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Background: His bundle (HB) potentials vary in amplitude and duration in patients with and without slow pathways. The aim of this study was to determine the characteristics of HB potentials and to elucidate whether they can provide clues for identification of slow pathway (SP)., Methods: The present research prospectively studied the electrophysiological findings of 162 patients with symptomatic atrioventricular nodal reentrant tachycardia (AVNRT) due to slow-fast or fast-slow type and atrioventricular reentrant tachycardia (AVRT). Maximal HB potential (HBmax, HB with the highest amplitude) among HB cloud was recorded in both groups. For AVNRT patients, the following were measured: (1) AH interval at the "jump" during programmed atrial stimulation (A2H2, taken as a reflection of SP conduction time); (2) Distance from HBmax to the successful SP ablation site (HBmax-ABL) and from HBmax to the ostium of coronary sinus (HBmax-CSO)., Results: HBmax was 0.29 ± 0.10 mV in AVNRT patients, whereas it was 0.17 ± 0.05 mV in AVRT group (p < 0.0001). Likewise, the HBmax duration was 22 ± 5 ms in AVNRT group and 16 ± 3 ms in AVRT group (p < 0.0001). The area under the receiver operating characteristic curve of HBmax amplitude in AVNRT patients was 0.86 and the optimal HBmax cut-off to predict AVNRT was ≥ 0.22 mV with a sensitivity of 0.78 and specificity of 0.84. HBmax-CSO was positively correlated with HBmax-ABL, and HBmax-ABL was positively correlated with A2H2., Conclusions: HBmax amplitudes were higher and durations longer in patients with AVNRT, as compared to those with AVRT. Moreover, the distance between HBmax and successful ablation site was positively correlated with the SP conduction time and with the distance from HBmax to the CSO.

Background: Flecainide and propafenone are Class Ic antiarrhythmic drugs that block the cardiac fast inwards Na+ current and are used for rhythm control in patients with atrial fibrillation (AF). However, data on long-term clinical efficacy and safety of these drugs in a real-world setting are scarce., Methods: Patients with AF who received chronic flecainide or propafenone therapy were retrospectively studied from the database of a tertiary care center. The primary outcome of the study was clinical efficacy of Class Ic antiarrhythmics, which was assessed based on the improvement of arrhythmia-related symptoms at the time of last follow-up., Results: Among the 361 patients (261 males, 72.3%) with a mean age of 56 ± 12 years, 287 (79.5%) were using long-term flecainide, and 74 (20.5%) patients propafenone. The majority of the patients had paroxysmal AF (n = 331, 91.7%) and had an atrioventricular-nodal blocking co-medication (n = 287, 79.5%). A total of 117 (32%) patients discontinued therapy after a median of 210 days (interquartile range 62-855 days). Clinical efficacy was observed in 188 (52%) patients. The most common reason for therapy discontinuation was adverse drug effects, particularly proarrhythmic effects (48% for flecainide and 33% for propafenone). Patients who did not clinically benefit from Class Ic antiarrhythmics more often underwent pulmonary vein isolation (p = 0.02)., Conclusions: Long-term therapy with Class Ic antiarrhythmics showed clinical efficacy in approximately half of the patients with paroxysmal or persistent AF. However, these drugs were also associated with a relatively high rate of adverse events, and in particular proarrhythmic effects, which often resulted in therapy discontinuation rendering appropriate patient selection and therapy surveillance essential.

Background: Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients suffering from chronic heart failure (CHF). Optimal device programming is crucial for maximum patient benefit. The goal of the present study was to assess device settings from CHF patients undergoing CRT optimization in a "real world" setting, and to delineate parameters most frequently requiring adjustment., Methods: All patients who underwent CRT device implantation in the Cardiology Clinicat the University Hospital Zurich between January 2011 and September 2012 and in whom follow-up was available were included in this analysis., Results: A total of 170 CHF patients were included in this analysis. True biventricular pacing was present in 44% of all patients, while QRS fusion was detected in 49.9%. The majority of the patients presented with suboptimal atrioventricular (AV) delays requiring adjustment. AV delays were therefore shortened due to the presence of QRS fusion in 53.3% and 38.1% of patients (sAV and pAV, respectively) or prolonged because of truncation of the A wave in the left ventricular inflow pulse wave Doppler measurement (17.5% and 28.4% for sAV and pAV, respectively). In contrast, interventricular delay (VV delay) was rarely changed (11.9%)., Conclusions: In our "real world" cohort, a substantial proportion of patients presented to their first post-operative consultation with suboptimal device settings. Our data indicate that the opportunity to optimize device settings is frequently wasted in the "real world", underlining the necessity for expert device follow-up to deliver optimal care to this challenging group of heart failure patients.