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Background: Although radiofrequency (RF) catheter ablation of cavo-tricuspid isthmus (CTI) is an established treatment for typical right atrial flutter (RAFL), it remains to be established whether local tissue impedance (LI) is able to predict effective CTI ablation and what LI drop values during ablation should be used to judge a lesion as effective. We aimed to investigate the ability of LI to predict ablation efficacy in patients with RAFL., Methods: RF delivery was guided by the DirectSense™ algorithm. Successful single RF application was defined according to a defragmentation of atrial potentials (DAP), reduction of voltage (RedV) by at least 80% or changes on unipolar electrogram (UPC). The ablation endpoint was the creation of bidirectional conduction block (BDB) across the isthmus., Results: 392 point-by-point RF applications were analyzed in 48 consecutive RAFL patients. The mean baseline LI was 105.4 ± 12Ω prior to ablation and 92.0 ± 11Ω after ablation (p < 0.0001). According to validation criteria, absolute drops in impedance were larger at successful ablation sites than at ineffective ablation sites (DAP: 17.8 ± 6Ω vs. 8.7 ± 4Ω; RedV: 17.2 ± 6Ω vs. 7.8 ± 5Ω; UPC: 19.6 ± 6Ω vs. 10.1 ± 5Ω, all p < 0.0001). LI drop values significantly increased according to the number of criteria satisfied (ranging from 7.5Ω to 19.9). BDB was obtained in all cases. No procedure-related adverse events were reported., Conclusions: A LI-guided approach to CTI ablation was safe and effective in treating RAFL. The magnitude of LI drop was associated with effective lesion formation and BDB and could be used as a marker of ablation efficacy., Clinical Trial Registration: Catheter Ablation of Arrhythmias with a High-Density Mapping System in Real-World Practice (CHARISMA). URL: http://clinicaltrials.gov/ Identifier: NCT03793998., (© 2022 Wiley Periodicals LLC.)

Background: Optimizing dual-chamber pacing to prevent recurrences of atrial tachyarrhythmias (AT) in sinus node dysfunction is still debated. Despite the large number of studies, efficacy of sophisticated preventive algorithms has never been proven. It is not clear whether this is due to imperfect study designs or to a substantial inefficacy of pacing therapies., Aim: To intraindividually compare AT burden between an atrial overdrive and two heart rate modulation approaches: a conventional accelerometric-sensor-based DDDR mode and a contractility-driven rate responsive closed loop (CLS) algorithm., Methods and Results: Four hundred fifty-one patients with Brady-Tachy syndrome (BTS), severe bradycardia, and a documented episode of atrial fibrillation were enrolled. One month after implant, each pacing therapy was activated for 3 months in random order. A simple log transformation was used to handle large and skew AT burden distributions. Estimates were adjusted for false-positive AT episodes and reported as geometric means (95% confidence interval). A significantly higher AT burden was observed during overdrive, 0.14% (0.09%, 0.23%) (adjusted, 0.12%[0.07%, 0.20%]). Both DDDR and CLS performed better: respectively, 0.11% (0.07%, 0.17%) (adjusted, 0.08%[0.05%, 0.14%]), 0.06% (0.03%, 0.09%) (adjusted, 0.04%[0.03%, 0.07%]). All the comparisons were statistically significant. During overdrive significantly more patients had AT episodes of duration between 1 minute and 1 hour. No significant differences were observed for longer episodes., Conclusions: Atrial overdrive showed the worst performance in terms of AT burden reduction and should not be preferred to heart rate modulation approaches that still have to be considered as a first-choice pacing mode in BTS.

