Hyoung-Mo Yang

Optimal Intravascular Ultrasound Criteria and Their Accuracy for Defining the Functional Significance of Intermediate Coronary Stenoses of Different Locations

OBJECTIVESnWe performed this study to determine the optimal intravascular ultrasound (IVUS) criteria and to evaluate their accuracy for defining the functional significance of intermediate coronary stenoses in different locations of the coronary tree.nnnBACKGROUNDnPresence of myocardial ischemia is the most important prognostic factor in patients with coronary artery disease and is determined by both the lesion severity and the amount of myocardium supplied.nnnMETHODSnIVUS and fractional flow reserve (FFR) measurements were performed in 267 intermediate lesions located at the proximal or mid part of major epicardial coronary arteries. Optimal IVUS criteria and their diagnostic accuracy for functionally significant stenoses (FFR <0.8) were assessed.nnnRESULTSnFFR was <0.8 in 88 lesions (33%). The determinants of FFR were minimum lumen area (MLA) and lesion location. The diagnostic accuracy of MLA was highly variable according to the location of lesions. The best cutoff value of MLA to define the functional significance was 3.0 mm(2) (area under the curve [AUC]: 0.81, 95% confidence interval [CI]: 0.68 to 0.91) for proximal left anterior descending artery (LAD) lesions and 2.75 mm(2) for mid-LAD lesions located before the second diagonal branch (AUC: 0.76, 95% CI: 0.66 to 0.84). However, the appropriate MLA to predict the functional significance of lesions could not be found in other segments.nnnCONCLUSIONSnWhen IVUS parameters are used to determine the functional significance of lesions in patients with intermediate coronary artery stenoses, different criteria should be used according to lesion location. In segments or vessels with anatomic variations, IVUS cannot be used for functional assessment of a stenosis. (Comparison of Fractional Flow Reserve and Intravascular Ultrasound; NCT01133015).

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

AIMSnThe 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).nnnMETHODS AND RESULTSnAfter 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].nnnCONCLUSIONnIndex 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.

The relationship between volumetric plaque components and classical cardiovascular risk factors and the metabolic syndrome a 3-vessel coronary artery virtual histology-intravascular ultrasound analysis.

OBJECTIVESnThe aim of this study was to analyze volumetric plaque composition of the coronary arterial tree according to the classical cardiovascular risk factors and metabolic syndrome (MS) using virtual histology-intravascular ultrasound (VH-IVUS).nnnBACKGROUNDnIt remains unclear how the cardiovascular risk factors correlate with the histological components of coronary plaques.nnnMETHODSnWhole vessel VH-IVUS analysis was performed in 189 vessels of 63 patients. The components of atherosclerotic plaques were classified as fibrous, fibrofatty, necrotic core (NC), and dense calcium. Quantitative assessment of these plaque components and the presence of VH-IVUS-derived thin-cap fibroatheroma in the coronary arterial trees were compared with cardiovascular risk factors.nnnRESULTSnThere was a significantly larger mean plaque-plus-media burden in patients with diabetes mellitus (DM) (47 ± 5% vs. 39 ± 7% in non-DM patients, p < 0.001) and MS (47 ± 4% vs. 39 ± 7% in non-MS patients, p < 0.001). DM patients had a significantly larger %NC (17.8 ± 5.6% vs. 12.5 ± 6.1%, p = 0.003) compared with non-DM patients; and MS patients had a significantly larger %NC (17.3 ± 5.8% vs. 12.8 ± 6.2%, p = 0.016) as compared to non-MS patients. Finally, VH-IVUS-derived thin-cap fibroatheromas were more frequent in DM patients (3.4 ± 2.0 vs. 2.1 ± 1.7 in non-DM patients, p = 0.016) and in MS patients (4.1 ± 2.1 vs. 1.9 ± 1.4 in non-MS patients, p = 0.001).nnnCONCLUSIONSnThree-vessel VH-IVUS analysis showed that DM and MS patients, compared to patients without DM or MS, had a larger plaque-plus-media burden, larger amount of NC, and more frequent VH-IVUS-derived thin-cap fibroatheromas in coronary arterial trees, implying greater plaque vulnerability in DM and MS patients.

