Shock Efficacy Research Articles

Long-term outcomes associated with subcutaneous implantable cardioverter-defibrillators in patients with hypertrophic cardiomyopathy

Abstract Background In patients with Hypertrophic Cardiomyopathy (HCM) S-ICD is usually the preferred option as pacing is generally not indicated. However, limited data are available on its current practice adoption and long term follow-up. Purpose The present study was designed to examine in a multicenter, open-label, long-term study, the patient’s selection process for S-ICD implantation, the short and long term complications, the appropriate shock (AS) rates, shock efficacy and outcome. Methods Consecutive HCM patients with an S-ICD implanted between 2013 and 2021 in 3 international centers were enrolled in this prospective observational study. Baseline, procedural and follow-up data together with clinical evaluation, ECG, echocardiography, and telemetry checks of the S-ICD were regularly collected. Results Seventy patients (64% males) were enrolled, implanted at 41±15 years, 62 (89%) in primary prevention with a mean ESC SCD risk score of 4,5±1.9%: 25 (40%) at low risk, 17 (27%) at intermediate and 20 (33%) at high risk. Patients were followed-up for 5.1±2.3 years (327 person-years). Notably, 25 (36%) were followed for more than 6 years up to 10 years. Two patients (3%) received an appropriate shock on ventricular fibrillation and 17 (24%) were diagnosed with a de-novo atrial fibrillation, sub-clinical in 6 (9%). One TIA and 2 strokes were reported. Inappropriate shocks occurred in 4 patients (6%), all before Smart-Pass algorithm implementation. Eight patients experienced device related adverse events (11%). Conclusions S-ICDs in HCM patients followed for over 5 years showed to be effective in the conversion of VF in 2 ESC SCD high risk patients (3%) and useful in the detection of sub-clinical AF in 6 (9%). S-ICDs are implanted in patients with an overall low-intermediate ESC SCD risk, probably reflecting both the inclusion of additional risk markers (i.e extensive LGE, reduced EF and apical aneurism) and the physician perception of low device-related complications S-ICD is generally safe, but greater scrutiny may be required to avoid overtreatment in HCM patients with milder risk profiles.Real world use and candidacy of S-ICDAppropriate and inappropriate shocks

Antibiotic Augmentation of Thermal Eradication of Staphylococcus epidermidis Biofilm Infections.

Staphylococcus epidermidis is a major contributor to bacterial infections on medical implants, currently treated by surgical removal of the device and the surrounding infected tissue at considerable morbidity and expense. In situ hyperthermia is being investigated as a non-invasive means of mitigating these bacterial biofilm infections, but minimizing damage to the surrounding tissue requires augmenting the thermal shock with other approaches such as antibiotics and discerning the minimum shock required to eliminate the biofilm. S. epidermidis biofilms were systematically shocked at a variety of temperatures (50-80 °C) and durations (1-10 min) to characterize their thermal susceptibility and compare it to other common nosocomial pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa. Biofilms were also exposed to three classes of antibiotics (ciprofloxacin, tobramycin and erythromycin) separately at concentrations ranging from 0 to 128 μg mL-1 to evaluate their impact on the efficacy of thermal shock and the subsequent potential regrowth of the biofilm. S. epidermidis biofilms were shown to be more thermally susceptible to hyperthermia than other common bacterial pathogens. All three antibiotics substantially decreased the duration and/or temperature needed to eliminate the biofilms, though this augmentation did not meet the criteria of synergism immediately following thermal shock. Subsequent reincubation, however, revealed strong synergism on a longer timescale.

Predictive value of the PRAETORIAN score for defibrillation test success in patients with subcutaneous ICD: A subanalysis of the PRAETORIAN-DFT trial

BackgroundThe PRAETORIAN score estimates the risk of failure of subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy by using generator and lead positioning on bidirectional chest radiographs. The PRospective randomized compArative trial of subcutanEous implanTable cardiOverter-defibrillatoR ImplANtation with and without DeFibrillation Testing (PRAETORIAN-DFT) investigates whether PRAETORIAN score calculation is noninferior to defibrillation testing (DFT) with regard to first shock efficacy in spontaneous events. ObjectiveThis prespecified subanalysis assessed the predictive value of the PRAETORIAN score for defibrillation success in induced ventricular arrhythmias. MethodsThis multicenter investigator-initiated trial randomized 965 patients between DFT and PRAETORIAN score calculation after de novo S-ICD implantation. Successful DFT was defined as conversion of induced ventricular arrhythmia in <5 seconds from shock delivery within 2 attempts. Bidirectional chest radiographs were obtained after implantation. The predictive value of the PRAETORIAN score for DFT success was calculated for patients in the DFT arm. ResultsIn total, 482 patients were randomized to undergo DFT. Of these patients, 457 (95%) underwent DFT according to protocol, of whom 445 (97%) had successful DFT and 12 (3%) had failed DFT. A PRAETORIAN score of ≥90 had a positive predictive value of 25% for failed DFT, and a PRAETORIAN score of <90 had a negative predictive value of 99% for successful DFT. A PRAETORIAN score of ≥90 was the strongest independent predictor for failed DFT (odds ratio 33.77; confidence interval 6.13–279.95; P < .001). ConclusionA PRAETORIAN score of <90 serves as a reliable indicator for DFT success in patients with S-ICD, and a PRAETORIAN score of ≥90 is a strong predictor for DFT failure.

