Impact of impaired glucose tolerance on clopidogrel response in patients with coronary artery disease.

Although patients with impaired glucose tolerance (IGT) are at increased atherothrombotic risk, it is unclear how antiplatelet drugs act in patients with IGT. The aim of this study was to investigate the pharmacodynamic response to clopidogrel in patients with IGT and insulin resistance (IR). A 75 g oral glucose tolerance test was performed in 65 coronary artery disease (CAD) patients on aspirin and clopidogrel therapy. Platelet function tests were assessed at 3 time-points by light transmittance aggregometry using ADP (5 and 20 µmol/L) stimuli. 30 patients had IGT and 35 normal glucose tolerance (NGT). Among them, 13 patients showed IR. Following ADP stimuli, patients with IGT showed significantly higher maximal platelet aggregation at each time point than those with NGT patients. This resulted in greater high on-treatment platelet reactivity (HPR) rates at each time point in IGT patients (53.3-36.7 vs. 14.3-11.4 %, p < 0.05). A multivariable logistic regression analysis showed that IGT status was the strongest predictor of HPR (odds ratio 7.54, 95 % CI 1.95-29.1, p = 0.003). Following a glucose load, profiles of platelet reactivity varied according to IR status, with minimal changes over time in patients with IR, while there was a significant reduction in the non-IR patients. In aspirin and clopidogrel-treated patients with CAD, IGT is associated with enhanced platelet reactivity and increased rates of HPR compared with NGT patients. These findings suggest the presence of platelet dysfunction in patients with IGT, which may be attributed to the presence of IR.

Clinical utility of low-pressure implantation of drug-eluting stent into very small vessels.

BACKGROUND: Although drug-eluting stents (DES) reduce restenosis, the best strategy for DES implantation in small vessels has not been established. PURPOSE: We investigated the clinical usefulness of low-pressure implantation of a 2.5-mm DES for small vessels less than 2.5mm in diameter. METHODS: In 118 patients, a 2.5-mm DES was implanted for small vessels less than 2.5mm in diameter between 2007 and 2009 in our hospital. The patients were divided into two groups by initial deployment pressure: low-pressure (LP; n=46) and nominal-pressure (NP; n=72). RESULTS: Patients with impaired glucose tolerance were more frequent (p=0.02) and the target vessel diameter was significantly smaller (p=0.01) in the LP group than in the NP group. A smaller minimum lumen diameter (MLD) was obtained (LP: 2.22±0.27mm vs. NP: 2.34±0.26mm, p=0.02) after DES implantation with a smaller balloon-to-artery ratio (p=0.03) in the LP group. However, at mid-term follow-up (7.7±3.9 months), MLD (p=0.55) and the binary restenosis rate (LP: 2.6% vs. NP: 11.1%, p=0.12) were not significantly different between the LP and NP groups. Furthermore, by Kaplan-Meier analysis, the incidence of major adverse cardiac events was not different between the groups during the long-term follow-up (32.4±8.6 months). CONCLUSION: The present study indicates that low-pressure implantation of 2.5-mm DES for very small vessels may be feasible with regard to short- and long-term clinical outcomes.

Difference in statin effects on neointimal coverage after implantation of drug-eluting stents.

