Vasoconstrictor component of atherothrombotic culprit lesions in ST-segment elevation myocardial infarction.

OBJECTIVE: The vasoconstrictor component of atherothrombotic culprit lesions in ST-elevation myocardial infarction (STEMI) patients has not been fully investigated. This study was aimed at assessing the vasoconstrictor component of atherothrombotic culprit lesions in patients with STEMI receiving primary percutaneous coronary intervention (PCI). METHODS: A group of 100 patients with STEMI were enrolled prospectively. Baseline coronary angiography achieving normal antegrade flow was followed by 200 µg of intracoronary nitroglycerin (NTG) injection and repeat coronary angiography at the same projection view for culprit lesions was performed. End points were the changes in lesion length, reference vessel diameter, minimal lumen diameter, and diameter stenosis by quantitative coronary analysis before and after NTG injection. RESULTS: Reference vessel diameter (2.7 ±â€¯0.5 mm vs. 2.9 ±â€¯0.5 mm, p < 0.001) and minimal lumen diameter (0.9 ±â€¯0.4 mm vs. 1.2 ±â€¯0.5 mm, p < 0.001) increased after NTG injection, whereas lesion length (24.1 ±â€¯7.4 mm vs. 23.4 ±â€¯7.6 mm, p = 0.001) and diameter stenosis (66.6 ±â€¯14.8% vs. 58.3 ±â€¯16.1%, p < 0.001) decreased. The median percentage change of diameter stenosis was -4.0% (Interquartile range: -13.8% to -1.0%), which was used as the cut-off value to divide the cohort into NTG responder or nonresponder groups accordingly. Total stent length was significantly shorter in the responder group compared with the nonresponder group (27.4 ±â€¯11.6 mm vs. 33.7 ±â€¯16.8 mm, p = 0.042). CONCLUSION: This study showed the presence of a vasoconstrictor component in atherothrombotic culprit lesions in STEMI patients receiving primary PCI. Vasodilating effort by NTG may decrease stent length used for culprit lesions.

"Angiographic late catch-up" phenomenon after sirolimus-eluting stent implantation.

BACKGROUND: Although several randomized trials have shown that sirolimus-eluting stent (SES) substantially reduces in-stent restenosis, recent studies have suggested the possibility of late catch-up after SES implantation. We investigated long-term angiographic outcomes after SES implantation in real-world practice. METHODS: This study was conducted on 195 patients with 253 lesions who underwent the first and long-term angiographic follow-up after SES implantation. First follow-up was done at near 6 months after SES implantation. Long-term angiographic follow-up was defined as that performed at least 36 months after index procedure. Angiographies in patients who experienced target lesion revascularization at the time of the first angiographic follow-up were excluded from the current analysis. RESULTS: Minimal luminal diameter at long-term angiographic follow-up was significantly smaller compared with that at the first follow-up (2.21 ± 0.65 vs. 2.40 ± 0.55, p<0.001). In-stent late lumen loss between the first and long-term follow-up tended to be larger compared with that between SES implantation and the first follow-up (0.19 ± 0.47 vs. 0.15 ± 0.39, p=0.298). There was a trend for increased incidence of coronary artery aneurysm (1.6% and 7.5% at the first and long-term follow-up) and stent fracture (4.3% and 10.3%). Two stent aneurysms and one stent fracture were related with definite very late stent thrombosis. CONCLUSION: An "angiographic late catch-up" phenomenon and a trend toward increased incidence of coronary artery aneurysm and stent fracture were found at a median 46.5-month angiographic follow-up compared with a median 6-month follow-up.

Relationship between symptom-onset-to-balloon time and long-term mortality in patients with acute myocardial infarction treated with drug-eluting stents.

BACKGROUND: Time from hospital arrival to reperfusion in ST-segment elevation myocardial infarction (STEMI) has been predictive of in-hospital mortality. The purpose of this study was to evaluate the relationship between symptom-onset-to-balloon time and long-term mortality in patients with STEMI in the drug-eluting stent (DES) era. METHODS: A series of 393 patients with STEMI treated with DES from 2005 to 2007 was stratified according to risk profile and preprocedural Thrombolysis In Myocardial Infarction (TIMI) flow grade, and clinical, angiographic, and follow-up data were collected. RESULTS: A total of 98 (24.9%) low-risk patients and 295 (75.1%) non-low-risk patients were identified. Three-year mortality rate was 3.1% for low-risk patients and 10.2% for non-low-risk patients (p=0.034), respectively; however it did not differ according to symptom-onset-to-balloon time in either low-risk (p=0.333) or non-low-risk patients (p=0.881). Similarly, symptom-onset-to-balloon time and mortality were not related to preprocedural TIMI flow (p=0.474 for TIMI 0-1; p=0.428 for TIMI 2-3). In multivariate analysis, final TIMI flow 0-2, systolic blood pressure <100 mmHg at admission, age ≥70 years, anterior infarction, C-reactive protein level, and peak creatine kinase myocardial band isoenzyme level were identified as independent predictors of 3-year mortality while symptom-onset-to-balloon time and preprocedural TIMI flow were not. CONCLUSIONS: In STEMI patients treated with DES, symptom-onset-to-balloon time does not affect long-term outcomes even in individuals at non-low risk and with poor preprocedural TIMI flow grade.

T-S model based indirect adaptive fuzzy control using online parameter estimation.

A parameter estimation scheme with an appropriate adaptive law for updating the parameters is designed and analyzed based on the Lyapunov theory for the general MIMO Takagi-Sugeno (T-S) fuzzy models. The parameters of the Takagi-Sugeno fuzzy models can be estimated by observing the behavior of the system and with the online parameter estimator, any type of fuzzy controllers works adaptively to the parameter perturbation. In order to show the applicability of the proposed estimator, an existing fuzzy state feedback controller is adopted and indirect adaptive fuzzy control design with the proposed estimator is shown. From the numerical simulations and experiments, it is shown that the derived adaptive law works for the estimation model to follows the parameterized plant model and the overall control system has robustness to the parameter perturbation.