Development and Validation of the Atri-Risk Conduction Index Risk Score to Predict Risk of Atrial Fibrillation After Typical Atrial Flutter Ablation.

BACKGROUND: Identification of patients at risk for atrial fibrillation (AF) after typical atrial flutter ablation (tAFl) is important to guide monitoring and treatment. OBJECTIVE: To create and validate a risk score to predict AF after tAFl ablation METHODS: We identified patients who underwent tAFL ablation with no AF history between 2017-2022 and randomly allocated to derivation and validation cohorts. We collected clinical variables and measured conduction parameters in sinus rhythm on an electrophysiology recording system (CardioLab, GE Healthcare). Univariate and multivariate logistic regressions (LogR) were used to evaluate association with AF development. RESULTS: 242 consecutive patients (81% males, mean age 66+/-11) were divided into derivation and validation cohorts, (n=142 and n=100). 42% developed AF over a median follow up of 330 days. In multivariate LogR (derivation cohort) , proximal to distal coronary sinus time (pCS-dCS) ≥70ms (OR 16.7 CI 5.6-49), pCS time≥36ms (OR 4.5 CI 1.5-13), and CHADS2VASc≥3 (OR 4.3 CI 1.6-11.8) were independently associated with new AF in follow-up. The Atri-Risk Conduction Index (ARCI) score was created with 0 as minimal and 4 as high-risk using pCS-dCS ≥70ms =2 points, pCS≥36ms=1 point, and CHADS2VASC≥3=1point. In the validation cohort, 0% of patients with ARCI score of 0 developed AF while 89% of patients with ARCI score of 4 developed AF. CONCLUSION: We developed and validated a risk-score using atrial conduction parameters and clinical risk factors to predict AF after tAFl ablation. It stratifies low, moderate, and high-risk patients and may be helpful in individualizing approaches to AF monitoring and anticoagulation.

Risk of atrial arrhythmias in patients with ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: In arrhythmogenic right ventricular cardiomyopathy (ARVC), risk of atrial arrhythmias (AAs) persists after ventricular tachycardia (VT) ablation. OBJECTIVE: The purpose of this study was to determine the type, prevalence, outcome, and risk correlates of AA in ARVC in patients undergoing VT ablation. METHODS: Prospectively collected procedural and clinical data on ARVC patients undergoing VT ablation were analyzed. Risk score for typical atrial flutter was determined from univariate logistic regression analysis. RESULTS: Of 119 consecutive patients with ARVC and VT ablation, 40 (34%) had AA: atrial fibrillation (AF) in 31, typical isthmus-dependent atrial flutter (AFL) in 27, and atrial tachycardia/atypical flutter (AT) in 10. Seventeen patients (43%) with AA experienced inappropriate defibrillator therapy, with 15 patients experiencing shocks. Ablation was performed for typical AFL in 21 (53%), AT in 5 (13%), and pulmonary vein isolation for AF in 4 (10%) patients and prevented AA in 78% and all AFL during additional mean follow-up of 65 months. Risk score for typical flutter included age >40 years (1 point), ≥moderate right ventricular dysfunction (2 points), ≥moderate tricuspid regurgitation (2 points), ≥moderate right atrial dilation (2 points), and right ventricular volume >250 cc (3points), with score >4 identifying 50% prevalence of typical flutter. CONCLUSION: AAs are common in patients with ARVC and VT, can result in inappropriate implantable cardioverter-defibrillator shocks, and typically are controlled with atrial ablation. A risk score can be used to identify patients at high risk for typical AFL who may be considered for isthmus ablation at the time of VT ablation.

One-year outcomes after stereotactic body radiotherapy for refractory ventricular tachycardia.

BACKGROUND: Cardiac stereotactic body radiotherapy (SBRT) has emerged as a promising noninvasive treatment for refractory ventricular tachycardia (VT). OBJECTIVE: The purpose of this study was to describe the safety and effectiveness of SBRT for VT in refractory to extensive ablation. METHODS: After maximal medical and ablation therapy, patients were enrolled in a prospective registry. Available electrophysiological and imaging data were integrated to generate a plan target volume. All SBRTs were planned with a single 25 Gy fraction using respiratory motion mitigation strategies. Clinical outcomes at 6 weeks, 6 months, and 12 months were analyzed and compared with the 6 months prior to treatment. VT burden (implantable cardioverter-defibrillator [ICD] shocks and antitachycardia pacing sequences) as well as clinical and safety outcomes were the main outcomes. RESULTS: Fifteen patients were enrolled and underwent planning. Fourteen (93%) underwent treatment, with 12 (80%) surviving to the end of the 6-week period and 10 (67%) surviving to 12 months. From 6 week to 12 months, there was recurrence of VT, which resulted in either appropriate antitachycardia pacing or ICD shocks in 33% (4 of 12). There were significant reductions in treated VT at 6 weeks to 6 months (98%) and at 12 months (99%) compared to the 6 months before treatment. There was a nonsignificant trend toward lower amiodarone dose at 12 months. Four deaths occurred after treatment, with no changes in ventricular function. CONCLUSION: For a select group of high-risk patients with VT refractory to standard therapy, SBRT is associated with a reduction in VT and appropriate ICD therapies over 1 year.

