of three single nucleotide polymorphisms (SNPs) of the P-glycoprotein intestinal efflux transporter. To further determine the cause of PDC variations, we examined the relationship between PDC, activated partial prothrombin time (APTT), and D-dimer (DD) levels, which are surrogate markers for thrombotic risk. RESULTS: Multivariate analysis showed significant relations among creatinine, creatinine clearance, and CHA2D2-VaSc scores (p=0.04, p=0.01, and p=0.04, respectively). In addition, creatinine and creatinine clearance were significantly correlated with trough and 90min PDC (p<0.01), respectively. There was a clear linear relation between PDC and APTT, but not DD levels. However, higher DD levels (>0.5µg/mL) were associated with lower trough and 90min PDCs. CONCLUSIONS: Renal function and CHA2D2-VaSc scores affect PDC, suggesting these may be primary factors influencing the wide variation observed in PDCs under these conditions. Variations in APTT can primarily be explained by variations in PDC; patients with lower PDCs may have a higher risk of thromboembolism events.

Plaque distribution patterns in left main trunk bifurcations: prediction of branch vessel compromise by multidetector row computed topography after percutaneous coronary intervention.

AIMS: We investigated the mechanism and predictors of jailed branch vessel (BV) compromise during the stenting of left main trunk (LMT) bifurcation lesions from a multidetector row computed tomography (MDCT) analysis. METHODS AND RESULTS: Eighty patients who underwent MDCT and stenting for LMT bifurcation lesions were examined. The patients were retrospectively classified into a BV stenosis (BVS; n=38) group and a non-BV stenosis (NBVS; n=42) group according to a coronary angiography obtained just after crossover stent deployment for the target vessel (TV). The angle between the LMT and TV was significantly wider in the BVS group than in the NBVS group (140.2±10.3 degree vs. 132.6±14.2 degree, p=0.0076), and the frequency of carina side plaque at the TV in the long and short axis was significantly higher in the BVS group than in the NBVS group (50.0% vs. 16.7%; p=0.0012, 63.2% vs. 38.1%; p=0.0251, respectively). In a multivariate analysis, the presence of carina side plaque at the TV in the long and short axis were independent predictors of BVS (odds ratio: 5.15, p=0.0086, odds ratio: 3.83, p=0.0231, respectively). CONCLUSIONS: The plaque distribution and morphology assessed by MDCT may provide useful information that can predict the potential compromise of the BV during treatment for an LMT bifurcation lesion.

Late catch-up phenomenon associated with stent fracture after sirolimus-eluting stent implantation: incidence and outcome.

OBJECTIVE: To examine the long-term outcome of the stent fracture (SF) and the potential predictive factors contributing to in-stent restenosis (ISR) in the fractured stent. BACKGROUND: The SF is thought to be a higher risk of ISR in drug-eluting stent, although SF does not always develop ISR. METHODS: The consecutive 1,228 de novo lesions in 1,079 patients who underwent sirolimus-eluting stents implantation and assessed by 8 months follow-up coronary angiography were retrospectively analyzed. RESULTS: One hundred and seventeen SFs (9.5%) were identified in 100 patients and 22 (18.8%) SFs revealed ISR at the first follow-up. In addition, 16 (13.7%) developed new ISRs from 95 residual SFs without ISR prior to the second follow-up. Overall, 38 (32.5%) of all 117 SFs developed ISR, and 16 (42.1%) of 38 SFs occurred in a late phase beyond the first 8 months follow-up. A higher risk of ISR in the SF site was associated with the chronic total occlusion (ISR vs. no ISR: 34.2% vs. 16.5%, P = 0.0304), calcified lesions (55.3% vs. 34.2%, P = 0.0299), and correspondence 89.5% versus 43.0%, P < 0.0001 (SF site occurring at the original target lesion site) in the univariate analysis. The correspondence was identified as the only strong predictive factor for ISR at the SF site according to a multivariate logistic regression analysis (odds ratio 12.6, 95% confidence interval 3.82-53.5, P < 0.0001). CONCLUSIONS: SF occurring at the site of the original target lesion was a strong independent predictor of ISR. This indicates the need for a careful, long-term follow-up in those situations, even when no significant ISR is initially detected.

Normal myocardial perfusion scan portends a benign prognosis independent from the pretest probability of coronary artery disease. Sub-analysis of the J-ACCESS study.

