Michael Efremidis

Anticoagulation and antiplatelet therapy in implantation of electrophysiological devices

The growing implantations of electrophysiological devices in the context of increasing rates of chronic antithrombotic therapy in cardiovascular disease patients underscore the importance of an effective periprocedural prophylactic strategy for prevention of bleeding complications. In this review, we provide a concise overview of the data regarding anticoagulation and antiplatelet therapy in arrhythmia device surgery. Also, we critically discuss risk factors and procedural parameters that are potentially associated with haemorrhagic untoward events in this setting. Of note, current evidence suggests that heparin bridging therapy in patients on chronic anticoagulation and dual-antiplatelet therapy are associated with increased risk of pocket haematoma formation. Continuation of oral anticoagulation and short-term interruption of clopidogrel with aspirin maintenance in eligible patients, respectively, represent promising strategies with an acceptable safety profile. Besides the perioperative management of antithrombotic therapy, some extra supportive measures may also reduce the incidence of haematomas. High-risk cases should be better treated by experienced operators in high-volume centres. More randomized studies are needed to elucidate the exact role of particular antithrombotic therapy protocols. Finally, the recently accumulated data on this subject should be incorporated into the professional guidelines regarding arrhythmia device therapy.

Effect of Atrial Pressure Increase on Effective Refractory Period and Vulnerability to Atrial Fibrillation in Patients with Lone Atrial Fibrillation

Background: There is evidence suggesting that atrial fibrillation (AF) may be induced by acute increase of atrial pressure. The aim of the present study was to investigate the effect of alterations in atrial pressure, induced by varying the atrioventricular (AV) interval, on atrial refractoriness, and on the frequency of induction of (AF), in patients with a history of lone atrial fibrillation (LAF).Methods and Results: Twenty-five patients were included in this study. The patients were divided in two groups: the LAF group, and the control group. None of the patients in either group had organic heart disease. Effective refractory period (ERP) and duration of atrial extrastimulus electrogram (A2) were measured at two right atrial sites (high lateral wall, atrial appendage) during AV pacing (cycle length: 500 msec) with different AV intervals. Peak, minimal and mean atrial pressure increased from 8.57 ± 2.37 to 18.14 ± 4.74 mm Hg, 2 ± 2.23 to 5.14 ± 2.60 mm Hg (p = 0.0001) and from 4.28 ± 1.6 mm Hg to 9.77 ± 2.9 mm Hg (p = 0.001), respectively during AV interval modification. During lateral and atrial appendage pacing, with a progressive decrease of AV interval to 160, 100, 80, 40, 0 msec, the ERP, the dispersion of ERP, functional refractory period (FRP), A2 and latency period (LP) did not change significantly, in both groups. The frequency of induction of AF was not statistically different in both lateral atrial wall and appendage, during pacing in different AV intervals.Conclusions: This study demonstrates that alterations in the intraatrial pressure does not have important effects on atrial refractoriness and does not increase vulnerability to AF in patients with a history of LAF.

Long-term prognosis of asymptomatic individuals with spontaneous or drug-induced type 1 electrocardiographic phenotype of Brugada syndrome

BACKGROUNDnRisk stratification of asymptomatic individuals with type 1 electrocardiogram (ECG) phenotype of Brugada syndrome (BS) still remains controversial. This study investigated the long-term prognosis of asymptomatic subjects with spontaneous or drug-induced type 1 ECG pattern of BS.nnnMETHODS AND RESULTSnData from 33 apparently healthy individuals (30 males; age, 43.6 ± 13.4 years) with spontaneous (n = 12) or drug-induced (n = 21) type 1 ECG pattern of BS were retrospectively analyzed. Thirteen subjects (39.4%) displayed a positive family history of BS and/or sudden cardiac death. Electrophysiologic study was performed in 16 subjects, and programed right ventricular stimulation induced polymorphic ventricular tachycardia in 9 (56.3%) of them. A cardioverter defibrillator was implanted in 6 cases. During a mean follow-up period of 5.3 ± 2.8 years, all subjects remained asymptomatic. None of them had syncope or cardioverter defibrillator discharges due to ventricular arrhythmias.nnnCONCLUSIONSnAsymptomatic individuals with spontaneous or drug-induced type 1 ECG phenotype of BS display a benign clinical course during long-term follow-up.