Utility of Very High-Output Pacing to Identify VT Circuits in Patients Manifesting Traditionally Inexcitable Scar.

BACKGROUND: Entrainment and pace mapping are used to identify critical components (CCs) of ventricular tachycardia (VT) circuits. In patients with dense myocardial scarring, VT circuits may elude capture at standard high pacing outputs (up to 10 mA at a 2-millisecond pulse width). OBJECTIVES: The purpose of this study was to assess the utility of very high-output pacing (V-HOP, 50 mA at 2 milliseconds) for identifying CCs of VT circuits after standard high pacing output failed to elicit capture in densely scarred myocardial tissue. METHODS: Our standard VT ablation approach included electroanatomic mapping for substrate characterization and entrainment and/or pace mapping to identify CCs of VT circuits. Patients that required V-HOP to capture sites of interest comprised the study cohort. Ablation endpoints were VT termination and noninducibility. RESULTS: Twenty-five patients (71 ± 10 years of age, all males) undergoing 26 VT ablations met the inclusion criteria. The mean left ventricular ejection fraction was 30% ± 14%, and 85% had ischemic cardiomyopathy. V-HOP was used to successfully entrain VT in 17 patients, yielding central isthmus sites in 10 and entrance/exit sites in 4. VT terminated with radiofrequency ablation at these sites in 15 patients. In 9 patients, V-HOP identified scar locations with a delayed exit. Acute procedural success was achieved in 24 patients without any adverse events. Over a follow-up period of 16 ± 21 months, 2 patients experienced VT recurrence requiring repeat ablation during which the same location was targeted successfully in 1 patient. CONCLUSIONS: In VT patients with a dense scar that is traditionally inexcitable, V-HOP can identify CCs of the re-entrant circuit and guide successful ablation.

PRIME score for prediction of permanent pacemaker implantation after transcatheter aortic valve replacement.

OBJECTIVES: We sought to produce a simple scoring system that can be applied at clinical visits before transcatheter aortic valve replacement (TAVR) to stratify the risk of permanent pacemaker (PPM) after the procedure. BACKGROUND: Atrioventricular block is a known complication of TAVR. Current models for predicting the risk of PPM after TAVR are not designed to be applied clinically to assist with preprocedural planning. METHODS: Patients undergoing TAVR at the University of Colorado were split into a training cohort for the development of a predictive model, and a testing cohort for model validation. Stepwise and binary logistic regressions were performed on the training cohort to produce a predictive model. Beta coefficients from the binary logistic regression were used to create a simple scoring system for predicting the need for PPM implantation. Scores were then applied to the validation cohort to assess predictive accuracy. RESULTS: Patients undergoing TAVR from 2013 to 2019 were analyzed: with 483 included in the training cohort and 123 included in the validation cohort. The need for a pacemaker was associated with five preprocedure variables in the training cohort: PR interval > 200 ms, Right bundle branch block, valve-In-valve procedure, prior Myocardial infarction, and self-Expandable valve. The PRIME score was developed using these clinical features, and was highly accurate for predicting PPM in both the training and model validation cohorts (area under the curve 0.804 and 0.830 in the model training and validation cohorts, respectively). CONCLUSIONS: The PRIME score is a simple and accurate preprocedural tool for predicting the need for PPM implantation after TAVR.

Mask Mirroring: A Novel Approach to Healthcare Empathy in the COVID-19 Era.