Two-incision versus three-incision implantation technique of subcutaneous implantable cardioverter defibrillator: Systematic review and meta-analysis of 2076 patients.

The implantable cardioverter-defibrillator (ICD) was designed to detect and treat ventricular arrhythmias, which account for nearly half of all cardiovascular fatalities. Transvenous ICD (TV-ICD) complications were reduced by introducing subcutaneous ICD (S-ICD). S-ICD can be implanted using a three (3IT)- or two (2IT)-incision technique. This systematic review and meta-analysis was conducted to compare the 3IT to the 2IT. We searched medical electronic databases of Cochrane Central, Embase, PubMed, Scopus, and Web of Science (WOS) from the study's inception until March 8, 2023. We compared 2IT and 3IT techniques of S-ICDs in terms of procedural, safety, and efficacy outcomes. We used Review Manager software for the statistical analysis. We calculated the risk ratio (RR) with its 95% confidence interval (CI) for dichotomous variables; and the mean difference with its 95% CI for continuous variables. We measured the heterogeneity using the chi-squared and I-squared tests. If the data were heterogeneous, the random-effect (RE) model was applied; otherwise, the fixed-effect model (FE) was used. We included three retrospective observational studies of 2076 patients, 1209 in the 2IT group and 867 in the 3IT. There was no statistically significant difference in erosion after S-ICD when 2IT compared with 3IT (RR=0.27, 95% CI: [0.07, 1.02]; P=.05) (I2=0%, P=.90). There was no difference in risk of infection, lead dislocation, or inappropriate shock with either incision technique (RR=0.78, 95% CI: [0.48, 1.29]; P=.34) (I2=0%, P=.71) and (RR=0.37, 95% CI: [0.02, 8.14]; P=.53) (I2=66%, P=.05) respectively. Our meta-analysis showed that the efficacy of both techniques is comparable; Appropriate shock (RR=0.94, 95% CI: [0.78, 1.12]; P=.48) (I2=0%, P=.81) and first shock efficacy (RR=0.89, 95% CI: [0.44, 1.82]; P=.76) (I2=0%, P=.87). 2IT and 3IT of S-ICD have comparable efficacy and complication rates; however, the 3IT exposes patients to an additional incision without any additional benefits. These findings may provide clinicians with a simpler method for subcutaneous ICD implantation and likely result in improved cosmetic outcomes. Before the 2IT technique can be considered the standard of care, randomized controlled trials (RCTs) must be conducted to assess its long-term safety and efficacy.

Local anesthesia during S-ICD implantation gives similar post procedural pain perception as sedation

Abstract Introduction The PRAETORIAN-DFT trial hypothesises that subcutaneous implantable cardioverter defibrillator (S-ICD) implant without defibrillation test (DFT) but with PRAETORIAN score is non-inferior to S-ICD implant with DFT with regard to first shock efficacy in spontaneous events. Various anesthesia protocols are used for S-ICD implant, ranging from local to general anesthesia. Sedation of the patient during S-ICD implantation is required because of DFT. Without the need for DFT, local anesthesia may suffice, thereby reducing the logistical burden associated with sedation and general anesthesia. However, data comparing the effects of various anesthesia methods are lacking. Purpose This prespecified analysis of the PRAETORIAN-DFT trial aims to investigate the effect of three different anesthesia methods on (post-)operative pain during S-ICD implant. Methods In the PRAETORIAN-DFT trial (NCT03495297), 965 patients were randomised to DFT (N=483) or no DFT with PRAETORIAN Score calculation (N=482). Choice of anesthesia protocol was per local routine and physician discretion and was listed as local anesthesia (LA), monitored anesthesia care (MAC) or general anesthesia (GA). Patients under LA who underwent DFT, had MAC or GA during the test. Pain scores were assessed using the Numerical Rating Scale (NRS), prior to implant (baseline) and at 1-3 hours, 5-7 hours and 1 day post implant. Mean change in NRS compared to baseline was calculated at every time point. Exact pain scores as well as mean change in NRS were compared between anesthesia methods using a Kruskal Wallis Test. Results Pre-implant pain questionnaires were completed by 97% of patients. In the complete study cohort, 149/965 (15%) of implants were performed under LA, 327/965 (34%) under MAC and 489/965 (51%) under GA. This distribution did not differ between the randomised arms (p=0.301). There was no difference in NRS or mean change compared to baseline between the groups at any time post implant. The mean change in NRS compared to baseline was highest at 5-7 hours post implant in all groups (Figure). Analysis with patients under LA and MAC or GA during DFT as independent group showed similar results. Conclusion There was no difference in pain perception after S-ICD implantation between implant under local anesthesia, MAC and general anesthesia. These results confirm that S-ICD implantation under local anesthesia is feasible and sedation may be no longer necessary if defibrillation testing becomes redundant.Mean changes in NRS compared to baseline

