Accessory pathway localization with probabilistic density maps generated by a mobile application: Assessment of a full pre-excitation net-vector method.

INTRODUCTION: Precise electrocardiographic localization of accessory pathways (AP) can be challenging. Seminal AP localization studies were limited by complexity of algorithms and sample size. We aimed to create a nonalgorithmic method for AP localization based on color-coded maps of AP distribution generated by a web-based application. METHODS: APs were categorized into 19 regions/types based on invasive electrophysiologic mapping. Preexcited QRS complexes were categorized into 6 types based on polarity and notch/slur. For each QRS type in each lead the distribution of APs was visualized on a gradient map. The principle of common set was used to combine the single lead maps to create the distribution map for AP with any combination of QRS types in several leads. For the validation phase, a separate cohort of APs was obtained. RESULTS: A total of 800 patients with overt APs were studied. The application used the exploratory data set of 553 consecutive APs and the corresponding QRS complexes to generate AP localization maps for any possible combination of QRS types in 12 leads. Optimized approach (on average 3 steps) for evaluation of preexcited electrcardiogram was developed. The area of maximum probability of AP localization was pinpointed by providing the QRS type for the subsequent leads. The exploratory data set was validated with the separate cohort of APs (n = 256); p = .23 for difference in AP distribution. CONCLUSIONS: In the largest data set of APs to-date, a novel probabilistic and semi-automatic approach to electrocardiographic localization of APs was highly predictive for anatomic localization.

Ventricular Arrhythmias in Left Ventricular Assist Device Patients-Current Diagnostic and Therapeutic Considerations.

Left ventricular assist devices (LVAD) are used in the treatment of advanced left ventricular heart failure. LVAD can serve as a bridge to orthotopic heart transplantation or as a destination therapy in cases where orthotopic heart transplantation is contraindicated. Ventricular arrhythmias are frequently observed in patients with LVAD. This problem is further compounded as a result of diagnostic difficulties arising from presently available electrocardiographic methods. Due to artifacts from LVAD-generated electromagnetic fields, it can be challenging to assess the origin of arrhythmias in standard ECG tracings. In this article, we will review and discuss common mechanisms, diagnostics methods, and therapeutic strategies for ventricular arrhythmia treatment, as well as numerous problems we face in LVAD implant patients.

Cryoballoon ablation without use of contrast for the treatment of paroxysmal atrial fibrillation.

BACKGROUND: Cryoballoon ablation (CBA) for atrial fibrillation (AF) is usually preceded by demonstrating pulmonary vein (PV) occlusion using contrast. The aim of the study was to determine efficacy and safety of a simplified protocol for CBA performed without demonstrating PV occlusion and compare achieved results with conventional CBA. METHODS: Paroxysmal AF patients undergoing a first-time CBA were prospectively included. In the non-contrast (NC) group CBA was performed using standardized protocol without demonstrating PV occlusion. In the conventional contrast (CC) group ablations were performed after confirmation of PV occlusion. RESULTS: The NC and CC groups comprised 51 and 22 patients, respectively. PVI according to the group assignment was achieved in 34 (67%) and 21 (95.5%) patients from the NC and CC groups, respectively (p < 0.001). In the NC group, 184 (90%) out of 204 veins were isolated without venography. There were no differences between the NC and CC groups in terms of procedure duration (89.7 ± 22.6 vs. 90.0 ± 20.6 min; p = 0.7) and fluoroscopy time (15.3 ± 6.3 vs. 15 ± 4.5 min; p = 0.8). In the NC group, the use of contrast was significantly lower compared to the CC group (4.9 ± 10.1 vs. 19.4 ± 8.6 mL, p < 0.001). There were no serious adverse events in both groups. A 1-year freedom from AF was achieved in 73.5% and 71.5% of patients from the NC and CC groups, respectively (p = 1). CONCLUSIONS: Cryoballoon ablation without demonstrating vein occlusion with contrast is safe and feasible. Proposed simplified approach enables isolation of the vast majority of pulmonary veins with a significant reduction in the amount of contrast used.

Diagnostic electrocardiographic trap: A case of conduction system pacing.