OBJECTIVE: This study was carried out to examine the difference in effects between rosuvastatin and pravastatin on neointimal formation after the placement of a drug-eluting stent (DES). MATERIALS AND METHODS: Forty patients who underwent placement of a DES in our hospital were prospectively randomized to receive rosuvastatin (n=20) or pravastatin (n=20), and analyzed by optical coherence tomography at the chronic stage. The main outcome measure was comparison of neointimal coverage analyzed at a strut level. RESULTS: A significant reduction in total cholesterol, low-density lipoprotein, and white blood cell count was observed during the study in the rosuvastatin group (total cholesterol, from 4.82±0.90 to 4.43±0.77 mmol/l, P=0.038; low-density lipoprotein, from 2.85±0.76 to 2.34±0.57 mmol/l, P=0.006; white blood cell count, from 5810±1399 to 5355±1257/µl, P=0.048), but not in the pravastatin group. Although not statistically significant, C-reactive protein was lower in the rosuvastatin than in the pravastatin group at the chronic stage (1.14±1.21 vs. 7.67±13.67 mg/l, P=0.051). Malapposed and uncovered struts were significantly less frequent in the rosuvastatin group than in the pravastatin group (malapposed, 0.06 vs. 0.60%, P<0.001; uncovered, 6.49 vs. 11.29%, P<0.001). The difference in uncovered struts was maintained even when stent types were analyzed separately (everolimus-eluting stent, 4.81 vs. 6.21%, P=0.007; sirolimus-eluting stent, 14.40 vs. 20.86%, P<0.001). Comparison of neointimal thickness between the rosuvastatin and the pravastatin groups showed inconsistent results depending on the stent types analyzed. CONCLUSION: Compared with pravastatin, the use of rosuvastatin resulted in lower frequency of uncovered and malapposed struts after the placement of a DES, which might be mediated through improved inflammatory and lipid profiles.

Difference in neointimal coverage at chronic stage between bare metal stent and sirolimus-eluting stent evaluated at stent-strut level by optical coherence tomography.

Compared with the bare metal stent (BMS), suppression of neointimal growth in the sirolimus-eluting stent (SES) reduced restenosis at the cost of more exposed struts that could impose the risk of stent thrombosis. The present study was conducted to analyze neointimal coverage patterns of stents at a strut-level after implantation of BMS or SES with the use of optical coherence tomography (OCT). We enrolled 35 patients and analyzed neointimal coverage of every strut from 41 stents (BMS: n = 8, SES: n = 33) by using OCT at follow-up of the stent implantation. All of the 371 struts from eight BMSs were covered with ≥100 µm of neointima, while 19.8 and 3.5% of 3,478 struts from 33 SESs were uncovered (neointimal thickness of <10 µm) and malapposed, respectively. The histogram of neointimal thickness showed basically normal distribution in BMS but skewed in SES. No regional difference in neointimal thickness was observed in BMS (proximal, 535.7 ± 25.2 µm; body, 532.4 ± 17.0 µm; distal, 485.8 ± 27.0 µm). In SES, however, the body segment showed thinner neointima [median 40 µm (interquartile range (IQR) 10-90 µm)] than proximal [60 µm (IQR 10-140 µm), p < 0.001] or distal [50 µm (IQR 10-110 µm), p < 0.001] segment, while uncovered and malapposed struts were more frequent in the proximal and body segments. In conclusion, SES, compared with BMS, showed more suppressed neointimal growth with regional variation: neointimal thickness was the least in the body part while the ratio of exposed and malapposed struts was minimal in the distal segment. OCT was useful for a strut-level analysis of neointimal coverage over the whole stent.

Quantitative myocardial perfusion analysis using multi-row detector CT in acute myocardial infarction.

OBJECTIVE: To assess the feasibility of quantitative myocardial perfusion imaging (MPI) in acute myocardial infarction (AMI), using multi-row detector CT (MDCT) with a model-based deconvolution method. DESIGN, SETTING, PATIENTS AND INTERVENTIONS: Fifteen normal subjects with normal coronary arteries and 26 patients with AMI after reperfusion therapy underwent MPI with MDCT. Perfusion parameters: tissue blood flow (TBF), tissue blood volume (TBV) and mean transit time (MTT) were obtained and compared with clinical parameters, angiography and single-photon emission CT (SPECT) data. Furthermore, the MPI data were compared with data from myocardial magnetic resonance (MR) in 10 subjects. RESULTS: The TBF and TBV of infarcted myocardium were significantly lower than those of non-infarcted areas (TBF, 51.96±19.42 vs 108.84±13.29 ml/100 g/min, p<0.01; TBV, 4.47±2.23 vs 9.79±2.58 ml/100 g, p<0.01). The MTT of infarcted areas did not differ from that of non-infarcted areas. The defect areas on TBV colour maps were significantly associated with peak creatine kinase level, QRS score and SPECT defect score. The ratio of TBF or TBV in the epicardial to endocardial side was significantly higher in infarct myocardium with good collateral circulation than in myocardium with poor/no collateral circulation (p<0.01 for both). The TBF measurements with CT- and MR-MPI were in good agreement by linear regression analysis (R=0.55, p<0.01). CONCLUSIONS: This study demonstrated that MDCT perfusion imaging with deconvolution analysis could quantitatively detect myocardial perfusion abnormalities in patients with AMI and may provide the basis for the non-invasive and quantitative assessment of myocardial infarction.

