Efficacy and safety of driver-guided catheter ablation for atrial fibrillation: A systematic review and meta-analysis.

INTRODUCTION: Targeting localized drivers (electrical rotors or focal impulses) during catheter ablation for atrial fibrillation (AF) has been proposed as a strategy to improve procedural success. However, the strength and quality of the evidence to support this approach is unclear. METHODS AND RESULTS: Clinical studies reporting efficacy or safety outcomes of driver-guided ablation for AF were identified in Medline, Embase, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, Pubmed, and conference abstracts from major scientific meetings. Random-effects meta-analysis of efficacy outcomes from controlled studies was performed. Thirty-one reports from 30 studies were included: two randomized controlled trials, five nonrandomized controlled studies, and 23 uncontrolled studies. In controlled studies, driver-guided ablation has been associated with higher rates of acute AF termination (RR 2.08, 95% CI 1.43-3.05; P < 0.001) and increased freedom from AF/atrial tachycardia (AT) at ≥1 year (RR 1.34, 95% CI 1.05-1.70; P = 0.02). Similar rates of procedural complications have been reported between ablation strategies. Overall, current data on driver-guided ablation are predominantly from nonrandomized studies with considerable heterogeneity in mapping and ablation strategies used and in clinical outcomes reported. CONCLUSION: Pooled data on the efficacy of AF driver-guided catheter ablation suggest increased freedom from AF/AT relative to conventional strategies. However, most studies are nonrandomized and of moderate quality. Though promising data exist, there remains no conclusive evidence for the efficacy of AF driver ablation. Robust data from randomized trials are needed.

Zero-Shot Super-Resolution With a Physically-Motivated Downsampling Kernel for Endomicroscopy.

Super-resolution (SR) methods have seen significant advances thanks to the development of convolutional neural networks (CNNs). CNNs have been successfully employed to improve the quality of endomicroscopy imaging. Yet, the inherent limitation of research on SR in endomicroscopy remains the lack of ground truth high-resolution (HR) images, commonly used for both supervised training and reference-based image quality assessment (IQA). Therefore, alternative methods, such as unsupervised SR are being explored. To address the need for non-reference image quality improvement, we designed a novel zero-shot super-resolution (ZSSR) approach that relies only on the endomicroscopy data to be processed in a self-supervised manner without the need for ground-truth HR images. We tailored the proposed pipeline to the idiosyncrasies of endomicroscopy by introducing both: a physically-motivated Voronoi downscaling kernel accounting for the endomicroscope's irregular fibre-based sampling pattern, and realistic noise patterns. We also took advantage of video sequences to exploit a sequence of images for self-supervised zero-shot image quality improvement. We run ablation studies to assess our contribution in regards to the downscaling kernel and noise simulation. We validate our methodology on both synthetic and original data. Synthetic experiments were assessed with reference-based IQA, while our results for original images were evaluated in a user study conducted with both expert and non-expert observers. The results demonstrated superior performance in image quality of ZSSR reconstructions in comparison to the baseline method. The ZSSR is also competitive when compared to supervised single-image SR, especially being the preferred reconstruction technique by experts.

Learning from irregularly sampled data for endomicroscopy super-resolution: a comparative study of sparse and dense approaches.

PURPOSE: Probe-based confocal laser endomicroscopy (pCLE) enables performing an optical biopsy via a probe. pCLE probes consist of multiple optical fibres arranged in a bundle, which taken together generate signals in an irregularly sampled pattern. Current pCLE reconstruction is based on interpolating irregular signals onto an over-sampled Cartesian grid, using a naive linear interpolation. It was shown that convolutional neural networks (CNNs) could improve pCLE image quality. Yet classical CNNs may be suboptimal in regard to irregular data. METHODS: We compare pCLE reconstruction and super-resolution (SR) methods taking irregularly sampled or reconstructed pCLE images as input. We also propose to embed a Nadaraya-Watson (NW) kernel regression into the CNN framework as a novel trainable CNN layer. We design deep learning architectures allowing for reconstructing high-quality pCLE images directly from the irregularly sampled input data. We created synthetic sparse pCLE images to evaluate our methodology. RESULTS: The results were validated through an image quality assessment based on a combination of the following metrics: peak signal-to-noise ratio and the structural similarity index. Our analysis indicates that both dense and sparse CNNs outperform the reconstruction method currently used in the clinic. CONCLUSION: The main contributions of our study are a comparison of sparse and dense approach in pCLE image reconstruction. We also implement trainable generalised NW kernel regression as a novel sparse approach. We also generated synthetic data for training pCLE SR.

