The aim of this study was to examine the hypothesis that seasonal variation in the prevalence of metabolic syndrome (MetS) is associated with increased insulin resistance. Among 840 Japanese male workers who were evaluated using the homeostasis model assessment of insulin resistance (HOMA-IR) in June (summer) 2010, we prospectively studied a total of 758 subjects (40-65 years of age) who underwent an assessment in December (winter) 2010. MetS was defined according to the criteria proposed by the International Diabetes Federation (IDF) and the Japanese Society of Internal Medicine (JSIM). The median level of HOMA-IR in the study subjects was 0.84 (interquartile range: 0.60-1.19). The prevalence rates of IDF- and JSIM-MetS significantly increased from 12.4 and 9.6% in the summer to 16.6 and 13.3% in the winter, respectively (each P<0.05). Our data suggest that these increases are mainly due to increases in blood pressure (BP) and glucose during the winter assessment. The prevalence rates of IDF-MetS in the first, second, third and fourth quartiles of HOMA-IR were 1.1, 5.8, 14.3 and 29.1% in the summer and 3.1, 10.6, 21.9, and 31.3% in the winter, respectively. Similar results were obtained when using the JSIM criteria. In the third quartile, the frequency of elevated BP increased from 42.4% in the summer to 61.2% in the winter (P<0.05), and these values were mainly correlated with significant variations in IDF- and JSIM-MetS prevalence rates. This study demonstrates that seasonal variation in MetS prevalence is associated with mildly to moderately increased insulin resistance in middle-aged Japanese men.

Previous optical coherence tomography (OCT) study reported that irregular protrusion (IP) post drug-eluting stent (DES) implantation was an independent predictor of clinical outcome; however, the relationship between IP and the presence of subsequent in-stent neoatherosclerosis remains unclear. This study aimed to assess the relationship between IP and in-stent neoatheroscrerosis formation using OCT. We evaluated 83 patients (101 lesions) who underwent second-generation DES implantation and 8-month follow-up (8M-FU) using OCT. Lesions were divided into two groups in presence of IP (IP: n = 43, non-IP: n = 58). At prepercutaneous coronary intervention (pre-PCI), lipid-rich plaque, lesions with positive remodeling, and in-stent thrombus formation were more frequent in IP than in non-IP. On multivariate analysis, the thrombus at pre-PCI and the lesions with positive remodeling were independent predictors of IP. At 8M-FU, heterogeneous neointima, microvessel, lipid-laden neointima, and thin-cap fibro-atheroma like neointima were more frequent in IP than in non-IP (respectively, P < 0.05). On multivariate analysis, IP was associated with heterogeneous neointima. Binary restenosis was more frequent and late lumen loss tended to be larger in IP than in non-IP (19% versus 5%, P = 0.04; 1.25 ± 1.24 mm versus 0.91 ± 0.63 mm, P = 0.09); however, the target lesion revascularization rate was similar in both groups at 8M-FU. In conclusion, our study suggested that poststent IP was associated with subsequent neoatherosclerosis formation at 8M-FU after the second-generation DES implantation.

Previous studies have suggested that the deterioration of renal function increases the risk of major adverse clinical events not only in culprit lesions but also in non-culprit lesions (NCLs) after percutaneous coronary intervention (PCI). This study evaluated serial coronary plaque change of NCL in patients with different stages of chronic kidney disease (CKD) using intravascular ultrasound (IVUS) and integrated backscatter IVUS (IB-IVUS). In 113 patients (113 NCLs) underwent both IVUS-guided PCI and follow-up IVUS, volumetric IVUS analyses were performed at proximal reference NCLs in de novo target vessels post PCI and at 8-month follow-up. NCLs were divided into 4 groups based on baseline CKD stage: CKD-1, n = 18; CKD-2, n = 42; CKD-3, n = 29; and CKD4–5, n = 24. We compared serial changes of plaque burden and composition among groups under statin treatment. Plaque progression occurred in CKD-3 (+4.6 mm3, p < 0.001) and CKD4–5 (+9.8 mm3, p < 0.001) despite anti-atherosclerotic treatment, whereas plaque regression occurred in CKD-1 (−5.4 mm3, p = 0.002) and CKD-2 (−3.2 mm3, p = 0.001) mainly due to initiate statin treatment after PCI. Plaque volume change was correlated with eGFR (p < 0.0001). Multivariate analysis showed CKD stage 3–5 was an independent predictor of plaque progression. Regarding IB-IVUS analyses, lipid plaque increased in CKD-3 (+4.6 mm3, p < 0.001) and CKD4–5 (+5.4 mm3, p < 0.001), but decreased in CKD-2 (−2.7 mm3, p < 0.05). Fibrotic plaque also increased in CKD4–5 (+3.4 mm3, p < 0.001). Moderate to advanced CKD was associated with coronary plaque progression characterized by greater lipid and fibrotic plaque volumes in NCL under statin treatment after culprit PCI.