The COVID-19 pandemic has brought forth substantial changes to societal norms and global health infrastructure, one of the most impactful being mask wearing. With varying attitudes toward mask usage in a post-pandemic environment, this paper introduces the concept of "mask mirroring" in healthcare settings. This strategy involves healthcare providers reciprocating the mask-wearing behavior of their patients, intending to respect patients' choices and alleviate their potential concerns and anxieties. It is hypothesized that mask mirroring could serve as a symbol of empathy and solidarity, enhancing the doctor-patient rapport and facilitating effective healthcare delivery. In addition, it could reduce the transmission of respiratory infections, fostering a safer healthcare environment. Importantly, mask mirroring addresses the power dynamics between healthcare providers and patients, allowing patients' preferences and comfort to be prioritized. The implementation of this concept requires clear communication about its purpose and symbolism, striking a balance between reassurance and respect for differing viewpoints. The ultimate aim of mask mirroring is to promote patient-centric care, reflecting our commitment to understanding and empathizing with patients' concerns in a world recovering from COVID-19.

Safety and Effectiveness of Adjunctive Posterior Wall Isolation in Atrial Fibrillation Patients: An Updated Meta-Analysis.

As the atrial fibrillation (AF) recurrence rate remains high after pulmonary vein isolation (PVI), additional left atrial posterior wall isolation (PWI) has been studied in randomized controlled trials, however, the results are conflicting. We performed an updated meta-analysis by searching online databases for the randomized controlled trials comparing the PWI + PVI group to the PVI alone group in patients with AF. The outcomes of interest were AF recurrence, all atrial arrhythmia recurrence, and atrial flutter/atrial tachycardia (AT) recurrence. Risk ratio (RR) with a 95% confidence interval (CI) was estimated using a random effects model. A total of 1,612 patients, with 807 in the PWI + PVI group and 805 in the PVI alone group were included. The mean age was 60 (9) years, 75% were men and 71% had persistent AF. The PWI + PVI group had lower AF recurrence as compared with the PVI alone group (25% vs 32%, RR 0.73, 95% CI 0.56 to 0.96, p = 0.02). There were no significant differences in all atrial arrhythmia recurrence (RR 0.90, 95% CI 0.78 to 1.04, p = 0.16), atrial flutter/AT recurrence (RR 1.19, 95% CI 0.92 to 1.55, p = 0.19) or adverse event rates in the 2 groups (36 vs 31; RR 1.09, 95% CI 0.67 to 1.77, p = 0.73). In conclusion, adjunctive PWI in addition to PVI can be achieved with lower AF recurrence but with a nonsignificant increase in atrial flutter/AT recurrence, resulting in an overall similar rate of all atrial arrhythmia recurrence without increasing the risk of adverse events, when compared with PVI alone strategy.

Evaluation of Quantitative Decision-Making for Rhythm Management of Atrial Fibrillation Using Tabular Q-Learning.

Background Rhythm management is a complex decision for patients with atrial fibrillation (AF). Although clinical trials have identified subsets of patients who might benefit from a given rhythm-management strategy, for individual patients it is not always clear which strategy is expected to have the greatest mortality benefit or durability. Methods and Results In this investigation 52 547 patients with a new atrial fibrillation diagnosis between 2010 and 2020 were retrospectively identified. We applied a type of artificial intelligence called tabular Q-learning to identify the optimal initial rhythm-management strategy, based on a composite outcome of mortality, change in treatment, and sustainability of the given treatment, termed the reward function. We first applied an unsupervised learning algorithm using a variational autoencoder with K-means clustering to cluster atrial fibrillation patients into 8 distinct phenotypes. We then fit a Q-learning algorithm to predict the best outcome for each cluster. Although rate-control strategy was most frequently selected by treating providers, the outcome was superior for rhythm-control strategies across all clusters. Subjects in whom provider-selected treatment matched the Q-table recommendation had fewer total deaths (4 [8.5%] versus 473 [22.4%], odds ratio=0.32, P=0.02) and a greater reward (P=4.8×10-6). We then demonstrated application of dynamic learning by updating the Q-table prospectively using batch gradient descent, in which the optimal strategy in some clusters changed from cardioversion to ablation. Conclusions Tabular Q-learning provides a dynamic and interpretable approach to apply artificial intelligence to clinical decision-making for atrial fibrillation. Further work is needed to examine application of Q-learning prospectively in clinical patients.

Evaluating temperature gradients across the posterior left atrium with radiofrequency ablation.