Adversarial training with cycle consistency for unsupervised super-resolution in endomicroscopy.

In recent years, endomicroscopy has become increasingly used for diagnostic purposes and interventional guidance. It can provide intraoperative aids for real-time tissue characterization and can help to perform visual investigations aimed for example to discover epithelial cancers. Due to physical constraints on the acquisition process, endomicroscopy images, still today have a low number of informative pixels which hampers their quality. Post-processing techniques, such as Super-Resolution (SR), are a potential solution to increase the quality of these images. SR techniques are often supervised, requiring aligned pairs of low-resolution (LR) and high-resolution (HR) images patches to train a model. However, in our domain, the lack of HR images hinders the collection of such pairs and makes supervised training unsuitable. For this reason, we propose an unsupervised SR framework based on an adversarial deep neural network with a physically-inspired cycle consistency, designed to impose some acquisition properties on the super-resolved images. Our framework can exploit HR images, regardless of the domain where they are coming from, to transfer the quality of the HR images to the initial LR images. This property can be particularly useful in all situations where pairs of LR/HR are not available during the training. Our quantitative analysis, validated using a database of 238 endomicroscopy video sequences from 143 patients, shows the ability of the pipeline to produce convincing super-resolved images. A Mean Opinion Score (MOS) study also confirms this quantitative image quality assessment.

Type and use of digital technology in learning health systems: a scoping review protocol.

INTRODUCTION: Health systems in North America and Europe have been criticised for their lack of safety, efficiency and effectiveness despite rising healthcare costs. In response, healthcare leaders and researchers have articulated the need to transform current health systems into continuously and rapidly learning health systems (LHSs). While digital technology has been envisioned as providing the transformational power for LHSs by generating timely evidence and supporting best care practices, it remains to be ascertained if it is indeed playing this role in current LHS initiatives. This paper presents a protocol for a scoping review that aims at providing a comprehensive understanding of how and to what extent digital technology is used within LHSs. Results will help to identify gaps in the literature as a means to guide future research on this topic. METHODS AND ANALYSIS: Multiple databases and grey literature will be searched with terms related to learning health systems. Records selection will be done in duplicate by two reviewers applying pre-defined inclusion and exclusion criteria. Data extraction from selected records will be done by two reviewers using a piloted data charting form. Results will be synthesised through a descriptive numerical summary and a mapping of digital technology use onto types of LHSs and phases of learning within LHSs. ETHICS AND DISSEMINATION: Ethical approval is not required for this scoping review. Preliminary results will be shared with stakeholders to account for their perspectives when drawing conclusions. Final results will be disseminated through presentations at relevant conferences and publications in peer-reviewed journals.

Effective deep learning training for single-image super-resolution in endomicroscopy exploiting video-registration-based reconstruction.

PURPOSE: Probe-based confocal laser endomicroscopy (pCLE) is a recent imaging modality that allows performing in vivo optical biopsies. The design of pCLE hardware, and its reliance on an optical fibre bundle, fundamentally limits the image quality with a few tens of thousands fibres, each acting as the equivalent of a single-pixel detector, assembled into a single fibre bundle. Video registration techniques can be used to estimate high-resolution (HR) images by exploiting the temporal information contained in a sequence of low-resolution (LR) images. However, the alignment of LR frames, required for the fusion, is computationally demanding and prone to artefacts. METHODS: In this work, we propose a novel synthetic data generation approach to train exemplar-based Deep Neural Networks (DNNs). HR pCLE images with enhanced quality are recovered by the models trained on pairs of estimated HR images (generated by the video registration algorithm) and realistic synthetic LR images. Performance of three different state-of-the-art DNNs techniques were analysed on a Smart Atlas database of 8806 images from 238 pCLE video sequences. The results were validated through an extensive image quality assessment that takes into account different quality scores, including a Mean Opinion Score (MOS). RESULTS: Results indicate that the proposed solution produces an effective improvement in the quality of the obtained reconstructed image. CONCLUSION: The proposed training strategy and associated DNNs allows us to perform convincing super-resolution of pCLE images.

