Byoung-Joo Choi

Relationship of Epicardial Adipose Tissue by Echocardiography to Coronary Artery Disease

Objective: To study the relationship of echocardiographic epicardial adipose tissue (EAT) with coronary artery disease (CAD) risk factors and the extent of coronary atherosclerosis. Methods: EAT thickness was measured in 527 patients undergoing their first coronary angiography. EAT was defined as an echo-lucent area on the free wall of the right ventricle on the still image of the two-dimensional echocardiogram at end diastole in the parasternal long-axis and parasternal short-axis views. A CT scan at the umbilicus was acquired to measure abdominal visceral adipose tissue (VAT) from a random sample of 30 patients. The extent of coronary atherosclerosis was assessed using a coronary atherosclerosis score based on the quantitative coronary angiography results. Results: EAT thickness was correlated with abdominal VAT (rs = 0.626, p<0.001), age (rs = 0.480, p<0.001), waist circumference (rs = 0.309, p<0.001), body mass index (rs = 0.233, p<0.001), C reactive protein (rs = 0.224, p<0.001), and the homoeostasis model assessment score (rs = 0.249, p<0.001). EAT was thicker in subjects with CAD than in those without CAD (4.0 vs 1.5 mm, p<0.001). Patients with unstable angina had thicker EAT than those with stable angina or atypical chest pain (4.0, 3.0, and 1.5 mm, respectively, p<0.001). EAT (⩾3.0 mm) was an independent factor of CAD on multiple logistic analysis (odds ratio  =  3.357; 95% CI 2.177 to 5.175, p<0.001). Conclusions: These results suggest that EAT may reflect the amount of visceral fat, which is associated with insulin resistance and inflammation. The echocardiographic measurement of EAT may provide additional information for assessing CAD risk and predicting the extent and activity of CAD.

Longitudinal Strain and Torsion Assessed by Two-Dimensional Speckle Tracking Correlate with the Serum Level of Tissue Inhibitor of Matrix Metalloproteinase-1, a Marker of Myocardial Fibrosis, in Patients with Hypertension

BACKGROUND We hypothesized that the alterations of myocardial collagen turnover in patients with hypertension may be involved in the early changes of regional contractile function assessed by a new speckle tracking method. METHODS In 56 patients with untreated hypertension (48 +/- 11 years, ejection fraction > 55%) and 20 age-matched control subjects, the serum levels of aminoterminal propeptide of procollagen I/III and tissue inhibitor of matrix metalloproteinase (TIMP)-1 were measured by radioimmunoassay and enzyme immunoassay. To assess the regional contractile function, the average of negative longitudinal strain of 6 segments at apical 4-chamber view (longitudinal epsilon), the average of radial strain (radial epsilon) and the average of circumferential strain (circumferential epsilon) of 6 mid-left ventricular (LV) segments, and basal-to-apical torsion were obtained by 2-dimensional speckle tracking imaging. RESULTS Compared with control group, longitudinal epsilon was significantly decreased (-20.4 +/- 3.0% vs -22.1 +/- 2.2%, P = .030) and basal-to-apical torsion was increased (20.5 +/- 5.7 degrees vs 17.4 +/- 3.7 degrees, P = .013) in patient group. The serum level of log TIMP-1 was higher in the patients (3.6 +/- 0.6 vs 3.0 +/- 0.5, P < .001). The serum log TIMP-1 significantly correlated with longitudinal epsilon (r = 0.405, P = .015), basal-to-apical torsion (r = 0.331, P = .017), and the LV mass (r = 0.266, P = .047). In multivariate analysis, longitudinal epsilon (beta = 0.326, P = .015) and basal-to-apical torsion (beta = 0.402, P = .003) independently correlated with the serum TIMP-1 level. CONCLUSION In patients who are hypertensive with normal ejection fraction, impaired longitudinal epsilon and increased LV torsion correlated with serum TIMP-1, which suggests that the change in collagen turnover and the myocardial fibrotic process may affect the early contractile dysfunction of LV.