BACKGROUND AND PURPOSE: We assessed the usefulness of gated stress/rest 99mTc-tetrofosmin myocardial perfusion single photon emission computed tomography (SPECT) to predict ischemic cardiac events in Japanese patients with various estimated pretest probabilities of coronary artery disease (CAD). METHODS AND RESULTS: Of the 4031 consecutively registered patients for a J-ACCESS (Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated SPECT) study, 1904 patients without prior cardiac events were selected. Gated stress/rest myocardial perfusion SPECT was performed and segmental perfusion scores and quantitative gated SPECT results were derived. The pretest probability for having CAD was estimated using the American College of Cardiology/American Heart Association/American College of Physicians-American Society of Internal Medicine guideline data for the management of patients with chronic stable angina, which includes age, gender, and type of chest discomfort. The patients were followed up for three years. During the three-year follow-up period, 96 developed ischemic cardiac events: 17 cardiac deaths, 8 nonfatal myocardial infarction, and 71 clinically driven revascularization. The summed stress score (SSS) was the most powerful independent predictor of all ischemic cardiac events (hazard ratio 1.077, CI 1.045-1.110). Abnormal SSS (> 3) was associated with a significantly higher cardiac event rate in patients with an intermediate to high pretest probability of CAD. Normal SSS (< or = 3) was associated with a low event rate in patients with any pretest probability of CAD. CONCLUSIONS: Myocardial perfusion SPECT is useful for further risk-stratification of patients with suspected CAD. The abnormal scan result (SSS > 3) is discriminative for subsequent cardiac events only in the groups with an intermediate to high pretest probability of CAD. The salient result is that normal scan results portend a benign prognosis independent from the pretest probability of CAD.

Characterization of hyperintense plaque with noncontrast T(1)-weighted cardiac magnetic resonance coronary plaque imaging: comparison with multislice computed tomography and intravascular ultrasound.

OBJECTIVES: This study sought to characterize coronary hyperintense plaques (HIP) using noncontrast T(1)-weighted imaging (T1WI) in cardiac magnetic resonance, which was then compared with multislice computed tomography and intravascular ultrasound. BACKGROUND: Carotid plaque components such as intraplaque hemorrhages and/or lipid-rich necrotic cores can be detected as HIP by noncontrast T1WI. Although coronary HIPs have been successfully detected using this technique, the properties of hyperintense signals in coronary plaques have not yet been systematically evaluated. METHODS: Thirty-eight lesions from 37 patients with angina pectoris who demonstrated >70% coronary stenosis on multislice computed tomography were evaluated by noncontrast T1WI using a 1.5-T magnetic resonance imager, and 25 lesions were evaluated by intravascular ultrasound. Signal intensity of coronary plaque to cardiac muscle ratio >1.0 was defined as HIP. We divided 25 lesions into the 2 groups, according to the presence or absence of HIP: HIP (n = 18) and non-HIP (n = 7) groups. RESULTS: In comparison with the non-HIP group, the HIP group demonstrated significantly higher coronary plaque to cardiac muscle ratio (1.7 +/- 0.7 vs. 0.9 +/- 0.1, p < 0.01), higher frequency of positive remodeling as observed by both multislice computed tomography (89% vs. 0%, p<0.0001) and intravascular ultrasound (94% vs. 14%, p < 0.001) and ultrasound attenuation (100% vs. 14.3%, p < 0.0001). The frequency of spotty calcification tended to be higher in HIP (89% vs. 50%, p = 0.079). The HIP group also exhibited a significantly lower computed tomography density (-23.2 +/- 20.7 Hounsfield units [HU] vs. 9.6 +/- 20.5 HU, p < 0.01). In addition, the incidence of transient slow-flow phenomena was significantly higher in the HIP group than in the non-HIP group (83% vs. 14%, p < 0.01). CONCLUSIONS: The typical HIP case was associated with ultrasound attenuation, positive remodeling, remarkably low computed tomography density, and a high incidence of slow-flow phenomena. Noncontrast T1WI in cardiac magnetic resonance imaging may be useful for the assessment of coronary plaque characterization in patients with coronary artery disease.

The bifurcation study using 64 multislice computed tomography.