His-bundle pacing (HBP) is a relatively new method of cardiac pacing, with recent studies showing an association between HBP and a lower risk of developing right ventricular heart failure compared to classical pacing methods. However, HBP is also associated with a higher risk of lead dislodgement, undersensing, and loss of capture. As such, a detailed assessment of pacing effectiveness in pacemaker patients is vital. In the presented case, an electrocardiogram (ECG) recording seems to present successful selective His-bundle pacing, while pacemaker follow-up demonstrated the loss of ventricular capture. In conclusion, patients receiving HBP should undergo ECG alongside pacing parameter analysis and pacing electrograms, as differences in successful and unsuccessful pacing ECG can be very subtle.

Bipolar Endo-Epicardial Radiofrequency Ablation of Therapy-Resistant Ventricular Arrhythmias: A Brief Case Series.

Despite extensive conventional endoepicardial ablation, significant intramural arrhythmogenic substrate may remain out of reach of unipolar radiofrequency ablation (RFA). The authors present clinical findings and procedural workflow for bipolar radiofrequency ablation (B-RFA) with 1 catheter placed against the endocardium and the other in the pericardial sac to ablate refractory ventricular arrhythmias. No serious adverse events occurred during B-RFA procedures, and the short-term and midterm clinical results were satisfactory. Optimal catheter choice and ablation parameters settings for B-RFA remain to be determined.

Flecainide in clinical practice.

Flecainide, similar to encainide and propafenone, is IC class antiarrhythmic, inhibiting Nav1.5 sodium channels in heart muscle cells and modulates cardiac conduction. Despite its over 40-year presence in clinical practice, strong evidence and well-known safety profile, flecainide distribution in Europe has not always been equal. In Poland, the drug has been available in pharmacies only since October this year, and previously it had to be imported on request. Flecainide can be used successfully in both the acute and chronic treatment of cardiac arrhythmias. The main indication for flecainide is the treatment of paroxysmal supraventricular tachycardias, including atrial fibrillation, atrioventricular nodal re-entrant tachycardia, atrioventricular re-entrant tachycardia and ventricular arrhythmias in patients without structural heart disease. Beyond that, it may be used in some supraventricular tachycardia in children and for sustained fetal tachycardia. Many studies indicate its efficacy comparable to or better than previously used drugs such as propafenone and amiodarone, depending on the indication. This review aims to highlight the most important clinical uses of flecainide in the light of the latest scientific evidence and to provide an overview of the practical aspects of treatment, including indications, off-label use, contraindications, areas of use, monitoring of treatment and most common complications, taking into account special populations: children and pregnant women.

Multimorbid management in atrial fibrillation: The Polish perspective in the EHRA-PATHS study.

BACKGROUND: Atrial fibrillation (AF) is the most common arrhythmia and places a significant burden on individuals as well as the healthcare system. AF management requires a multidisciplinary approach in which tackling comorbidities is an important aspect. AIMS: To evaluate how multimorbidity is currently assessed and managed and to determine if interdisciplinary care is undertaken. METHODS: A 21-item online survey was undertaken over four weeks as part of the EHRA-PATHS study examining comorbidities in Atrial Fibrillation and distributed to European Heart Rhythm Association members in Europe. RESULTS: A total of 341 eligible responses were received of which 35 (10%) were from Polish physicians. Compared to other European locations, the rates of specialist services and referrals varied but were not significantly different. However, there were higher numbers of specialised services reported in Poland compared to the rest of Europe for hypertension (57% vs. 37%; P = 0.02) and palpitations/arrhythmias (63% vs. 41%; P = 0.01) and the rates of sleep apnea services tended to be lower (20% vs. 34%; P = 0.10) and comprehensive geriatric care (14% vs. 36%; P = 0.01). The only statistical difference between Poland and the rest of Europe in reasons for referral rates was the barrier relating to insurance and financial reasons (31% vs. 11%; P <0.01, respectively). CONCLUSIONS: There is a clear need for an integrated approach to patients with AF and associated comorbidities. Prepardeness of Polish physicians to deliver such care seems to be similar to other European countries but may be hampered by financial obstacles.

Rate-Responsive Cardiac Pacing: Technological Solutions and Their Applications.

