Hong Seok Lim

Invasive Evaluation of Patients With Angina in the Absence of Obstructive Coronary Artery Disease

Background— More than 20% of patients presenting to the cardiac catheterization laboratory with angina have no angiographic evidence of coronary artery disease. Despite a “normal” angiogram, these patients often have persistent symptoms, recurrent hospitalizations, a poor functional status, and adverse cardiovascular outcomes, without a clear diagnosis. Methods and Results— In 139 patients with angina in the absence of obstructive coronary artery disease (no diameter stenosis >50%), endothelial function was assessed; the index of microcirculatory resistance, coronary flow reserve, and fractional flow reserve were measured; and intravascular ultrasound was performed. There were no complications. The average age was 54.0±11.4 years, and 107 (77%) were women. All patients had at least some evidence of atherosclerosis based on an intravascular ultrasound examination of the left anterior descending artery. Endothelial dysfunction (a decrease in luminal diameter of >20% after intracoronary acetylcholine) was present in 61 patients (44%). Microvascular impairment (an index of microcirculatory resistance ≥25) was present in 29 patients (21%). Seven patients (5%) had a fractional flow reserve ⩽0.80. A myocardial bridge was present in 70 patients (58%). Overall, only 32 patients (23%) had no coronary explanation for their angina, with normal endothelial function, normal coronary physiological assessment, and no myocardial bridging. Conclusions— The majority of patients with angina in the absence of obstructive coronary artery disease have occult coronary abnormalities. A comprehensive invasive assessment of these patients at the time of coronary angiography can be performed safely and provides important diagnostic information that may affect treatment and outcomes.

Usefulness of Combined Assessment With Computed Tomographic Signs of Right Ventricular Dysfunction and Cardiac Troponin T for Risk Stratification of Acute Pulmonary Embolism

The aim of this study was to evaluate the incremental value of combined assessment with computed tomographic (CT) signs of right ventricular (RV) dysfunction and cardiac troponin T level for predicting early death or adverse outcomes due to acute pulmonary embolism (PE). One hundred seventy-three non-high-risk patients with acute PE, confirmed by CT pulmonary angiography, were retrospectively evaluated. The area under the curve and hazard ratio of CT signs and troponin T levels were compared for predicting early death or adverse outcomes. Patients were classified into intermediate- and low-risk groups on the basis of CT signs and troponin T levels, and mortality was compared. Seventeen patients (9.8%) died within 3 months. Early mortality of intermediate-risk patients (14% to 19%) was higher than that of low-risk patents (2% to 6%). A ratio of RV volume to left ventricular volume > 1.5 had the highest area under the curve (0.709) and hazard ratio (5.402) for predicting early death. The combination of CT signs and elevated troponin T level had an increased area under the curve and hazard ratio for predicting early death and adverse outcomes compared to those of CT signs or elevated troponin T level alone. In conclusion, the combined assessment of the ratio of RV volume to left ventricular volume and an elevated troponin T level provided incrementally more prognostic information in non-high-risk patients with acute PE compared to the single predictor of CT signs or troponin T level.

The impact of age on fractional flow reserve-guided percutaneous coronary intervention: A FAME (Fractional Flow Reserve versus Angiography for Multivessel Evaluation) trial substudy

BACKGROUND Fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) improved outcomes compared with an angiography-guided strategy in patients with multivessel coronary artery disease (CAD). However, the effect of age on FFR has not been well-studied. We aimed to evaluate the impact of age on the favorable results of routine FFR-guided PCI for multivessel CAD. METHODS We compared 1 year outcomes between FFR-guided PCI and angiography-guided PCI in the 512 patients enrolled in the FAME study <65 years old compared to the 493 patients ≥ 65 years old. We also evaluated the effect of age on the FFR result of varying degrees of visually estimated coronary stenosis. RESULTS The 1-year rate of death, myocardial infarction or repeat revascularization in the angiography-guided group tended to be higher than in the FFR-guided group for both those patients <65 (17.2% vs. 12.0%, P = 0.098) and those ≥ 65 years old (19.7% vs. 14.3%, P = 0.111) with no significant interaction based on age (P = 0.920). Older patients had higher FFR in vessels with 50% to 70% stenosis (0.83 ± 0.11 vs. 0.80 ± 0.13, P = 0.028) and in vessels with 71% to 90% stenosis (0.69 ± 0.15 vs. 0.65 ± 0.16, P = 0.002). The proportion of functionally significant lesions (FFR ≤ 0.80) in vessels with 71% to 90% stenosis was significantly lower in elderly compared to younger patients (75.3% vs. 84.1%, P = 0.013). CONCLUSIONS FFR-guided PCI is beneficial regardless of age, however, older patients have fewer functionally significant lesions, despite a similar angiographic appearance.