Abstract 418: Characteristics of Post-Shock Refibrillation in Out-of-Hospital Cardiac Arrest

Introduction: Early defibrillation is critical for out-of-hospital cardiac arrest (OHCA) patients with shockable rhythms. Following successful shocks, refibrillation is common. The present study investigated three outcomes including shock efficacy, refibrillation rate, and refibrillation time (defined as the interval between shock delivery and refibrillation) in OHCA patients. Methods: Adult cases treated with Philips SMART Biphasic 150 J shocks from four US EMS agencies were included. The shocks were delivered by professional level HeartStart FR3 AEDs which are more likely to encounter longer patient down time compared to public access AEDs. Two rhythm experts independently annotated shock success, defined as the presence of a non-shockable rhythm for at least 5 seconds (s) after the shock. Successful shocks followed by a CPR period of ≥ 60 s were further annotated with refibrillation time if it occurred. If post-shock outcome could not be determined due to excessive artifact or post-shock data &lt; 5 s, the shock success and/or the refibrillation were annotated as undeterminable. Annotator disagreements were resolved by review with a third rhythm expert to reach consensus. Results: A total of 464 shocks from 254 cases were analyzed. Shock efficacy was 87.7% for the first shock and 85.5% for all shocks. Shockable rhythms were successfully terminated at least once in 94.2% of the patients. Following successful shocks, the refibrillation rate was 55.9% for the first shock and 61.0% for all shocks. The median refibrillation time was 32.7 s (range: 5.1-582.4 s). The distribution of the refibrillation time is shown in Figure 1. Conclusions: Most patients needed more than one shock mainly due to refibrillation. About 50% of the refibrillations occurred within 30 s, which suggests that identification of early refibrillation for prompt defibrillation may be beneficial.

Postapproval Study of a Subcutaneous Implantable Cardioverter-Defibrillator System

BackgroundThe subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to avoid complications related to transvenous implantable cardioverter-defibrillator (TV-ICD) leads. Device safety and efficacy were demonstrated previously with atypical clinical patients or limited follow-up. ObjectivesThe S-ICD PAS (Subcutaneous Implantable Cardioverter-Defibrillator System Post Approval Study) is a real-world, multicenter, registry of U.S. centers that was designed to assess long-term S-ICD safety and efficacy in a diverse group of patients and implantation centers. MethodsPatients were enrolled in 86 U.S. centers with standard S-ICD indications and were observed for up to 5 years. Efficacy endpoints were first and final shock efficacy. Safety endpoints were complications directly related to the S-ICD system or implantation procedure. Endpoints were assessed using prespecified performance goals. ResultsA total of 1,643 patients were prospectively enrolled, with a median follow-up of 4.2 years. All prespecified safety and efficacy endpoint goals were met. Shock efficacy rates for discrete episodes of ventricular tachycardia or ventricular fibrillation were 98.4%, and they did not differ significantly across follow-up years (P = 0.68). S-ICD–related and electrode-related complication-free rates were 93.4% and 99.3%, respectively. Only 1.6% of patients had their devices replaced by a TV-ICD for a pacing need. Cumulative all-cause mortality was 21.7%. ConclusionsIn the largest prospective study of the S-ICD to date, all study endpoints were met, despite a cohort with more comorbidities than in most previous trials. Complication rates were low and shock efficacy was high. These results demonstrate the 5-year S-ICD safety and efficacy for a large, diverse cohort of S-ICD recipients. (Subcutaneous Implantable Cardioverter-Defibrillator [S-ICD] System Post Approval Study [PAS]; NCT01736618)

Capsulectomy: a safe and effective way to lower shock impedance in S-ICD replacement procedures

