Publications by authors named "Michael Efremidis"

Approximately 10 % of patients who have suffered from myocardial infarction develop new-onset atrial fibrillation (AF). Coronary artery disease implicating atrial branches has been associated with AF. The following variables have been associated with new-onset AF in the setting of acute coronary syndrome: older age, history of hypertension, history of angina, history of stroke, chronic renal failure, body mass index, no statin use, worse nutritional status, worse Killip class, admission heart rate ≥ 85 bpm, complete atrioventricular block, Glasgow prognostic score, Syntax score, CHEST score > 3, PRECISE-DAPT score ≥ 25, left ventricular ejection fraction ≤40 %, increased left atrial diameter, E/E' ratio > 12, epicardial fat tissue thickness, and thrombolysis in myocardial infarction flow <3.

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Background: A novel focal lattice-tip catheter allowing the delivery of either pulsed field (PF) or radiofrequency (RF) energy has recently received regulatory approval. The technology features a proprietary 3-dimensional electroanatomic mapping system.

Objective: We describe the first real-world and multicenter experience.

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Introduction: Pulsed field ablation (PFA) is a form of nonthermal energy that has been recently introduced for pulmonary vein isolation (PVI). A multi-electrode pentaspline catheter for delivery of PFA guided by fluoroscopy has become widely available for clinical use.

Methods And Results: In this study, we aimed to assess whether the addition of electroanatomical mapping (EAM) for confirmation of PVI in the acute phase can increase the efficacy of the procedure in terms of arrhythmia recurrences.

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Article Synopsis
  • A novel lattice-tip catheter designed for high-density mapping and dual ablation was studied for its effectiveness in diagnosing and treating atrial tachycardias (ATs).
  • The study involved 20 patients, where activation mapping accurately identified AT mechanisms, and successful conversion to sinus rhythm was achieved in most cases without major complications.
  • The results suggest that this catheter provides effective mapping and ablation for ATs, but certain limitations need to be recognized.
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Aims: The left bundle branch block (LBBB) is a strong predictor of response to cardiac resynchronization therapy (CRT). However, a significant number of patients do not respond to the treatment. The study sought to evaluate the impact of the stricter Strauss criteria for left bundle branch block (St-LBBB) on CRT response, hospitalizations, ventricular arrhythmia (VA) events and mortality.

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Introduction: A young man was referred to our Center for refractory cardiogenic shock, accompanied with uncontrolled atrial flutter of unknown duration. The patient was supported with VenoArterial Extracorporeal Membrane Oxygenation (VA ECMO) and Intra-Aortic Balloon Pump (IABP) as a bridge to decision.

Case Report: His course was complicated by pulmonary hemorrhage due to an unknown endobronchial mass.

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  • Atrial fibrillation (AF) is the most common arrhythmia after surgery, and this study aimed to find out how often it occurs (postoperative AF or POAF) and what factors predict it, especially focusing on inflammation markers like C-reactive protein (CRP).
  • In a study with over 53,000 patients, POAF happened in 570 patients (1.1%), primarily occurring around 3.4 days post-surgery, with a notable link between higher CRP levels and the likelihood of developing POAF.
  • The research found that patients undergoing lung and cardiovascular surgeries had the highest risk of POAF, indicating that surgery type and levels of inflammation are key predictors of this condition.
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Atrial fibrillation (AF) significantly increases the risk of stroke and heart failure, but is frequently asymptomatic and intermittent; therefore, its timely diagnosis poses challenges. Early detection in selected patients may aid in stroke prevention and mitigate structural heart complications through prompt intervention. Smartwatches, coupled with powerful artificial intelligence (AI)-enabled algorithms, offer a promising tool for early detection due to their widespread use, easiness of use, and potential cost-effectiveness.

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Background: Left atrial (LA) fibrosis has been shown to be associated with atrial fibrillation (AF) recurrence. Beat-to-beat (B2B) index is a non-invasive classifier, based on B2B P-wave morphological and wavelet analysis, shown to be associated with AF incidence and recurrence. In this study, we tested the hypothesis that the B2B index is associated with the extent of LA low-voltage areas (LVAs) on electroanatomical mapping.

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Article Synopsis
  • * Follow-up over approximately 29 months revealed that ILRs helped establish diagnoses in significant portions of these patients, particularly detecting issues like atrial fibrillation in those with a history of cryptogenic stroke.
  • * The findings suggest that ILRs not only aid in diagnosis but also lead to changes in treatment strategies for around one-fourth of the patients, making them a valuable tool in cardiac evaluations.
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Background: High-power short-duration (HPSD) and very-high-power short-duration (vHPSD-90 W/4 s) radiofrequency (RF) technology has reduced the procedure time of pulmonary vein isolation (PVI) using RF without compromising the efficacy of the technique. The current study compares the novel technology of HPSD/vHPSD with cryoablation (CRYO) in terms of efficacy, safety, and procedure time in a cohort of symptomatic patients with paroxysmal atrial fibrillation (pAF).

Methods: This is a prospective, non-randomized trial.