Prognosis, risk stratification, and management of asymptomatic individuals with Brugada syndrome: A systematic review

Brugada syndrome (BrS) is a primary electrical disease associated with increased risk of sudden cardiac death due to polymorphic ventricular arrhythmias. The prognosis, risk stratification, and management of asymptomatic individuals remain the most controversial issues in BrS. Furthermore, the decision to manage asymptomatic patients with an implantable cardioverter‐defibrillator should be made after weighing the potential individual risk of future arrhythmic events against the risk of complications associated with the implant and follow‐up of patients living with such devices, and the accompanying impairment of the quality of life. Several clinical, electrocardiographic, and electrophysiological markers have been proposed for risk stratification of subjects with BrS phenotype, but the majority have not yet been tested in a prospective manner in asymptomatic individuals. Recent data suggest that current risk factors are insufficient and cannot accurately predict sudden cardiac death events in this setting. This systematic review aims to discuss contemporary data regarding prognosis, risk stratification, and management of asymptomatic individuals with diagnosis of Brugada electrocardiogram pattern and to delineate the therapeutic approach in such cases.

High risk electrocardiographic markers in Brugada syndrome

Several clinical, electrocardiographic (ECG) and electrophysiological markers have been proposed to provide optimal risk stratification in patients with Brugada syndrome (BrS). Of the different markers, only a spontaneous type 1 ECG pattern has clearly shown a sufficiently high predictive value. This review article highlights specific ECG markers based on depolarization and/or repolarization that have been associated with an increased risk of arrhythmic events in patients with BrS.

Right Ventricular Outflow Tract Electroanatomical Abnormalities Predict Ventricular Fibrillation Inducibility in Brugada Syndrome

Electroanatomical mapping has demonstrated abnormal bipolar electrograms at the anterior aspect of the right ventricular outflow tract (RVOT) epicardium along with histopathologic evidence of fibrosis in patients with Brugada syndrome (BrS).1,2 These epicardial abnormalities are believed to serve as the electric substrate for ventricular fibrillation (VF) initiation and maintenance in BrS.1,2 We have recently demonstrated that patients with BrS display wide areas of endocardial unipolar voltage abnormalities that possibly reflect epicardial structural abnormalities at the free wall of the RVOT.3 We hypothesized that electroanatomical abnormalities detected by high-density endocardial unipolar voltage mapping at the RVOT predict VF inducibility during programmed ventricular stimulation (PVS).nnThe study population consisted of 17 asymptomatic probands (15 males, 37.3±10.8 years) with spontaneous type 1 BrS ECG pattern referred for risk stratification with PVS. A comprehensive evaluation including late gadolinium enhancement cardiac magnetic resonance imaging ruled out structural heart disease in all patients. The study was approved by the Hospital Ethics Committee and written informed consent was obtained from all patients.nnHigh-density electroanatomical mapping of the RVOT during sinus rhythm was performed as described previously (Methods in the Data Supplement).3 In brief, a minimum of 800 points were sampled to …

Impact of ranolazine on ventricular arrhythmias - A systematic review

Ranolazine is a new medication for the treatment of refractory angina. However, except its anti‐anginal properties, it has been found to act as an anti‐arrhythmic. The aim of our systematic review is to present the existing data about the impact of ranolazine in ventricular arrhythmias. We searched MEDLINE and Cochrane databases as well clinicaltrials.gov until September 1, 2017 to find all studies (clinical trials, observational studies, case reports/series) reported data about the impact of ranolazine in ventricular arrhythmias. Our search revealed 14 studies (3 clinical trials, 2 observational studies, 8 case reports, 1 case series). These data reported a beneficial impact of ranolazine in ventricular tachycardia/fibrillation, premature ventricular beats, and ICD interventions in different clinical settings. The existing data highlight the anti‐arrhythmic properties of ranolazine in ventricular arrhythmias.

Predictors of arrhythmia recurrence in patients with heart failure undergoing left atrial ablation for atrial fibrillation

Atrial fibrillation (AF) ablation is increasingly used in patients with reduced left ventricular ejection fraction (LVEF). The aim of the present study was to evaluate the long‐term results of a single radiofrequency catheter ablation procedure in heart failure (HF) patients with AF.

Impact of baseline renal function on all-cause mortality in patients who underwent cardiac resynchronization therapy: A systematic review and meta-analysis

Cardiac resynchronization therapy (CRT) improves both morbidity and mortality in selected patients with heart failure and increased QRS duration. However, chronic kidney disease (CKD) may have an adverse effect on patient outcome. The aim of this systematic review was to analyze the existing data regarding the impact of baseline renal function on all‐cause mortality in patients who underwent CRT.