Usefulness of the index of microcirculatory resistance for invasively assessing myocardial viability immediately after primary angioplasty for anterior myocardial infarction.

AIMS The aim of this study is to evaluate the usefulness of the index of microcirculatory resistance (IMR) for predicting myocardial viability and left ventricular (LV) function recovery in acute myocardial infarction (AMI). METHODS AND RESULTS After successful primary percutaneous coronary intervention in 40 patients with anterior AMI, IMR was measured using a pressure-temperature sensor-tipped coronary guidewire. Myocardial viability was quantified by 18F-fluorodeoxyglucose (FDG) positron emission tomography in 38 patients. Echocardiographic regional wall motion was analysed to calculate the anterior wall motion score (A-WMS) and percent change in A-WMS after revascularization and at 6-month follow-up. IMR correlated significantly with regional myocardial FDG uptake (r = -0.738, P < 0.001) and it demonstrated significant correlation with percent change in A-WMS (r = -0.464, P = 0.003). The area under the receiver operating curve of IMR for predicting LV function recovery was 0.89 [95% CI 0.888-0.894]. CONCLUSION Index of microcirculatory resistance, a new index representing microvascular integrity, is a reliable early on-site determinant of myocardial viability and LV recovery after primary stenting for AMI.

Comparison of 64-Slice Multidetector Computed Tomography With Spectral Analysis of Intravascular Ultrasound Backscatter Signals for Characterizations of Noncalcified Coronary Arterial Plaques

In vivo identification of plaque composition may allow the detection of vulnerable plaques before rupture. However, the clinical relevance of multidetector computed tomography (MDCT) in characterizing coronary plaques is currently a subject of debate. We compared 64-slice MDCT with virtual histology to investigate the potential role of 64-slice MDCT in the differentiation of composition of noncalcified coronary plaques. Fifty-nine consecutive patients (stable/unstable angina 34/21) were enrolled. Mean computed tomographic (CT) density (Hounsfield units) of noncalcified coronary plaques (n = 80) was compared with a relative volume of each plaque component (fibrous, fibrofatty, calcium, and necrotic core) analyzed by virtual histology. Mean heart rate during MDCT was 58 +/- 9 beats/min. There was a negative correlation between mean CT density and the necrotic core (r = -0.539, p <0.001) and a positive correlation between mean CT density and the fibrotic tissue component (r = 0.571, p <0.001). Mean CT density of the plaques with a <10% necrotic core was significantly higher than that of a >or=10% necrotic core (93.1 +/- 37.5 vs 41.3 +/- 26.4 HU, p <0.001). However, overlapping of mean CT densities between plaques with a <10% necrotic core and those with a >or=10% necrotic core was found. In conclusion, mean CT density of noncalcified coronary plaques measured by 64-slice MDCT may depend on the relative volumes of the necrotic core and fibrotic component. Sixty-four-slice MDCT may have the potential for determining composition of noncalcified coronary plaques, which needs further studies for clinical application.

Impact of Body Mass Index on the relationship of epicardial adipose tissue to metabolic syndrome and coronary artery disease in an Asian population

