Distribution and magnitude of shear stress after coronary bifurcation lesions stenting with the classical crush technique: a new predictor for in-stent restenosis

Impact of intravascular ultrasound and final kissing balloon dilatation on long-term clinical outcome in percutaneous revascularization with 1-stent strategy for left main coronary artery stenosis in drug-eluting stent era

BACKGROUND

It remains uncertain whether intravascular ultrasound (IVUS) use and final kissing balloon (FKB) dilatation would be standard care of percutaneous coronary intervention (PCI) with a simple 1-stent technique in unprotected left main coronary artery (LMCA) stenosis. This study sought to investigate the impact of IVUS use and FKB dilatation on long-term major adverse cardiac events (MACEs) in PCI with a simple 1-stent technique for unprotected LMCA stenosis.

METHODS

Between June 2006 and December 2012, 255 patients who underwent PCI with 1 drug-eluting stent for LMCA stenosis were analyzed. Mean follow-up duration was 1663 ± 946 days. Long-term MACEs were defined as death, nonfatal myocardial infarction (MI) and repeat revascularizations.

RESULTS

During the follow-up, 72 (28.2%) MACEs occurred including 38 (14.9%) deaths, 21 (8.2%) nonfatal MIs and 13 (5.1%) revascularizations. The IVUS examination and FKB dilatation were done in 158 (62.0%) and 119 (46.7%), respectively. IVUS use (20.3 versus 41.2%; log-rank P < 0.001), not FKB dilatation (30.3 versus 26.5%; log-rank P = 0.614), significantly reduced MACEs. In multivariate analysis, IVUS use was a negative predictor of MACEs [hazards ratio 0.51; 95% confidence interval (CI) 0.29-0.88; P = 0.017], whereas FKB dilatation (hazard ratio 1.68; 95% CI, 1.01-2.80; P = 0.047) was a positive predictor of MACEs. In bifurcation LMCA stenosis, IVUS use (18.7 versus 48.0%; log-rank P < 0.001) significantly reduced MACEs. In nonbifurcation LMCA stenosis, FKB dilatation showed a trend of increased MACEs (P = 0.076).

CONCLUSION

IVUS examination is helpful in reducing clinical events in PCI for LMCA bifurcation lesions, whereas mandatory FKB dilatation after the 1-stent technique might be harmful in nonbifurcation LMCA stenosis.

Left Main Disease and Bifurcation Percutaneous Coronary Intervention: Focus on Antithrombotic Therapy

Revascularization of both left main and bifurcation lesions is currently considered an important feature of complex percutaneous coronary intervention (PCI), whereas stenting distal left main bifurcation is fairly challenging. Recent evidence shows that such lesions are associated with an increased risk of ischemic events. There is no universal consensus on the optimal PCI strategy or the appropriate type and duration of antithrombotic therapy to mitigate the thrombotic risk. Prolonged dual antiplatelet therapy or use of more potent P2Y12 inhibitors have been investigated in the context of this high-risk subset of the population undergoing PCI. Thus, while complex PCI is a growing field in interventional cardiology, left main and bifurcation PCI constitutes a fair amount of the total complex procedures performed recently, and there is cumulative interest regarding antithrombotic therapy type and duration in this subset of patients, with decision-making mostly based on clinical presentation, baseline bleeding, and ischemic risk, as well as the performed stenting strategy.

Coronary artery double stenting techniques and their results in complex left main bifurcation disease

Aim: Complex left main (LM) bifurcation disease seems to be better approached by a planned double stent technique. Materials & methods: Medline search for articles including randomized trials, prospective series, large registries and retrospective studies >50 patients has been performed. Results: Double kissing crush demonstrated its superiority over culotte stenting and cross over, while other techniques such as the T-stenting and T-stent and Protrusion have not been extensively reported in LM setting. The nano inverted-T-stenting has provided evidences that the use of ultrathin strut stents and very minimal crush is beneficial for both the physiological and rheological properties. Conclusion: The double stenting techniques used in LM should be evaluated in terms of procedural differences and technical simplicity.

Thin and crush: The new mantra in left main stenting?

Complex bifurcations have been suggested to be better approached by a planned double stent technique; however, recent randomized trials have shown better outcomes of provisional compared to planned two-stent strategy, in terms of both short-term efficacy and safety. In left main (LM) bifurcations, double kissing (DK)-Crush has demonstrated its superiority over Culotte and provisional-T in terms of restenosis and stent thrombosis, gaining respect as one of the most performant techniques for bifurcations stenting. On the other hand, the Nano-Crush technique has recently become part of the repertoire of double stenting techniques, providing evidence that the use of ultrathin strut stents and very minimal crush would be beneficial for both the physiological and rheological properties of the complex bifurcations, even in LM scenario, leading to a lower rate of thrombosis and restenosis at both side branch and true carina. Finally, the newest generation of ultrathin strut stents are gaining a reputation for its safe and effective use in LM treatment thanks to improved design with increased expansion rate capable of LM treatment up to 5-6 mm diameter. The modern crush techniques, such as DK-Crush and Nano-Crush, are providing excellent results on mid and long-term follow up, suggesting that minimal crushing obtained using ultra-thin stents is a good way to obtain surgical-like outcomes in the treatment of complex LM bifurcation disease.

