Technical success, clinical efficacy, and insight into the causes of restenosis after the percutaneous coronary intervention of de novo coronary artery lesions using a paclitaxel-coated balloon with citrate ester excipient

Objectives

The aim of this all-comers registry study was to investigate the technical success, clinical efficacy, and safety of a drug-coated balloon (DCB) with paclitaxel combined with citrate ester excipient (CEE) in percutaneous coronary intervention (PCI) of de novo coronary lesions in an all-comers population.

Materials and methods

A total of 338 consecutive PCIs using the DCB (CEE)-only approach comprising 406 de novo lesions were included in the study. Technical success was determined by the successful delivery of the device and no need for bailout stenting.

Results

The mean follow-up time was 25 ± 12 months. The mean age of patients was 71 ± 11 years, and 48% had the acute coronary syndrome. A total of 55% of the patients were at risk of factor bleeding. The delivery of DCB was successful in 98% of cases. The overall technical success rate was 83%. Bailout stenting was used in 9% of lesions. Rotational atherectomy was used in 11% of cases before the DCB-only approach. The mean diameter of the DCBs used was 2.7 ± 0.5 mm and 38% of DCBs were large (≥3.0 mm). The 12-month MACE rates were 5.4 ± 1.7 and 18.3 ± 3.1% in stable CAD and in ACS, respectively. The respective target lesion revascularization (TLR) rates were 3.0 ± 1.3 and 8.5 ± 2.3%. Unacceptable acute recoil (>30%) was found in 74% of cases that needed repeat revascularization. No acute vessel closures occurred after DCB treatment.

Conclusion

The DCB-only strategy using a paclitaxel-coated (CEE) device was technically feasible, safe, and effective in an all-comers population. Acute recoil was found as a significant cause of restenosis after the DCB-only strategy.

Drug-coated balloon for treatment of de-novo coronary artery lesions in patients with high bleeding risk (DEBUT): a single-blind, randomised, non-inferiority trial

BACKGROUND

The optimal technique of percutaneous coronary intervention in patients at high bleeding risk is not known. The hypothesis of the DEBUT trial was that percutaneous coronary intervention with drug-coated balloons is non-inferior to percutaneous coronary intervention with bare-metal stents for this population.

METHODS

The DEBUT trial is a randomised, single-blind non-inferiority trial done at five sites in Finland. Patients were eligible if they had an ischaemic de-novo lesion in a coronary artery or bypass graft that could be treated with drug-coated balloons, at least one risk factor for bleeding, and a reference vessel diameter of 2·5-4·0 mm. Those with myocardial infarction with ST-elevation, bifurcation lesions needing a two-stent technique, in-stent restenosis, and flow-limiting dissection or substantial recoil (>30%) of the target lesion after predilation were excluded. After successful predilation of the target lesion, patients were randomly assigned (1:1), by use of a computer-generated random sequence, to percutaneous coronary intervention with a balloon coated with paclitaxel and iopromide or a bare-metal stent. The primary outcome was major adverse cardiac events at 9 months. Non-inferiority was shown if the absolute risk difference was no more than 3%. All prespecified analyses were done in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT01781546.

FINDINGS

Between May 22, 2013, and Jan 16, 2017, 220 patients were recruited for the study and 208 patients were assigned to percutaneous coronary intervention with drug-coated balloon (n=102) or bare metal stent (n=106). At 9 months, major adverse cardiac events had occurred in one patient (1%) in the drug-coated balloon group and in 15 patients (14%) in the bare-metal stent group (absolute risk difference -13·2 percentage points [95% CI -6·2 to -21·1], risk ratio 0·07 [95% CI 0·01 to 0·52]; p<0·00001 for non-inferiority and p=0·00034 for superiority). Two definitive stent thrombosis events occurred in the bare metal stent group but no acute vessel closures in the drug-coated balloon group.

INTERPRETATIONS

Percutaneous coronary intervention with drug-coated balloon was superior to bare-metal stents in patients at bleeding risk. The drug-coated balloon-only coronary intervention is a novel strategy to treat this difficult patient population. Comparison of this approach to the new generation drug-eluting stents is warranted in the future.

FUNDING

B Braun Medical AG, AstraZeneca, and Competitive State Research Funding of the Kuopio University Hospital Catchment Area.

Hanbury Brown-Twiss effect with electromagnetic waves

The classic Hanbury Brown-Twiss experiment is analyzed in the space-frequency domain by taking into account the vectorial nature of the radiation. We show that as in scalar theory, the degree of electromagnetic coherence fully characterizes the fluctuations of the photoelectron currents when a random vector field with Gaussian statistics is incident onto the detectors. Interpretation of this result in terms of the modulations of optical intensity and polarization state in two-beam interference is discussed. We demonstrate that the degree of cross-polarization may generally diverge. We also evaluate the effects of the state of polarization on the correlations of intensity fluctuations in various circumstances.

