Optimal Intravascular Ultrasound-Guided Percutaneous Coronary Intervention in Patients With Multivessel Disease and Diabetes

There is a scarcity of data on clinical outcomes after intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) in patients with multivessel disease and diabetes. OPTIVUS-Complex PCI study multivessel cohort was a prospective multicenter single-arm trial enrolling 1021 patients who underwent multivessel PCI including left anterior descending coronary artery using IVUS aiming to meet the prespecified OPTIVUS criteria for optimal stent expansion. We compared the clinical outcomes between those patients with and without diabetes. The primary endpoint was a composite of death, myocardial infarction, stroke, or any coronary revascularization. There were 560 patients (54.8%) with diabetes, and 461 patients (45.2%) without diabetes. Mean age was not different between the 2 groups (70.9±9.7 years versus 71.7±10.4 years, P=0.17). Patients with diabetes more often had chronic kidney disease and complex coronary artery disease as indicated by the greater total number of stents and longer total stent length. The rate of meeting OPTIVUS criteria was not different between the 2 groups (61.2% vs. 60.7%, P=0.83). The cumulative 1-year incidence of the primary endpoint was not different between the 2 groups (10.8% versus 9.8%, log-rank P=0.65). After adjusting confounders, the risk of diabetes relative to non-diabetes remained insignificant for the primary endpoint (HR, 0.97; 95%CI, 0.65-1.44; P=0.88). In conclusion, in patients who underwent multivessel IVUS-guided PCI, and were managed with contemporary clinical practice, patients with diabetes had similar 1-year outcomes compared with patients without diabetes.

Dual Antiplatelet Therapy Duration After Multivessel Optimal Intravascular Ultrasound-Guided Percutaneous Coronary Intervention

BACKGROUND

There is a scarcity of data evaluating contemporary real-world dual antiplatelet therapy (DAPT) strategies after percutaneous coronary intervention (PCI).Methods and Results: In the OPTIVUS-Complex PCI study multivessel cohort enrolling 982 patients undergoing multivessel PCI, including left anterior descending coronary artery using intravascular ultrasound (IVUS), we conducted 90-day landmark analyses to compare shorter and longer DAPT. DAPT discontinuation was defined as withdrawal of P2Y12inhibitors or aspirin for at least 2 months. The prevalence of acute coronary syndrome and high bleeding risk by the Bleeding Academic Research Consortium were 14.2% and 52.5%, respectively. The cumulative incidence of DAPT discontinuation was 22.6% at 90 days, and 68.8% at 1 year. In the 90-day landmark analyses, there were no differences in the incidences of a composite of death, myocardial infarction, stroke, or any coronary revascularization (5.9% vs. 9.2%, log-rank P=0.12; adjusted hazard ratio, 0.59; 95% confidence interval, 0.32-1.08; P=0.09) and BARC type 3 or 5 bleeding (1.4% vs. 1.9%, log-rank P=0.62) between the off- and on-DAPT groups at 90 days.

CONCLUSIONS

The adoption of short DAPT duration was still low in this trial conducted after the release of the STOPDAPT-2 trial results. The 1-year incidence of cardiovascular events was not different between the shorter and longer DAPT groups, suggesting no apparent benefit of prolonged DAPT in reducing cardiovascular events even in patients who undergo multivessel PCI.

Comparison of the OPTIVUS-Complex PCI Multivessel Cohort With the Historical CREDO-Kyoto Registry Cohort-3

BACKGROUND

There is a paucity of data on the effect of optimal intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) compared with standard PCI or coronary artery bypass grafting (CABG) in patients with multivessel disease.Methods and Results: The OPTIVUS-Complex PCI study multivessel cohort was a prospective multicenter single-arm study enrolling 1,021 patients undergoing multivessel PCI including the left anterior descending coronary artery using IVUS aiming to meet the prespecified criteria for optimal stent expansion. We conducted propensity score matching analyses between the OPTIVUS group and historical PCI or CABG control groups from the CREDO-Kyoto registry cohort-3 (1,565 and 899 patients) fulfilling the inclusion criteria for this study. The primary endpoint was a composite of death, myocardial infarction, stroke, or any coronary revascularization. In the propensity score-matched cohort (OPTIVUS vs. historical PCI control: 926 patients in each group; OPTIVUS vs. historical CABG control: 436 patients in each group), the cumulative 1-year incidence of the primary endpoint was significantly lower in the OPTIVUS group than in the historical PCI control group (10.4% vs. 23.3%; log-rank P<0.001) or the historical CABG control group (11.8% vs. 16.5%; log-rank P=0.02).

CONCLUSIONS

IVUS-guided PCI targeting the OPTIVUS criteria combined with contemporary clinical practice was associated with superior clinical outcomes at 1 year compared with not only the historical PCI control, but also the historical CABG control.

Single-Session Versus Staged Multivessel Optimal IVUS-Guided PCI in Patients With CCS or NSTE-ACS

Background

There are no studies comparing single-session vs staged multivessel intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) in patients with chronic coronary syndrome (CCS) or non-ST-segment-elevation acute coronary syndrome (NSTE-ACS).

Objectives

The authors aimed to compare single-session vs staged multivessel IVUS-guided PCI in patients with CCS or NSTE-ACS.

Methods

The OPTIVUS-Complex PCI study multivessel cohort was a prospective multicenter single-arm trial enrolling 1,021 patients with CCS or NSTE-ACS undergoing multivessel PCI including left anterior descending coronary artery using IVUS aiming to meet the prespecified OPTIVUS criteria for optimal stent expansion. We compared single-session vs staged multivessel PCI. The primary endpoint was a composite of death, myocardial infarction, stroke, or any coronary revascularization.

