Yuichi Kobori

Tokyo Medical University, Edo, Tōkyō, Japan

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Publications (5)12.99 Total impact

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    ABSTRACT: The objective of this study was to examine the usefulness of fractional flow reserve (FFR) in determining the indication of target lesion revascularization (TLR) at follow-up angiography after percutaneous coronary intervention (PCI). One hundred forty-seven patients with 155 lesions that had intermediate restenosis took part in this study. FFR was measured in all patients for the evaluation of stenosis severity. Then TLR was performed when FFR was < 0.75, and TLR was deferred when FFR was > or = 0.75. Patients in whom TLR was deferred were followed up clinically (25 +/- 11 months). In 98 patients (67%) who underwent stress myocardial scintigraphy before angiography, the results of the scintigraphy were compared with FFR results. TLR was performed in 34 lesions (22%). After TLR, the Canadian Cardiovascular Society class decreased significantly (from 1.5 +/- 0.7 to 1.1 +/- 0.5; P < 0.05). In 113 patients who did not undergo TLR, only 4 patients (3.5%) had cardiac events (re-PCI in 1 patient and a positive SPECT in 3 patients). Discordance between the results of scintigraphy and FFR was observed in 30 patients (30%), but the patients who had good values of FFR > or = 0.75 showed a nil event rate (0%). FFR might be useful for the determination of the indication of TLR.
    Catheterization and Cardiovascular Interventions 07/2005; 65(3):355-60. · 2.51 Impact Factor
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    ABSTRACT: Measurements of changes in plaque temperature may predict plaque rupture. The present study investigated variations in temperature within the atherosclerotic coronary artery using a pressure guide wire with thermal sensor (dual sensor guide wire). Seventy-seven patients (78 lesions), who had no significant lesion at the orifice of the culprit coronary artery, were studied. The patients had acute myocardial infarction (22 patients), unstable angina pectoris (20 patients), and stable angina pectoris (35 patients). The thermal sensor was calibrated at the orifice of the coronary artery, and then inserted into the culprit coronary artery. deltaT was defined as the difference between the intracoronary temperature at the position of the pressure gradient and at the orifice. deltaT was higher in patients with acute myocardial infarction and unstable angina pectoris than in patients with stable angina pectoris (0.09 +/- 0.07 and 0.07 +/- 0.07 vs 0.03 +/- 0.04 degrees C, p < 0.001, p = 0.02, respectively). There was no significant difference in deltaT between patients with acute myocardial infarction and unstable angina pectoris (p = 0.48). Patients with acute myocardial infarction and unstable angina pectoris showed a significant relationship between deltaT and C-reactive protein (r = 0.59, p = 0.0004). The variations in intracoronary temperature of the culprit coronary arteries in patients with acute coronary syndrome were higher than those in patients with stable angina pectoris. These variations may be related to inflammation of vulnerable plaque.
    Journal of Cardiology 05/2005; 45(5):185-91. · 2.30 Impact Factor
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    ABSTRACT: This study investigated the relationship between serum homocysteine level and coronary artery disease in Japanese. Serum homocysteine level was measured in 200 consecutive patients who underwent coronary angiography for the assessment of ischemic heart disease. Patients with acute myocardial infarction were excluded, so 197 patients were included in this study. The patients were classified into four groups based on number of diseased vessels identified by coronary angiography: no significant stenosis group (non-vessel group), one-vessel group, two-vessel group, and three-vessel group. More than 50% stenosis was defined as diseased vessels. Serum homocysteine level in the three-vessel group (13.5 +/- 8.0 microM) was significantly higher than that in the non-vessel group (9.9 +/- 2.7 microM), one-vessel group (9.1 +/- 2.3 microM), and two-vessel group (10.4 +/- 3.3 microM). Patients were classified into quartile groups according to the serum homocysteine level. The number of diseased vessels and frequency of three-vessel disease tended to be higher with increasing serum homocysteine level. There was no significant relationship between serum homocysteine level and coronary risk factors (diabetes mellitus, hyperlipidemia, smoking habit) except hypertension. Multivariate analysis for the predictor of number of diseased vessels showed diabetes mellitus, hypertension, and serum homocysteine level were independent predictors. Elevation of plasma homocysteine level is related to the severity of coronary artery disease in Japanese.
    Journal of Cardiology 06/2004; 43(5):223-9. · 2.30 Impact Factor
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    ABSTRACT: To assess the coronary flow velocity - pressure relationship distal to a stenosis, and to evaluate the influence of microvascular abnormalities on this relationship, coronary flow velocity and coronary pressure were measured simultaneously in 38 patients (42 vessels). The instantaneous peak coronary flow velocity was plotted against the simultaneous measured distal coronary pressure, and the slope of the relation in the phase of diastolic flow decrease was calculated as the flow - pressure slope index (FPSI) and the X-intercept of the slope was calculated as zero-flow pressure (Pzf). The slope of the curve increased from 2.0+/-2.6 to 4.5+/-4.1 (p<0.001) and the X-intercept decreased from 42+/-16 to 27+/-13 mmHg (p<0.001) after papaverine injection. After successful coronary intervention, Pzf increased from 23+/-10 to 35+/-11 (p<0.01) and FPSI decreased from 6.8+/-5.1 to 3.5+/-1.8 (p<0.05). Pzf was higher in patients with an old myocardial infarction. It is feasible to assess the relationship between coronary flow and pressure distal to a stenosis in the clinical setting, and the relationship may provide additional information regarding coronary microcirculation. Microvascular abnormalities may play an important role in the coronary flow - pressure relationship distal to stenosis.
    Circulation Journal 07/2003; 67(6):525-9. · 3.58 Impact Factor
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    ABSTRACT: Fractional flow reserve and coronary flow reserve (CFR) are indices of the severity of coronary artery stenosis influenced by both epicardial and microcirculatory dysfunction. The CFR was measured using the new pressure guide wire with thermal sensor (dual sensor guide wire) on the basis of the thermodilution principle (CFR-thermo), and compared to the CFR as measured by the Doppler method (CFR-Doppler), and the relationships were evaluated between CFR-thermo, fractional flow reserve and stress myocardial scintigraphy. CFR-thermo and CFR-Doppler were measured in 14 patients (20 vessels) by the dual sensor guide wire and Doppler guide wire, respectively. A significant positive correlation was found between CFR-Doppler and CFR-thermo (y = 0.80 x + 0.10, r = 0.70, p < 0.0001). Stress myocardial perfusion single photon emission computed tomography (SPECT) was performed before coronary angiography in 56 patients (70 vessels), and then fractional flow reserve and CFR-thermo were measured using the dual sensor guide wire. CFR-thermo and fractional flow reserve were significantly lower in coronary segments with positive SPECT image (n = 32) than in coronary segments with negative SPECT image (n = 38) (1.29 +/- 0.24 vs 1.96 +/- 0.69, p < 0.0001; 0.61 +/- 0.13 vs 0.85 +/- 0.09, p < 0.0001). The cut-off values of CFR-thermo and fractional flow reserve for detection of ischemic segments demonstrated by SPECT image were 1.47 and 0.76, respectively. The sensitivity and specificity for detecting ischemia were 78% and 84% for CFR-thermo, 88% and 92% for fractional flow reserve, respectively. A significant correlation was found between CFR-thermo measured by the thermodilution principle using the dual sensor guide wire and CFR measured by the Doppler method. CFR-thermo measured by the dual sensor guide wire may be useful to detect myocardial ischemia.
    Journal of Cardiology 12/2002; 40(5):189-97. · 2.30 Impact Factor