BACKGROUND: Various two-stent techniques have been applied to aggressively treat bifurcation lesions as the introduction of drug-eluting stents (DES) and the importance of the bifurcation angle and three-dimensional (3D) structure has come to be recognized. Recent 64 multislice computed tomography (MSCT) technology provides accurate information about the 3D bifurcation geometry of the coronary arteries and with reproducibility. OBJECTIVES: The purpose of this study is to disclose the coronary bifurcation angle and 3D structure in humans and elucidate the importance of bifurcation angle for the crush technique using MSCT. METHODS: Two hundred and nine patients who were suspected to have angina pectoris and underwent CT angiography using MSCT were examined. The 3D-volume rendering (VR) image was reconstructed by two technicians and was used for the assessment of each coronary bifurcation angles. RESULTS: The average LMT bifurcation angles (angle LMT-LAD, angle LMT-LCx, angle LAD-LCx) were 143 +/- 13 degrees , 121 +/- 21 degrees , and 72 +/- 22 degrees , respectively, the average angle LAD-D was 138 +/- 19 degrees , the average angle LCx-OM was 134 +/- 23 degrees , the average distal RCA bifurcation angles (angle RCA-4AV, angle RCA-4PD, angle 4AV-4PD) were 152 +/- 15 degrees , 137 +/- 20 degrees , and 61 +/- 21 degrees , respectively. In addition, a percentage of steep angled bifurcation (<110 degrees ) was significantly higher in the LMT (26%) than in other bifurcations (P < 0.05). CONCLUSIONS: LMT bifurcation has been shown to have a higher rate of steep angled bifurcation in humans, it is therefore necessary to take the bifurcation angle into consideration in the case of LMT stenting. These data suggest that a bifurcation study using MSCT can clarify the 3D structure of coronary bifurcation and may provide useful information for bifurcation stenting.

Impact of a prolonged delivery inflation time for optimal drug-eluting stent expansion.

PURPOSE: We examined the importance of prolonged inflation time for optimal sirolimus-eluting stent (SES) or paclitaxel-eluting stent (PES) expansion. METHODS: Eighty-one de novo lesions deployed single SES or PES between April 2007 and March 2008 were divided into four groups; group 1: 21 SES deployed at 20 atm x 60 sec, group 2: 20 SES deployed with 2-step inflation at 20 atm x 60 sec following 20 atm x 20 sec, group 3: 20 PES deployed same as group 1, group 4: 20 PES deployed same as group 2. The minimal lumen diameter (MLD) and stent expansion ratio (SER; stent cross- sectional area at lesion/balloon cross-sectional area which was calculated according to the compliance chart at the same atmosphere as stent deployment) were compared between group 1 and group 2 in SES, between group 3 and group 4 in PES. RESULTS: The MLD of post 60 sec was significantly higher than that of post 20 sec (2.84 +/- 0.28 mm in group 1, 2.76 +/- 0.33 mm in group 2 vs. 2.54 +/- 0.33 mm in group 2; P = 0.003, 0.045, respectively and 2.94 +/- 0.28 mm in group 3, 3.00 +/- 0.34 mm in group 4 vs. 2.69 +/- 0.35 mm in group 4; P = 0.022, 0.007, respectively). The SER of post 60 sec was significantly higher than that of post 20 sec (79.3% +/- 8.5% in group 1, 80.8% +/- 7.8% in group 2 vs. 71.1% +/- 10.2% in group 2; P = 0.014, 0.011, respectively and 81.1% +/- 7.9% in group 3, 84.3% +/- 9.9% in group 4 vs. 72.6% +/- 10.5% in group 4, P = 0.011, 0.001, respectively). CONCLUSION: The prolonged delivery inflation for 60 sec may result in a more optimal stent expansion. It is therefore considered to be a useful method for deploying drug-eluting stent.

Left ventricular false-pseudo and pseudo aneurysm: serial observations by cardiac magnetic resonance imaging.

A case of extensive inferior myocardial infarction complicated by a large ventricular aneurysm is presented. Magnetic resonance (MR) imaging 4 days after the onset showed a small protrusion from the necrotic inferior myocardium, which expanded 10 days after onset with a marked pericardial effusion. The follow-up examination by MR and CT imaging 6 months after the onset revealed a large ventricular aneurysm from the inferior cardiac wall. After the aneurysmectomy, the histological study revealed that the aneurysm wall was made up of 2 different types of walls; the peripheral part was a false-pseudo aneurysm and the central part was a pseudo aneurysm. From the serial MR imaging, it is considered that such an aneurysm is primarily formed from a small discontinuation of the LV wall followed by oozing type rupture. Finally, the ruptured central part of the LV wall, which was covered by the pericardium, formed a pseudo aneurysm and the stretched peripheral area, which contains myocardium, formed a false-pseudo aneurysm afterward and then they extended together. Thus, MR imaging provided the important information for the understanding of the formation process of the pseudo and false pseudo LV aneurysm.

Low-dose aspirin for prevention of stroke in low-risk patients with atrial fibrillation: Japan Atrial Fibrillation Stroke Trial.