Intravascular ultrasound (IVUS)-derived minimum lumen cross-sectional area (MLA) is useful to predict myocardial ischemia using fractional flow reserve (FFR). Recent studies reported an increase in the intraluminal ultrasonic integrated backscatter (IB) value using IVUS across the coronary artery stenosis (CAS) was significantly correlated with FFR. However, these details have not been fully understood. We evaluated the utility of intraluminal IB analysis for predicting myocardial ischemia based on FFR measurements by comparing that with conventional IVUS-derived MLA. A total of 65 patients with 75 intermediate lesions underwent both FFR and IB-IVUS simultaneously were analyzed. We measured IVUS-derived MLA and intraluminal IB value at the coronary ostial site, 5 mm distal site to the CAS, and far distal site, which is the same as the position of the pressure wire sensor. The increase in IB values was calculated as the distal IB value - the ostial IB value (focal ∆IB) and the far distal IB value - the ostial IB value (total ∆IB). MLA did not show a significant correlation with FFR (p = 0.13); however, focal ∆IB and total ∆IB showed significant correlations with FFR (p = 0.008 and p < 0.001, respectively). The receiver operating characteristic curve analysis shows that the best cut-off value of focal ∆IB and total ∆IB was 8 and 14, respectively. Although the diagnostic abilities to predict FFR ≤ 0.75 among IVUS-derived MLA ≤ 3.0 mm, focal ∆IB ≥ 8, and total ∆IB ≥ 14 were similar, a multivariate analysis showed that total ∆IB was the most useful index (p < 0.001). In conclusion, total ∆IB, which is measured at the same as the position of FFR measurement, might be useful for functional assessment of intermediate CAS.

Although in-stent restenosis (ISR) occurs after drug-eluting stents (DES) implantation, neointimal tissue characteristics have not been fully investigated. We assessed neointimal tissue components using integrated backscatter intravascular ultrasound (IB-IVUS) after DES and bare-metal stents (BMS) implantation. Fifty-seven consecutive patients with 61 lesions underwent repeated percutaneous coronary intervention (PCI) for the treatment of ISR (DES: 24 lesions, BMS: 37 lesions). PCI was performed using plain old balloon angioplasty (POBA). Before PCI, we assessed neointimal tissue characteristics using IB-IVUS. Neointima was divided into four categories: category 1 (-11 to -29 dB), category 2 (-29 to -35 dB), category 3 (-35 to -49 dB), and category 4 (-49 to -130 dB) according to IB values. We compared neointimal tissue components between DES and BMS. Thirty-three patients with 33 lesions (DES: 17, BMS: 16) were finally included. Neointima was predominantly composed of category 3 tissue in both groups (DES: 68 ± 8%, BMS: 73 ± 5%, P = 0.053). DES had a broader distribution of category 4 tissue component than BMS. After POBA, distal slow flow phenomenon occurred in 5 of DES (29%), whereas none of BMS. In DES, the optimal threshold of category 4 tissue to predict distal slow flow phenomenon after POBA was 30% (sensitivity: 100%, specificity: 92%). Neointima was mainly composed of category 3 tissue at ISR site, irrespective of DES or BMS. In DES, there was a subgroup with category 4 rich tissue, which caused distal slow flow phenomenon after POBA. IB-IVUS might be useful to identify vulnerable neointima in DES restenosis.