Modelling the transport of ionizing radiation using the finite element method

Radiation therapy treatment planning is based on the calculation of the absorbed dose in the patient domain. For exact dose calculations, the solution of three coupled Boltzmann transport equations (BTEs) is needed to cover the transport of photons, electrons and positrons. In many situations, however, two coupled systems for photons and electrons are enough. The use of numerical methods in finding the exact solution of the unknown particle fluxes is necessary. In the stationary case, the BTE has six variables, three spatial, two directional and one energy variable. In this paper, we describe an approach in which the finite element method (FEM) is used to solve the six-dimensional problem. For the coupled photon-electron system, the variational formulation and the existence and uniqueness of the solution are derived. We simulate the solution of two coupled BTEs describing the travelling of photons and electrons in two spatial dimensions. The results are compared to Monte Carlo calculations with good agreement.

Simulations for inverse radiation therapy treatment planning using a dynamic MLC algorithm

The inverse radiation treatment planning model for a dynamic multileaf collimator (MLC) is used to find the optimal solution of planning problem. The model for dynamic MLC is explained in Tervo et al (2003 Appl. Math. Comput. 135 227-50). The advantage of this model is that it optimizes leaf velocity parameters directly. Our algorithm uses a gradient-based local optimization method. Two patient cases, prostate carcinoma and tonsilla carcinoma, are studied. Field arrangements are pre-selected and velocity parameters for MLC leaves are optimized to obtain the prescribed dose in the patient space. In both simulated cases, high dose distribution conforms the planning target volume well and organs-at-risk are saved in most parts. Simulations show that the model has its functionality in patient treatments, although it is still formal and needs further development.

Self-imaging of electromagnetic fields

The electromagnetic theory of self-imaging fields is considered. Several features are presented, which have no counterparts within the scalar theory of self-imaging. For example, the electromagnetic field self-images at one half of the classical self-imaging distance for scalar fields, the electric and magnetic energy densities can self-image while the scalar field components do not, and the self-imaging distances of the electric and magnetic energy densities can be different. In addition, general expressions for TE and TM polarized fields are presented by using the concept of the angular spectrum of the field.

Rotating scale-invariant electromagnetic fields

The concept of scalar fields with uniformly rotating intensity distributions and propagation-invariant radial scales is extended to the case of electromagnetic fields with rotating but otherwise propagation-invariant states of polarization. It is shown that the conditions for field rotation are different for scalar and electromagnetic fields and that the electromagentic analysis brings in new aspects such as the possibility that different components of a rotating electromagnetic field can rotate in opposite directions.

Deterministic diffractive diffusers for displays

A LCD backlighting device that uses a diffractive light extractor has been developed for applications in which pointlike light sources are employed. The novel system eliminates the images of light sources, which appear as bright lines emanating from each source in the conventional diffractive approach. In addition, the system illuminates the LCD uniformly: Modulation of the diffractive structure as a function of position is used to control the output field of this extended planar light source.

Paraxial-domain diffractive elements with 100% efficiency based on polarization gratings

The concept of polarization freedom is employed to design diffraction gratings that are capable of transforming an electromagnetic plane wave into two or three diffraction orders with an arbitrary efficiency distribution among them, such that the combined efficiency of the signal orders is always equal to 100%. As a special case we consider paraxial-domain duplicators and triplicators with 100% efficiency, which is not possible for illumination by scalar waves: Diffractive elements that are capable of performing the required wave transformation must modulate the state of polarization of the incident field.

Use of the Cimmino algorithm and continuous approximation for the dose deposition kernel in the inverse problem of radiation treatment planning

An approximate continuous data fitting model for the dose deposition kernel was developed. The model uses a discrete Fourier transform to interpolate dose values in patient space and intensity distribution in treatment space. The continuous kernel was applied to the inverse problem of radiation treatment planning. In the problem a prescribed dose distribution was to be created using intensity modulation of several fields. The Cimmino algorithm suitable for solving large systems of inequalities was adapted. Upper and lower dose constraints for planning target volume (PTV) and organs at risk (OAR) can be implemented into the algorithm. Using continuous and discrete kernels an intensity modulation was computed in a two-dimensional phantom with a PTV and low-dose region, and in the real three-dimensional patient planning. Intensity modulations obtained using continuous and discrete kernels were in good agreement.

A cyclic isomer of 2-hydroxymelatonin: a novel metabolite of melatonin

A previously unknown melatonin metabolite was isolated by chloroform extraction and reverse phase HPLC from human and rat urine after administration of synthetic melatonin and characterized by mass spectroscopy and proton magnetic resonance spectroscopy to 1-acetyl-1,2,3,3a,8,8a-hexahydro-8a-hydroxy-5-methoxypyrrolo[2,3-b ]indole, a cyclic isomer of 2-hydroxymelatonin. This isolation was based on the fact that our melatonin antibody (a-MT-K1) cross-reacted against this novel metabolite at a level of 0.1% (melatonin 100%). In our HPLC program for indoles the cyclic 2-hydroxymelatonin eluted at 25 min, separately from synthetic indoles, between 6-hydroxymelatonin (19 min) and melatonin (35 min). In [3H] melatonin studies it was found to be present (at 25 min in our HPLC), accounting for 5% of the urinary metabolites of melatonin in the rat. Since beta-glucuronidase-arylsulfatase treatment of rat urine did not liberate the cyclic 2-hydroxymelatonin this would appear to be excreted into urine as the free form.