Impact of insulin resistance on post-procedural myocardial injury and clinical outcomes in patients who underwent elective coronary interventions with drug-eluting stents.

OBJECTIVES: This study sought to evaluate the associations between homeostatic indexes of insulin resistance (HOMA-IR) and post-procedural myocardial injury and clinical outcome after a percutaneous coronary intervention (PCI) with a drug-eluting stent. BACKGROUND: Insulin resistance increases the risk of cardiovascular events. However, the association between insulin resistance and clinical outcome after coronary intervention is unclear. METHODS: We evaluated 516 consecutive patients who underwent elective PCI with drug-eluting stents. Blood samples were collected from venous blood after overnight fasting, and fasting plasma glucose and insulin levels were measured. HOMA-IR was calculated according to the homeostasis model assessment. Post-procedural myocardial injury was evaluated by analysis of troponin T and creatine kinase-myocardial band isozyme levels hours after PCI. Cardiac event was defined as the composite endpoint of cardiovascular death, myocardial infarction, and any revascularization. RESULTS: With increasing tertiles of HOMA-IR, post-procedural troponin T and creatine kinase-myocardial band levels increased. In the multiple regression analysis, HOMA-IR was independently associated with troponin T elevation. During a median follow-up of 623 days, patients with the highest tertiles of HOMA-IR had the highest risk of cardiovascular events. The Cox proportional hazard models identified HOMA-IR as independently associated with worse clinical outcome after adjustment for clinical and procedural factors. CONCLUSIONS: These results indicated the impact of insulin resistance on post-procedural myocardial injury and clinical outcome after elective PCI with drug-eluting stent deployment. Evaluation of insulin resistance may provide useful information for predicting clinical outcomes after elective PCI.

Comparison of tissue characteristics between acute coronary syndrome and stable angina pectoris. An integrated backscatter intravascular ultrasound analysis of culprit and non-culprit lesions.

BACKGROUND: Patients with acute coronary syndrome (ACS) have multiple complex coronary plaques associated with plaque vulnerability. The present study assessed the tissue characteristics of coronary plaques between ACS and stable angina pectoris (SAP) of culprit and non-culprit lesions using integrated backscatter intravascular ultrasound (IB-IVUS). METHODS AND RESULTS: IVUS was performed in 165 patients (40 patients with ACS) with 225 culprit (65 lesions in ACS) and 171 non-culprit lesions (42 lesions in ACS). The percentage of fibrous area (fibrous area/plaque area, %FIB) and the percentage of lipid area (lipid area/plaque area, %LIP) at the segment with minimal luminal area were calculated using IB-IVUS system. Culprit and non-culprit lesions with ACS showed a significant increase in %LIP (38±18 vs. 30±15%, P=0.002, and 38±21 vs. 32±17%, P=0.03, respectively) and a significant decrease in %FIB (59±15 vs. 63±12 %, P=0.04, and 57±18 vs. 62±14%, P=0.04, respectively) compared to those with SAP. On logistic regression analysis, not only culprit lesions but also non-culprit lesions with ACS patients were significantly associated with the lipid-rich plaque. CONCLUSIONS: Non-culprit coronary lesions with ACS patients are associated with the lipid-rich plaque, suggesting the extensive development of plaques instability in these patients.

Volumetric analysis of coronary plaque characterization in patients with metabolic syndrome using 64-slice multi-detector computed tomography.

BACKGROUND: Metabolic syndrome (MetS) is associated with adverse cardiovascular events and mortality, where acute coronary syndrome significantly impacts on mortality and morbidity. In contrast, evidences have accumulated that the lipid-rich plaque might play a critical role in acute coronary syndrome. METHODS AND RESULTS: The study population consisted of 94 patients with suspected angina pectoris who underwent multi-detector computed tomography (MDCT). Of those, we identified 41 with MetS. In MDCT analysis, low-density plaque volume (LDPV) (42 ± 28 vs 24 ± 18 mm(3), P=0.0003), moderate-density plaque volume (105 ± 41 vs 82 ± 33 mm(3), P=0.003), total plaque volume (164 ± 70 vs 118 ± 59 mm(3), P=0.0008) and %LDPV (24.2 ± 10.0 vs 18.3 ± 7.1%, P=0.01) were significantly increased in the MetS group compared to the non-MetS group. Multivariate linear regression analysis after adjusting for confounding variables revealed that MetS was significantly correlated with an increase in %LDPV (ß=0.48, P=0.0001). Multivariate logistic regression analysis for lipid-rich plaque after adjusting for confounding variables indicated that MetS was significantly associated with lipid-rich plaque (odds ratio: 5.99, 95% confidence intervals: 1.94-18.6, P=0.002). CONCLUSIONS: Patients with MetS were strongly related to having a lipid-rich composition in their coronary plaque, as detected by MDCT.

The association between plaque characterization by CT angiography and post-procedural myocardial infarction in patients with elective stent implantation.