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Experimental in vivo and in vitro studies showed that electric currents applied during the absolute refractory period can modulate cardiac contractility. In preclinical studies, cardiac contractility modulation (CCM) was found to improve calcium handling, reverse the foetal myocyte gene programming associated with heart failure (HF), and facilitate reverse remodeling. Randomized control trials and observational studies have provided evidence about the safety and efficacy of CCM in patients with HF.

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Key Clinical Message: R-wave double counting is a rare cause of ventricular oversensing that can lead to inappropriate shocks. Optimizing device programming is essential for the avoidance of subsequent inappropriate therapies.

Abstract: R-wave double counting is a rare cause of ventricular oversensing that can lead to inappropriate shocks.

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Article Synopsis
  • Patients with end-stage heart failure often experience increased ventricular arrhythmias that negatively impact heart function and lead to hospitalizations.
  • While implantable cardioverter-defibrillators can stop dangerous arrhythmias, they don't reduce the overall frequency of these episodes.
  • Effective management usually involves a combination of invasive and noninvasive treatments, with this review highlighting recent advancements in catheter ablation and a structured treatment approach.
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Cardioneuroablation is an emerging alternative therapeutic modality for young patients with severe neurally-mediated syncope. We present two images of cardioneuroablation performed in young patients who suffered from recurrent neurally-mediated syncope with asystole and functional atrioventricular block. The patients remain syncope-free during follow-ups.

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Background: Balloon pulmonary angioplasty (BPA) has provided an effective invasive treatment for inoperable patients with chronic thromboembolic pulmonary hypertension (CTEPH). The hemodynamic improvement achieved by BPA has significantly increased the long-term prognosis of these patients, mostly by reversing the negative remodeling of the right ventricle (RV).

Materials And Methods: In a cohort of 17 patients with symptomatic CTEPH hemodynamic data were collected before and after the completion of BPA sessions.

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Mitral valve prolapse (MVP) has an estimated prevalence of 2-3% in the general population. Patients with MVP have an increased risk of ventricular arrhythmic events. The aim of this meta-analysis was to identify easily obtained markers that can be used for the arrhythmic risk stratification of MVP patients.

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Introduction: Patients with persistent atrial fibrillation (AF) represent a challenging population for rhythm control therapies. Catheter ablation (CA) with pulmonary vein isolation (PVI) is an effective treatment option for the reduction of the arrhythmic burden. Data regarding the comparability between radiofrequency (RF) and cryoballoon ablation (CRYO) in persistent AF are limited.

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We present a case of a previously healthy 23-year-old male who presented with chest pain, palpitations and spontaneous type 1 Brugada electrocardiographic (ECG) pattern. Positive family history for sudden cardiac death (SCD) was remarkable. Initially, clinical symptoms in combination with myocardial enzymes elevation, regional myocardial oedema with late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) and inflammatory lymphocytoid-cell infiltrates in the endomyocardial biopsy (EMB) suggested the diagnosis of a myocarditis-induced Brugada phenocopy (BrP).

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In the setting of structural heart disease, ventricular tachycardia (VT) is typically associated with a re-entrant mechanism. In patients with hemodynamically tolerated VTs, activation and entrainment mapping remain the gold standard for the identification of the critical parts of the circuit. However, this is rarely accomplished, as most VTs are not hemodynamically tolerated to permit mapping during tachycardia.

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Atrial cardiomyopathy (AC) is an evolving pathophysiological entity that has expanded our understanding regarding the atrium and its role in arrhythmogenesis and cardiac thromboembolism. The pathological myocardium in AC promotes arrhythmogenesis through mechanical dysfunction (hypocontractility, fibrosis), adverse alterations of the endothelium and secretion of prothrombotic factors (IL-6, IL-8, TNF-a). 'Red flags', indicative of AC, can be recognized either non-invasively by electrocardiography, echocardiography and cardiac magnetic resonance imaging or invasively by high-density electroanatomical mapping as low bipolar voltage areas of the affected myocardium.

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Although mitral valve prolapse (MVP) is usually considered a benign clinical condition, it has been linked with ventricular arrhythmias and sudden cardiac death in patients with a certain "arrhythmic" phenotype, raising awareness and mandating a specific risk stratification protocol. Mitral annular disjunction (MAD) is considered a "red flag" in malignant MVP syndrome along with bileaflet myxomatous prolapse, female gender, negative or biphasic T waves in the inferior leads, fibrosis in the papillary muscles or inferobasal wall detected by cardiac magnetic resonance imaging and complex arrhythmias of right bundle branch morphology. MAD seems to play a critical role in the chain of morphofunctional abnormalities which lead to increased mechanical stretch and subsequent fibrosis mainly in the papillary muscles, forming the vulnerable anatomic substrate prone to arrhythmogenesis, and associated with long-term severe ventricular arrhythmias.

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Despite the strict indications for cardiac resynchronization therapy (CRT) implantation, a significant proportion of patients will fail to adequately respond to the treatment. This systematic review aims to present the existing evidence about the role of cardiac magnetic resonance (CMR) in identifying patients who are likely to respond better to the CRT. A systematic search in the MedLine database and Cochrane Library from their inception to August 2021 was performed, without any limitations, by two independent investigators.

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