Publications by authors named "Georgios Kollias"

Article Synopsis
  • Heart failure (HF) is a serious health issue that has high rates of illness and death, with electrical conduction problems being a key factor in its progression.
  • Conduction system pacing (CSP) is a new treatment method that includes techniques like His bundle pacing and left bundle branch area pacing, recommended for certain patients despite mainly being supported by observational studies.
  • There are significant challenges in implementing CSP, such as difficulties with lead implantation and the need for better tools, making future large-scale randomized controlled trials necessary for improving treatment strategies for HF patients.
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Article Synopsis
  • The peQasus study evaluates the safety and effectiveness of a new temperature-controlled high-power short-duration (HPSD) radiofrequency catheter (QDOT Micro) for pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF).
  • Conducted across 15 centers in Europe, the study involved 1,023 patients and compared outcomes between a very HPSD technique and a hybrid approach.
  • Results indicated complete PVI success, a mean procedure time of about 98 minutes, and a similar safety profile for both techniques, with 12-month arrhythmia-free survival rates around 77%.
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Article Synopsis
  • Advanced bipolar radiofrequency catheter ablation (Bi-RFA) is being studied as a new treatment for patients with ventricular tachycardia (VT) and premature ventricular contractions (PVC) that do not respond to standard unipolar radiofrequency ablation (Uni-RFA).
  • A multicenter registry conducted in Europe showed that out of 91 patients treated with Bi-RFA, 74% achieved elimination of clinical VT/PVC, and 78% experienced a significant reduction in PVC burden during follow-up.
  • The procedure was found to be generally safe and feasible, though there were some major complications reported, indicating that Bi-RFA could be a valid option for managing refractory VT/PVC
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The current gold standard in device therapy for advanced heart failure (HF), which has been firmly established in HF management for more than 25 years, is classical biventricular pacing (BiV-CRT). In the last decade, a new pacing modality called conduction system pacing (CSP) has emerged as a variant for advanced cardiac device therapy. It provides pacing with preserved intrinsic cardiac activation by direct stimulation of the specific cardiac conduction system.

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Pulmonary vein isolation (PVI) using radiofrequency ablation (RFA) is a standard-of-care treatment in the rhythm control strategy of symptomatic atrial fibrillation (AF). Ablation protocols, varying in the power and duration of energy delivery, have changed rapidly in recent years. Very high-power very short-duration ablation (vHPvSD) is expected to shorten procedural times compared to conventional ablation approaches.

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In recent decades, diagnosing, risk-stratifying, and treating patients with primary electrical diseases, as well as heart rhythm disorders, have improved substantially [...

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Waldenström macroglobulinemia (WM) is characterized by the expansion of clonal lymphoplasmacytic cells; the MYD88L265P somatic mutation is found in >90% of patients, but malignant B cells may still display intra-clonal heterogeneity. To assess clonal heterogeneity in WM, we generated and performed single-cell RNA sequencing of CD19 sorted cells from five patients with and two patients with genotype as well as two healthy donors. We identified distinct transcriptional patterns in the clonal subpopulations not only between the two genetically distinct WM subgroups but also among patients, which affected the B cell composition in the different subgroups.

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Atrial fibrillation is associated with neurocognitive comorbidities such as stroke and dementia. Evidence suggests that rhythm control-especially if implemented early-may reduce the risk of cognitive decline. Catheter ablation is highly efficacious for restoring sinus rhythm in the setting of atrial fibrillation; however, ablation within the left atrium has been shown to result in MRI-detected silent cerebral lesions.

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Magnetic Resonance images (MRIs) are employed in brain Stereotactic Radiosurgery and Radiotherapy (SRS/SRT) for target and/or critical organ localization and delineation. However, MRIs are inherently distorted, which also impacts the accuracy of the Magnetic Resonance Imaging/Computed Tomography (MRI/CT) co-registration process. In this phantom-based study, geometric distortion is assessed in 3T T2-weighted images (T2WIs), while the efficacy of an MRI distortion correction technique is also evaluated.

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Purpose: In frame-based Gamma Knife (GK) stereotactic radiosurgery two treatment planning workflows are commonly employed; one based solely on magnetic resonance (MR) images and the other based on magnetic resonance/computed tomography (MR/CT) co-registered images. In both workflows, target localization accuracy (TLA) can be deteriorated due to MR-related geometric distortions and/or MR/CT co-registration uncertainties. In this study, the overall TLA following both clinical workflows is evaluated for cases of multiple brain metastases.

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Background: A 19-year-old woman with an established diagnosis of long QT syndrome (LQTS) 2 and underlying KCNH2-mutation was referred to our centre for recurrent polymorphic ventricular tachycardia (VT) and ventricular fibrillation (VF) refractory to medical therapy and bilateral thoracic sympathectomy.