Results

There were 246 patients (24.1%) undergoing single-session multivessel PCI, and 775 patients (75.9%) undergoing staged multivessel PCI. There was a wide variation in the prevalence of single-session multivessel PCI across the participating centers. The staged multivessel PCI group more often had complex coronary anatomy such as 3-vessel disease, chronic total occlusion, and calcified lesions requiring an atherectomy device compared with the single-session multivessel PCI group. The rates of PCI success, procedural complications, and meeting OPTIVUS criteria were not different between groups. The cumulative 1-year incidence of the primary endpoint was not different between single-session and staged multivessel PCI groups (9.0% vs 10.8%, log-rank P = 0.42). After adjusting confounders, the effect of single-session multivessel PCI relative to staged multivessel PCI was not significant for the primary endpoint (HR: 0.95; 95% CI: 0.58-1.55; P = 0.84).

Conclusions

Single-session and staged multivessel IVUS-guided PCI had similar 1-year outcomes.

Target Lesion Revascularization After Intravascular Ultrasound-Guided Percutaneous Coronary Intervention

BACKGROUND

Several stent expansion criteria derived from the intravascular ultrasound (IVUS) evaluation have been proposed to predict future clinical outcomes, but optimal stent expansion criteria as a guide during percutaneous coronary intervention (PCI) are still controversial. There are no studies evaluating the utility of stent expansion criteria along with the clinical and procedural factors in predicting target lesion revascularization (TLR) after contemporary IVUS-guided PCI.

METHODS

OPTIVUS-Complex PCI study (Optimal Intravascular Ultrasound Guided Complex Percutaneous Coronary Intervention) multivessel cohort was a prospective multicenter study enrolling 961 patients undergoing multivessel PCI including left anterior descending coronary artery using IVUS with an intention to meet the prespecified criteria for optimal stent expansion. We compared several stent expansion criteria (minimum stent area [MSA], MSA/distal or average reference lumen area, MSA/distal or average reference vessel area, OPTIVUS criteria, IVUS-XPL [Impact of Intravascular Ultrasound Guidance on Outcomes of Xience Prime Stents in Long Lesions] criteria, ULTIMATE [Intravascular Ultrasound Guided Drug Eluting Stents Implantation in "All-Comers" Coronary Lesions] criteria, and modified MUSIC [Multicenter Ultrasound Stenting in Coronaries Study] criteria) as well as clinical, angiographic, and procedural characteristics between lesions with and without TLR.

RESULTS

Among 1957 lesions, the cumulative 1-year incidence of lesion-based TLR was 1.6% (30 lesions). Hemodialysis, treatment of proximal left anterior descending coronary artery lesions, calcified lesions, small proximal reference lumen area, and small MSA had univariate associations with TLR, while all of the stent expansion criteria except for MSA were not associated with TLR. The independent risk factors of TLR were calcified lesions (hazard ratio, 2.34 [95% CI, 1.03-5.32]; P=0.04) and small proximal reference lumen area (Tertile 1: hazard ratio, 7.01 [95% CI, 1.45-33.93]; P=0.02; and Tertile 2: hazard ratio, 5.40 [95% CI, 1.17-24.90]; P=0.03).

CONCLUSIONS

In contemporary IVUS-guided PCI practice, the 1-year incidence of TLR was very low. MSA, but not other stent expansion criteria, had univariate association with TLR. Independent risk factors of TLR were calcified lesions and small proximal reference lumen area, although the findings should be interpreted with caution due to small number of TLR events, limited lesion complexity, and short duration of follow-up.

Optimal Intravascular Ultrasound-Guided Percutaneous Coronary Intervention in Patients With Multivessel Disease

Background

Intravascular ultrasound (IVUS) was only rarely used in landmark trials comparing percutaneous coronary intervention (PCI) with coronary artery bypass grafting (CABG) in patients with multivessel disease.

Objectives

The authors aimed to evaluate clinical outcomes after optimal IVUS-guided PCI in patients undergoing multivessel PCI.

Methods

The OPTIVUS (OPTimal IntraVascular UltraSound)-Complex PCI study multivessel cohort was a prospective multicenter single-arm study enrolling 1,021 patients undergoing multivessel PCI, including left anterior descending coronary artery using IVUS, aiming to meet the prespecified criteria (OPTIVUS criteria: minimum stent area > distal reference lumen area [stent length ≥28mm], and minimum stent area >0.8 × average reference lumen area [stent length <28mm]) for optimal stent expansion. The primary endpoint was major adverse cardiac and cerebrovascular events (MACCE) (death/myocardial infarction/stroke/any coronary revascularization). The predefined performance goals were derived from the CREDO-Kyoto (Coronary REvascularization Demonstrating Outcome study in Kyoto) PCI/CABG registry cohort-2 fulfilling the inclusion criteria in this study.

Results

In this study, 40.1% of the patients met OPTIVUS criteria in all stented lesions. The cumulative 1-year incidence of the primary endpoint was 10.3% (95% CI: 8.4%-12.2%), which was significantly lower than the predefined PCI performance goal of 27.5% (P < 0.001), and which was numerically lower than the predefined CABG performance goal of 13.8%. The cumulative 1-year incidence of the primary endpoint was not significantly different regardless of meeting or not meeting OPTIVUS criteria.

Conclusions

Contemporary PCI practice conducted in the OPTIVUS-Complex PCI study multivessel cohort was associated with a significantly lower MACCE rate than the predefined PCI performance goal, and with a numerically lower MACCE rate than the predefined CABG performance goal at 1 year.

A systematic review and meta-analysis of upgrade to biventricular or conduction system pacing approaches

Introduction

Chronic RV pacing has been recognised as being harmful to cardiac function. Patients undergoing a de novo pacemaker implant with even mild LV impairment are recommended to instead receive a physiological pacing strategy (biventricular or conduction system pacing [CSP]). No corresponding guideline recommendation exists for patients who already have a pacemaker.

Methods

We undertook a random-effects meta-analysis of all RCTs and observational studies covering device upgrade to biventricular pacing or conduction system pacing.

Results

6 RCTs assessing effect of upgrade to BiV pacing randomising 161 patients were eligible for analysis. Eligible observational studies included 46 of BiV upgrade and 7 of CSP upgrade totalling 2795 patients.