Complex coronary bifurcation treatment by a novel stenting technique: Bench test, fluid dynamic study and clinical outcomes

OBJECTIVES

We assess the mid-term outcomes of ultrathin biodegradable polymer double stenting using a very minimal crushing (Nano-Crush) technique in large complex coronary bifurcation.

BACKGROUND

Complex bifurcations have been suggested to be better approached by a planned double stent technique.

METHODS

Two hundred and five consecutive patients (107 males and 98 females) referred for large complex coronary bifurcation percutaneous coronary interventions were enrolled. The technique was also evaluated by both a bench test with a silicon tubes phantom resembling a coronary bifurcation and a computed fluid dynamic (CFD) analysis.

RESULTS

Left main bifurcation accounted for 40.9% of cases (84 patients). Mean angles between main branch (MB) and side branch (SB) were 63.6 ± 21.3°. SB intravascular ultrasound-calculated MSA was 5.6 ± 1.5 mm² . Clinical follow-up was available for 100% of patients and at a mean follow-up of 16.2 ± 6.7 months 8 deaths, all due to cardiovascular reason, (3.9%, 4 patients for stroke, two for heart failure, one after surgical aortic valve substitution, and one after acute massive pulmonary embolism) and no presumptive stent thrombosis or target vessel induced ischemia were observed. Angiographic follow-up was available in 108 patients (52.7%) and showed a very low significant restenosis (5 patients, 4.6%). Bench study and CFD evaluation suggested a complete coverage of the SB ostium with a very high strut-free area at the SB.

CONCLUSIONS

The revascularization of complex large coronary bifurcation disease using the Nano-crush technique appeared promising thanks to the favorable fluid dynamic profile, complete coverage of the SD ostium, and very small metal amount at the carina.

Evaluation of Different Meshing Techniques for the Case of a Stented Artery

The formation and progression of in-stent restenosis (ISR) in bifurcated vessels may vary depending on the technique used for stenting. This study evaluates the effect of a variety of mesh styles on the accuracy and reliability of computational fluid dynamics (CFD) models in predicting these regions, using an idealized stented nonbifurcated model. The wall shear stress (WSS) and the near-stent recirculating vortices are used as determinants. The meshes comprise unstructured tetrahedral and polyhedral elements. The effects of local refinement, as well as higher-order elements such as prismatic inflation layers and internal hexahedral core, have also been examined. The uncertainty associated with individual mesh style was assessed through verification of calculations using the grid convergence index (GCI) method. The results obtained show that the only condition which allows the reliable comparison of uncertainty estimation between different meshing styles is that the monotonic convergence of grid solutions is in the asymptotic range. Comparisons show the superiority of a flow-adaptive polyhedral mesh over the commonly used adaptive and nonadaptive tetrahedral meshes in terms of resolving the near-stent flow features, GCI value, and prediction of WSS. More accurate estimation of hemodynamic factors was obtained using higher-order elements, such as hexahedral or prismatic grids. Incorporating these higher-order elements, however, was shown to introduce some degrees of numerical diffusion at the transitional area between the two meshes, not necessarily translating into high GCI value. Our data also confirmed the key role of local refinement in improving the performance and accuracy of nonadaptive mesh in predicting flow parameters in models of stented artery. The results of this study can provide a guideline for modeling biofluid domain in complex bifurcated arteries stented in regards to various stenting techniques.

Complex coronary bifurcation revascularization by means of very minimal crushing and ultrathin biodegradable polymer DES: Feasibility and 1-year outcomes of the "Nano-crush" technique

AIM

To assess feasibility and 1-year outcomes of ultrathin biodegradable polymer double stenting using a very minimal crushing (nano-crush technique) in a series of patients with large (≥2.5mm) complex coronary bifurcation.

METHODS

From January 2015 to June 2016, patients referred for large (≥2.5mm) complex coronary bifurcation percutaneous coronary interventions (PCI) were enrolled to receive Orsiro (Biotronik Inc., Bulack, Switzerland) double stenting using a very minimal crush technique (nano-crush). Per our institutional protocol, follow-up was conducted by physical examination at 1, 6, 12month and yearly whereas angiographic control was eventually scheduled at 6-8months on the basis of symptoms recurrence or/and positive induced ischemia tests.