Case Summary: Holter monitoring revealed a relevant premature ventricular complex (PVC) burden of two different morphologies. One PVC was originating from the left anterior fascicle, the other from the left posterior fascicle.

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The novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread rapidly during the first months of 2020 and continues to expand in multiple areas across the globe. Molecular epidemiology has provided an added value to traditional public health tools by identifying SARS-CoV-2 clusters or providing evidence that clusters based on virus sequences and contact tracing are highly concordant. Our aim was to infer the levels of virus importation and to estimate the impact of public health measures related to travel restrictions to local transmission in Greece.

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Purpose: Cerebral thromboembolic events are well-known complications of pulmonary vein isolation (PVI) and can manifest as stroke or silent cerebral embolic lesions. The aim of this study was to compare the incidence of cerebral embolic lesions (including silent cerebral embolism and stroke) after AF ablation in patients on vitamin K antagonists versus patients on non-vitamin K-dependent oral anticoagulants, and to identify corresponding clinical and procedural risk factors.

Methods: A total of 421 patients undergoing PVI were prospectively included into the study.

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We develop a proxy model based on deep learning methods to accelerate the simulations of oil reservoirs-by three orders of magnitude-compared to industry-strength physics-based PDE solvers. This paper describes a new architectural approach to this task modeling a simulator as an end-to-end black box, accompanied by a thorough experimental evaluation on a publicly available reservoir model. We demonstrate that in a practical setting a speedup of more than 2000X can be achieved with an average sequence error of about 10% relative to the simulator.

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This work focuses on MR-related sequence dependent geometric distortions, which are associated with B inhomogeneity and patient-induced distortion (susceptibility differences and chemical shift effects), in MR images used in stereotactic radiosurgery (SRS) applications. Emphasis is put on characterizing distortion at target brain areas identified by gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) paramagnetic contrast agent uptake. A custom-made phantom for distortion detection was modified to accommodate two small cylindrical inserts, simulating small brain targets.

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Renal denervation (RDN) has been proposed as a novel interventional antihypertensive technique. However, existing evidence was mainly from patients with severe resistant hypertension. The authors aimed to evaluate the efficacy of RDN in patients with resistant hypertension with mildly elevated blood pressure (BP).

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Background: Sufficient electrode-tissue contact is crucial for adequate lesion formation in radiofrequency catheter ablation (RFCA).

Objective: We assessed the impact of direct catheter force measurement on acute procedural parameters and outcome of RFCA for paroxysmal and persistent atrial fibrillation (AF).

Methods: Ninety-nine consecutive patients (70% men) with paroxysmal (63.

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Objective: To test the hypothesis that left-ventricular hypertrophy (LVH) is better associated with aortic, than brachial, 24-h average blood pressure (BP) in individuals with hypertension.

Background: The office aortic BP is associated better with organ damage, such as LVH, than the office brachial BP; whether the 24-h average aortic BP associates better with LVH, than the 24-h average brachial BP, has never been tested.

Methods: Aortic ambulatory BP monitoring (ABPM) was performed with a novel validated oscillometric cuff-based BP recording device, also used for simultaneous brachial ABPM, and the application of pulse wave analysis method.

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Context: Although adrenal incidentalomas (AIs) are associated with a high prevalence of cardiovascular risk (CVR) factors, it is not clear whether patients with nonfunctioning AI (NFAI) have increased CVR.

Objective: Our objective was to investigate CVR in patients with NFAI.

Design And Setting: This case-control study was performed in a tertiary general hospital.

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Although long-term weight gain has been associated with cardiovascular risk and intima-media thickening (IMT), no sufficient data exist on possible associations of such weight changes with more advanced stages of subclinical atherosclerosis. Moreover, the value of self-reported weight changes, a more practical approach to assess long-term history in adiposity status, is still a matter of debate. In this longitudinal study, long-term changes in BMI and overweight status were assessed in 106 healthy young adults (age 40.

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Background: Hyperprolactinemia has been recently associated with hypertension and endothelial dysfunction in humans, confirming animal studies performed in the 1970s that showed high prolactin levels to exert positive chronotropic and vasoconstrictive effects. Whether prolactin affects endothelial function, in the absence of hyperprolactinemia, remains unknown. Considering that secretion of prolactin presents circadian rhythmicity, we tested the hypothesis that in patients with hypertension, who present diurnal variation in their endothelial function as well, prolactin levels correlate with endothelial function and/or blood pressure.

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Objective: The extent of target organ damage has been associated with both central hemodynamics and arterial stiffening, and the time rate of blood pressure (BP) changes in essential hypertension. However, the relative significance of these parameters has not been examined.

Methods: We recruited 232 consecutive uncomplicated newly diagnosed hypertensive patients and 241 normotensive individuals.

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