[Evaluation of echocardiographic left ventricular wall motion analysis supported by internet picture viewing system].

BACKGROUND: Assessment of deterioration of regional wall motion by echocardiography is not only subjective but also features difficulties with interobserver agreement. Progress in digital communication technology has made it possible to send video images from a distant location via the Internet. OBJECTIVES: The possibility of evaluating left ventricular wall motion using video images sent via the Internet to distant institutions was evaluated. METHODS: Twenty-two subjects were randomly selected. Four sets of video images (parasternal long-axis view, parasternal short-axis view, apical four-chamber view, and apical two-chamber view) were taken for one cardiac cycle. The images were sent via the Internet to two institutions (observer C in facility A and observers D and E in facility B) for evaluation. Great care was taken to prevent disclosure of patient information to these observers. Parasternal long-axis images were divided into four segments, and the parasternal short-axis view, apical four-chamber view, and apical two-chamber view were divided into six segments. One of the following assessments, normokinesis, hypokinesis, akinesis, or dyskinesis, was assigned to each segment. The interobserver rates of agreement in judgments between observers C and D, observers C and E, and intraobserver agreement rate (for observer D) were calculated. RESULTS: The rate of interobserver agreement was 85.7% (394/460 segments; Kappa = 0.65) between observers C and D, 76.7% (353/460 segments; Kappa = 0.39) between observers D and E, and 76.3% (351/460 segments; Kappa = 0.36)between observers C and E, and intraobserver agreement was 94.3% (434/460; Kappa = 0.86). Segments of difference judgments between observers C and D were normokinesis-hypokinesis; 62.1%, hypokinesis-akinesis; 33.3%, akinesis-dyskinesis; 3.0%, and normokinesis-akinesis; 1.5%. CONCLUSIONS: Wall motion can be evaluated at remote institutions via the Internet.

[Diagnosis of vascular complications at the puncture site after cardiac catheterization].

OBJECTIVES: Cardiac catheterization is increasingly used for the diagnosis or treatment of coronary artery disease. Previous studies that revealed the incidence of complications such as arteriovenous fistula and pseudoaneurysm were based on retrospective analysis of cohorts referred to vascular surgery. This study was designed to determine the incidence of arteriovenous fistula and pseudoaneurysm after percutaneous transluminal angiography. METHODS: All 557 consecutive patients undergoing cardiac catheterization were examined by ultrasonography from March 1, 2001 to April 1, 2002, to investigate the occurrence of arteriovenous fistula and pseudoaneurysm at the puncture site. RESULTS: Pseudoaneurysm was found in 16 patients (2.9%), and arteriovenous fistula in 12 patients (2.2%). Pseudoaneurysm in 7 patients (43.8%) and arteriovenous fistula in 6 patients (50.0%) were diagnosed only by ultrasonic examination. There were more female patients (9 patients, 56.3%) than male with pseudoaneurysm (p < 0.01). The puncture site was located after the division of the deep femoral artery and superficial femoral artery in all patients with complications. CONCLUSIONS: Ultrasonic examination was useful for diagnosis of complications such as arteriovenous fistula and pseudoaneurysm after cardiac catheterization.