Impact of Female Gender on Bleeding Complications After Transradial Coronary Intervention (from the Korean Transradial Coronary Intervention Registry)

Besides poor clinical outcomes, female gender has been known as a high-risk factor for bleeding complications. This study aimed to investigate the impact of gender on clinical outcomes and bleeding complications after transradial coronary intervention (TRI). The Korean TRI registry is a retrospective multicenter registry with 4,890 patients who underwent percutaneous coronary intervention in 2009 at 12 centers. To compare clinical outcomes and bleeding complications between the male and female groups, we performed a propensity score matching in patients who received TRI. A total of 1,194 patients (597 in each group) were studied. The primary outcome was 1-year major adverse cardiac events, including all-cause mortality, myocardial infarction, target vessel revascularization, and stroke. The secondary outcome was major bleeding (composite of bleeding requiring transfusion of ≥2 units of packed cells or bleeding that was fatal). The proportion of major adverse cardiac events was similar between the 2 groups (6.2% vs 4.7%, p = 0.308). The female group had a greater incidence of major bleeding (0.3% vs 3.2%, p <0.001). On multivariate analysis, female gender (odds ratio [OR] 7.748, 95% confidence interval [CI] 1.767 to 13.399), age ≥75 years (OR 5.824, 95% CI 2.085 to 16.274), and chronic kidney disease (OR 7.264, 95% CI 2.369 to 12.276) were independent predictors of major bleeding. In conclusion, the female gender had a tendency for more bleeding complications than male gender after TRI without difference in the clinical outcome.

Validation of three-dimensional echocardiography for quantification of aortic root geometry: comparison with multi-detector computed tomography.

Background Three-dimensional (3D) echocardiography has been reported to be valuable for evaluating the geometry of cardiac chambers. We validated the accuracy of 3D transthoracic echocardiography for quantifying aortic root geometry in comparison with cardiac multi-detector computed tomography (MDCT). Methods Twenty-three patients who underwent cardiac MDCT and showed normal left ventricular ejection fraction (> 55%), as assessed by 2-dimensional transthoracic echocardiography, were enrolled (12 male, mean 53 ± 9 years). We defined the aortic root volume as the volume from the aortic annulus to the sinotubular junction. The aortic root volume at end-diastole measured by both cardiac MDCT and 3D echocardiography was assessed. Results The cross-sectional area of the aortic root was asymmetric. At the annulus level, the cross-sectional area showed asymmetric triangle. From the aortic annulus to the most dilated point of the sinus of Valsalva, the asymmetric triangular shape was maintained. From the most dilated point of the sinus of Valsalva to the sinotubular junction, the cross-sectional shape of the aortic root changed to oval. The average aortic root volumes measured by 3D echocardiography (ARV-3DE) were 13.6 ± 4.8 mL at end-diastole and 14.1 ± 5.3 mL at end-systole, respectively. The average aortic root volume measured by MDCT at end-diastole (ARV-CT) was 14.1 ± 5.7 mL. At end-diastole, the ARV-3DE correlated well with the ARV-CT (R2 = 0.926, difference = 0.5 ± 1.7 mL), and the two methods were in excellent agreement (the percent difference was 0%). Conclusion Our results demonstrate both the feasibility and accuracy of 3D echocardiography for the clinical assessment of the geometry of the aortic root.

CT comparison of visual and computerised quantification of coronary stenosis according to plaque composition.

ObjectiveTo compare the diagnostic performance of computerised quantification with visual assessment for the detection of significant coronary stenosis using MDCT, and to determine the impact of plaque composition on diagnostic procedure.MethodsWe retrospectively evaluated 1564 coronary segments of 127 patients who underwent 64-slice MDCT and quantitative coronary angiography (QCA). The lesions were analysed with both methods of visual assessment and computerised quantification using an automatic vessel contour detection tool, and the results were compared with the QCA results. Plaques detected with MDCT were classified as calcified, mixed, and non-calcified according to plaque composition.ResultsThe sensitivity and PPV of visual assessment (computerised quantification) were 95% (86%) and 76% (81%), respectively. Bland-Altman analysis demonstrated a mean difference of −5.2 ± 21.6% for all lesions, 2.2 ± 23.7 for calcified plaques, and −12.0 ± 17.2% for non-calcified plaques. The correlation coefficients and limits of agreement between CTA and QCA were 0.48 and ±46.5% (0.74 and ±33.7%) in the lesions with calcified plaques (non-calcified plaques).ConclusionsThe computerised quantification decreases the sensitivity due to underestimation of non-calcified plaques compared with visual assessment, and had a poorer correlation and a larger limit of agreement in the lesions with calcified plaque compared with non-calcified plaques.