Abstract Funding Acknowledgements Type of funding sources: None. Background The safety and efficacy of the subcutaneous implantable cardioverter-defibrillator (S-ICD) has been proven in various clinical trials. Due to intermuscular device placement, higher shock energy is required for effective treatment of ventricular tachyarrhythmia. High shock impedance is a risk marker for ineffective defibrillation. Previous studies have shown reduced shock efficacy in device replacement procedures, possibly due to fibrous encapsulation of the device associated with dwelling time of the system. Therefore, in case of significant capsulation, capsulectomy became part of device replacement procedure in our center. In this study we analyzed the results of intraoperative testing before and after capsulectomy measured by results of high-voltage impedance. Purpose Aim of our study was to show that removal of the fibrous capsulation can help to reduce high voltage impedance without relevant perioperative adverse events at the device replacement procedure. Methods Between January 2018 and November 2022, a total of 68 consecutive patients underwent S-ICD device replacement in our center. Pre-operative high-voltage impedance was determined either through recent therapy deliveries or by a 10J test shock immediately before device replacement. Device replacement was performed according to international standards. In case of significant capsulation, additional capsulectomy was performed. Defibrillation testing was routinely performed by the end of the procedure in the absence of contraindications. Results Of 68 patients, 81% were male, mean age at device replacement was 55 ± 17 years. Most patients were implanted for primary prevention (69%). Defibrillation testing with 65 J at initial device implantation was successful in 87% of patients. Mean dwelling time of the S-ICD System was 61 months (±19 months). Shock impedance increased significantly to 98±33 Ω vs. 80±20 Ω (p=0.013) at initial implantation. Capsulectomy of the S-ICD pocket resulted in a significant decrease of high-voltage impedance to 83±23 Ω as compared to measurement prior to replacement (p=0.03). Defibrillation testing was successful in all patients. First shock efficacy with 65 J was 92%. No acute complications (defined as significant bleeding, prolongation of hospital stay, etc.) were observed in short term follow-up and patients could be discharged as planned. Conclusion Capsulectomy of S-ICD pocket appears to be a safe and effective way to reduce shock impedance which has proven to be a predictor of successful defibrillation in testing as well as in spontaneous episodes. Despite the additional step during device replacement, no complications were observed in our study. Randomized trials regarding defibrillation testing during first implantation are ongoing. Trials addressing the optimal device replacement strategy however are warranted.

LB-456087-1 FIRST RESULTS OF THE RANDOMIZED PRAETORIAN-DFT TRIAL: PROSPECTIVE VALIDATION OF THE PRAETORIAN SCORE FOR PREDICTION OF DEFIBRILLATION TEST SUCCESS AFTER SUBCUTANEOUS ICD IMPLANT

The PRAETORIAN score was developed to predict the defibrillation success of the subcutaneous ICD (S-ICD), based on anatomical device position on a chest X-ray, as an alternative to defibrillation testing (DFT). Although only retrospectively validated, the score is currently being used in both research and clinical practice. The prospective randomized PRAETORIAN-DFT trial investigates whether the PRAETORIAN score is non-inferior to the DFT in regard to predicting first shock efficacy. The current analysis is the first prospective validation of the PRAETORIAN score for defibrillation success in induced ventricular arrhythmias.

AMplitude spectral area of ventricular fibrillation and amiOdarone Study in patients with out-of-hospital cArdIaC arrest. The MOSAIC study.

Antiarrhythmic drugs are recommended for out of hospital cardiac arrest (OHCA) with shock-refractory ventricular fibrillation (VF). Amplitude Spectral Area (AMSA) of VF is a quantitative waveform measure that describes the amplitude-weighted mean frequency of VF, it correlates with intramyocardial adenosine triphosphate (ATP) concentration, it is a predictor of shock efficacy and an emerging indicator to guide defibrillation and resuscitation efforts. How AMSA might be influenced by amiodarone administration is unknown. In this international multicentre observational study, all OHCAs receiving at least one shock were included. AMSA values were calculated by retrospectively analysing the pre-shock ECG interval of 2 s. Multivariable models were run and a propensity score based on the probability of receiving amiodarone was created to compare two randomly matched samples. 2,077 shocks were included: 1,407 in the amiodarone group and 670 in the non-amiodarone group. AMSA values were lower in the amiodarone group [8.8 (6-12.7) mV·Hz vs. 9.8 (6-14) mV·Hz, p = 0.035]. In two randomly matched propensity score-based groups of 261 shocks, AMSA was lower in the amiodarone group [8.2 (5.8-13.5) mV·Hz vs. 9.6 (5.6-11.6), p = 0.042]. AMSA was a predictor of shock success in both groups but the predictive power was lower in the amiodarone group [Area Under the Curve (AUC) non-amiodarone group 0.812, 95%CI: 0.78-0.841 vs. AUC amiodarone group 0.706, 95%CI: 0.68-0.73; p < 0.001]. Amiodarone administration was independently associated with the probability of recording lower values of AMSA. In patients who have received amiodarone during cardiac arrest the predictive value of AMSA for shock success is significantly lower, but still statistically significant.

