The first article of the June 2023 issue is titled “Stellate ganglion instrumentation for pharmacological blockade, nerve recording, and stimulation in patients with ventricular arrhythmias: Preliminary experience”. The purpose of this study was to assess the outcomes of SGB and the feasibility of SG stimulation and recording in humans with VAs. Group 1 included 25 patients who underwent SGB for VAs. Nineteen patients (76.0%) were free of VA up to 72 hours postprocedure. However, 15 (60.0%) had VAs recurrence for a mean of 5.47 days. Group 2 included 11 patients. SG stimulation caused consistent increases in systolic blood pressure. They recorded unequivocal signals with temporal association with arrhythmias in 4 of 11 patients. The authors conclude that SGB provides short-term VA control, but has no benefit in the absence of definitive VA therapies. SG recording and stimulation is feasible and may have value to elicit VA and understand neural mechanisms of VA in the electrophysiology laboratory.

The second paper is “Comparison of combined substrate-based mapping techniques to identify critical sites for Ventricular Tachycardia Ablation”. Electroanatomic substrate maps were created and retrospectively analyzed in 27 patients in whom 33 VT critical sites were identified. Isochronal late activation mapping deceleration zones were observed over a median of 9 cm2, while abnormal omnipolar conduction velocity was observed over 10 cm2 areas. Conduction velocity identified 100% of critical sites in areas with a local point density of >50 points/cm2. The authors conclude that isochronal late activation mapping, fractionation, and conduction velocity mapping each identified distinct critical sites and provided a smaller area of interest than voltage mapping alone. The sensitivity of novel mapping modalities improved with greater local point density.

Up next is “Progressive outcomes of bundle branch reentrant ventricular tachycardia in patients without structural heart disease”. Eleven consecutive BBRT patients without obvious structural heart disease were enrolled. During 72 months of follow-up, PR interval and QRS duration each increased significantly compared with postablation. Right- and left-sided chamber dilation and reduced left ventricular ejection fraction (LVEF) also were observed. Clinical deterioration or events occurred in 8 patients. Genetic testing results showed that 6 of 10 patients (excluding the patient with sudden death) had ≥1 potential pathogenic candidate variants. The authors conclude that further deterioration of His–Purkinje system conduction was observed in young BBRT patients without SHD after ablation. The His–Purkinje system may be the first target of genetic predisposition.

The next one is “Ivabradine for controlling heart rate in permanent atrial fibrillation: a translational clinical trial”. The authors performed in vitro experiments, computer simulation and a multicenter, randomized, open-label, phase III clinical trial comparing ivabradine versus digoxin for uncontrolled permanent atrial fibrillation. The results show that ivabradine inhibited If and IKr, slowed the firing frequency of a modelled human AV nodal action potential. Thirty-five patients were randomized to ivabradine and 33 to digoxin. Mean daytime heart rate decreased by 11.6 bpm (-11.5%) in the ivabradine arm versus 19.6 (-20.6%) in the digoxin arm (p<0.001). Primary safety endpoint occurred in 3 (8.6%) patients on ivabradine and in 8 (24.2%) on digoxin (p=0.10). The authors conclude that ivabradine produced a moderate rate reduction in patients with permanent atrial fibrillation. Compared with digoxin, ivabradine was less effective, better tolerated, and had a similar rate of serious adverse events.

Coming up is “Early Mortality after Inpatient versus Outpatient Catheter Ablation in Patients with Atrial Fibrillation”. Using the Medicare Fee for Service database, we analyzed 122,289 patients who underwent catheter ablation for the treatment of AF between 2016 and 2019. Overall, 82% underwent AF ablation as an outpatient. Mortality rate 30 days after catheter ablation was 0.6%, with inpatients accounting for 71.5% of deaths (P <.001). Early mortality rates were 0.2% for outpatient procedures and 2.4% for inpatient procedures. The prevalence of comorbidities was significantly higher in patients with early mortality. Hospitals with high overall ablation volume had 31% lower odds of early mortality. The authors conclude that AF ablation conducted in the inpatient setting is associated with a higher rate of early mortality than outpatient AF ablation. Comorbidities are associated with an enhanced risk of early mortality. High overall ablation volume is associated with a lower risk of early mortality.

Up next is “Sinus Rhythm Electrocardiographic Abnormalities, Sites of Origin, and Ablation Outcomes of Ventricular Premature Depolarizations Initiating Ventricular Fibrillation”. The authors compared a cohort with no apparent structural heart disease and VPDs initiating VF (group 1; n=42) to a reference cohort (group 2; n=61) of patients with no structural heart disease and symptomatic unifocal VPDs. The authors found that a reduced QRS amplitude (<0.55 mV) in aVF, fractionated QRS in ≥2 contiguous leads, and/or an early repolarization pattern are frequently observed in patients with VPDs initiating VF. VPDs initiating VF typically originate from the distal Purkinje system and papillary muscles and can be successfully eliminated with catheter ablation.

The next article is “Concomitant Leadless Pacing in Pacemaker Dependent Patients Undergoing Transvenous Lead Extraction for Active Infection: Mid-Term Follow-Up”.This study involved all leadless pacemaker implantation procedures performed during transvenous lead extraction in 86 patients with indications for ongoing pacing. There were no procedure-related complications. Sixty-five patients (76%) had evidence of bacteremia, 80% of whom were discharged to complete their antimicrobial treatment. During a median follow-up of 163 days, there were no recurrent infections. Of the 25 deaths (29%) during the study period, 22 (88%) were unrelated to the initial infection. The authors conclude that leadless pacing is a safe and efficacious approach for managing patients with pacing requirements that undergo CIED extraction in the setting of active infection.