INTRODUCTION: Esophageal injury is a well-known complication associated with catheter ablation. Though novel methods to mitigate esophageal injury have been developed, few studies have evaluated temperature gradients with catheter ablation across the posterior wall of the left atrium, interstitium, and esophagus. METHODS: To investigate temperature gradients across the tissue, we developed a porcine heart-esophageal model to perform ex vivo catheter ablation on the posterior wall of the left atrium (LA), with juxtaposed interstitial tissue and esophagus. Circulating saline (5 L/min) was used to mimic blood flow along the LA and alteration of ionic content to modulate impedance. Thermistors along the region of interest were used to analyze temperature gradients. Varying time and power, radiofrequency (RF) ablation lesions were applied with an externally irrigated ablation catheter. Ablation strategies were divided into standard approaches (SAs, 10-15 g, 25-35 W, 30 s) or high-power short duration (HPSD, 10-15 g, 40-50 W, 10 s). Temperature gradients, time to the maximum measured temperature, and the relationship between measured temperature as a function of distance from the site of ablation was analyzed. RESULTS: In total, five experiments were conducted each utilizing new porcine posterior LA wall-esophageal specimens for RF ablation (n = 60 lesions each for SA and HPSD). For both SA and HPSD, maximum temperature rise from baseline was markedly higher at the anterior wall (AW) of the esophagus compared to the esophageal lumen (SA: 4.29°C vs. 0.41°C, p < .0001 and HPSD: 3.13°C vs. 0.28°C, p < .0001). Across ablation strategies, the average temperature rise at the AW of the esophagus was significantly higher with SA relative to HPSD ablation (4.29°C vs. 3.13°C, p = .01). From the start of ablation, the average time to reach a maximum temperature as measured at the AW of the esophagus with SA was 36.49 ± 12.12 s, compared to 16.57 ± 4.54 s with HPSD ablation, p < .0001. Fit to a linear scale, a 0.37°C drop in temperature was seen for every 1 cm increase in distance from the site of ablation and thermistor location at the AW of the esophagus. CONCLUSION: Both SA and HPSD ablation strategies resulted in markedly higher temperatures measured at the AW of the esophagus compared to the esophageal lumen, raising concern about the value of clinical intraluminal temperature monitoring. The temperature rise at the AW was lower with HPSD. A significant time delay was seen to reach the maximum measured temperature and a modest increase in distance between the site of ablation and thermistor location impacted the accuracy of monitored temperatures.

Presence of sinus rhythm at time of ablation in patients with persistent atrial fibrillation undergoing pulmonary vein isolation is associated with improved long-term arrhythmia outcomes.

BACKGROUND: Adverse structural and electrical remodeling underlie persistent atrial fibrillation (PersAF). Restoration of sinus rhythm (SR) prior to ablation in PersAF may improve the underlying substrate, thus improving arrhythmia outcomes. The aim of this study was to evaluate if the presence of SR at time of ablation is associated with improved long-term arrhythmia outcomes of a limited catheter ablation (CA) strategy in PersAF. METHODS: Patients with PersAF undergoing pulmonary vein isolation at our institution from 2014-2018 were included. We compared patients who presented for ablation in SR (by cardioversion and/or antiarrhythmic drugs [AADs]) to those who presented in AF. Primary outcome of interest was freedom from atrial arrhythmias (AAs) on or off AADs at 1 year after single ablation. Secondary outcomes included freedom from AAs on or off AADs overall, freedom from AAs off AADs at 1 year, and time to recurrent AF. RESULTS: Five hundred seventeen patients were included (322 presented in AF, 195 SR). The primary outcome was higher in those who presented for CA in SR as compared to AF (85.6% vs. 77.0%, p = 0.017). Freedom from AAs off AAD at 12 months was also higher in those presenting in SR (59.0% vs. 44.4%; p = 0.001) and time to recurrent AF was longer (p = 0.008). Presence of SR at CA was independently associated with the primary outcome at 12 months (OR 1.77; 95% CI 1.08-2.90) and overall (OR 1.89; 95% CI 1.26-2.82). CONCLUSIONS: Presence of SR at time of ablation is associated with improved long-term arrhythmia outcomes of limited CA in PersAF.

Limitations of Unipolar Signals in Guiding Successful Outflow Tract Premature Ventricular Contraction Ablation.