PO-03-058 S-ICD GENERATOR EXCHANGE AND PERFORMANCE: A SINGLE TERTIARY CARE EXPERIENCE

Limited data exist on outcomes of subcutaneous implantable cardiac defibrillators (S-ICDs) generator exchange. Few studies have found that shock impedance increases after S-ICD Gen exchange which correlates with increase in DFT and possibly reduction in S-ICD effectiveness. We describe the performance of S-ICDs after generator exchange in a cohort of patients implanted and followed in a single tertiary-care referral center. We reviewed the device clinic interrogation reports of 525 patients who received S-ICDs between 2012 and 2022 and compared device parameters before and after generator exchanges specifically high-voltage impedance and shock efficacy during follow-up using the paired sample t-test with a 95% CI and p-value of 0.05. A total of 525 S-ICDs were implanted at our facility with an average age at implant of 51±16 years, predominantly males (n=348, 66.3%). The majority of S-ICDs were implanted for primary prevention (413, 79%), and ischemic cardiomyopathy (CM) was the most common type of CM (127, 24%). The average ejection fraction (EF) was 30±12%, and comorbidities were prevalent: 56% hypertension, 29% diabetes, 38% with history of coronary artery disease (CAD), and 33% end-stage renal disease (ESRD). Of those, 76 (15%) underwent generator battery exchange at a median time of 4.5± 2 years. Before generator exchange, a total of 114 shocks (22%) were delivered with an impedance of 68± 23Ω. Of those, 89 (78%) were appropriate shocks. Efficacy of the appropriate shocks was 95%. [F1] [IR2] After generator exchange (n=76), 10 appropriate shocks (13%) were administered with an impedance of 82± 29 Ω, and a shock efficacy of 100%. High voltage impedance and shock efficacy were not statistically different before and after Gen exchange (p=0.178 and p=0.158 respectively). The S-ICD generator exchange demonstrates high safety profile with relatively no change in device impedance or shock efficacy pre- and post- Gen exchange.

Personalizing configuration for atrial fibrillation external electrical cardioversion to improve first shock efficacy

Despite the common use of biphasic electrical cardioversion (ECV) to convert atrial fibrillation (AF), we lack definite recommendations on electrode configuration. We adopted a quasi-experimental design enrolling all candidates to ECV for AF. In the first stage, two units were involved, one using antero-apical pads (AAP) and the second antero-posterior adhesive patches (APP). These data enabled the creation of a decision algorithm to personalize the ECV approach, which was subsequently validated during the second stage. A total of 492 patients were enrolled overall. In the first stage, APP and AAP presented similar conversion rates (87.4 vs. 86.9% at first attempt of a step-up protocol, P = 0.661). While body surface area (BSA) ≤2.12 m2 was an independent predictor in the overall population, the two components (height and weight) acted differently in the two configurations: being height ≤1.73 m2 a significant cut-off value in the AAP subgroup, and weight <83 kg in the APP subgroup. Considering these cut-offs, we developed a decision algorithm for electrode configuration. In the second stage, algorithm validation confirmed an improvement in the first shock efficacy with respect to the results of the first stage (93.2 vs. 87.2%, P = 0.025), with a significant reduction in shock impedance (70.8 ± 15.3 vs. 81.8 ± 15.6, P < 0.001). Patients with high BSA require high energy shocks for sinus rhythm restoration with ECV. Weight seems to affect more APP configuration, while height seems to impact more for the AAP. These findings have the potential to optimize ECV in clinical practice.

Non-Valvular Atrial Fibrillation Cardioversion: Experience of the Cardiology department of Mohammed V Military Teaching Hospital

anticoagulation therapy would be the removal of this arrhythmia and any future recurrence, a goal often difficult to achieve.The aim of this work is to evaluate the efficacy of atrial fibrillation cardioversion as well as the success predictive factors of sinus rhythm maintenance at one year following a successful cardioversion. Materials and methods: 50 patients with non-valvular atrial fibrillation underwent cardioversion: 70% by electrical shock and 30% by pharmacological means, the clinical characteristics of the patients the results of cardioversion and follow-up were collected and analyzed. Results: The average age of our patients was 53 years with a sex ratio of 2. 30% of patients had hypertensive heart disease, 8% ischemic heart disease, 8% dilated cardiomyopathy and the rest had no underlying heart disease. The average diameter of the left atrium was 41 mm and the average surface area was 20 cm². Primary success rate of cardioversion was 82% with better efficacy of electric shock compared to pharmacological cardioversion. The maintenance rate of sinus rhythm at 1 year was 70%. Predictive factors of failure and / or recurrence at 1 year were old atrial fibrillation and significant dilation of the left atrium. Conclusion: This study confirms the interest of atrial fibrillation cardioversion and underlines the importance of preliminary selection of the patients, such a selection must be made on the basis of the predictive factors of success usually recognized in the literature.