BackgroundIn a previous study, we demonstrated that the thickness of epicardial adipose tissue (EAT), measured by echocardiography, was increased in patients with metabolic syndrome (MS) and coronary artery disease (CAD). Several studies on obese patients, however, failed to demonstrate any relationship between EAT and CAD. We hypothesized that body mass index (BMI) affected the link between EAT and MS and CAD.MethodsWe consecutively enrolled 643 patients (302 males, 341 females; 59 ± 11 years), who underwent echocardiography and coronary angiography. The EAT thickness was measured on the free wall of the right ventricle at the end of diastole. All patients were divided into two groups: high BMI group, ≥27 kg/m2 (n = 165), and non-high BMI group, < 27 kg/m2 (n = 478).ResultsThe median and mean EAT thickness of 643 patients were 3.0 mm and 3.1 ± 2.4 mm, respectively. In the non-high BMI group, the median EAT thickness was significantly increased in patients with MS compared to those without MS (3.5 vs. 1.9 mm, p < 0.001). In the high BMI group, however, there was no significant difference in the median EAT thickness between patients with and without MS (3.0 vs. 2.5 mm, p = 0.813). A receiver operating characteristic (ROC) curve analysis predicting MS revealed that the area under the curve (AUC) of the non-high BMI group was significantly larger than that of the high BMI group (0.659 vs. 0.506, p = 0.007). When compared to patients without CAD, patients with CAD in both the non-high and high BMI groups had a significantly higher median EAT thickness (3.5 vs. 1.5 mm, p < 0.001 and 4.0 vs. 2.5 mm, p = 0.001, respectively). However, an ROC curve analysis predicting CAD revealed that the AUC of the non-high BMI group tended to be larger than that of the high BMI group (0.735 vs. 0.657, p = 0.055).ConclusionsWhile EAT thickness was significantly increased in patients with MS and CAD, the power of EAT thickness to predict MS and CAD was stronger in patients with BMI < 27 kg/m2. These findings showed that the measurement of EAT thickness by echocardiography might be especially useful in an Asian population with a non-high BMI, less than 27 kg/m2.

Comparison of the intracoronary continuous infusion method using a microcatheter and the intravenous continuous adenosine infusion method for inducing maximal hyperemia for fractional flow reserve measurement

BACKGROUND Inducing stable maximal coronary hyperemia is essential for measurement of fractional flow reserve (FFR). We evaluated the efficacy of the intracoronary (IC) continuous adenosine infusion method via a microcatheter for inducing maximal coronary hyperemia. METHODS In 43 patients with 44 intermediate coronary lesions, FFR was measured consecutively by IC bolus adenosine injection (48-80 microg in left coronary artery, 36-60 microg in the right coronary artery) and a standard intravenous (IV) adenosine infusion (140 microg x min(-1) x kg(-1)). After completion of the IV infusion method, the tip of an IC microcatheter (Progreat Microcatheter System, Terumo, Japan) was positioned at the coronary ostium, and FFR was measured with increasing IC continuous adenosine infusion rates from 60 to 360 microg/min via the microcatheter. RESULTS Fractional flow reserve decreased with increasing IC adenosine infusion rates, and no further decrease was observed after 300 microg/min. All patients were well tolerated during the procedures. Fractional flow reserves measured by IC adenosine infusion with 180, 240, 300, and 360 microg/min were significantly lower than those by IV infusion (P < .05). Intracoronary infusion at 180, 240, 300, and 360 microg/min was able to shorten the times to induction of optimal and steady-stable hyperemia compared to IV infusion (P < .05). Functional significances were changed in 5 lesions by IC infusion at 240 to 360 microg/min but not by IV infusion. CONCLUSIONS The results of this study suggest that an IC adenosine continuous infusion method via a microcatheter is safe and effective in inducing steady-state hyperemia and more potent and quicker in inducing optimal hyperemia than the standard IV infusion method.

Relationship between intravascular ultrasound parameters and fractional flow reserve in intermediate coronary artery stenosis of left anterior descending artery: Intravascular ultrasound volumetric analysis

The objective of this study was to assess the relationship between intravascular ultrasound (IVUS) parameters, including volumetric analysis, and fractional flow reserve (FFR).

The Impact of Exercise-Induced Changes in Intraventricular Dyssynchrony on Functional Improvement in Patients with Nonischemic Cardiomyopathy