Exact analytical expressions for the dispersion relation of one-dimensional chiral photonic crystals

We consider one-dimensional photonic crystals made of alternating layers of two kinds of isotropic chiral media. The two layers are characterized by the dielectric permittivities ε1 and ε2, the magnetic permeabilities μ1 and μ2, the chirality parameters γ1 and γ2 and the thicknesses d 1 and d 2. By diagonalizing an 8 × 8 matrix derived from the two coupled wave equations satisfied by our system, we obtain exact analytical expressions for the dispersion relation for plane electromagnetic waves propagating at an arbitrary angle with respect to the layers. We present a detailed analysis of our dispersion relation and explore the evolution of the photonic band structure as the frequency, the chirality parameter and the incident angle vary, with a special emphasis on the generation of the cross- and co-polarization bandgaps.

The impact of left ventricular ejection fraction on fractional flow reserve: Insights from the FAME (Fractional flow reserve versus Angiography for Multivessel Evaluation) trial

BACKGROUND Fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) significantly improves outcomes compared with angio-guided PCI in patients with multivessel coronary artery disease. However, there is a theoretical concern that in patients with reduced left ventricular ejection fraction (EF) FFR may be less accurate and FFR-guided PCI less beneficial. METHODS From the FAME (Fractional flow reserve versus Angiography for Multivessel Evaluation) trial database, we compared FFR values between patients with reduced EF (both ≤ 40%, n = 90 and ≤ 50%, n = 252) and preserved EF (> 40%, n = 825 and > 50%, n = 663) according to the angiographic stenosis severity. We also compared differences in 1 year outcomes between FFR- vs. angio-guided PCI in patients with reduced and preserved EF. RESULTS Both groups had similar FFR values in lesions with 50-70% stenosis (p = 0.49) and with 71-90% stenosis (p = 0.89). The reduced EF group had a higher mean FFR compared to the preserved EF group across lesions with 91-99% stenosis (0.55 vs. 0.50, p = 0.02), although the vast majority of FFR values remained ≤ 0.80. There was a similar reduction in the composite end point of death, nonfatal myocardial infarction, and repeat revascularization with FFR-guided compared to angio-guided PCI for both the reduced (14.5% vs. 19.0%, relative risk = 0.76, p = 0.34) and the preserved EF group (13.8 vs. 17.0%, relative risk = 0.81, p = 0.25). The results were similar with an EF cutoff of 40%. CONCLUSION Reduced EF has no influence on the FFR value unless the stenosis is very tight, in which case a theoretically explainable, but clinically irrelevant overestimation might occur. As a result, FFR-guided PCI remains beneficial regardless of EF.

Impact of age on the functional significance of intermediate Epicardial artery disease

BACKGROUND The functional significance of an intermediate coronary lesion is crucial for determining the treatment strategy, but age-related changes in cardiovascular function could affect the functional significance of an epicardial stenosis. The aim of this study was therefore to investigate the impact of age on fractional flow reserve (FFR) measurements in patients with intermediate coronary artery disease (CAD). METHODSANDRESULTS Intracoronary pressure measurements and intravascular ultrasound (IVUS) were performed in 178 left anterior descending coronary arteries with intermediate stenosis. The morphological characteristics and FFR of 91 lesions in patients <65 years old were compared with those of 87 patients ≥65 years old. There was no difference in lesion location, diameter stenosis, minimum lumen area, plaque burden, or lesion length between the 2 age groups. Elderly patients had higher FFR (0.81±0.06 vs. 0.79±0.06, P=0.004) and lower ∆FFR, defined as the difference between resting Pd/Pa and FFR (0.13±0.05 vs. 0.15±0.05, P=0.014). Age, along with the location and degree of stenosis, was independently associated with FFR and ∆FFR (β=0.162, P=0.008; β=-0.131, P=0.043, respectively). CONCLUSIONS Elderly patients with intermediate CAD are more likely to have higher FFR and lower ∆FFR, despite a similar degree of epicardial stenosis, compared with younger patients. (Circ J 2016; 80: 1583-1589).

Propagation of p-polarized electromagnetic waves obliquely incident on stratified random media : Random phase approximation

We consider the propagation of p-polarized electromagnetic waves obliquely incident on stratified random dielectric media. Using the invariant imbedding method generalized to random media and applying the random phase approximation, we derive a simple analytical expression of the localization length and calculate the disorder-averaged reflectance and transmittance and the fluctuations of the localization length and the reflectance as functions of the incident angle. We also calculate the disorder-averaged intensity profile of the magnetic field inside the random medium. We find that within the random phase approximation, the p wave can be delocalized and transmitted completely at a certain critical incident angle, which is bigger than the Brewster angle in the uniform case.