The same stress elicits different effects on anxiety-like behavior in rat models of Fmr1-/y and Pten+/-

Individuals affected by autism spectrum disorders (ASDs) exhibit affective symptoms such as enhanced anxiety, which has been seen in rodent models of ASDs as well. Exposure to stress is also known to be anxiogenic. However, the effects of stress on animal models of ASDs remains less explored. Hence, in the present study we examined the impact of acute foot shock stress on anxiety-like behavior in two monogenic rat models of ASDs, fragile X mental retardation 1 knockout (Fmr1-/y) and phosphatase and tensin homolog heterozygous (Pten+/-). Before exposure to stress, the basal levels of anxiety-like behavior in both Fmr1-/y and Pten+/- rats were comparable to that seen in wild-type (WT) control rats in an open-field arena. After exposure to the foot shock stress, however, Fmr1-/y rats showed the highest levels of anxiety-like behavior. WT animals also showed enhanced anxiety-like behavior but not as robustly as the Fmr1-/y animals. In Pten+/- animals, on the other hand, the same stressor did not elicit any anxiogenic effects. In a separate group of rats, the efficacy of the acute foot shock in triggering a stress response was confirmed wherein a comparable surge in circulating corticosterone was seen in all three experimental groups. Thus, the same acute stress led to different effects on anxiety-like behavior in different rodent models of ASDs, suggesting that vulnerability to stress-induced changes in anxiety may vary with the underlying genetic mutations.

A Multi-Site Assessment of Anesthetic Overdose, Hypothermic Shock, and Electrical Stunning as Methods of Euthanasia for Zebrafish (Danio rerio) Embryos and Larvae.

Simple SummaryZebrafish (Danio rerio) younger than five days post fertilization are not protected by legislation, and protocols for their euthanasia are poorly explored. In the present paper, we assess the euthanasic efficacy of anesthetic overdose, hypothermic shock, and electrical stunning on zebrafish at <12 h post fertilization, and 1 and 4 days post fertilization utilizing laboratories in different countries. Based on the survival/recovery rates 24 h after treatment, the most effective methods were an overdose with either clove oil or lidocaine with ethanol, and electrical stunning. For the oldest larvae, signs of aversion during treatment demonstrated that all the tested anesthetics, except lidocaine, induced aversive behavior. Therefore, the most suited anesthetic treatment was lidocaine hydrochloride, 1 g/L, buffered with 2 g/L of sodium bicarbonate and mixed with 50 mL/L of ethanol. Electrical stunning also euthanized embryos and larvae efficiently and without signs of aversion; this method is new and needs further assessment in other laboratories to draw firm conclusions.Euthanasia in zebrafish (Danio rerio) younger than 5 days post fertilization (dpf) is poorly described in the literature, and standardized protocols are lacking, most likely because larvae not capable of independent feeding are often not protected under national legislations. We assessed the euthanasia efficacy in laboratories in different countries of a one hour anesthetic overdose immersion with buffered lidocaine hydrochloride (1 g/L, with or without 50 mL/L of ethanol), buffered tricaine (1 g/L), clove oil (0.1%), benzocaine (1 g/L), or 2-phenoxyethanol (3 mL/L), as well as the efficacy of hypothermic shock (one hour immersion) and electrical stunning (for one minute), on zebrafish at <12 h post fertilization (hpf), 24 hpf, and 4 dpf. Based on the survival/recovery rates 24 h after treatment, the most effective methods were clove oil, lidocaine with ethanol, and electrical stunning. For 4 dpf larvae, signs of aversion during treatment demonstrated that all anesthetics, except lidocaine, induced aversive behavior. Therefore, the most suited euthanasic treatment was lidocaine hydrochloride 1 g/L, buffered with 2 g/L of sodium bicarbonate and mixed with 50 mL/L of ethanol, which euthanized both embryos and larvae in an efficient and stress-free manner. Electrical stunning also euthanized embryos and larvae efficiently and without signs of aversion; this method needs further assessment in other laboratories to draw firm conclusions.