OBJECTIVES: This study sought to evaluate the association between volumetric characterization of target lesions by multidetector computed tomography (MDCT) angiography and the risk of post-procedural myocardial injury after elective stent implantation. BACKGROUND: Previous reports have shown that plaque characterization of the target lesion may provide useful information for stratifying the risk of coronary stenting. METHODS: A total of 189 consecutive patients were enrolled; they underwent elective stent implantation after volumetric plaque analysis with 64-slice MDCT. Each plaque component and lumen (filled with dye) was defined as follows: 1) low-attenuation plaque (LAP) (<50 HU); 2) moderate-attenuation plaque (MAP) (50 to 150 HU); 3) lumen (151 to 500 HU); and 4) high-attenuation plaque (HAP) (>500 HU). The volume of each plaque component in the target lesion was calculated using Color Code Plaque. Post-procedural creatine kinase-MB isoform and troponin-T (TnT) at 18 h after percutaneous coronary intervention were also evaluated. RESULTS: The volumes of LAP (87.9+/-94.8 mm3 vs. 47.4+/-43.7 mm3, p<0.01) and MAP (111.6+/-77.5 mm3 vs. 89.8+/-67.1 mm3, p<0.05) were larger in patients with post-procedural myocardial injury (defined as positive TnT) than in those with negative TnT. The volumes of LAP and MAP and fraction of LAP in total plaque (LAP volume/total plaque volume) correlated with biomarkers; the MAP fraction was inversely correlated with biomarkers. The volume of LAP was an independent predictor of positive TnT after adjusting for patient background, conventional IVUS parameters, and procedural factors. CONCLUSIONS: Post-procedural myocardial injury was associated with the volume and fraction of LAP as detected by MDCT. The volume of LAP was an independent predictor of positive TnT. Plaque analysis by MDCT would be a useful method for predicting post-procedural myocardial injury after percutaneous coronary intervention.

Intracoronary electrocardiogram recording with a bare-wire system: perioperative ST-segment elevation in the intracoronary electrocardiogram is associated with myocardial injury after elective coronary stent implantation.

OBJECTIVES: With an intracoronary electrocardiogram (IcECG) recording with insulated polymer-coated guidewire without balloon catheter, we sought to examine the association between ST-segment elevation in the IcECG after elective stenting and myocardial injury. BACKGROUND: An IcECG is a sensitive method to detect local myocardial ischemia. Occasionally, persistent ST-segment elevation in the IcECG was recorded after successful coronary intervention. Conventionally IcECG was recorded with a guidewire and over-the-wire system. METHODS: Patients who underwent elective stenting were enrolled (n = 339). The IcECG both at baseline and after procedure were obtained with a guidewire with an insulating coated shaft suitable for IcECG recording. The presence of chest pain after percutaneous coronary intervention was recorded. Cardiac biomarkers were examined 18 h after the procedure. RESULTS: The ST-segment elevation in the IcECG after procedure was recorded in 65 patients, and no change was recorded in 274 patients. Troponin-T, creatine phosphokinase, and creatine kinase MB isoform after the procedure were significantly higher in patients with post-procedural ST-segment elevation in the IcECG than patients without ST-segment elevation. Multivariate analysis demonstrated that ST-segment elevation in the IcECG is an independent predictor of post-procedural myocardial injury. The incidence of ST-segment elevation in the IcECG was significantly higher in patients with post-procedural chest pain than patients without chest pain (p < 0.001). CONCLUSIONS: We demonstrated a facile method to record IcECG with a guidewire with a polymer-coated shaft. The IcECG is a useful method for predicting post-procedural myocardial injuries.

The correlation between lipid volume in the target lesion, measured by integrated backscatter intravascular ultrasound, and post-procedural myocardial infarction in patients with elective stent implantation.

AIMS: The aim of this study was to perform quantitative analysis of the plaques of target lesions by integrated backscatter intravascular ultrasound (IB-IVUS) and to investigate the association between these data and the risk of post-procedural myocardial injury after stenting. METHODS AND RESULTS: One hundred and fourteen consecutive patients who received elective stent implantations following IB-IVUS analysis were enrolled. The volume of each plaque component (lipid, fibrous, and calcified) was calculated for the target lesion. Creatine kinase-MB (CK-MB) and troponin-T (TnT) were also evaluated 18 h after procedure. We defined a post-procedural TnT level higher than three times the normal limit as a post-procedural myocardial injury. Lipid, fibrous, and calcified volumes were greater in patients with myocardial injury than in those without myocardial injury. Lipid and fibrous volumes correlated with post-procedural cardiac biomarkers, and the lipid volume fraction (lipid volume/total plaque volume) also correlated with post-procedural TnT and CK-MB. The fibrous volume fraction for plaques was found to be inversely correlated with post-procedural TnT and CK-MB. Hence, lipid volume and volume fraction were concluded to be independent predictors of post-procedural myocardial injury. CONCLUSION: A larger plaque volume and lipid-rich plaque may be indicative of embolic events after stent implantation, resulting in myocardial injury.

Abnormal glucose regulation is associated with lipid-rich coronary plaque: relationship to insulin resistance.

