Paul J. Wang:

Welcome to the monthly podcast, On the Beat for Circulation, Arrhythmia and Electrophysiology. I'm Dr. Paul Wang, editor-in-chief with some of the key highlights from this month's issue.

In our first paper, Bruce Wilkoff and associates evaluated antibacterial envelope cost effectiveness compared to standard of care infection prevention strategies in the US healthcare system. Decision tree model was used to compare costs and outcomes of the antimicrobial envelope used adjunctive to standard of care infection prevention versus standard of care alone over a lifelong time horizon. The analysis was performed from an integrated payer provider network perspective. Infection rates, antimicrobial envelope effectiveness, infection treatment costs and patterns, infection related mortality and utility estimates were obtained from the WRAP-IT study. Life expectancy and long-term costs associated with device replacement, follow-up, and healthcare utilization were sourced from the literature. Costs and quality life adjusted years were discounted at 3%. An upper willingness-to-pay threshold of $100,000 per quality adjusted life year was used to determine cost-effectiveness in alignment with the American College of Cardiology and American Heart Association practice guidelines and as supported by the World Health Organization and contemporary literature. The base case incremental cost-effectiveness ratio (ICER) of the antibacterial envelope compared with standard-of-care was $112,603 per quality-adjusted life year. The ICER remained lower than the threshold in 74% of iterations in the probabilistic sensitivity analysis and was most sensitive to the following model inputs: infection-related mortality, life expectancy, and infection cost. The authors concluded that the absorbable antibacterial envelope was associated with a cost-effectiveness ratio below contemporary benchmarks in the WRAP-IT patient population, suggesting that the envelope provides value for the US healthcare system by reducing the incidence of CIED infection.

In our next paper, Peter Loh and associates in this study aim to investigate the feasibility and safety of single pulse irreversible electroporation (IRE) pulmonary vein (PV) isolation in patients with atrial fibrillation (AF). Ten patients with symptomatic paroxysmal or persistent AF underwent single pulse IRE pulmonary vein isolation under general anesthesia. Three-dimensional reconstruction and electroanatomical voltage mapping of the left atrium and pulmonary veins were performed using a conventional circular mapping catheter. Pulmonary vein isolation was performed by delivering nonarcing, nonbarotraumatic 6 ms, 200 Joule direct current IRE applications via a custom nondeflectable 14-polar circular IRE ablation catheter with a variable hoop diameter (16–27 millimeters). A deflectable sheath was used to maneuver the ablation catheter. A minimum of 2 IRE applications with slightly different catheter positions were delivered per vein to achieve circular tissue contact, even if pulmonary vein potentials were abolished after the first application. Bidirectional pulmonary vein isolation was confirmed with the circular mapping catheter and a post ablation voltage map. After a 30-minute waiting period, adenosine testing was used to reveal dormant pulmonary vein conduction. All 40 pulmonary veins could be successfully isolated with a mean of 2.4 IRE applications per pulmonary vein. Mean delivery peak voltage and peak current were 2154 volts and 33.9 amperes. No pulmonary vein reconnections occurred during the waiting period and adenosine testing. No periprocedural complications were observed. The authors concluded that in 10 patients in this first in-human study, acute bidirectional electrical pulmonary vein isolation could be achieved safely using single pulse IRE ablation.

In our next paper, Christian Sohns and associates studied the relationship between left ventricular ejection fraction (LVEF) New York Heart Association (NYHA) class on presentation and the end points of mortality and heart failure (HF) admissions in the CASTLE-AF study population. Furthermore, predictors for LVEF improvement were examined. The CASTLE-AF patients with coexisting heart failure and AF (n=363) were randomized in a multicenter prospective controlled fashion to ablation (n=179) versus pharmacological therapy (n=184). Left ventricular function in NYHA class were assessed at baseline after randomization and at each follow-up visit. In the ablation arm, a significantly higher number of patients experienced an improvement in their LVEF to greater than 35% at the end of the study (odds ratio, 2.17; P<0.001). Compared with the pharmacological therapy arm, both ablation patient groups were severe, less than 20% or moderate/severe, greater than 20% and less than 35% baseline LVEF had a significantly lower number of composite end points (hazard ratio 0.60; P=0.006), all-cause mortality (hazard radio 0.54; P=0.019), and cardiovascular hospitalizations (hazard ratio 0.66; P=0.017). In the ablation group, NYHA I/II patients at the time of treatment had the strongest improvement in clinical outcomes (primary end point: hazard ratio 0.43; P<0.001; mortality: hazard ratio 0.30; P=0.001). The authors concluded that compared with pharmacological treatment, AF ablation was associated with a significant improvement in LVEF, independent from the severity of left ventricular dysfunction, indicating that AF ablation should be performed at early stages of a patient’s heart failure symptoms.