Subcutaneous implantable cardioverter-defibrillators: long-term results of the EFFORTLESS study.

AimsTo report 5-year outcomes of EFFORTLESS registry patients with early generation subcutaneous implantable cardioverter-defibrillator (S-ICD) devices.Methods and resultsKaplan–Meier, trend and multivariable analyses were performed for mortality and late (years 2–5) complications, appropriate shock (AS) and inappropriate shock (IAS) rates. Nine hundred and eighty-four of 994 enrolled patients with diverse diagnoses (28% female, 48 ± 17 years, body mass index 27 ± 6 kg/m2, ejection fraction 43 ± 18%) underwent S-ICD implantation. Median follow-up was 5.1 years (interquartile range 4.7–5.5 years). All-cause mortality was 9.3% (95% confidence interval 7.2–11.3%) at 5 years; 703 patients remained in follow-up on study completion, 171 withdrew including 87 (8.8%) with device explanted, and 65 (6.6%) lost to follow-up. Of the explants, only 20 (2.0%) patients needed a transvenous device for pacing indications. First and final shock efficacy for discrete ventricular arrhythmias was consistent at 90% and 98%, respectively, with storm episode final shock efficacy at 95.2%. Time to therapy remained unaltered. Overall 1- and 5-year complication rates were 8.9% and 15.2%, respectively. Early complications did not predict later complications. There were no structural lead failures. Inappropriate shock rates at 1 and 5 years were 8.7% and 16.9%, respectively. Self-terminating inappropriately sensed episodes predicted late IAS. Predictors of late AS included self-terminating appropriately sensed episodes and earlier AS.ConclusionIn this diverse S-ICD registry population, spontaneous shock efficacy was consistently high over 5 years. Very few patients underwent S-ICD replacement with a transvenous device for pacing indications. Treated and self-terminating arrhythmic episodes predict future shock events, which should encourage more personalized device optimization.

Low Efficacy of Periodical Thermal Shock for Long-Term Control of Legionella spp. in Hot Water System of Hotels.

Different guidelines and regulations for the prevention of legionellosis in public facilities include the recommendation of a periodical thermal shock in the hot water system. The purpose of this study was to assess the efficacy of periodical thermal shocks along a 1-year period on the presence of Legionella spp. in the domestic hot water system of hotels. The Legionella testing results from the period January–December 2019 coming from a group of 77 hotel facilities in the Balearic Islands (Spain) conducting periodical thermal shocks were analyzed. A second group of 44 hotels operating without periodical thermal shocks was used for a comparative analysis. In the facilities where the periodical thermal shock was performed, 16.0% of the results (429 hot water samples collected) were positive for Legionella spp., compared to 21.1% (298 samples), where periodical thermal shock was not performed. Overall, in the thermal shock group, 32.5% of the sites presented at least 1 positive sample along the period of study versus 45.5% in the control group. None of these differences was statistically significant (p-value > 0.05). These findings suggest that the efficacy of regular thermal shock for long-term control of Legionella spp. in domestic hot water systems of hotels is low.

Abstract 13358: Pediatric Defibrillation; Safety and Efficacy of Shocks in Both Ventricular Fibrillation and Sinus Rhythm in a Porcine Model

Introduction: Pediatric sudden cardiac arrest may require the delivery of a defibrillating shock to promote return of spontaneous circulation (ROSC). Fear of harm is a barrier for the use of automated external defibrillators by lay personnel, particularly when the patient is a child. The aim of this study was to observe the effects of delivering pediatric defibrillation shocks to pediatric weight swine who are in a perfusing rhythm or ventricular fibrillation (VF). Methods: Eight swine (10.3-26.8 kg) were studied under anesthesia. Up to 30 shocks were applied using modified samaritan AEDs (HeartSine, UK) to animals either in sinus rhythm or after 30 seconds of VF. Shocks delivered in sinus rhythm were unsynchronized. Four different shock types were applied, utilizing two different waveforms (Waveform-A at 50 J, Waveform-A at 75 J, Waveform-A at 90J and Waveform-B at 50 J). Left ventricular (LV) pressures were recorded invasively (Millar, USA). If the shock was successful, the animal entered a rest period of approximately 5 minutes, after which the next shock was applied. Results: Data presented in Table 1. Out of a total of 77 shocks delivered in sinus rhythm, 2 (2.6%) resulted in conversion to a cardiac arrest rhythm. Analysis of LV pressures demonstrated no significant differences in the change of LV dP/dt from baseline at 1, 10 and 60 seconds post-shock. There was no significant difference in shock success or ROSC between the shock types for defibrillation of VF. Analysis of LV pressures demonstrated no significant differences in the change of LV dP/dt from baseline at at 1, 10 and 60 seconds post-shock between the groups. Conclusions: The results of this study indicate defibrillation shocks applied to swine in sinus rhythm rarely result in conversion to an arrhythmia. Additionally, the variety of shock types demonstrated similar levels of safety and efficacy in this porcine model.

