Silent Cerebral Events/Lesions Related to Atrial Fibrillation Ablation: A Clinical Review

Brain magnetic resonance imaging (MRI) has identified a high incidence of cerebral ischemia in asymptomatic patients after atrial fibrillation (AF) ablation (silent). Detection of cerebral ischemic events on MRI is based on acute hyperintense lesions on diffusion‐weighted imaging. In the literature, the incidence is related to specifications of MRI and depends on the definition applied. In comparative studies, silent cerebral events (SCE, diffusion‐weighted MRI [DWI] positive only) appear to be approximately 3 times more common compared to using a definition of silent cerebral lesions (SCL; without fluid attenuated inverse recovery sequence [FLAIR] positivity). Whereas the FLAIR sequence may turn positive within days after the ischemic event, SCE definition is highly sensitive for early phases of ischemic brain damage. SCE/SCL appear to represent cerebral ischemic infarcts and determine the “embolic fingerprint” of a specific ablation technology and strategy used. The optimum time point for detecting SCE is early after AF ablation (24–72 hours), whereas detection of SCL can only be performed within the first 2–7 days (due to delay of FLAIR positivity). Different technology‐, procedure‐, and patient‐related parameters have been identified to play a role in the multifactorial genesis of SCE/SCL. In recent years, evidence has been gathered that there may be differences of SCE/SCL rates depending upon the ablation technology used, but small patient numbers and a large number of potential confounders hamper all studies. As major findings of recent studies, mode of periprocedural and intraprocedural anticoagulation has been identified as a major predictor for incidences of SCE/SCL. Whereas procedural characteristics related to higher SCE/SCL‐rates may be modified, unchangeable patient‐related factors should be taken into account for future individualized risk assessment. Novel ablation devices introduced into the market should be tested for their potential embolic fingerprint and refinements of ablation procedures to reduce their embolic potential should be prompted. The knowledge of “best practice” in terms of low SCE/SCL rates has prompted changes in work‐flow, which have been implemented into ablation procedures using novel ablation devices. So far, no study has linked SCE/SCL to neuropsychological decline and the low number of AF‐ablation‐associated events needs to be weighted against the multitude of preexisting asymptomatic MRI‐detected brain lesions related to the course of AF itself. Future studies are needed to evaluate if more white matter hyperintensities due to AF may be prevented by AF ablation (producing only a small number of SCE/SCL).     

Long‐Term Follow‐Up of Coronary Venous Bypass Graft Lesions Treated with a New Generation Drug‐Eluting Stent with Bioabsorbable Polymer

Background

To date, no published data are available regarding long‐term follow‐up of new generation DES implanted in coronary artery bypass graft (CABG) lesions.

Objectives

To assess the long‐term clinical outcome of patients receiving the new generation Biolimus A9‐coated drug‐eluting stent (DES) with biodegradable polymer in saphenous vein grafts (SVG).

Methods

Three thousand sixty‐seven patients were included in the NOBORI 2 registry: 71 patients with a total of 117 lesions received at least 1 biolimus A9 DES in SVG lesions and 2,959 patients received percutaneous coronary intervention in other lesions. Clinical follow‐up was performed at 1, 6, and 12 months, and annually up to 3 years.

Results

Compared to the non‐CABG group, patients with CABG lesions were older (P < 0.001), had a higher Charlson Comorbidity Index (P = 0.004), and presented more often with acute coronary syndrome (P = 0.02). At 3‐year follow‐up, cardiac death occurred in 9.7% versus 2.1% (P < 0.001), myocardial infarction (MI) in 8.3% versus 3.0% (P = 0.02), target lesion failure in 13.9% versus 6.4% (P = 0.03), and major adverse cardiac event in 18.1% versus 8.6% (P = 0.01). No differences were observed in TV‐MI and TLR, nor stent thrombosis (ST) which was generally low in both groups (1.4% vs 0.8%, P = NS).

Conclusion

Albeit 3‐year outcomes were less favorable in the CABG group, the higher cardiac mortality was apparently not driven by ST, target vessel MI, or TLR, but is likely due to advanced disease and age as well as comorbidity. The low TLR rate as well as the absence of late and very late ST suggest that BES are safe and effective for the treatment of CABG lesions. (J Interven Cardiol 2013;26:425‐433)

     

CELLULAR KINETIC AND PHENOTYPIC HETEROGENEITY IN AND AMONG BURKITT'S AND BURKITT-LIKE LYMPHOMAS

This study asks whether the known genotypic heterogeneity within and between endemic or sporadic Burkitt's lymphomas (eBLs and sBLs, n=10 each), and Burkitt-like lymphomas (BLLs, n-12), is reflected in divergent cytokinetics and related immunophenotypes. There was strong evidence that eBL and BLL grow markedly faster than sBL, as shown by differences in mitotic and apoptotic indices. Furthermore, in BLL, the median percentage of neoplastic cells immunoreactive for the bcl-2 protein was much higher than that observed in eBL and sBL. The reverse was true for the median fraction of cells containing c-myc protein. In eBL and sBL, the median fraction of bcl-6 protein-positive cells reached values above 50 per cent, while cells of 8/12 BLLs did not contain detectable amounts of this protein. This observation indicates that in this respect, eBL and sBL resemble normal germinal centres of lymphatic tissue much more than do BLL. Evidence for infection of neoplastic cells by the Epstein-Barr virus (EBV) was observed in 9/10 cases of eBL and in 3/10 of sBL, but not in BLL. EBV-positive lymphomas were associated with distinctly lower apoptotic indices and smaller median percentages of bcl-6-positive cells than EBV-negative tumours. © 1997 John Wiley & Sons, Ltd.     

Transport and Metabolic Pathway of Thymocartin (TP4) in Excised Bovine Nasal Mucosa

Thymocartin (TP4, Arg-Lys-Asp-Val) is the 32–35 fragment of the naturally occuring thymic factor (thymopoietin). Here studies on the nasal transport and metabolism of TP4 were performed. Freshly excised bovine nasal mucosa was taken as a model membrane. For permeation studies typical donor-receiver experiments (side-by-side) and finite-dose experiments with small volumes of highly concentrated solutions were carried out. The metabolic pathway of TP4 in nasal mucosa was found to occur according to a typical aminopeptidase cleavage pattern, stepwise forming Lys-Asp-Val and Asp-Val. TP4 metabolism experiments under reflection kinetics showed a saturation profile above 0.5 μmol mL^?1. A non-linear kinetic model consisting of three steps in sequence was sufficient to describe the kinetics: for the first step saturable Michaelis-Meat kinetics, and for the second and the third step first-order kinetics were assured. The model was capable of simultaneously fitting the data for the full range of initial concentrations from 0.1 up to 1.0 μmol mL^?1. Saturation kinetics was also found to be the prominent feature of the permeation experiments performed. In the lower concentration range (<0.4 μmol mL^?1), transport of TP4 across nasal mucosa was controlled by metabolism, in the higher concentration range (>0.85 μmol mL^?1) diffusion control became more important. We conclude that enhancement of absorption can be achieved when nasal aminopeptidases are saturated, e.g. at high TP4 concentrations.     

Technique for Human Marrow Grafting

A technique is described for marrow aspiration from living human donors andfor processing the marrow for intravenous infusion to marrow graft recipients.

Submitted on February 17, 1970 Revised on March 20, 1970 Accepted on March 26, 1970