In the next paper, Milena Leo and associates conducted a randomized study to compare risk of esophageal heating and acute procedure success of different LSI-guided ablation protocols combining higher or lower radiofrequency power or different target LSI values. Eighty consecutive patients were prospectively enrolled and randomized to one of 4 combinations of radiofrequency (RF) power and target LSI for ablation of the left atrial posterior wall (that is 20 watts LSI 4, 20 watts LSI 5, 40 watts LSI 4, and 40 watts LSI 5). The primary end point of the study was the occurrence and number of esophageal temperature alerts (ETAs) per patient during ablation. Acute indicators of procedure success were considered as secondary end points. Long-term follow-up data was also collected for all patients. Esophageal temperature alerts (ETAs) occurred in a similar proportion of patients in all groups. Significantly, shorter RF durations was required to achieve the target LSI in the 40 watt groups. Less than 50% of the RF lesions reached the target LSI of 5 when using 20 watts despite a longer RF duration. A lower rate of first-pass pulmonary vein isolation and a higher rate of acute pulmonary vein reconnection were recorded in the group 20 watts LSI 5. A lower AF recurrence rate was observed in the 40 watt groups compared with the 20 watts groups at 29 months follow-up. The authors concluded that when guided by LSI, posterior wall ablation with 40 watts is associated with a similar rate of ETAs and a lower AF recurrence rate at follow-up if compared with 20 watts. These data will provide a basis to plan future randomized trials.

In the next paper, Shohreh Honarbakhsh and associates in this study aimed to determine whether STAR mapping using sequential recordings from conventional pulmonary vein mapping catheters could achieve similar results. Patients with persistent AF less than 2 years were included. Following pulmonary vein isolation (PVI), AF drivers were identified on sequential STAR maps created with PentaRay, IntellaMap Orion, or Advisor HD Grid catheters. Patients had a minimum of 10 multipolar recordings of 30 seconds each. These were processed in real-time and AF drivers were targeted with ablation. An ablation response was determined as AF termination or cycle length slowing greater than or equal to 30 milliseconds. Thirty patients were included, 62.4 years old, AF duration 14.1 months, of which 3 had AF terminated on pulmonary vein isolation, leaving 27 patients that underwent STAR-guided AF driver ablation. Eighty-three potential AF drivers were identified 3.1 per patient of which 70 were targeted with ablation (2.6 per patient). An ablation response was seen at 54 AFDs, 77.1% of AF drivers with 21 AF termination and 33 cycle length slowing and occurred in all 27 patients. No complications occurred. At 17.3 months, 22 out of 27 or 81.5% of patients undergoing STAR-guided ablation were free from atrial fibrillation, atrial tachycardia off antiarrhythmic drugs. The authors concluded that STAR-guided AF driver ablation through sequential mapping with a multipolar catheter effectively achieved an ablation response in all patients. AF termination in a majority of patients, with a high freedom from atrial fibrillation atrial tachycardia off antiarrhythmic drugs at long-term follow-up.

In our next paper, Takashi Kaneshiro and associates sought to evaluate the characteristics of esophageal injuries in atrial fibrillation (AF) ablation using high power short duration setting. After exclusion of 5 patients with their esophagus at the right portion of left atrium and 21 patients with additional ablations such as box isolation and/or low voltage area in left atrium posterior wall, 271 consecutive patients, 62 years, 56 women, who underwent pulmonary vein isolation (PVI) by radiofrequency catheter ablation were analyzed. In the 101 patients, high power short duration setting at 45 to 50 watts with an Ablation Index module was used. In the remaining 170 patients, before introduction of the high power short duration setting, a conventional power setting of 20 to 30 watts with contact force monitoring was used, that is the conventional group. They performed esophagogastroduodenoscopy after pulmonary vein isolation in all patients and investigated the incidence and characteristics of esophageal thermal injury. Although