Using coronary calcification to exclude an ischemic etiology for cardiomyopathy: A validation study and systematic review.

BACKGROUND: Preliminary data suggests the absence of coronary artery calcification (CAC) excludes ischemic etiologies of cardiomyopathy. We prospectively validate and perform a systematic review to determine the utility of an Agatston score=0 to exclude the diagnosis of ischemic cardiomyopathy. METHODS AND RESULTS: Patients with newly diagnosed LV dysfunction were prospectively enrolled. Patients underwent CAC imaging and were followed until an etiologic diagnosis of cardiomyopathy was made. Eighty-two patients were enrolled in the study and underwent CAC imaging with 81.7% patients having non-ischemic cardiomyopathy. An Agatston score=0 successfully excluded an ischemic etiology for cardiomyopathy with a specificity of 100% (CI: 74.7-100%) and a positive predictive value of 100% (CI: 85.0%-100%). A systematic literature review was performed and studies were deemed suitable for inclusion if: 1) patients with CHF, cardiomyopathy or LV dysfunction were enrolled, 2) underwent CAC imaging and patients were assessed for an Agatston score=0 or the absence of CAC, and 3) the final etiologic diagnosis (ischemic or non-ischemic) was provided. Eight studies provided sufficient information to calculate operating characteristics for an Agatston score=0 and were combined with our validation cohort for a total of 754 patients. An Agatston score=0 excluded ischemic cardiomyopathy with specificity and positive predictive values of 98.4% (CI: 95.6-99.5%), and 98.3% (CI: 95.5-99.5%), respectively. CONCLUSIONS: In patients with cardiomyopathy of unknown etiology, an Agatston score=0 appears to rule out an ischemic etiology. A screening CAC may be a simple and cost-effective method of triaging patients, identifying those who do and do not need additional CAD investigations.

Relationship Between Pulmonary Vein Reconnection and Atrial Fibrillation Recurrence: A Systematic Review and Meta-Analysis.

OBJECTIVES: This study systematically reviewed the prevalence of pulmonary vein (PV) reconnection in subjects with and without AF recurrence and assessed the relationship between PV reconnection and freedom from atrial fibrillation (AF). BACKGROUND: Pulmonary vein reconnection is frequently observed in patients experiencing recurrent AF post catheter ablation. However, its prevalence in AF-free patients has not been well studied. METHODS: An electronic search was performed for studies describing PV electrical conduction in subjects with and without AF recurrence post PV isolation (PVI). RESULTS: Eleven of 5,665 articles met selection criteria. A total of 683 subjects were included in the meta-analysis; 379 had AF recurrence, and 304 were AF-free. Among patients with AF recurrence, 324 of 379 patients (85.5%) had at least 1 pulmonary vein reconnected. Among AF-free patients, 178 of 304 patients (58.6%) had at least 1 PV electrically reconnected, and 126 of 304 (41.4%) had durable PVI. The relative risk (RR) of recurrent AF was significantly lower with durable PVI than with PV reconnection (RR: 0.57; 95% confidence interval [CI]: 0.37 to 0.86; p = 0.008). Analysis of 7 studies including exclusively paroxysmal AF patients (n = 470) showed RR of 0.69 (95% CI: 0.45 to 1.05; p = 0.09). CONCLUSIONS: This meta-analysis shows that durable PVI is associated with a lower risk of AF recurrence after catheter ablation. However, the association was modest, and PV electrical reconnection is common, affecting 58% of AF-free patients. Analysis of studies that included exclusively patients with paroxysmal AF showed a weaker relationship. Additional research is warranted to better understand the mechanism(s) of benefit of catheter ablation for AF and investigate whether PVI should be the primary goal.

Predictors of Energy Compensation during Exercise Interventions: A Systematic Review.