Efficacy and Safety of Appropriate Shocks and Antitachycardia Pacing in Transvenous and Subcutaneous Implantable Defibrillators: Analysis of All Appropriate Therapy in the PRAETORIAN Trial.

The PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) showed noninferiority of subcutaneous implantable cardioverter defibrillator (S-ICD) compared with transvenous implantable cardioverter defibrillator (TV-ICD) with regard to inappropriate shocks and complications. In contrast to TV-ICD, S-ICD cannot provide antitachycardia pacing for monomorphic ventricular tachycardia. This prespecified secondary analysis evaluates appropriate therapy and whether antitachycardia pacing reduces the number of appropriate shocks. The PRAETORIAN trial was an international, investigator-initiated randomized trial that included patients with an indication for implantable cardioverter defibrillator (ICD) therapy. Patients with previous ventricular tachycardia <170 bpm or refractory recurrent monomorphic ventricular tachycardia were excluded. In 39 centers, 849 patients were randomized to receive an S-ICD (n=426) or TV-ICD (n=423) and were followed for a median of 49.1 months. ICD programming was mandated by protocol. Appropriate ICD therapy was defined as therapy for ventricular arrhythmias. Arrhythmias were classified as discrete episodes and storm episodes (≥3 episodes within 24 hours). Analyses were performed in the modified intention-to-treat population. In the S-ICD group, 86 of 426 patients received appropriate therapy, versus 78 of 423 patients in the TV-ICD group, during a median follow-up of 52 months (48-month Kaplan-Meier estimates 19.4% and 17.5%; P=0.45). In the S-ICD group, 83 patients received at least 1 shock, versus 57 patients in the TV-ICD group (48-month Kaplan-Meier estimates 19.2% and 11.5%; P=0.02). Patients in the S-ICD group had a total of 254 shocks, compared with 228 shocks in the TV-ICD group (P=0.68). First shock efficacy was 93.8% in the S-ICD group and 91.6% in the TV-ICD group (P=0.40). The first antitachycardia pacing attempt successfully terminated 46% of all monomorphic ventricular tachycardias, but accelerated the arrhythmia in 9.4%. Ten patients with S-ICD experienced 13 electrical storms, versus 18 patients with TV-ICD with 19 electrical storms. Patients with appropriate therapy had an almost 2-fold increased relative risk of electrical storms in the TV-ICD group compared with the S-ICD group (P=0.05). In this trial, no difference was observed in shock efficacy of S-ICD compared with TV-ICD. Although patients in the S-ICD group were more likely to receive an ICD shock, the total number of appropriate shocks was not different between the 2 groups. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022.

Acute shock efficacy of the subcutaneous implantable cardioverter-defibrillator according to the implantation technique.

The traditional technique for subcutaneous implantable cardioverter defibrillator (S-ICD) implantation involves three incisions and a subcutaneous (SC) pocket. An intermuscular (IM) 2-incision technique has been recently adopted. We assessed acute defibrillation efficacy (DE) of S-ICD (DE ≤65 J) according to the implantation technique. We analyzed consecutive patients who underwent S-ICD implantation and DE testing at 53 Italian centers. Regression analysis was used to determine the association between DFT and implantation technique. A total of 805 patients were enrolled. Four groups were assessed: IM + 2 incisions (n = 546), SC + 2 incisions (n = 133), SC + 3 incisions (n = 111), and IM + 3 incisions (n = 15). DE was ≤65 J in 782 (97.1%) patients. Patients with DE ≤65 J showed a trend towards lower body mass index (25.1 vs. 26.5; p = .12), were less frequently on antiarrhythmic drugs (13% vs. 26%; p = .06) and more commonly underwent implantation with the 2-incision technique (85% vs. 70%; p = .04). The IM + 2-incision technique showed the lowest defibrillation failure rate (2.2%) and shock impedance (66 Ohm, interquartile range: 57-77). On multivariate analysis, the 2-incision technique was associated with a lower incidence of shock failure (hazard ratio: 0.305; 95% confidence interval: 0.102-0.907; p = .033). Shock impedance was lower with the IM than with the SC approach (66 vs. 70 Ohm p = .002) and with the 2-incision than the 3-incision technique (67 vs. 72 Ohm; p = .006). In a large population of S-ICD patients, we observed a high defibrillation success rate. The IM + 2-incision technique provides lower shock impedance and a higher likelihood of successful defibrillation.