Mean LVEF improved by +8.3% from 34.4% in BiV upgrade RCTs (p=0.001) and +8.3% from 25.7% in BiV upgrade observational studies (p&lt;0.001).

In observational studies of upgrade to CSP, LVEF increased by +10.1% from 38.4% (p=0.001) despite less severe LV impairment at baseline (p=0.004 vs mean EF in BiV RCTs and p&lt;0.0001 vs mean EF in BiV observational studies).

LVESV decreased significantly by −25.4 ml, −23.7 ml, and −19.8 ml in BiV RCTs, BiV observational studies and CSP observational studies. Significant changes were also seen in NYHA class (decreased by −0.4, −0.8 and −1.0 respectively).

Minnesota Heart Failure Score (−6.9 points) and peak oxygen uptake (+1.1 ml/kg/min) increased significantly in RCTs of BiV upgrade. This was also seen in observational studies of BiV upgrade (−21.0 points and +2.63 ml/kg/min respectively).

Conclusions

RCTs and observational studies of upgrade to BiV pacing show significant physiological and symptomatic benefit. Observational studies of CSP upgrade show similar benefit with significant improvements in LVEF, LVESV and NYHA class in patients with an even milder degree of baseline LV impairment.

Funding Acknowledgement

Type of funding sources: None.

Laser doppler derived peripheral perfusion can distinguish haemodynamically tolerated VT from haemodynamically compromised VT

Funding Acknowledgements

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): NIHR Imperial Biomedical Research Centre

Introduction

Implantable Cardioverter-Defibrillators (ICDs) cannot distinguish between ventricular tachycardia (VT) with haemodynamic compromise from haemodynamically tolerated VT to ensure that therapies are delivered only when necessary. Currently, unnecessary therapies are reduced by longer duration thresholds and higher rate thresholds. This can result in ICDs withholding or delaying therapies during haemodynamically compromising VT while potentially still providing therapies during rapid or prolonged VT that is haemodynamically well tolerated.

Laser doppler perfusion monitoring (LDPM) allows assessment of peripheral blood flow as a surrogate for haemodynamic status. We have previously demonstrated that laser doppler perfusion signals, analysed using an electro-mechanical coupling algorithm (SafeShock), can reliably identify loss of perfusion during ventricular fibrillation (VF), as well as discriminate VF from simulated lead fractures and T wave over-sensing. The utility of LDPM signals in VT, however, has not been established.

Purpose

In this study we assessed the utility of LDPM using the SafeShock algorithm to discriminate haemodynamically tolerated VT from VT with haemodynamic compromise.

Methods

Recruited participants underwent a rapid ventricular pacing protocol to simulate VT at different rates. Pacing was performed using the right ventricular lead of an implanted pacing device or a temporary pacing wire in the right ventricular apex. 3-lead ECG, blood pressure (either invasively using a radial artery catheter or non-invasively using beat-by-beat finometry) and LDPM signal were continuously recorded during the protocol. LDPM signals during simulated VT were analysed using the SafeShock electro-mechanical algorithm and compared to blood pressure change from baseline intrinsic rhythm to simulated VT.

Results

We obtained 588 recordings of simulated VT in 56 patients at rates of 100 bpm, 120 bpm, 140 bpm, 160 bpm, 180 bpm and 200 bpm. Percentage change in systolic blood pressure from baseline to VT correlated with LDPM-derived perfusion value during VT (Spearman’s Rho = 0.7786, p &lt; 0.0001).

Using a cut-off of 5 units, perfusion value predicted a 20% drop in systolic blood pressure in VT with an accuracy of 89.4% (sensitivity 94.8%, specificity 83.6%, p value &lt;0.0001).

Conclusions

Peripheral perfusion measurements, analysed using an electro-mechanical algorithm, can accurately discriminate haemodynamically tolerated VT from VT with haemodynamic compromise. ICDs with integrated LDPM sensors and algorithms could make therapy decisions based on the circulatory status of patients with arrhythmias not just rate and duration parameters. This could reduce unnecessary therapies while facilitating prompt treatment of compromising arrhythmias. Abstract Figure 1

Validity of the Low-Impact Dance for exercise-based cardiac rehabilitation program

PURPOSE

The aim of this study was to evaluate the oxygen uptake in patients with cardiovascular disease during the low-impact dance program and to compare the findings with the values at peak oxygen uptake (VO2) and aerobic threshold (AT).

METHODS

The study included 19 patients with cardiovascular disease [age, 68.3±8.7 years; left-ventricular ejection fraction, 60.3%±8.7%; peak VO2, 6.6±1.1 metabolic equivalents (METs)] who were receiving optimal medical treatment. Their heart rate and VO2 were monitored during cardiopulmonary exercise testing (CPET) and during the low impact dance. The dance involved low-impact dynamic sequences. The patients completed two patterns of low-impact dance, and metabolic gas exchange measurements were obtained using a portable ergospirometry carried in a backpack during the dance sessions.

RESULTS

The mean values of VO2 (4.0±0.2 METs and 3.9±0.3 METs) and those of heart rate (105.2±2.9 bpm and 96.8±2.6 bpm) during the dance program were not significantly differ from the AT value (4.5±0.2 METs) obtained in CPET. The median (and interquartile range) RPE reported after the dance exercise trials was 11 (9-13). No signs of overexertion were observed in any of the patients during either dance exercise trial.

CONCLUSIONS

The results suggest that it is reasonable to consider the low-impact dance program as an aerobic exercise program in cardiac rehabilitation. Our findings have important implications for exercise training programs in the cardiac rehabilitation setting and for future studies.

