Nobusada Funabashi

Diagnostic accuracy of 320-slice computed-tomography for detection of significant coronary artery stenosis in patients with various heart rates and heart rhythms compared with conventional coronary-angiography

PURPOSE To evaluate the diagnostic accuracy of 320-slice CT for detection of significant coronary artery stenosis in patients with various heart rates (HR) and heart rhythms, including tachycardia and chronic atrial-fibrillation (CAF) compared with conventional-coronary-angiography (CAG). MATERIALS AND METHODS One-hundred-six consecutive patients underwent both 320-slice CT and CAG within 3 months (normal-sinus-rhythm [NSR] 91.5%, CAF 8.5%, mean HR 65 ± 15 beats/min). There were no cardiac events between the 2 procedures. Patients were divided in 2 groups: Group 1 (HR <65 with NSR at CT scan, n=62), and Group 2 (HR >64 with NSR or heart rhythm irregularities at CT scan, n=44). Patients with >50% or >75% luminal stenosis on CT were compared with those with >50% or >75% stenosis on CAG, respectively. RESULTS In a segment-by-segment analysis, in all patients, sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of >50% stenosis on CT for predicting >50% stenosis on CAG were 69, 98, 78, and 97%, respectively, and those of >75% stenosis on CT for predicting >75% stenosis on CAG were 78, 98, 64, and 99%, respectively. Sensitivity, specificity, PPV, and NPV of >50% and 75% stenosis on CT for predicting >50% and >75% stenosis, respectively, on CAG were comparable. Diagnostic accuracy was essentially the same in both groups. CONCLUSION 320-slice CT had high diagnostic accuracy for the detection of significant coronary artery stenosis compared with CAG. Even though the numbers were small, patients with high HR or heart rhythm irregularities might have essentially equivalent results to those with low HR with NSR.

Quality of coronary arterial 320-slice computed tomography images in subjects with chronic atrial fibrillation compared with normal sinus rhythm

PURPOSE To evaluate coronary arterial image quality on 320-slice CT in subjects with chronic atrial fibrillation (CAf) vs. normal sinus rhythm (NSR). MATERIALS AND METHODS In 92 consecutive subjects, 46 each with CAf (male:female ratio 2.54:1.00, age 69.7 ± 9.9 years) and NSR (male:female ratio 1.88:1.00, age 63.7 ± 13.7 years), 320-slice CT (Aquilion-one) was performed with enhanced images reconstructed at 80% of ECG R-to-R intervals. Visualized coronary vessels >1.5mm diameter in the right coronary artery, left anterior descending (LAD), and circumflex (LCx) distribution were evaluated for length, percentage of length free from motion artifacts, and image quality on a scale ranging from 1 (highest quality) to 5 (lowest quality). RESULTS LCx length measurements were significantly greater in subjects with NSR (108.8 ± 27.0mm) than CAf (96.6 ± 31.4mm) (P = 0.049), whereas percentages of length free from motion artifacts did not differ between the three vascular beds. Image quality, was significantly but marginally better overall in NSR than in CAF, as well as for LAD and LCx vascular beds. Mean scores in subjects with CAf and NSR were 1.4 ± 0.7 and 1.3 ± 0.6 in all arteries, 1.4 ± 0.7 and 1.2 ± 0.5 in LAD, and 1.5 ± 0.7 and 1.2 ± 0.5 in LCx, respectively (all P<0.001). Despite this difference in image quality, mean scores for both CAf and NSR were weighted toward the high quality end of the scale. CONCLUSION By 320-slice CT, the overall length of visualized coronary arteries, motion artifact-free length, and image quality using a 5-point scale showed values equal to or slightly lower in CAf than in NSR, but the absolute values were quite acceptable in both groups.

Left atrial wall thickness in paroxysmal atrial fibrillation by multislice-CT is initial marker of structural remodeling and predictor of transition from paroxysmal to chronic form