RESULTS

Fifty-two patients (15 females mean age 77.2±6.2years) were enrolled. Mean angles between main branch and side branch were 63.6±21.3°. The mean diameter and length of implanted stents were 3.8±0.4mm and 27.1±8.7mm in main branch and 2.8±0.3mm and 22.1±.7.1mm in side branch. Immediate success was 100%. Clinical follow-up was available for 100% of patients: at a mean follow-up of 12.0±2.6months, no patient death, or acute myocardial infarction or target vessel revascularization were observed. Angiographic follow-up was available in 25/52 patients (48%) at a mean time from the procedure of 7.2±0.5months and showed no significant angiographic restenosis.

CONCLUSIONS

The revascularization of complex large (≥2.5mm) coronary bifurcation disease using the nano-crush technique and the ultrathin polymer biodegradable stent appeared feasible in our small study with promising 1year outcomes.

Impact of Side Branch Modeling on Computation of Endothelial Shear Stress in Coronary Artery Disease: Coronary Tree Reconstruction by Fusion of 3D Angiography and OCT

BACKGROUND

Computational fluid dynamics allow virtual evaluation of coronary physiology and shear stress (SS). Most studies hitherto assumed the vessel as a single conduit without accounting for the flow through side branches.

OBJECTIVES

This study sought to develop a new approach to reconstruct coronary geometry that also computes outgoing flow through side branches in hemodynamic and biomechanical calculations, using fusion of optical coherence tomography (OCT) and 3-dimensional (3D) angiography.

METHODS

Twenty-one patients enrolled in the DOCTOR (Does Optical Coherence Tomography Optimize Revascularization) fusion study underwent OCT and 3D-angiography of the target vessel (9 left anterior descending, 2 left circumflex, 10 right coronary artery). Coronary 3D reconstruction was performed by fusion of OCT and angiography, creating a true anatomical tree model (TM) including the side branches, and a traditional single-conduit model (SCM) disregarding the side branches.

RESULTS

The distal coronary pressure to aortic pressure (Pd/Pa) ratio was significantly higher in TMs than in SCMs (0.904 vs. 0.842; p < 0.0001). Agreement between TM and SCM in identifying patients with a Pd/Pa ratio ≤0.80 under basal flow conditions was only k = 0.417 (p = 0.019). Average SS was 4.64 Pascal lower in TMs than in SCMs (p < 0.0001), with marked differences in the point-per-point comparison, ranging from -60.71 to 7.47 Pascal.

CONCLUSIONS

True anatomical TMs that take into account the flow through side branches are feasible for accurate hemodynamic and biomechanical calculations. Traditional SCMs underestimate Pd/Pa and are inaccurate for regional SS estimation. Implementation of TMs might improve the accuracy of SS and virtual fractional flow reserve calculations, thus improving the consistency of biomechanical studies.

Rapamycin attenuates endothelial apoptosis induced by low shear stress via mTOR and sestrin1 related redox regulation

Background. Studies indicate the dramatic reduction of shear stress (SS) within the rapamycin eluting stent (RES) segment of coronary arteries. It remains unclear about the role of rapamycin in endothelialization of stented arteries where SS becomes low. Since mTOR (mammalian target of rapamycin) pathway is involved in the antioxidative sestrins expression, we hypothesized that rapamycin attenuated low SS (LSS) induced endothelial dysfunction through mTOR and sestrin1 associated redox regulation. Methods and Results. To mimic the effect of LSS on the stented arteries, a parallel plate flow chamber was used to observe the interplay of LSS and rapamycin on endothelial cells (ECs). The results showed LSS significantly induced EC apoptosis which was mitigated by pretreatment of rapamycin. Rapamycin attenuated LSS induced reactive oxygen species (ROS) and reactive nitrogen species (RNS) production via prohibition of sestrin1 downregulation. Activities of mTORC1 and mTORC2 were detected contradictorily modulated by LSS. Inhibition of rictor expression by target small interfering RNA (siRNA) transfection prohibited sestrin1 downregulation induced by LSS, but inhibition of raptor did not. Conclusions. Rapamycin may prohibit sestrin1 downregulation through targeting mTORC2 in appeasing LSS induced EC oxidative apoptosis. Our results provide the in vitro evidence to explain the pathophysiology of RES stented arteries.