Effects of sitagliptin on coronary atherosclerosis in patients with type 2 diabetes-A serial integrated backscatter-intravascular ultrasound study

Dipeptidyl peptidase-4 (DPP-4) inhibitors have demonstrated anti-inflammatory and anti-atherogenic effects in an animal model. However, the clinical usefulness of DPP-4 inhibitors, particularly its effects on coronary atherosclerosis, has not been evaluated thus far. Therefore, in this study, we evaluated the effects of sitagliptin, a DPP-4 inhibitor, on coronary atherosclerosis using integrated backscatter (IB)-intravascular ultrasound (IVUS) in patients with type 2 diabetes. This trial was a prospective, open-labeled, randomized, multicenter study. Twenty-eight patients with type 2 diabetes who underwent elective percutaneous coronary intervention (PCI) were randomly assigned to either the sitagliptin group (group S) or the control group (group C). Non-PCI lesions were evaluated using IB-IVUS at the time of PCI and at the 48-week follow-up. The primary endpoint was the percentage change in plaque volume measured using grayscale IVUS, and the secondary endpoint was changes in plaque composition evaluated using IB-IVUS. Grayscale IVUS analysis demonstrated that plaque volume tended to decrease in both groups (group S: -1.7±8.5%; group C: -3.2±12.2%), but a between-group difference was not observed. A decrease in the lipid plaque volume (group S: from 200.1±116.2 to 179.8±121.0 mm³, P = 0.02; group C: from 298.3±363.0 to 256.6±386.1 mm³, P = 0.1) and an increase in the calcified plaque volume (group S: from 2.1±0.9 to 3.2±1.8 mm³, P = 0.06; group C: from 2.3±1.7 to 4.8±3.5 mm³, P = 0.04) was observed on IB-IVUS analysis. Univariate and multivariate regression analyses showed that the percentage change in serum non-high-density lipoprotein (HDL) cholesterol level was an independent and significant predictor of a reduction in lipid plaque volume (β = 0.445, P = 0.04). In conclusions, sitagliptin did not significantly reduce coronary plaque volume in patients with type 2 diabetes. However, a decrease in the lipid plaque volume was observed in the sitagliptin group. A decrease in non-HDL cholesterol level was associated with a reduction in the lipid volume of coronary artery plaques.

Peri-stent contrast staining and very late stent thrombosis after sirolimus-eluting stent implantation: an observation from the RESTART (REgistry of Stent Thrombosis for review And Re-evaluaTion) angiographic substudy

AIMS

The aim of the study was to clarify the angiographic characteristics of stent thrombosis (ST) in relation to sirolimus-eluting stents (SES).

METHODS AND RESULTS

RESTART is a Japanese registry of SES-associated ST. As an angiographic substudy, coronary angiograms at baseline, at six to 12 months and at the time of ST were analysed. Angiograms of 313 patients (early ST [EST] 169 patients, late ST [LST] 59 patients, and very late ST [VLST] 85 patients) were investigated. Residual dissection post procedure was more frequently seen in the EST group. Stent fracture was more frequently seen in the VLST group than in the EST and LST groups (16.5%, 3.0%, and 3.4%, respectively; p<0.001). Peri-stent contrast staining (PSS), defined as contrast staining outside the stent contour extending to ≥20% of the stent diameter, was remarkably more prevalent in the VLST group than in the EST and LST groups (34.1%, 4.7%, and 6.8%, respectively; p<0.001).

CONCLUSIONS

Abnormal angiographic findings such as PSS and stent fracture were found significantly more frequently in lesions with VLST than in lesions with EST and LST.

Effects of sitagliptin on coronary atherosclerosis evaluated using integrated backscatter intravascular ultrasound in patients with type 2 diabetes: rationale and design of the TRUST study

Patients with diabetes mellitus are at high risk for developing coronary artery disease (CAD), even if they are treated with statins. Several studies have shown the beneficial effects of dipeptidyl peptidase-4 (DPP-4) inhibitors on the cardiovascular system in an animal model. However, recent clinical trials using DPP-4 inhibitors have shown that these inhibitors fail to reduce the occurrence of cardiovascular events. Therefore, this study will be performed to evaluate the effects of sitagliptin, a DPP-4 inhibitor, on coronary atherosclerosis in patients with type 2 diabetes. This study will be a prospective, open-label, randomized multicenter trial performed in 6 centers in Japan. Stable CAD patients with type 2 diabetes who have undergone successful percutaneous coronary intervention under integrated backscatter (IB)-intravascular ultrasound (IVUS) guidance will be studied. They will be randomly assigned to either the sitagliptin group or a control group. After 48 weeks' treatment, the IVUS examination will be repeated in the same coronary artery as at baseline. The primary end point will be the percentage change in plaque volume measured using grayscale IVUS from baseline to the 48-week follow-up. This study will be the first multicenter trial to evaluate the effects of a DPP-4 inhibitor on coronary atherosclerosis evaluated using IB-IVUS, and the findings will clarify the anti-atherogenic effects of sitagliptin.

Angiographic findings of everolimus-eluting as compared to sirolimus-eluting stents: angiographic sub-study from the Randomized Evaluation of Sirolimus-eluting versus Everolimus-eluting stent Trial (RESET)

Several recent randomized trials comparing everolimus-eluting stent (EES) and sirolimus-eluting stent (SES) reported similar clinical outcomes. This study was aimed to clarify the differences in the angiographic findings of EES as compared to SES. Randomized Evaluation of Sirolimus-eluting versus Everolimus-eluting stent Trial is a prospective multicenter randomized open-label trial comparing EES with SES in Japan. From February to July 2010, 3197 patients were randomly assigned to receive either EES or SES. Of these, angiographic sub-study enrolled 571 patients (EES 285 patients, SES 286 patients). Angiograms were assessed qualitatively and quantitatively at procedure and at 8-12 months in the independent core angiographic laboratory. Late loss of the proximal edges tended to be greater in the EES group than that in the SES group (0.12 ± 0.49 vs. 0.04 ± 0.43 mm, P = 0.05), although late loss in the other segments was similar between the 2 groups. Edge restenosis was mainly observed in EES group, whereas body restenosis was demonstrated in half of SES group. Stent fracture was observed only in the SES group (1.5 %), and peri-stent contrast staining (PSS) tended to be more frequently observed in the SES group than in the EES group (3.6 and 1.5 %, P = 0.18). Restenotic response in the proximal edge was more prominent in the EES group as compared to the SES group. Abnormal angiographic findings such as stent fracture and PSS tended to be more frequent in the SES group.