PURPOSE We used ECG-gated MSCT to evaluate alterations in the LA wall in patients with paroxysmal atrial fibrillation (AF) (PAF) and compared with chronic AF (CAF) and normal sinus rhythm (NSR). MATERIALS AND METHODS We enrolled 3 groups, each consisting of 62 patients with either recurrent PAF (48 males, 65 ± 11 years), CAF (43 males, 69 ± 9 years), or NSR without any history of AF (40 males, 64 ± 11 years) for a total of 186 study patients. In CT, the absolute LA wall thickness (LAT) and LA volumes were calculated. RESULTS In CT, patients with PAF had significantly thicker LAT than those with either CAF or NSR (2.4 ± 0.2mm in PAF >2.1 ± 0.2mm in CAF or 1.9 ± 0.2mm in NSR, p<0.01). Patients with CAF had significantly larger LA volume than those with either PAF or NSR (p<0.01). Subsequently, 9 of the 62 patients with PAF developed CAF over a mean follow-up period of 19 ± 22 months. The mean LAT was significantly thinner in patients who had transitioned from PAF to CAF than in those who had not (2.2 ± 0.2mm and 2.4 ± 0.2mm, respectively) (p<0.01). Receiver operating characteristic analysis demonstrated that the area under the curve for LAT was greater than that for LA volume in CT and LAD in transthoracic echocardiogram. In the Kaplan-Meier analysis, the transition from PAF to CAF was observed more frequently in patients with LAT<2.4mm than LAT ≥ 2.4mm (p=0.018). CONCLUSIONS Alteration of the LA wall may suggest a part of structural remodeling in AF before the occurrence of LA dilatation. LAT in CT seems to be a useful predictor of the transition from PAF to CAF in patients with PAF.

Impairment factors for evaluating the patency of drug-eluting stents and bare metal stents in coronary arteries by 64-slice computed tomography versus conventional coronary angiography

PURPOSE To identify, using logistic regression models, factors impairing evaluation of patency of drug-eluting stents (DES) and bare metal stents (BMS) in coronary arteries by 64-slice MSCT versus conventional coronary angiography (CAG). MATERIALS AND METHODS We evaluated 75 stents (16 DES and 59 BMS; 57 in males) implanted in 49 consecutive subjects (35 males; aged 68+/-10 years) by enhanced ECG-gated MSCT (Light Speed VCT, General Electrics) and CAG. Stents were classified by implantation site: (1) right coronary artery, (2) left anterior descending branch (LAD), and (3) left circumflex branch. Logistic regression models were used to predict agreement of findings between CT and CAG and impossibility of evaluating stent patency by CT, using age, sex, body mass index (BMI), heart rate, stent type, stent size, diabetes mellitus, and hypertension. RESULTS By CAG, patency was confirmed in 15 DES (94%) and 54 BMS (91%); significant in-stent restenosis of >/=50% was observed in 1 DES (6%) and 4 BMS (7%), and total occlusion in 1 BMS (2%). By CT, patency was confirmed in 69% DES and 78% BMS; 5 BMS (8%) revealed a low CT area inside the stent with significant in-stent restenosis, and 2 BMS (3%) revealed total occlusion. Patency of 31% DES and 22% BMS was unconfirmed by CT. Agreement of findings between CT and CAG was observed in 69% DES and 80% BMS. Significant negative predictors of agreement of findings between CT and CAG were, by category: (1) BMI (relative risks, 0.77; 95% confidence intervals [95% CI], 0.62-0.97); (2) site of implantation in LAD only (positive predictor) and BMI (relative risks, 4.59 and 0.77; 95% CI, 1.02-20.6 and 0.61-0.97, respectively); (3) BMI (relative risks, 0.77; 95% CI, 0.62-0.97). Significant predictors of impossibility of evaluating stent patency by CT were, by category: (1) BMI (relative risks, 1.54; 95% CI, 1.01-2.36); (2) none; (3) BMI (relative risk, 1.65; 95% CI, 1.03-2.63). Stent type and size were not significant predictors in any category. The percentage agreement of findings between CT and CAG was significantly higher in subjects with BMI<22 kg/m(2) than in those with 22 kg/m(2)</=BMI<25 kg/m(2) (p=0.035) and 30 kg/m(2)</=BMI (p<0.01). Analysis of evaluable stents by CT only revealed no significant negative predictor of agreement of findings between CT and CAG. CONCLUSION 64-slice MSCT is a non-invasive diagnostic modality with potential for evaluating patency of DES with a low incidence of restenosis. When BMI is high, however, it remains difficult to accurately evaluate stent patency irrespective of stent type and size.