Background: Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice. The natural history of this disturbance and its effect on survival is still not known in patients with implantable cardioverter defibrillators (ICDs)., Methods and Results: Several controlled trials for both secondary and primary prevention of sudden death using ICDs have been published in literature, and meta-analysis of them provided useful clinical information on the outcome during the follow-up of this population. AF occurs in about 25% of the patients with secondary prevention indication for ICD implantation. The prevalence of AF in patients with primary prevention indication for ICD implantation is much more difficult to define; it seems to be higher in patients with left ventricular dysfunction due to nonischemic etiology (ranging from 15% to 25%), and is lower in patients with ischemic etiology (about 5-10%). However, data from clinical registries, which are expected to better reflect clinical practice than randomized trials, seem to show a substantial difference as compared to the latter ones. A history of AF episodes in patients with an ICD indication for both primary and secondary prevention is probably associated with a higher risk of death. This is particularly evident in secondary prevention in ICD recipients, while it is still controversial in patients who received an ICD for primary prevention, particularly when patients with nonischemic etiology of their left ventricular dysfunction are considered. In a population of patients implanted with an ICD, there are several other clinical factors (ejection fraction, New York Heart Association functional class, age) that can interfere with the risk of death much more than AF itself., Conclusions: Further large-scale registries are needed to further characterize the population receiving ICD implantation, assessing the course of risk of death with regard to clinical variables and to evaluate the degree of acceptance of trials in clinical practice.

Unlabelled: The efficacy and safety of propafenone as an oral loading dose (600-mg single oral dose) in converting recent-onset atrial fibrillation (< or = 7 days duration) to sinus rhythm were evaluated in a single-blind, placebo-controlled study according to patients' age. Overall, 240 hospitalized patients, NYHA Class < or = 2 without signs or symptoms of heart failure were enrolled: among patients aged < or = 60 years, 55 were allocated to propafenone treatment and 59 to placebo, respectively, and among patients aged > 60 years, 64 were allocated to propafenone treatment and 62 to placebo, respectively., Results: In each age group, the likelihood of conversion to sinus rhythm was significantly greater after propafenone compared with placebo at 3 and 8 hours. For patients aged < or = 60 years, corresponding odd ratios were 3.78 (95% CI = 1.80-7.92, P = 0.04) at 3 hours and 4.74 (95% CI = 2.12-10.54, P = 0.02) at 8 hours; for patients aged > 60 years odd ratios were 5.03 (95% CI = 2.08-12.12, P = 0.02) at 3 hours and 6.75 (95% CI = 3.28-73.86, P = 0.01) at 8 hours, respectively. Logistic regression analysis showed that conversion to sinus rhythm within 3 hours was predicted by age < or = 60 years (P = 0.0064) and by propafenone treatment (P < 0.0001), and conversion to sinus rhythm within 8 hours was predicted by age < or = 60 years (P = 0.0467) and by propafenone treatment (P < 0.0001). The occurrence of adverse effects was observed in 14%-16% of propafenone treated patients and in 8% of placebo treated patients without significant differences according to age. In conclusion, in patients with recent-onset atrial fibrillation without signs of heart failure, propafenone as a single oral loading dose is effective. It is also effective in selected elderly subjects with a favorable safety profile. Moreover, spontaneous conversion to sinus rhythm appears to occur less frequently in elderly patients.