Validity and reliability of new intravascular ultrasound analysis software for morphological measurement of coronary artery disease

BACKGROUND

Intravascular ultrasound (IVUS) analysis software enables precise planimetry measurement and tissue characterization of coronary plaque. Recently, a new IVUS analysis software compatible with integrated backscatter-IVUS, VISIATLAS(TM), was developed. The validity and reliability of VISIATLAS(TM) were evaluated.

METHODS AND RESULTS

Forty patients who underwent IVUS-guided percutaneous coronary intervention were enrolled, and planimetry measurements were performed by 2 observers using VISIATLAS(TM) and echoPlaque(TM). IVUS analysis was performed in non-stent segments in 10 patients (non-target vessel, n=5; target vessel before stent implantation, n=5) at every 2.5mm for 20 slices in each patient. Stent segments were analyzed in the remaining 30 patients. With VISIATLAS(TM), the intraobserver and interobserver intraclass correlation coefficients (ICC) for the area of external elastic membrane (EEM), lumen, and plaque plus media (P+M) were 0.999 and 0.999, 0.996 and 0.993, and 0.993 and 0.991, respectively. The intersoftware ICC for EEM, lumen, and P+M area were 0.997, 0.993, and 0.985, respectively. The ICC of stent volume for intraobserver, interobserver and intersoftware comparisons were 0.997, 0.993, and 0.998, respectively. Bland-Altman plots showed small differences and narrow limits of agreement for all of the above parameters.

CONCLUSIONS

VISIATLAS(TM) has high repeatability and reproducibility of measurement. This new IVUS analysis software is suitable for accurate measurement of coronary artery and stent structure in future IVUS studies.

Sex differences in neointimal hyperplasia following endeavor zotarolimus-eluting stent implantation

Inconsistent results in outcomes have been observed between the genders after drug-eluting stent implantation. The aim of this study was to investigate gender differences in neointimal proliferation for the Endeavor zotarolimus-eluting stent (ZES) and the Driver bare-metal stent (BMS). A total of 476 (n = 391 ZES, n = 85 BMS) patients whose volumetric intravascular ultrasound analyses were available at 8-month follow-up were studied. At 8 months, neointimal obstruction and maximum cross-sectional narrowing (CSN) were significantly lower in women than in men receiving ZES (neointimal obstruction 15.5 ± 9.5% vs 18.2 ± 10.9%, p = 0.025; maximum CSN 30.3 ± 13.2% vs 34.8 ± 15.0%, p = 0.007). Conversely, these parameters tended to be higher in women than in men receiving BMS (neointimal obstruction 36.3 ± 15.9% vs 27.5 ± 17.2%, p = 0.053; maximum CSN 54.3 ± 18.6% vs 45.6 ± 18.3%, p = 0.080). There was a significant interaction between stent type and gender regarding neointimal obstruction (p = 0.001) and maximum CSN (p = 0.003). Multivariate linear regression analysis revealed that female gender was independently associated with lower neointimal obstruction (p = 0.027) and maximum CSN (p = 0.004) for ZES but not for BMS. Compared to BMS, ZES were independently associated with a reduced risk for binary restenosis in both genders (odds ratio for women 0.003, p = 0.001; odds ratio for men 0.191, p <0.001), but the magnitude of this risk reduction with ZES was significantly greater in women than men (p = 0.015). In conclusion, female gender is independently associated with decreased neointimal hyperplasia in patients treated with ZES. The magnitude of risk reduction for binary restenosis with ZES is significantly greater in women than in men.

[Current percutaneous coronary intervention technology for management of coronary artery disease]

Enormous advance was obtained in the field of percutaneous coronary intervention, treatment for coronary artery disease. Drug eluting stent (DES) offers advantages over bare metal stent (BMS) such as reduction in restenosis rates. However, several concerns were proposed when compared with BMS. Currently, numerous technologies are under development to avert the complications of DES, such as stent thrombosis, or to challenge complex lesion, such as left main trunk/bifurcation. We summarized some of the development that is emerging on current management of coronary intervention.

Coronary artery stent evaluation using a vascular model at 64-detector row CT: comparison between prospective and retrospective ECG-gated axial scans

Objective

We wanted to evaluate the performance of prospective electrocardiogram (ECG)-gated axial scans for assessing coronary stents as compared with retrospective ECG-gated helical scans.

Materials and Methods

As for a vascular model of the coronary artery, a tube of approximately 2.5-mm inner diameter was adopted and as for stents, three (Bx-Velocity, Express2, and Micro Driver) different kinds of stents were inserted into the tube. Both patent and stenotic models of coronary artery were made by instillating different attenuation (396 vs. 79 Hounsfield unit [HU]) of contrast medium within the tube in tube model. The models were scanned with two types of scan methods with a simulated ECG of 60 beats per minute and using display field of views (FOVs) of 9 and 18 cm. We evaluated the in-stent stenosis visually, and we measured the attenuation values and the diameter of the patent stent lumen.

Results

The visualization of the stent lumen of the vascular models was improved with using the prospective ECG-gated axial scans and a 9-cm FOV. The inner diameters of the vascular models were underestimated with mean measurement errors of -1.10 to -1.36 mm. The measurement errors were smaller with using the prospective ECG-gated axial scans (Bx-Velocity and Express2, p < 0.0001; Micro Driver, p = 0.0004) and a 9-cm FOV (all stents: p < 0.0001), as compared with the other conditions, respectively. The luminal attenuation value was overestimated in each condition. For the luminal attenuation measurement, the use of prospective ECG-gated axial scans provided less measurement error compared with the retrospective ECG-gated helical scans (all stents: p < 0.0001), and the use of a 9-cm FOV tended to decrease the measurement error.

Conclusion

The visualization of coronary stents is improved by the use of prospective ECG-gated axial scans and using a small FOV with reduced blooming artifacts and increased spatial resolution.