BACKGROUND AND PURPOSE: Although the efficacy of anticoagulant therapy for primary prevention of stroke in patients with nonvalvular atrial fibrillation (NVAF) has been established, efficacy of antiplatelet therapy for low-risk patients is disputable in Japanese patients because of the frequent hemorrhagic complications. We examined the efficacy and safety of aspirin therapy in Japanese patients with NVAF in a prospective randomized multicenter trial. METHODS: Patients with NVAF were randomized to an aspirin group (aspirin at 150 to 200 mg per day) or a control group without antiplatelet or anticoagulant therapy. Primary end points included cardiovascular death, symptomatic brain infarction, or transient ischemic attack. RESULTS: A total of 426 patients were randomized to aspirin group and 445 to no treatment. The trial was stopped earlier because there were 27 primary end point events (3.1% per year; 95% CI, 2.1% to 4.6% per year) in the aspirin group versus 23 (2.4% per year; 95% CI, 1.5% to 3.5% per year) in the control group, suggesting a low possibility of superiority of the aspirin treatment for prevention of the primary end point. In addition, treatment with aspirin caused a marginally increased risk of major bleeding (7 patients; 1.6%) compared with the control group (2 patients; 0.4%; Fisher exact test P=0.101). CONCLUSIONS: For prevention of stroke in patients with NVAF, aspirin at 150 to 200 mg per day does not seem to be either effective or safe. Further prospective studies are needed to determine the best preventive therapy for cerebrovascular events in Japanese patients with NVAF.

[Comparison of myocardial perfusion imaging by thallium-201 single-photon emission computed tomography with SUNY4001 (adenosine) and exercise--crossover clinical trial at multi-center].

We compared the ischemic diagnosis ability and adverse events of 201Tl myocardial perfusion imaging with SUNY4001 (adenosine) stress to that with exercise (ergometer) stress both on random crossover trial. Thirty one known or suspected chronic stable angina patients who are able to exercise and 10 healthy volunteers were enrolled for the trial. The early and delayed images were obtained by SPECT imaging. The concordance of diagnoses [ischemia vs. no ischemia] between the two types of stresses was 97.3% (36/37) [Kappa: 0.9068]. The sensitivity and specificity based on the exercise test were 100% (6/6) and 96.8% (30/31) respectively. The incidence of adverse events caused by SUNY4001 and the exercise were 44.7% (17/38) and 52.6% (20/38), respectively. Major adverse events caused by SUNY4001 were BP decrease, flushing and headache. And those by exercise were ST decrease, dyspnea and chest pain. None of the adverse events required the intervention or caused life-threatening complication in the trial. The trial showed that the ischemic diagnosis ability and safety of 201Tl scintigraphy with SUNY4001 stress are almost equal to those of the exercise stress that is considered as the standard stress method. We concluded that 201Tl imaging with SUNY4001 is safe and useful for detecting ischemic heart disease, especially for patients unable to exercise adequately.

Prognostic value of myocardial MIBG scintigraphy findings in patients with cardiomyopathy--importance of background correction for quantification of MIBG activity.

OBJECTIVE: To assess the prognostic value of I-123 metaiodobenzylguanidine (MIBG) scintigraphy findings, and establish the most appropriate method for calculating myocardial MIBG activity in patients with left ventricular dysfunction due to cardiomyopathy (CM). METHODS: Predictors of cardiac death related to progressive heart failure (HF) were examined in 150 patients with CM (80 patients with idiopathic CM and 70 patients with ischemic CM). All patients underwent MIBG scintigraphy at rest and other hemodynamic studies when their clinical status was stable. MIBG scintigrams were obtained 15 minutes and 4 hours after the injection of the isotope. The parameters for quantification of myocardial MIBG activity were heart/mediastinal activity ratio (H/M) and myocardial washout rate (WR). The WR was calculated with and without background (BG) correction. RESULTS: The WR showed better correlation with plasma norepinephrine and left ventricular ejection fraction after BG correction. During a mean follow-up period of 33 +/- 9 (7 to 54) months, 12 patients died due to HF; 7 patients due to progressive HF and 5 patients due to sudden cardiac death. Cox regression analysis indicated, the H/M and the WR with and withoutBG correction, were significant predictors of cardiac death (Wald chi-squared value: H/M [ 15 min] = 9.7, H/M [4 hr] = 19.5, WR with BG correction = 29.9, WR without BG correction = 12.6). WR prognostic value was better after BG correction, and a high WR with BG correction was the only independent predictor of cardiac death (relative risk [RR] = 1.174, p < 0.0001). CONCLUSIONS: Accelerated WR is a powerful predictor of the patient's prognosis and BG correction is essential for calculating WR.