BACKGROUND The assessment of dynamic intraventricular dyssynchrony has been reported to be feasible in a clinical setting. However, its prognostic implication in functional improvement has not yet been investigated. METHODS Symptom-limited, supine bicycle exercise was performed on 41 patients with nonischemic cardiomyopathy (52 +/- 12 years, ejection fraction < 40%). Using Doppler tissue imaging, the average of peak systolic velocities at 6 basal segments was obtained at rest and peak exercise. Dyssynchrony index (Ts-SD12) was defined as the SD of the time to peak systolic velocities at 12 left ventricular segments. The percent change of end-systolic volume (%Delta ESV) was calculated at follow-up. A 15% or greater reduction in end-systolic volume (%Delta ESV < -15%) was considered as functional improvement. RESULTS During exercise, changes in dyssynchrony (Delta Ts-SD12) were individually variable. Average of peak systolic velocities (V) at 6 basal segments at peak exercise independently correlated with Ts-SD12 at peak exercise (beta = -0.541, P < .001). Follow-up echocardiography was performed on 35 patients after medical treatment for 13.0 +/- 4.9 months. There was significant association of %Delta ESV with the change in mitral regurgitation (r = 0.434, P = .009), disease duration (r = 0.343, P = .045), QRS interval (r = 0.347, P = .041), and Delta Ts-SD12 (r = 0.511, P = .002). Multivariate analysis identified Ts-SD12 measured at peak exercise as the strongest predictor for functional improvement (%Delta ESV: beta = 0.577, P < .001; and Delta ejection fraction: beta = -0.563, P < .001). CONCLUSION In patients with heart failure, dynamic dyssynchrony can be assessed during exercise. Ts-SD12 at peak exercise may be an independent predictor for reverse remodeling with medical treatment.

The Relationship between Coronary Artery Calcification as Assessed by Multi-Detector Computed Tomography and Arterial Stiffness

Pulse wave analysis and intima-media thickness (IMT) of carotid artery are the non-invasive indicators of subclinical atherosclerosis. Coronary artery calcification (CAC) score measured by multi-detector computed tomography (MDCT) is well known as a predictor of coronary heart disease (CHD). We investigated the association between coronary calcification assessed by MDCT and extracoronary atherosclerosis measured by pulse wave analysis and IMT of carotid artery. Arterial stiffness and carotid IMT were measured consecutively in 133 patients who underwent their first coronary MDCT angiography due to chest pain. Patients were divided into three groups according to the CAC score (group 1, score = 0, n = 62; group 2, 0 < score < 400, n = 58; group 3, score ≥ 400, n = 13). The classification of CAC score was associated with age, prevalence of hypertension and dyslipidemia, systolic blood pressure, pulse pressure, brachial-ankle pulse wave velocity, percentage of brachial mean artery pressure, upstroke time (UT), augmentation index, and carotid IMT. In a multivariate analysis, age (P = .048), hypertension (P = .007), dyslipidemia (P = .24), and mean ankle UT (P = .038) were independent variables for the classification of CAC score. The UT of pulse wave was significantly associated with the CAC score. The increased UT of pulse wave might provide incremental risk prediction in addition to that defined by conventional CHD risk assessment.

Comparison of Accuracy in the Prediction of Left Ventricular Wall Motion Changes Between Invasively Assessed Microvascular Integrity Indexes and Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography in Patients With ST-Elevation Myocardial Infarction

We compared the accuracy in predicting regional wall motion score index (RWMSI) changes between microvascular integrity indexes measured during primary percutaneous coronary intervention (PCI) and fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) in ST-elevation myocardial infarction (STEMI). Fifty patients with STEMI were enrolled. Microvascular integrity indexes were measured using an intracoronary Doppler wire and a pressure wire after primary PCI. We performed FDG-PET 7 days after PCI. RWMSI on follow-up echocardiogram (5.8 +/- 1.7 months) revealed good correlations with coronary flow reserve (r = -0.442, p = 0.002), diastolic deceleration time (r = -0.511, p <0.001), microvascular resistance index (r = 0.443, p = 0.002), coronary wedge pressure (r = 0.474, p <0.001), and FDG uptake rate (r = -0.571, p <0.001). There were no significant differences in areas under the curve for predicting RWMSI changes between microvascular integrity indexes and FDG-PET (coronary flow reserve 0.696, diastolic deceleration time 0.731, microvascular resistance index 0.748, coronary wedge pressure 0.694, Thrombolysis In Myocardial Infarction myocardial perfusion grade 0.702, and FDG-PET 0.755). In conclusion, microvascular integrity indexes assessed during primary PCI are useful and comparable to FDG-PET in predicting left ventricular functional changes in STEMI.