Comparison of vascular response to zotarolimus-eluting stent versus sirolimus-eluting stent: intravascular ultrasound results from ENDEAVOR III

BACKGROUND

The purpose of this study was to investigate the vascular response of zotarolimus-eluting stent (ZES) and sirolimus-eluting stent (SES) using serial intravascular ultrasound (IVUS).

METHODS

Data were obtained from the Endeavor Drug-Eluting Coronary Stent System Versus the Center Siromlimus-Eluting Coronary Stent System in De Novo Native Coronary Artery Lesions (ENDEAVOR) III trial, a randomized study comparing ZES and SES for the treatment of de novo native coronary artery lesions. Serial (baseline and 8-month follow-up) IVUS was available in 258 patients (190 ZES, 68 SES).

RESULTS

At 8 months, ZES had greater percentage of neointimal volume index (ZES 1.1 +/- 0.8 mm3/mm vs SES 0.2 +/- 0.1 mm3/mm, P < .01), resulting in smaller lumen volume index (6.0 +/- 2.0 mm3/mm vs 7.0 +/- 2.1 mm3/mm, P < .05). Zotarolimus-eluting stents showed larger IVUS-detectable neointimal coverage over stent surface (50.2% vs 10.5%, P < .01) and greater mean neointimal thickness (0.19 +/- 0.07 mm vs 0.10 +/- 0.06 mm, P < .01). Zotarolimus-eluting stents had a significantly lower incidence of late-acquired incomplete stent apposition.

CONCLUSIONS

Zotarolimus-eluting stent is associated with a significantly greater amount of neointimal hyperplasia compared with SES. This amount of hyperplasia in ZES is distributed throughout the stent at 8-month follow-up.

Characterization of late incomplete stent apposition: a comparison among bare-metal stents, intracoronary radiation and sirolimus-eluting stents

BACKGROUND

Late incomplete stent apposition (LISA) develops following implantation of conventional bare-metal stents (BMS) or drug-eluting stents, or after adjunctive intracoronary radiation (IR). However, no study has systematically compared the morphology of LISA seen with various treatment modalities.

PURPOSE

To compare the morphometric features of LISA accompanying BMS, IR or sirolimus-eluting stents (SES) using serial intravascular ultrasound (IVUS).

METHODS

A query of Stanford University's IVUS database of the Cardiovascular Core Analysis Laboratory was performed to identify LISA cases. Dedicated software programs were used for volumetric IVUS analyses.

RESULTS

In 30 LISA cases (12 BMS, 6 IR and 12 SES), there was no intertreatment difference in the degree of LISA (lumen area minus stent area at follow up). Serial analyses of LISA segments showed that vessel area of SES and IR showed significant increase at follow up as compared with post procedure, while there was no significant change in plaque area. In contrast, the BMS group showed no increase in vessel area, whereas plaque area revealed significant reduction. Eight of 12 BMS cases were treated by directional atherectomy before stenting; however, there was no difference in the area change between patients with or without pre-stent atherectomy. Post-procedure plaque thickness beneath the stent struts of LISA was thinner for SES as compared with BMS.

CONCLUSIONS

Plaque reduction primarily contributes to LISA after BMS, whereas vessel expansion is the predominant factor in LISA development for IR and SES. Thus, the mechanism of LISA may vary among different interventional treatments.

Impact of gender on neointimal hyperplasia following coronary artery stenting

Whether gender affects long-term outcomes after bare metal stent implantation remains controversial. The aim of this study was to examine the impact of gender on neointimal hyperplasia in a large cohort of patients after stent implantation using 3-dimensional intravascular ultrasound. Lumen and stent areas were manually traced at 0.5-mm intervals throughout the stented segment. Using Simpson's method, lumen, stent, and neointimal (stent - lumen) volumes were calculated and standardized by stent length. Women were older, presented more often with hyperlipidemia or hypertension, and had smaller reference vessel diameter and mean stent area, compared with men. Although neointimal hyperplasia and neointimal thickness in women were similar to that in men, the percentage of neointimal hyperplasia (neointimal area divided by stent area) was higher in women due to the smaller stent area. After adjusting for stent area, the percentage of neointimal hyperplasia did not differ by gender. In conclusion, the results of this study indicate that neointimal hyperplasia after bare metal stent implantation in women is similar to that seen in men. Despite the similarity in outcome, there are several gender-specific differences in baseline characteristics.

Intracoronary nicorandil prior to reperfusion in acute myocardial infarction

BACKGROUND

A prospective, randomised, single centre study was designed to test the safety and efficacy of nicorandil infusion, a potassium channel opener, prior to reperfusion in ST-elevation acute myocardial infarction (STEMI).

METHODS AND RESULTS

Seventy STEMI patients with TIMI 0 to 2 flow were randomly assigned to nicorandil (Group N; n = 35) or control (Group C; n = 35) and underwent direct percutaneous coronary intervention (PCI). In Group N, 2 mg of nicorandil was infused directly into the infarct area prior to reperfusion. Incidence of anterior infarction was 60% in both groups. With nicorandil infusion, additional ST elevations without chest pain were observed for a few minutes in 94% of cases. However, no ventricular fibrillation or ventricular tachycardia occurred. TIMI myocardial perfusion grade 3 was significantly higher in Group N (40% vs. 17%, p<0.01). Patients were followed for up to 8 months, with similar incidence of major clinical adverse events, however left ventricular regional wall motion score significantly improved in Group N (P < 0.05). The effect of nicorandil was seen in patients without ischaemic preconditioning (P < 0.05).

CONCLUSION

This study suggests that direct infusion of nicorandil prior to revascularisation may be safe and beneficial.