Weight loss from exercise-induced energy deficits is usually less than expected. The objective of this systematic review was to investigate predictors of energy compensation, which is defined as body energy changes (fat mass and fat-free mass) over the total amount of exercise energy expenditure. A search was conducted in multiple databases without date limits. Of 4745 studies found, 61 were included in this systematic review with a total of 928 subjects. The overall mean energy compensation was 18% ± 93%. The analyses indicated that 48% of the variance of energy compensation is explained by the interaction between initial fat mass, age and duration of exercise interventions. Sex, frequency, intensity and dose of exercise energy expenditure were not significant predictors of energy compensation. The fitted model suggested that for a shorter study duration, lower energy compensation was observed in younger individuals with higher initial fat mass (FM). In contrast, higher energy compensation was noted for younger individuals with lower initial FM. From 25 weeks onward, energy compensation was no longer different for these predictors. For studies of longer duration (about 80 weeks), the energy compensation approached 84%. Lower energy compensation occurs with short-term exercise, and a much higher level of energy compensation accompanies long-term exercise interventions.

E-health physical activity interventions and moderate-to-vigorous intensity physical activity levels among working-age women: a systematic review protocol.

BACKGROUND: The rapid pace of modern life requires working-age women to juggle occupational, family, and social demands. Despite the large numbers of working-age women in developed countries and the proven benefits of regular moderate-to-vigorous intensity aerobic physical activity (MVPA) in chronic disease prevention, few women meet current physical activity (PA) recommendations of 150 min of MVPA per week. It is important that appropriate and effective behavioral interventions targeting PA are identified and developed to improve the MVPA levels of working-age women. As women worldwide embrace modern technologies, e-health innovations may provide opportune and convenient methods of implementing programs and strategies to target PA in an effort to improve MVPA levels and cardiometabolic health. Previous reviews on this topic have been limited; none have focused on working-age women from developed countries who exhibit inappropriately low PA levels. It remains unknown as to which e-health interventions are most effective at increasing MVPA levels in this population. The purpose of this systematic review is to examine the effectiveness of e-health interventions in raising MVPA levels among working-age women in developed countries and to examine the effectiveness of these interventions in improving the health of women. METHODS: Eight electronic databases will be searched to identify all prospective cohort and experimental studies examining the impact of e-health interventions for increasing MVPA levels among working-age women (mean age 18-65 years) in developed countries. Gray literature including theses, dissertations, and government reports will also be examined. Study quality will be assessed using a modified Downs and Black checklist, and risk of bias will be assessed within and across all included studies using the Cochrane's risk of bias tool and Grades of Recommendation, Assessment, Development and Evaluation approach. A quantitative synthesis in the form of meta-analyses for measures of MVPA and health outcomes will be conducted where possible. DISCUSSION: This review will determine the effectiveness of e-health interventions in raising MVPA levels in working-age women in developed countries. It will form a contemporary, rigorously developed, and reliable research base for policy makers and stakeholders; and inform and influence the development and implementation of effective e-health interventions designed to increase MVPA levels and improve health outcomes in this population. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42014009534.

What is the feasibility of implementing effective sodium reduction strategies to treat hypertension in primary care settings? A systematic review.

OBJECTIVE: To evaluate whether efficacious counseling methods on sodium restriction can be successfully incorporated into primary care models for the management of hypertension. METHODS: We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects and Health Technology Assessment to identify randomized controlled trials of dietary counseling for salt intake reduction that reported significant reduction in 24-h urinary sodium and blood pressure levels among adults with untreated hypertension. Data extraction and assessment of reproducibility and feasibility were done in duplicate and any disagreements were resolved by consensus. RESULTS: Six trials were included for assessment of methods as they were efficacious in reducing sodium intake (24-h urinary sodium excretion) by 73 to 93 mmol/day (intervention) vs. 3.2 to 12.5 mmol/day (control). This was paralleled with a reduction in blood pressure (-4 to -27  mmHg) between groups. In four of the six trials, the methods were described in sufficient detail to be reproducible, but in none of these trials were the 'counseling methods' feasible for application in primary care settings. Apart from multiple sessions of counseling, the reported interventions were supplemented with provision of prepared food, community cooking classes, and intensive inpatient training sessions. CONCLUSION: Despite the availability of efficacious counseling methods for the reduction of sodium intake among newly diagnosed hypertensive patients (feasible within a clinical trial setting), none of these methods, in their present form, are suitable for incorporation into existing primary care settings in countries such as Canada, United States, and UK.