Distinguishing focal fibrotic lesions and non-fibrotic lesions in hypertrophic cardiomyopathy by assessment of regional myocardial strain using two-dimensional speckle tracking echocardiography: Comparison with multislice CT

PURPOSE To distinguish focal fibrotic and non-fibrotic lesions in left-ventricular myocardium (LVM) in hypertrophic-cardiomyopathy (HCM)-subjects, we compared myocardial regional peak-strain values using two-dimensional speckle-tracking transthoracic-echocardiography (TTE) in multislice computed-tomography (CT)-detected fibrotic, non-fibrotic and normal control lesions. METHODS Twenty subjects (10 consecutive HCM-subjects (8-males, mean 63.4-years), 10 healthy controls (5-males, mean 51.5-years)) underwent speckle-tracking TTE (iE-33), and analysis of regional peak-longitudinal (LS) and radial-strain (RS), and corresponding strain rates in each of 17 LVM segments (American-Heart-Association classification). In HCM-subjects, fibrotic lesions were identified by early-phase defective enhancement and late-phase abnormal enhancement by CT (Light-Speed-Ultra-16). Regional peak LS and RS at basal, mid and apical levels were measured in MSCT-detected fibrotic and non-fibrotic LVM lesions. RESULTS In 10 HCM subjects, 143 lesions (84.1%) yielded good tracking on TTE. Twenty lesions showed fibrotic changes in 5 subjects by CT. Regional peak-LS and RS absolute values were significantly lower in both fibrotic and non-fibrotic lesions in HCM subjects than in controls at basal, mid, apical levels (all P<0.05). While peak-LS (%) absolute values were significantly lower in fibrotic than non-fibrotic lesions at basal, mid and apical levels (all P<0.05), regional peak-RS absolute values were significantly lower only at mid levels. LS was a more sensitive indicator than the corresponding rate, with better reproducibility. CONCLUSIONS In HCM, regional peak-LS was significantly lower in fibrotic than non-fibrotic lesions in LVM by CT. Regional peak-LS by speckle-tracking provides useful information noninvasively to distinguish fibrotic from non-fibrotic lesions in LVM in HCM and normal LVM in healthy controls.

Quantitative evaluation of left atrial volumes and ejection fraction by 320-slice computed-tomography in comparison with three- and two-dimensional echocardiography: A single-center retrospective-study in 22 subjects

PURPOSE To evaluate efficacy and reproducibility of 320-slice computed tomography (CT) for measuring left atrial (LA) maximum (LAVmax) and minimum volume (LAVmin) during the cardiac cycle, we compared CT with three- and two-dimensional (3D and 2D) transthoracic echocardiogram (TTE). MATERIALS AND METHODS LAVmax and LAVmin (ml), and LA ejection fraction (LAEF) (%) were assessed in 22 consecutive subjects (15 males, 59.5 ± 15.1 years) using retrospective electrocardiogram gated 320-slice CT (Aquilion One, Toshiba Medical) and 3D-TTE (IE-33, Phillips). LAVmax and LAVmin were selected from the time volume curve. LAEF was calculated as (LAVmax-LAVmin)/LAVmax×100(%). RESULTS Mean ± standard deviation (SD) of LAVmax and LAV min were significantly larger by CT than 3D-TTE or 2D-TTE (both P<0.01). LAEF was 25.3 ± 13.1% by CT, 30.2 ± 6.8% by 3D-TTE (P=NS) and 33.9 ± 8.9% by 2D-TTE (P<0.05). The correlation coefficients (CCs) between CT and 3D-TTE in LAVmax, LAmin, and LAEF were 0.64, 0.68 and 0.57, respectively. Mean difference ± 1.96SD of LAVmax, LAVmin and LAEF by Bland and Altman analysis calculated from CT minus 3D-TTE were 48.8 ± 59.1 ml, 41.1 ± 63.2 ml, and -4.9 ± 21.1%, respectively. The CCs and mean difference ± 1.96SD between CT and 2D-TTE had similar tendencies. The CCs of interobserver variation were (for CT, 3D-TTE, 2D-TTE, respectively): 0.90, 0.95 and 0.94 (LAVmax), 0.97 and 0.97 and 0.93 (LAVmin), and 0.64, 0.77 and 0.34 (LAEF). CONCLUSIONS 320-slice CT enables direct LAV measurements and has high reproducibility and positive correlation with 3D and 2D TTE. Absolute value of LAV by CT was larger than that by 3D and 2D TTE.

Delayed enhancement cardiovascular magnetic resonance as a novel technique to predict cardiac events in dilated cardiomyopathy patients

PURPOSE Delayed enhancement cardiovascular magnetic resonance (DE-CMR) can detect cardiac scarring and has the potential to visualize the progression of myocardial remodeling. We determined whether DE-CMR can predict cardiac events in dilated cardiomyopathy patients. MATERIALS AND METHODS Transthoracic echocardiography, coronary arteriography, and DE-CMR studies were performed in 60 consecutive dilated cardiomyopathy (DCM) patients. Percent delayed enhancement (%DE) was determined as the ratio of the area showing delayed enhancement to the total myocardial area in three short-axis views. Patients were classified as advanced group (Group A) when %DE was 10% or higher, and as non-advanced group (Group NA) when %DE was less than 10%. The incidence of cardiac events and the clinical history were compared between Group A and Group NA. RESULTS There were 11 patients in Group A and 49 patients in Group NA. The incidence of cardiac events was significantly higher in Group A (36%; 4/11 patients) than in Group NA (2.0%; 1/49 patients) (log rank, p=0.0001). CONCLUSION DE-CMR is a useful tool to predict cardiac events in DCM patients.