Heterogeneity of neointimal distribution of in-stent restenosis in patients with diabetes mellitus

Diabetes mellitus is an independent predictor of restenosis after percutaneous coronary intervention. The pattern of restenosis after bare metal stent implantation in diabetic patients was examined with 3-dimensional intravascular ultrasound analysis. Lumen and stent were manually traced at every 0.5-mm interval in stented segments. Using Simpson's method, stent, luminal, and neointimal (stent minus lumen) volumes were calculated and average area was calculated as volume data divided by length. To measure the cross-sectional and longitudinal severities of luminal encroachment by the neointima, percent neointimal area (neointimal area divided by stent area) and neointimal hyperplasia 50 (IH50) (defined as percent stent length with percent neointimal area >50%) were calculated. In 278 patients (68 with diabetes and 210 without diabetes), there was a significantly higher percentage of maximal percent neointimal area with significantly longer percent stent length that was severely encroached by the neointima in diabetic patients. Diabetic patients showed a more heterogenous pattern of the neointima after bare metal stenting, resulting in longer high-grade obstruction segments. This may have important implications for stent design and pharmacokinetic properties of next-generation drug-eluting technology for this complex patient subset.

Novel stent system for bifurcation lesions: Examination by intravascular ultrasound

Bifurcation disease represents a mechanical and biological challenge for definitive interventional treatment. This case report discusses an experience with a novel stent system designed for the treatment of bifurcation lesions.

The impact of metallic allergy on stent implantation

BACKGROUND

Relation between metallic allergy and in-stent restenosis (ISR) has been inconclusive. We hypothesized that mechanism of restenosis is different between initial stent implantation and dilatation for ISR. Thus, we studied metallic allergy and restenosis in these two different situations separately.

METHODS AND RESULTS

We performed follow-up angiography and patch test for metallic allergy in a total of 174 stented consecutive patients, 109 patients (63%) for restudy of initial stent implantation and 65 patients (37%) for restudy of treatment following ISR. The positive rate of patch test in initial stent implantation was not significantly different between with or without restenosis (10% vs. 9%; p=ns). Whereas, following dilatation of ISR, the incidence of positive patch test was significantly higher in patients with recurrence of restenosis than those without the recurrence (39% vs. 12%; p=0.02). Multivariate analysis revealed that the positive patch test (Odd Ratio 4.39, p=0.02) and diffuse typed ISR (Odd Ratio 3.68, p=0.03) were significant predictors of recurrent restenosis.

CONCLUSIONS

Metal allergy does not have any correlation with the restenosis after initial stent implantation. However, metal allergy is frequently observed in patients with recurrence of ISR. Metal allergy may contribute to a mechanism in the repeat recurrence of ISR, but not to restenosis after initial stent implantation.

Effect of lumen narrowing within coronary stents on proximal and distal vessel segments following bare metal stent implantation

Adjacent reference vessel response to smaller lumens at stented segments was examined with 3-dimensional intravascular ultrasound analysis. In 128 patients after bare metal stent implantation, minimal lumen area (MLA) within the stent and average lumen area at distal/proximal adjacent reference segments (5 mm) were obtained at baseline and follow-up. In the smaller in-stent MLA group (MLA <3 mm2), lumen area decreased significantly at the distal edge compared with the larger in-stent MLA group (MLA > or =3 mm2), although no significant difference was seen at the proximal edge. In-stent lumen patency may influence vascular responses at adjacent reference segments after bare metal stent implantation.

Initial characterization of Ikari Guide catheter for transradial coronary intervention

Ikari is a new guide catheter for transradial intervention (TRI) that produces stronger back-up force by utilizing an unfavorable angle between the subclavian and brachiocephalic arteries. We report the initial results of the Ikari guide catheter based on the experience of a single center. Six operators performed a total of 102 coronary interventions for 91 patients using the Ikari guide catheter, while 101 interventions were performed with the transfemoral approach (TFI) during the same period. A left Ikari catheter was used in 63 procedures, and a right Ikari catheter was used in 39. The success rate for the procedure was 97% with a 6 French Ikari catheter. All failures were due to tortuous brachiocephalic arteries. For the Ikari procedure, the average fluorescence time was 14.5 9.5 minutes and the dye volume used was 153 53 ml; these results were equal to or better than those of TFI during the same period (20.1 12.2 minutes and 184 61 ml, respectively). These preliminary data suggest that an acceptable success rate can be achieved in TRI using appropriate guides, such as an Ikari catheter.

Activation of the nicotinic acetylcholine receptor involves a switch in conformation of the alpha subunits

The nicotinic acetylcholine (ACh) receptor belongs to a superfamily of synaptic ion channels that open in response to the binding of chemical transmitters. Their mechanism of activation is not known in detail, but a time-resolved electron microscopic study of the muscle-type ACh receptor had suggested that a local disturbance in the ligand-binding region and consequent rotations in the ligand-binding alpha subunits, connecting to the transmembrane portion, are involved. A more precise interpretation of this structural change is given here, based on comparison of the extracellular domain of the ACh receptor with an ACh-binding protein (AChBP) to which a putative agonist is bound. We find that, to a good approximation, there are two alternative extended conformations of the ACh receptor subunits, one characteristic of either alpha subunit before activation, and the other characteristic of all three non-alpha subunits and the protomer of AChBP. Substitution in the three-dimensional maps of alpha by non-alpha subunits mimics the changes seen on activation, suggesting that the structures of the alpha subunits are modified initially by their interactions with neighbouring subunits and switch to the non-alpha form when ACh binds. This structural change, which entails 15-16 degrees rotations of the inner pore-facing parts of the alpha subunits, most likely acts as the trigger that opens the gate in the membrane-spanning pore.

