Temporal association between drops in thoracic impedance and malignant ventricular arrhythmia: A longitudinal analysis of remote monitoring trends.

INTRODUCTION: Thoracic impedance (TI) drops measured by implantable cardioverter-defibrillators (ICDs) have been reported to correlate with ventricular tachycardia/fibrillation (VT/VF). The aim of our study was to assess the temporal association of decreasing TI trends with VT/VF episodes through a longitudinal analysis of daily remote monitoring data from ICDs and cardiac resynchronization therapy defibrillators (CRT-Ds). METHODS AND RESULTS: Retrospective data from 2384 patients were randomized 1:1 into a derivation or validation cohort. The TI decrease rate was defined as the percentage of rolling weeks with a continuously decreasing TI trend. The derivation cohort was used to determine a TI decrease rate threshold for a ≥99% specificity of arrhythmia prediction. The associated risk of VT/VF episodes was estimated in the validation cohort by dividing the available follow-up into 60-day assessment intervals. Analyses were performed separately for 1354 ICD and 1030 CRT-D patients. During a median follow-up of 2.0 years, 727 patients (30.4%) experienced 3298 confirmed VT/VF episodes. In the ICD group, a TI decrease rate of >60% was associated with a higher risk of VT/VF episode in a 60-day assessment interval (stratified hazard ratio, 1.42; 95% confidence interval (CI), 1.05-1.92; p = .023). The TI decrease preceded (40.8%) or followed (59.2%) the VT/VF episodes. In the CRT-D group, no association between TI decrease and VT/VF episodes was observed (p = .84). CONCLUSION: In our longitudinal analysis, TI decrease was associated with VT/VF episodes only in ICD patients. Preventive interventions may be difficult since episodes can occur before or after TI decrease.

Circadian periodicity affects the type of ventricular arrhythmias and efficacy of implantable defibrillator therapies.

INTRODUCTION: Factors influencing malignant arrhythmia onset are not fully understood. We explored the circadian periodicity of ventricular arrhythmias (VAs) in patients with implantable cardioverter and cardiac resynchronization defibrillators (ICD/CRT-D). METHODS: Time, morphology (monomorphic/polymorphic), and mode of termination (anti-tachycardia pacing [ATP] or shock) of VAs stored in a database of remote monitoring data were adjudicated. Episodes were grouped in six 4-h timeslots from 00:00 to 24:00. Circadian distributions and adjusted marginal odds ratios (ORs), with 95% confidence interval (CI), were analyzed using mixed-effect models and logit generalized estimating equations, respectively, to account for within-subject correlation of multiple episodes. RESULTS: Among 1303 VA episodes from 446 patients (63% ICD and 37% CRT-D), 120 (9%) self-extinguished, and 842 (65%) were terminated by ATP, 343 (26%) by shock. VAs clustered from 08:00 to 16:00 with 44% of episodes, as compared with 22% from 00:00 to 08:00 (p < .001) and 34% from 16:00 to 24:00 (p = .005). Episodes were more likely to be polymorphic at night with an adjusted marginal OR of 1.66 (CI, 1.15-2.40; p = .007) at 00:00-04:00 versus other timeslots. Episodes were less likely to be terminated by ATP in the 00:00-04:00 (success-to-failure ratio, 0.67; CI, 0.46-0.98; p = .039) and 08:00-12:00 (0.70; CI, 0.51-0.96; p = .02) timeslots, and most likely to be terminated by ATP between 12:00 and 16:00 (success-to-failure ratio 1.42; CI, 1.06-1.91; p = .02). CONCLUSION: VAs did not distribute uniformly over the 24 h, with a majority of episodes occurring from 08:00 to 16:00. Nocturnal episodes were more likely to be polymorphic. The efficacy of ATP depended on the time of delivery.

Serratus anterior plane block in subcutaneous implantable cardioverter defibrillator implantation: A case-control analysis.

BACKGROUND: A two-incision technique, in association with inter-muscular positioning of the subcutaneous defibrillator (S-ICD), is now the most frequently adopted implantation approach in Europe. Ultrasound-guided serratus anterior plane block (SAPB) has been proposed to provide anesthesia/analgesia during S-ICD implantation. OBJECTIVE: We performed a case-control analysis in which a standardized SAPB approach was compared with the typical local anesthesia and sedation approach. METHODS: Ninety-one consecutive patients underwent implantation of an S-ICD with the SAPB approach for anesthesia/analgesia at 10 centers. The control group consisted of 55 consecutive patients who underwent S-ICD implantation with a standard local approach. RESULTS: The mean procedure duration was 59 ± 15 minutes in the SAPB group and 76 ± 23 minutes in the control group (P < .001). No operative complications were reported in either group. During the procedure, 79 (87%) patients in the SAPB group and 25 (46%) patients in the control group (P < .001) remained awake. Lower values of pain intensity at the device pocket (P = .005) and the lateral tunneling site (P = .046) were reported in the SAPB group. The difference in static (P = .002) and dynamic (P = .007) pain intensity between the groups persisted at 1 hour, while no differences were observed 6 hours after the end of the procedure. CONCLUSIONS: SAPB is feasible and effective in providing anesthesia/analgesia during S-ICD implantation. The procedures were successfully accomplished and no complications occurred in either group. However, SAPB was associated with lower pain levels, enabling the need for sedation to be reduced and more patients to remain awake. Moreover, it resulted in shorter procedure durations.

Successful selective ablation of fast atrioventricular node pathway by cryothermal energy application.

This paper reports the experience of successful cryoablation of fast atrioventricular nodal pathway in a patient with recurrent atrioventricular nodal reentrant tachycardia after previous unsuccessful attempts of slow pathway ablation. Slow formation of a permanent lesion by cryothermal energy application allowed precise modulation of atrioventricular nodal conduction until the endpoints of complete fast pathway ablation were met with long-term cure of the arrhythmia.