OBJECTIVES: This study sought to determine lipid and fibrous volume of coronary atherosclerotic plaques in subjects with abnormal glucose regulation (AGR) by integrated backscatter (IB) intravascular ultrasound (IVUS) during percutaneous coronary intervention. BACKGROUND: Abnormal glucose regulation, including impaired glucose regulation (IGR) and diabetes mellitus (DM), has emerged as an important determinant of cardiovascular risk. We hypothesized that AGR would be associated with coronary plaque instability. METHODS: Conventional intravascular ultrasound and IB-IVUS using a 40-MHz (motorized pullback 1 mm/s) intravascular catheter was performed in 172 consecutive patients. The percentage of fibrous area and the percentage of lipid area were automatically calculated by IB-IVUS. Three-dimensional analysis of IB-IVUS images was performed to determine the percentage of lipid volume (%LV) and fibrous volume (%FV). Following the World Health Organization criteria, the subjects were classified into the DM group, the IGR group, and the normal glucose regulation group. The cutoff point for the lipid-rich plaque was defined as %LV >44% or %FV <52%, which was the 75th percentile of %LV or the 25th percentile of %FV in this study population. Insulin resistance (IR) was defined as the homeostasis model assessment of insulin resistance (HOMA-IR). RESULTS: There were no significant differences in the baseline characteristics except for glucometabolic parameters. The conventional IVUS analysis indicated that the DM group had a significantly increased plaque volume (and percent plaque volume). In the IB-IVUS analysis, as compared with the normal glucose regulation group, the DM and the IGR groups showed a significant increase in %LV (36 +/- 14% and 37 +/- 13% vs. 29 +/- 14%, p = 0.02) and a significant decrease in %FV (59 +/- 11% and 58 +/- 11% vs. 64 +/- 11%, p = 0.03). The lipid-rich plaque rate was significantly associated with an increasing HOMA-IR in the tertile (p = 0.008). On logistic regression analysis after adjusting for confounding and coronary risk factors, the DM group (odds ratio 3.52, 95% confidence interval 1.13 to 11.0, p = 0.03) and the IGR group (odds ratio 3.92, 95% confidence interval 1.13 to 13.6, p = 0.03) were significantly associated with the lipid-rich plaque. CONCLUSIONS: Coronary lesions in patients with AGR are associated with more lipid-rich plaque content, which may be related to the increased IR in these patients.

Impact of metabolic syndrome on tissue characteristics of angiographically mild to moderate coronary lesions integrated backscatter intravascular ultrasound study.

OBJECTIVES: We assessed the impact of metabolic syndrome (MetS) on the tissue characteristics of coronary plaques using integrated backscatter intravascular ultrasound (IB-IVUS). BACKGROUND: Metabolic syndrome is associated with the increasing risk of cardiovascular disease. METHODS: We identified MetS by the definition of the National Cholesterol Education Program in Adult Treatment Panel III criterion. Non-target coronary lesions with mild to moderate stenosis were measured by conventional and IB-IVUS parameters using 40-MHz (motorized pullback 0.5 mm/s) intravascular catheter. A total of 20 IB-IVUS images were recorded at an interval of 0.5 mm for 10 mm length in each plaque. The 3-dimensional analyses were performed using commercially available software. RESULTS: The prevalence of MetS was 61 patients (50%) with 73 lesions (49%) among 122 patients with 148 lesions. Patients with MetS showed a significant increase in percentage lipid area (38 +/- 19% vs. 30 +/- 19%, p = 0.02) and percentage lipid volume (39 +/- 17% vs. 33 +/- 17%, p = 0.03), and they also showed a significant decrease in percentage of fibrous volume (57 +/- 14% vs. 61 +/- 13%, p = 0.03). Multivariate regression analysis after adjustment for potentially confounding risk factors showed that MetS remains correlated independently with the percentage of lipid volume (r = 0.223, p = 0.01). Logistic regression analysis after adjusting for confounding and non-MetS coronary risk factors showed that MetS (odds ratio 4.00, 95% confidence interval 1.33 to 12.0, p = 0.01) is proved to be an independent predictor of the lipid-rich plaque. CONCLUSIONS: Metabolic syndrome is associated with lipid-rich plaques, contributing to the increasing risk of plaque vulnerability.

Extraction of left ventricular contours from left ventriculograms by means of a neural edge detector.

We propose a method for extracting the left ventricular (LV) contours from left ventriculograms by means of a neural edge detector (NED) in order to extract the contours which accord with those traced by a cardiologist. The NED is a supervised edge detector based on a modified multilayer neural network, and is trained by use of a modified back-propagation algorithm. The NED can acquire the function of a desired edge detector through training with a set of input images and the desired edges obtained from the contours traced by a cardiologist. The proposed contour-extraction method consists of 1) detection of "subjective edges" by use of the NED; 2) extraction of rough contours by use of low-pass filtering and edge enhancement; and 3) a contour-tracing method based on the contour candidates synthesized from the edges detected by the NED and the rough contours. Through experiments, it was shown that the proposed method was able to extract the contours in agreement with those traced by an experienced cardiologist, i.e., we achieved an average contour error of 6.2% for left ventriculograms at end-diastole and an average difference between the ejection fractions obtained from the manually traced contours and those obtained from the computer-extracted contours of 4.1%.