The effect of heat conditioning of the primary area before and after induction of hyperalgesia by topical/intradermal capsaicin or by controlled heat injury

The aim of the present study was to test the effect of heat conditioning before and after the induction of hyperalgesia. Three different methods were used for induction of hyperalgesia, topical capsaicin, intradermal capsaicin injection, and a controlled heat injury. The vascular (blood flow and skin temperature) and sensory changes (area of secondary hyperalgesia and ongoing pain) associated with the cutaneous hyperalgesia were compared. Each experiment consisted of two randomized sessions separated by at least 2 days. In one session, pre-conditioning of the skin by heat was performed 30 min before the induction of hyperalgesia using a probe at 45 degrees C for 5 min in the center of the expected primary hyperalgesic area. After the induction of hyperalgesia, heat conditioning was performed twice in the center of the primary hyperalgesic area using a temperature of 2 degrees C above the present individual pain threshold. On the contra-lateral arm, no heat conditioning was applied while hyperalgesia was induced using the same method. This session was evaluated as a control. The pre-conditioning induced an increased skin temperature in the primary area for both topical capsaicin and the controlled heat injury. Post-conditioning caused increased blood flow in the secondary hyperalgesic area for the topical capsaicin method and increased blood flow in the primary hyperalgesic area for the controlled heat injury method. However, conditioning with heat in an attempt to increase the C-fiber input did not have any effect on the ongoing pain ratings and sensory test results in any of the methods. The results of the present study suggest that there is still a need for a better experimental model with more stable allodynia both between sessions and between subjects while at the same time minimizing discomfort to the volunteer.

Dominant distribution of mitochondrial DNA from recipient oocytes in bovine embryos and offspring after nuclear transfer

In the process of nuclear transfer, heteroplasmic sources of mitochondrial DNA from a donor cell and a recipient oocyte are mixed in the cytoplasm of the reconstituted embryo. The distribution of mitochondrial DNA heteroplasmy in nuclear transfer bovine embryos and resultant offspring was investigated by measuring polymorphism in the displacement loop region of mitochondrial DNA using PCR-mediated single-strand conformation polymorphism. Most offspring (20 of 21 calves) from recipient oocytes of undefined mitochondrial DNA genotypes showed different genotypes from the mitochondrial DNA of donor cells. The single calf that was an exception showed heteroplasmy, including the donor mitochondrial DNA genotype. Six cloned calves were produced from oocytes of a defined mitochondrial DNA genotype. All of these clonal members and various tissues showed only the mitochondrial DNA genotype derived from the oocyte. The mitochondrial DNA from donor cells appeared to be eliminated during early embryonic development; it gradually decreased at the early cleavage stages and was hardly detectable by the blastocyst stage. These results indicate that the genotype of mitochondrial DNA from recipient oocytes may become the dominant category of mitochondrial DNA in calves resulting from nuclear transfer.

Nicotinic acetylcholine receptor at 4.6 A resolution: transverse tunnels in the channel wall

The nicotinic acetylcholine (ACh) receptor is the neurotransmitter-gated ion channel responsible for the rapid propagation of electrical signals between cells at the nerve/muscle synapse. We report here the 4.6 A structure of this channel in the closed conformation, determined by electron microscopy of tubular crystals of Torpedo postsynaptic membranes embedded in amorphous ice. The analysis was conducted on images recorded at 4 K with a 300 kV field emission source, by combining data from four helical families of tubes (-16,6; -18,6; -15,7; -17,5), and applying three-dimensional corrections for lattice distortions. The study extends earlier work on the same specimen at 9 A resolution. Several features having functional implications now appear with better definition. The gate of the channel forms a narrow bridge, consisting of no more than one or two rings of side-chains, across the middle portion of the membrane-spanning pore. Tunnels, framed by twisted beta-sheet strands, are resolved in the extracellular wall of the channel connecting the water-filled vestibule to the putative ACh-binding pockets. A set of narrow openings through which ions can flow are resolved between alpha-helical segments forming part of the cytoplasmic wall of the channel. It is suggested that the extracellular tunnels are access routes to the binding pockets for ACh, and that the cytoplasmic openings serve as filters to exclude anions and other impermeant species from the vicinity of the pore. Both transverse pathways are likely to be important in achieving a rapid postsynaptic response.

The structure of bacteriorhodopsin at 3.0 A resolution based on electron crystallography: implication of the charge distribution

Electron crystallography has the potential to visualise the charge status of atoms. This is due to the significantly different scattering factors of neutral and ionised atoms for electrons in the low-resolution range (typically less than 5 A). In previous work, we observed two different types of densities around acidic residues in the experimental (|Fo|) map of bacteriorhodopsin (bR), a light-driven proton pump. We suggested that these might reflect different states of the acidic residues; namely, the protonated (neutral) and the deprotonated (negatively charged) state. To evaluate the observed charge more quantitatively, we refined the atomic model for bR and eight surrounding lipids using our electron crystallographic data set between 8.0 and 3.0 A resolution, where the charge effect is small. The refined model yielded an R-factor of 23.7% and a free R-factor of 33.0%. To evaluate the effect of charges on the density map, we calculated a difference (|Fo|-|Fc|) map including data of a resolution lower than 8.0 A resolution, where the charge effect is significant. We found strong peaks in the difference map mainly in the backbone region of the transmembrane helices. We interpreted these peaks to come from the polarisation of the polar groups in the main chain of the alpha-helices and we examined this by assuming a partial charge of 0.5 for the peptide carbonyl groups. The resulting R and free R-factors dropped from 0.250 and 0.341 to 0.246 and 0.336, respectively. Furthermore, we also observed some strong peaks around some side-chains, which could be assigned to positively charged atoms. Thus, we could show that Asp36 and Asp102 are likely to interact with cations nearby. In addition, peaks found around the acidic residues Glu74, Glu194 and Glu212 have different features and might represent positive charges on polarised water molecules or hydroxonium ions.

Macromolecular structure determination by electron microscopy: new advances and recent results

Electron microscopy is undergoing a mini-renaissance, as a number of biological systems are yielding to higher resolution analysis as a result of advances in instrumentation, specimen preparation and image-processing technology. The atomic structure of tubulin has now been solved, crucial elements of secondary structure have recently been revealed in several membrane proteins (rhodopsin, gap junctions, aquaporin, and Ca2+ and H+ ATPases) and in a virus particle, and macromolecular complexes are being seen in increasingly fine detail. This growth has been enhanced further by the ability to combine structures of macromolecular complexes derived by electron microscopy with X-ray structures of their components, in order to reconstruct molecular machines and large multiprotein complexes in immense detail.