Modern cardiac pacemakers are equipped with a function that allows the heart rate to adapt to the current needs of the patient in situations of increased demand related to exercise and stress ("rate-response" function). This function may be based on a variety of mechanisms, such as a built-in accelerometer responding to increased chest movement or algorithms sensing metabolic demand for oxygen, analysis of intrathoracic impedance, and analysis of the heart rhythm (Q-T interval). The latest technologies in the field of rate-response functionality relate to the use of an accelerometer in leadless endocavitary pacemakers; in these devices, the accelerometer enables mapping of the mechanical wave of the heart's work cycle, enabling the pacemaker to correctly sense native impulses and stimulate the ventricles in synchrony with the cycles of atria and heart valves. Another modern system for synchronizing pacing rate with the patient's real-time needs requires a closed-loop system that continuously monitors changes in the dynamics of heart contractions. This article discusses the technical details of various solutions for detecting and responding to situations related to increased oxygen demand (e.g., exercise or stress) in implantable pacemakers, and reviews the results of clinical trials regarding the use of these algorithms.

Simultaneous Entrainment Response Assessment at Multiple Sites.

BACKGROUND: The entrainment response, defined as the difference between the postpacing interval and the tachycardia cycle length (TCL) recorded from a mapping catheter, allows to track down the components of the tachycardia loop. OBJECTIVES: The aim of this study was to evaluate if the postpacing interval measured simultaneously from multiple sites that are remote from the pacing site (PPIR) could be clinically useful in mapping re-entrant circuits. METHODS: Ninety-two episodes of entrainment response in 29 patients with different macro-re-entrant tachycardias were evaluated using a standardized entrainment protocol. The spatial distribution of different values of PPIR-TCL in a simulation and a computational model of an entrained re-entrant tachycardia was also analyzed. RESULTS: The PPIR exceeded TCL by more than 20 milliseconds only if both pacing and recording sites were outside the tachycardia circuit. The PPIR-TCL at in-circuit sites was always ≤20 milliseconds. Sites with negative PPIR-TCL values were found either outside or inside the tachycardia circuit. CONCLUSIONS: Assessment of entrainment response from catheters remote from the pacing site may enhance spatial mapping of the tachycardia circuit. The PPIR-TCL above 20 milliseconds has an excellent positive predictive value in identifying sites outside the tachycardia circuit.

Association of left atrial enlargement and increased left ventricular wall thickness with arrhythmia recurrence after cryoballoon ablation for atrial fibrillation.

BACKGROUND: Left atrial enlargement (LAE) predicts atrial fibrillation (AF) recurrence after cryoballoon-based pulmonary vein isolation (CB). Increased left ventricular wall thickness (LVWT) is pathophysiologically associated with LAE and atrial arrhythmias. AIMS: To assess effect of increased LVWT on long-term outcomes of CB depending on coexistence of LAE. METHODS: LAE was defined using either echocardiography ( > 48 cm³/m²) or multislice computer tomography (MSCT, ≥63 cm³/m²). Increased LVWT was echocardiographic septal/posterior wall thickness > 10 mm in males and > 9 mm in females. All patients achieved 2-year follow-up. RESULTS: Of 250 patients (median [interquartile range, IQR] age of 61 [49.0-67.3] years; 30% female) with AF (40% non-paroxysmal), 66.5% had hypertension, and 27.2% underwent redo procedure. MSCT was done in 76%. During follow-up of 24.5 (IQR, 6.0-31.00) months the clinical success rate was 72%, despite 46% of patients having arrhythmia recurrence. Arrhythmia recurrence risk was increased by LAE and increased LVWT (hazard ratio [HR], 1.801; P = 0.002 and HR, 1.495; P = 0.036; respectively). The highest arrhythmia recurrence (61.9% at 2 years) was among patients with LAE and increased LVWT (33.6% of patients); intermediate (41.8%) among patients with isolated LAE; and lowest among patients with isolated increased LVWT or patients without LAE or increased LVWT (36.8% and 35.2% respectively, P = 0.004). After adjustment for body mass index (BMI), paroxysmal AF, CHA2DS2-VASc score, clinically-significant valvular heart disease, and cardiomyopathy, patients with LAE and concomitant increased LVWT diagnosis had a 1.8-times increased risk of arrhythmia recurrence (HR, 1.784; 95% confidence interval [CI], 1.017-3.130; P = 0.043). CONCLUSION: Joint occurrence of LAE and increased LVWT is associated with the highest rate of arrhythmia recurrence after CB for AF.