Two-year outcomes after deployment of XIENCE V everolimus-eluting stents in patients undergoing percutaneous coronary intervention of bifurcation lesions: a report from the SPIRIT V single arm study

The aim of this analysis was to analyze outcomes of patients undergoing Xience V EES treatment of bifurcation lesions, a subset in which treatment is particularly challenging. The SPIRIT V Study provided an evaluation of the Xience V everolimus eluting stent (EES) performance in complex patient and lesion population. The SPIRIT V Single Arm Study enrolled 2700 patients with de novo coronary artery lesions suitable to be optimally treated with a maximum of four planned Xience V EES. Lesion evaluation was by visual assessment. The outcomes of the 492 patients undergoing Xience V EES stenting of ≥1 bifurcation lesion were compared to those with no bifurcation lesion treated. Compared to those without bifurcation treatment, patients with bifurcation treatment were more likely to have multi-vessel disease (49% vs 40%), left main treatment (3.1% vs 0.9%), more lesions treated (1.5 vs 1.3), calcification (36.4% vs 27.5%), and ostial (17.1% vs 8.2%) and angulated lesions (29.3% vs 21.1%), all P < 0.001. The 30-day composite rate of death, myocardial infarction (MI), target vessel revascularization (TVR) was 4.3% in patients with bifurcation PCI and 2.2% in those with non-bifurcation PCI (P = 0.017). At 2 years, this composite event rate was 11.3% and 10.0% in these two groups, respectively (P = 0.403). Rates of cardiac death, MI, target lesion revascularization (TLR), TVR, and ARC defined definite or probable stent thrombosis (0.4% vs 0.9%, P = 0.402) were not significantly different between the two groups. Despite greater patient and lesion complexity, treatment of patients with bifurcation lesions using the Xience V EES in the SPIRIT V prospective Single Arm Study was safe and effective, with low overall event rates that were similar to those without bifurcation lesion treatment. © 2013 Wiley Periodicals, Inc.

Acute effects of nicardipine and esmolol on the cardiac cycle, intracardiac hemodynamic and endothelial shear stress in patients with unstable angina pectoris and moderate coronary stenosis: results from single center, randomized study

OBJECTIVE

This study aimed to compare the acute effects of nicardipine and esmolol on hemodynamic and endothelial shear stress (ESS) in patients with unstable angina (UA) and moderate coronary stenosis (MCS).

BACKGROUND

Nicardipine and esmolol exhibit cardioprotection via different mechanisms. However, their acute effects on hemodynamic and ESS are still unknown.

METHODS

One-hundred sixteen patients with UA and MSC were randomly divided into nicardipine (n = 59) and esmolol (n = 57) groups. Drugs were injected as a bolus followed by continuous infusion to achieve the steady states defined as the mean blood pressure (MBP) reduced by ≥ 10% or a heart-rate change by ≥ 15 bpm, lasting for at least 10 min. The aortic pressure (AP), EKG, blood velocity, right atrial pressure, distal coronary pressure (DCP), systolic time (ST), isovolumetric diastolic time (IVDT), speed filling time (SFT), and ESS were simultaneously calculated at baseline and steady states.

RESULTS

Both drugs significantly reduced blood pressure and rate-pressure load. Infusion of nicardipine was associated with negative remodeling of the distal segment (P= 0.005). Esmolol, rather than nicardipine, increased minimal lumen diameter (P= 0.040), prolonged SFT (0.34 ± 0.03 s vs. 0.41 ± 0.03 s, P < 0.001), reduced DCP (P < 0.001) and increased blood velocity (33.65 ± 1.07 cm/s vs. 43.36 ± 1.25 cm/s, P < 0.001) at SFT stages, with increased blood-flow (P < 0.001). Both drugs increased downstream ESS. Esmolol significantly reversed abnormally increased ESS (P < 0.001) and increased upstream ESS compared with nicardipine (P < 0.001).

CONCLUSION

Beyond a similar reduction of AP, patients with UA and MCS could benefit more from the reduction of heart rate induced by esmolol (ChiCTR-TRC-10000964).

Editorial: at the bifurcation of the last frontiers

The concept of coronary angioplasty percutaneous coronary intervention (PCI) was pioneered by Andreas Gruntzig. Since then, several modifications, innovative devices, techniques, and advances have revolutionized the practice of interventional cardiology. Coronary bifurcation and chronic total occlusion are the last two frontiers that continue to challenge the skills of the interventional cardiologists. Proceedings of the second Bifurcation Summit held from November 26 to 28, 2009 in Nanjing, China are published in this symposium. In a general review, the state of the art in management of bifurcation lesion is summarized in the statement of the "Bifurcation Club in KOKURA." A new-presented concept was the "extension distance" between the main vessel and the sidebranch ostia and its association with restenosis. The results of two studies on shear stress (SS) after PCI showed that contradictory lower SS after stenting was associated with lower in-stent restenosis. There was better fractional flow reserve after double kissing crush technique than provisional one-stent technique. There was also lower rate of stent thrombosis after bifurcation stenting with excellent final angiographic results. In a negative note, the SYNTAX score had no predictive values on trifurcated left main stenting. In summary, different aspects of percutaneous management for bifurcated lesion are described seen from different perspectives and evidenced by novel techniques and strategies.