Up next is “Outcomes of Conduction System Pacing for Cardiac Resynchronization Therapy in Patients with Heart Failure: A Multicenter Experience”. This multicenter retrospective study included 238 patients who fulfilled CRT indications and received conduction system pacing. Among them, 69 (29%) had His-bundle pacing, 50 (21%) had left bundle branch area pacing, and 119 (50%) had BiVP. Mean follow-up was around 300 days. The proportion of CRT responders was greater in the conduction system pacing group than in the BiVP group. The authors conclude that, in patients with heart failure and reduced ejection fraction, conduction system pacing resulted in greater improvement in LVEF compared to BiVP.

Up next is “Clinical predictors of incomplete coronary sinus lead removal during transvenous lead extraction in patients with cardiac resynchronization therapy”.Consecutive patients with CRT devices in the Cleveland Clinic Prospective Transvenous Lead Extraction Registry were included in the analysis. 231 CS leads removed from 226 patients were included. Complete CS lead extraction success was achieved in 220 (95.2%) of leads and in 216 (95.6%) of patients. Major complications occurred in 5 patients (2.2%). The authors conclude that the complete and safe lead removal rate of long implant duration CS leads by transvenous lead extraction was 95%. However, CS lead age and the order in which leads were extracted were independent predictors of incomplete CS lead removal. Therefore, before the CS lead is extracted, physicians should first extract the leads from the other chambers and use powered sheaths.

Coming up next is “Vagal response is involved in the occurrence of ventricular fibrillation in patients with early repolarization syndrome”. The authors enrolled 50 patients with ERS who received an ICD. Of these, 20 patients experienced VF recurrence (recurrent VF group). They found no significant difference in heart rate variability between the recurrent VF and nonrecurrent VF groups. However, in patients with ERS but not in the Brugada syndrome, baroreflex sensitivity was significantly higher in the recurrent VF group than in the nonrecurrent VF group. These findings suggest that in patients with ERS, an exaggerated vagal response may be involved in the risk of VF occurrence.

The next paper is “Imaging Modality for Left Ventricular Ejection Fraction Estimation and Effect of Implantable Cardioverter Defibrillator on Mortality in Patients with Heart Failure”. The purpose of this study was to examine whether the effect of ICD on mortality in patients with HF and LVEF ≤35% varied on the basis of LVEF measured by 2DE or MUGA. Of 1386 study patients, all-cause mortality occurred in 23.1% (160 of 692) and 29.7% (206 of 694) of patients randomized to ICD or placebo, respectively. They found no evidence that in patients with HF and LVEF ≤35%, the effect of ICD on mortality varied by the noninvasive imaging method used to measure LVEF.

Up next is “Catheter Ablation of Coronary Sinus Accessory Pathways in the Young”.Twenty-four children, aged between 2.7-17.3 years, underwent mapping and intended AP ablation within the coronary venous system. Overall procedural success was achieved in 20 of 22 study patients (90.9%) and in 46 of 48 controls (95.8%). Coronary artery injury after radiofrequency ablation was noted in 2 of 22 study patients (9%) and in 1 of 48 controls (2%). In coronary venous system patients, repeat SVT occurred in 5 of 22 patients (23%) during median follow-up of 8.5 years, and 4 of the 5 underwent reablation, resulting in 94.4% overall success. The authors conclude that success of CS-AP ablation in the young was comparable to that of endocardial AP ablation. Substantial risk of coronary artery injury should be considered when CS-AP ablation is performed in the young.

Coming up is “Mechanics of Lumenless Pacing Lead Strength During Extraction Procedures Based on Laboratory Bench Testing”. Multiple Medtronic SelectSecure Model 3830 lead preparation techniques, commonly used in extraction practices, were compared on the bench to assess rail strength in simple traction and use conditions with simulated scar. The authors found that, when extracting SelectSecure leads, the retained connector method to maintain cable engagement benefits the preservation of the extraction rail strength. Limiting traction force to <10 lbf (4.5 kgf) and avoiding poor lead preparation methods are critical to consistent extraction. Femoral snaring does not change rail strength when needed and offers a method to regain lead rail in cases of distal cable fracture.

The final original article is “Injectable Contraceptive, Depo-Provera, Produces Erratic Beating Patterns in Patient-Specific Re-Engineered Heart Cells with Type 2 Long QT Syndrome”. An induced pluripotent stem cell-cardiomyocyte, or iPSC-CM line was generated from a 40-year-old woman with p.G1006Afs∗49-KCNH2. Depo treatment significantly shortened the action potential duration at 90% repolarization of the variant iPSC-CMs. Combined Depo-Provera + ISO treatment increased the percentage of electrodes displaying erratic beating in the variant iPSC-CMs. The authors conclude that this cell study provides a potential mechanism for the patient’s clinically documented Depo-Provera associated episodes of recurrent ventricular fibrillation. This in vitro data should prompt a large-scale clinical assessment of Depo’s potential proarrhythmic effect in women with LQT2.