Characteristic myocardial strain identified in hypertrophic cardiomyopathy subjects with preserved left ventricular ejection fraction using a novel multi-layer transthoracic echocardiography technique

PURPOSE In order to evaluate compensatory mechanisms in hypertrophic-cardiomyopathy (HCM) subjects with preserved left-ventricular (LV) ejection-fraction (EF), we measured myocardial percentage endocardial strain dependency, as represented by 2D LV global longitudinal (GLS) and circumferential-strain (GCS), using a novel, multi-layer, speckle-tracking transthoracic-echocardiography (TTE) technique. METHODS A total of 60 subjects (40 HCM with preserved LV EF (30 male; 62 ± 15 years, all LV EF>50%)) and 20 controls (10 male; 59 ± 10 years) underwent TTE (Vivid-E9). Quantitative strain-measurements of: endocardial, all and epicardial layers were performed at each-site. We defined percentage endocardial strain dependency as the ratio of endocardial strain to epicardial strain. RESULTS Absolute GLS values at all views in all, endocardial and epicardial myocardial layers were significantly smaller in HCM subjects than in controls (all P<0.001). There were no significant differences between both-groups in absolute GCS values in the endocardial layers, at the mitral valve and papillary muscle levels. Percentage endocardial GCS dependency at all levels were greater in HCM subjects than in controls (all P<0.01). In HCM subjects, percentage endocardial GCS dependency at the mitral valve and papillary muscle levels revealed significant, moderate, negative correlations with LV end-diastolic and systolic dimensions (correlation coefficients -0.505, -0.451 (mitral valve level) and -0.533, -0.591 (papillary muscle level), respectively). CONCLUSIONS In HCM subjects with preserved LV EF, 2D LV GLS was lower than in controls, but endocardial GCS was maintained in compensation for reduction in endocardial GLS; thus percentage endocardial GCS dependency may increase, and the larger the LV size, the smaller this compensatory effect.

Increased subcutaneous fat accumulation has a protective role against subclinical atherosclerosis in asymptomatic subjects undergoing general health screening

PURPOSE To evaluate the clinical role of subcutaneous fat accumulation in subclinical arteriosclerosis, using computed tomography (CT), we measured the subcutaneous fat area (SFA), the visceral fat area (VFA) and the VFA/SFA ratio and compared these with the calcium score of the whole aorta (CSWA) in asymptomatic subjects who were undergoing general health screening. METHODS 122 consecutive asymptomatic subjects (40 female, mean age 56.2+/-8.4 years) were analyzed. Whole-body low-dose CT scan (mAs=50, slice thickness=5 mm) was performed. The SFA and VFA were measured at the umbilical level. Calcification of whole aorta was defined as an area with >90 HU and 1 mm(2), and CSWA was calculated using the modified Agatston method. RESULTS Mean+/-SD of SFA, VFA and log CSWA were 158+/-67.1 cm(2), 94.0+/-44.8 cm(2), and 7.93+/-1.08, respectively. SFA was significantly and inversely correlated with log CSWA (r=-0.219, P=0.015) but VFA was not (r=0.105, P=0.250) and as a result, the VFA/SFA ratio was significantly and positively correlated with log CSWA (r=0.221, P=0.015). Subsequently, all predictor variables were used in a stepwise multiple regression model with log CSWA as dependent variable, and age, SFA and fasting plasma glucose significantly influenced log CSWA (P<0.001) by the multiple regression formula Y=0.046X1***-0.005X2**+0.015X3*+4.426, (***P<0.001, **P<0.01, and *P<0.05) where Y=log CSWA, X1=age, X2=SFA, and X3=fasting plasma glucose). CONCLUSIONS SFA was significantly and inversely associated with log CSWA, in an independent fashion. These results suggest that subcutaneous fat accumulation might have a protective role against atherosclerosis in asymptomatic subjects.

Quantitative evaluation of right atrial volume and right atrial emptying fraction by 320-slice computed tomography compared with three-dimensional echocardiography

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