Association between the acquisition of antibodies against Lyme disease and the risk of atrial arrhythmias.

INTRODUCTION: The impact of antibodies against Borrelia burgdorferi (BB) on the occurrence of cardiac arrhythmias in patients without typical symptoms of Lyme disease (LD) is largely unknown. OBJECTIVES: We aimed to assess the risk of atrial fibrillation (AF) and other atrial arrhythmias (AAs) in patients who tested positive for anti-LD antibodies. PATIENTS AND METHODS: We included consecutive patients referred for the diagnosis and treatment of AAs who had no history of erythema migrans or other symptoms of LD. The presence of anti-BB antibodies (immunoglobulin [Ig] M and IgG) was assessed in each patient, and the diagnostic workup of cardiac arrhythmias was performed. RESULTS: Of the 527 patients enrolled in the study, 292 (55%) were diagnosed with AAs, and we detected BB antibodies in 131 individuals (24.8%). The patients with a serological history of Borrelia infection were older (mean [SD], 55.6 [15.7] vs 50.3 [18.6] years; P = 0.01), had a higher probability of developing AF or other supraventricular arrhythmias (SAs) (66.4% vs 51.8%; P = 0.03), and had elevated levels of N­terminal pro-B ­type natriuretic peptide (NT­proBNP) (58% vs 47.5%; P = 0.04). We also found an as-sociation between the occurrence of AF and other SAs in patients with anti-BB antibodies and elevated NT­proBNP values, and the risk of AAs in these patients increased almost 3­fold (P = 0.01). CONCLUSION: Our data indicated an association between the exposure to Borrelia infection and the risk for AF and other AAs in the patients with elevated levels of NT­proBNP, suggesting the need for a more efficacious diagnostic approach to patients with SAs, especially in LD­endemic regions.

Systematic, early rhythm control strategy for atrial fibrillation in patients with or without symptoms: the EAST-AFNET 4 trial.

AIMS: Clinical practice guidelines restrict rhythm control therapy to patients with symptomatic atrial fibrillation (AF). The EAST-AFNET 4 trial demonstrated that early, systematic rhythm control improves clinical outcomes compared to symptom-directed rhythm control. METHODS AND RESULTS: This prespecified EAST-AFNET 4 analysis compared the effect of early rhythm control therapy in asymptomatic patients (EHRA score I) to symptomatic patients. Primary outcome was a composite of death from cardiovascular causes, stroke, or hospitalization with worsening of heart failure or acute coronary syndrome, analyzed in a time-to-event analysis. At baseline, 801/2633 (30.4%) patients were asymptomatic [mean age 71.3 years, 37.5% women, mean CHA2DS2-VASc score 3.4, 169/801 (21.1%) heart failure]. Asymptomatic patients randomized to early rhythm control (395/801) received similar rhythm control therapies compared to symptomatic patients [e.g. AF ablation at 24 months: 75/395 (19.0%) in asymptomatic; 176/910 (19.3%) symptomatic patients, P = 0.672]. Anticoagulation and treatment of concomitant cardiovascular conditions was not different between symptomatic and asymptomatic patients. The primary outcome occurred in 79/395 asymptomatic patients randomized to early rhythm control and in 97/406 patients randomized to usual care (hazard ratio 0.76, 95% confidence interval [0.6; 1.03]), almost identical to symptomatic patients. At 24 months follow-up, change in symptom status was not different between randomized groups (P = 0.19). CONCLUSION: The clinical benefit of early, systematic rhythm control was not different between asymptomatic and symptomatic patients in EAST-AFNET 4. These results call for a shared decision discussing the benefits of rhythm control therapy in all patients with recently diagnosed AF and concomitant cardiovascular conditions (EAST-AFNET 4; ISRCTN04708680; NCT01288352; EudraCT2010-021258-20).