Epicardial adipose tissue thickness is a predictor for plaque vulnerability in patients with significant coronary artery disease

The aim of this study is to assess the relationship of epicardial adipose tissue (EAT) and plaque vulnerability. We consecutively enrolled 82 patients with coronary artery disease (CAD). A symptom-related vessel was imaged by virtual histology intravascular ultrasound (VH-IVUS). In 60 out of 82 patients, all three vessels were studied by VH-IVUS. EAT thickness was measured by echocardiography. All patients were divided into thick (≥3.5xa0mm) and thin EAT groups (<3.5xa0mm). VH-IVUS parameters were compared according to the EAT group. To evaluate the independent effect of EAT thickness on plaque vulnerability, a set of well-known CAD risk factors and EAT thickness were included in multiple linear regression models of VH-IVUS parameters which denotes plaque vulnerability. In a symptom-related vessel analysis, the thick EAT group had significantly more thin-cap fibroatheromas (TCFAs). In a symptom-related vessel analysis among 62 patients with unstable angina out of 82 patients, the thick EAT group had significantly more thin-cap fibroatheromas (TCFAs). In all three vessels analysis, the thick EAT group was associated with significantly larger total plaque volume, higher total plaque volume index, higher mean plaque burden, higher plaque volume indexes of the necrotic core (NC), and more total number of TCFAs than the thin EAT group. By multivariate analysis, total TCFAs of a symptom-related vessel, both in total population and in patients with unstable angina, and plaque volume index of the NC of all three vessels were independent factors associated with thick EAT. Inxa0multiple linear regression models of VH-IVUS parameters which means plaque vulnerability, EAT thickness was one of the independent factors. In the present study, the VH-IVUS parameters indicating vulnerable plaque were significantly related with the thickness of EAT.

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

BACKGROUNDnInducing 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.nnnMETHODSnIn 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.nnnRESULTSnFractional 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.nnnCONCLUSIONSnThe 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 relationship between intravascular ultrasound-derived percent total atheroma volume and fractional flow reserve in the intermediate stenosis of proximal or middle left anterior descending coronary artery

BACKGROUNDnIt remains undefined whether the atherosclerotic disease extent of the conductive vessel (expressed as intravascular ultrasound [IVUS]-derived percent total atheroma volume [%TAV]), correlates with functional severity of intermediate stenosis of left anterior descending artery (LAD).nnnMETHODSnAn IVUS study and fractional flow reserve (FFR) measurements performed in 130 patients with coronary angiographic intermediate stenosis of proximal or middle LAD. %TAV was calculated as the percentage of total vessel volume occupied by total atheroma volume on IVUS.nnnRESULTSnA significant correlation was observed between %TAV and FFR (r=-0.71, p<0.001). Minimal lumen area (MLA) correlated moderately with FFR (r=0.54, p<0.001). The independent predictors of FFR<0.8 were %TAV (odds ratio [OR]: 1.29, 95% confidence interval [CI]=1.18-1.40, p<0.001) and MLA (OR: 0.37, 95% CI=0.16-0.85, p=0.019). A receiver-operating characteristic curve suggested %TAV ≥ 39.0% (sensitivity 85%, specificity 83% and area under curve [AUC]=0.90) and MLA ≤ 2.6mm(2) (sensitivity 72%, specificity 70% and AUC=0.75) as the best cut-off values for FFR<0.8. Forty-eight point five (48.5%) of total studied lesions (63/130) showed %TAV ≥ 39.0%. Eighty-four point four (84.4%) of lesions (38/45) with %TAV ≥ 39.0% and MLA ≤ 2.6mm(2), and 72.2% of lesions (13/18) with %TAV ≥ 39.0% and MLA>2.6mm(2), FFR was less than 0.8.nnnCONCLUSIONSnVolumetric quantification of the atherosclerotic disease extent of the coronary artery, expressed as IVUS-derived %TAV, showed a strong correlation with FFR. Not only the segmental luminal narrowing but also the total plaque burden of conductive artery are major determinants for the presence of myocardial ischemia in intermediate stenosis of LAD.

The pattern of Tpeak-Tend and QT interval, and J wave during therapeutic hypothermia.

BACKGROUND AND PURPOSEnThe electrocardiogram manifestations of hypothermia include J waves and prolongation of QT intervals. This study described changes in repolarization patterns during therapeutic hypothermia (TH).nnnMETHODSnWe measured the QTc and the interval from the peak to the end of the T wave (TpTe) from the V4 and V6 leads in 20 patients with TH. The TpTe was also expressed as a ratio to the duration of QT ([TpTe/QT]×100%), and to the corrected value for heart rate (TpTe/√RR).nnnRESULTSnThe QTc became prolonged in all patients during TH. While the TpTe/√RR did not change, the ([TpTe/QTe]×100%] decreased significantly during TH. The J wave developed during TH in seven patients. With one patient, ventricular fibrillation occurred preceded by an abnormal J wave and prolonged TpTe during TH.nnnCONCLUSIONSnQTc prolongation without TpTe increase or abnormal J wave may not be arrhythmogenic during TH.

Long-term clinical and angiographic outcomes after implantation of sirolimus-eluting stents with a "modified mini-crush" technique in coronary bifurcation lesions.

We aimed to evaluate long‐term outcomes of a modified mini‐crush technique for treating bifurcation lesions.