A population of 123 patients with recent-onset (< 72 hours) atrial fibrillation (AF) without heart failure was randomly treated with propafenone (PFN) intravenously (i.v.) (2 mg/kg bolus followed by 0.0078 mg/kg/min infusion) or in a single oral dose (o.s.) (600 mg), or with placebo (PLA) (phase 1). If AF persisted 8 hours later, patients on active drugs received the alternative formulation (crossover), and patients receiving PLA remained on PLA (phase 2). A 24-hour Holter monitoring was performed and conversion to sinus rhythm (SR) at 1, 4, and 8 hours of each phase was used as the criterion of efficacy. Conversion to SR occurred within 1 hour in 48% of patients with i.v.-PFN, 15% with o.s.-PFN, and in 17% with PLA (both P < 0.05 vs i.v.-PFN). Oral PFN was superior to PLA at 4 hours (71% vs 33%, P = 0.001) and 8 hours (78% vs 48%, P < 0.01), and 1 at 8 hours also superior to i.v.-PFN (53%, P < 0.03). The mean conversion time within 4 hours was shorter with i.v.-PFN (25 +/- 15') than with o.s.-PFN (167 +/- 166', P < 0.001) or with PLA (156 +/- 107', P < 0.001). The rates of conversion to SR with i.v.-PFN after o.s.-PFN failure were comparable to PLA at any observation time, whereas nonresponders to i.v.-PFN who received o.s.-PFN had significantly higher conversion rates than with placebo at both 4 hours (65% vs 19%) and 8 hours (76% vs 24%; both P < 0.045). Neither serious adverse effects nor episodes of regular tachycardia with 1:1 AV conduction were noted. PFN administered intravenously or in a single oral loading dose was safe and efficacious in converting recent-onset AF to SR. The rates of conversion were different with different routes of administration: i.v.-PFN was superior to o.s.-PFN over a short observation period, while the overall efficacy of o.s.-PFN was superior at 8 hours.

A population of 283 patients with recent onset (< 72 hours) AF, without heart failure, who received a single 450- or 600-mg oral dose of propafenone, or digoxin 1 mg, or placebo for conversion to sinus rhythm (SR), was studied to determine whether a routine admission to the hospital for drug administration is justified. Previous bradyarrhythmias or sick sinus syndrome (SSS), and concomitant use of antiarrhythmic drugs were exclusion criteria. None of the 283 patients studied experienced VT or VF and none of them needed implantation of a temporary pacemaker. Periods of atrial tachyarrhythmias with regularization of atrial waves and 1:1 AV conduction were observed in only two cases, both receiving placebo. No predictor of proarrhythmia was found among the clinical variables considered (age, etiology, arrhythmia duration, atrial dimension, and blood potassium). No serious hemodynamic adverse effects were noted in either group. The rates of conversion to SR after 4 hours were: 80 (57%) of 141 patients who received propafenone and 35 (25%) of 142 patients who received digoxin or placebo (P < 0.001). Acute oral treatment with propafenone is simple and effective for the conversion of recent onset AF to SR in patients without clinical signs of heart failure. The routine admission of these patients to the hospital is not necessary. Home-based administration of oral propafenone to a selected group of patients could significantly increase the cost effectiveness of this treatment.

The incidence of fast atrial tachycardias with regular ventricular rhythm was assessed in a population of 243 patients with recent onset (< 72 hours) atrial fibrillation (AF), without heart failure, randomly treated with single loading oral dose of propafenone (600 mg), flecainide (300 mg), digoxin (1 mg), or placebo for acute conversion to sinus rhythm (SR). Fast atrial arrhythmias developed in 14 (6%) patients: 6/92 treated with propafenone, 3/34 treated with flecainide, 1/25 treated with digoxin, and 4/92 who received placebo (P = NS). Heart rate > 175 beats/min with 1:1 AV conduction ensued in 4 cases: 2 treated with flecainide and 2 treated with placebo; in the other cases 2:1 AV conduction was observed. Widening of QRS during regular tachycardia was observed in 4 patients; 3 who received propafenone and 1 who received flecainide. Conversion to SR within 4 hours was achieved in 55/92 (60%) patients treated with propafenone, 20/34 (59%) patients treated with flecainide, 7/25 (28%) patients treated with digoxin, and 19/92 (20%) treated with placebo (P < 0.001 propafenone vs placebo and flecainide vs placebo; P < 0.05 propafenone vs digoxin and flecainide vs digoxin). Periods of regular tachycardia are expected in recent onset AF and may not necessarily represent a proarrhythmic effect of Class 1C drugs, rather than mark the transition from AF to SR. Class 1C agents are probably responsible for widening of the QRS complex seen during these tachycardias. Propafenone and flecainide appear equally effective in converting recent onset AF.