BACKGROUND: Unipolar electrograms (UniEGMs) are commonly used to annotate earliest local activation of focal arrhythmias. However, their utility in guiding premature ventricular contractions (PVCs) ablation may be limited when the PVC source is less superficial. OBJECTIVES: The authors sought to compare bipolar electrograms (BiEGMs) vs UniEGMs in guiding successful ablation of right ventricular outflow tract (RVOT) vs intramural outflow tract (OT) PVCs. The authors hypothesized that: 1) earliest bipolar local activation time (LATBi) would better guide mapping and ablation, vs UniEGM dV/dt (LATUni) or QS morphology; and 2) LAT differences using bipolar vs unipolar EGMs (ΔLATBi-Uni) would be greater for intramural OT than RVOT PVCs. METHODS: Consecutive patients undergoing successful PVC ablation 2017 to2020 requiring only RVOT or RVOT+left ventricular OT (RVOT+LVOT) ablation were retrospectively analyzed. BiEGMs and UniEGMs at successful ablation sites were compared. RESULTS: Of 70 patients, 50 required RVOT-only, and 20 required RVOT+LVOT ablation for acute and long-term PVC suppression. Mean ΔLATBi-Uni was lower for RVOT vs RVOT+LVOT groups (9.3 ± 6.4 ms vs 17.4 ± 9.9 ms; P < 0.01). QS UniEGM was seen in 78% of RVOT, compared with 53% of RVOT+LVOT patients (P < 0.016). RVOT+LVOT sites most frequently included the posteroseptal RVOT and adjacent LVOT (73%), and 43% lacked a QS unipolar EGM. ΔLATBi-Uni ≥15 ms best distinguished sites in which RVOT-only vs RVOT+LVOT ablation achieved acute PVC suppression (area under the curve: 0.77). CONCLUSIONS: Earliest BiEGM activation guides successful ablation of OT PVCs better than UniEGM-guided analysis, especially when an intramural PVC source is present.

Utility of Prolonged Duration Endocardial Ablation for Ventricular Arrhythmias Originating From the Left Ventricular Summit.

OBJECTIVES: This study sought to explore whether prolonged duration (PD) radiofrequency ablation (RFA) from adjacent endocardial locations can improve catheter ablation (CA) outcomes of left ventricular summit (LVS) ventricular arrhythmias (Vas). BACKGROUND: CA of VAs originating from the LVS region can be challenging. METHODS: Patients undergoing CA of LVS VAs from January 1, 2015, to December 31, 2019, were included. Standard RFA approach involved incremental power titration (20-45 W) over 60-120 seconds with irrigated tip catheter to achieve 10%-12% impedance drop. Prolonged duration RFA involved similar power titration; however, lesion application was extended beyond 120 seconds (maximum 5 minutes). Lesions were confined to lowest aspect of aortic cusps and/or subvalvular LV outflow tract region (≤0.5 cm from the valve). Procedural success was defined as suppression of VA ≥30 minutes postablation and clinical success as no arrhythmia symptoms on follow-up and >80% reduction of VA burden on postprocedure monitor. RESULTS: This study included 102 patients (60±14 years old, 62% male): standard RFA in 80 and PD RFA in 38. Procedural success was achieved in 54 patients with standard and 32 patients with PD RFA (68% vs 84%; P = 0.05). Short-term clinical success was achieved in 48 patients (60%) with standard and 30 patients (79%) with PD RFA (P = 0.04). Two pericardial effusions occurred (1 in each group) and no steam pops were noted. Patients in whom standard RFA was successful were more likely to have R/S ratio >1 or absence of qS in lead I (odds ratio: 3.35; 95% CI: 1.20-9.35; P = 0.03). CONCLUSIONS: Prolonged duration RFA from adjacent endocardial locations is a safe and effective technique for successfully targeting challenging LVS VAs that fail standard RFA.

Safety and efficacy of left atrial appendage closure using an epicardial suture snaring device: Systematic review and current status.

INTRODUCTION: The LARIAT epicardial suture snaring device has been fraught with technical challenges and procedural complications. Over time, technique modification and improved operator experience have helped overcome many of these challenges. METHODS AND RESULTS: Studies reporting left atrial appendage epicardial closure over a 12-year period from 2009 to 2020 were evaluated. The primary efficacy outcome evaluated was left atrial appendage closure with residual flow ≤1 mm. Safety outcomes evaluated were periprocedural and long term complications after device placement. Nine studies consisting of 1430 patients were included in this analysis, of which 1386 (97%) underwent successful device placement. The mean age was 69.3 years, with a mean CHADS2 -VASC score of 3.78. Primary efficacy end point was achieved in 95.8% patients immediately after device placement, and in 92.8% patients on long term follow-up. Early procedural complications consisted of pericardial effusion 5.6%, cardiac perforation 2.7%, pericarditis 2.6%, and need for open heart surgery 1.5%. Long term complications consisted of all-cause mortality 2.3%, stroke 1.5%, and left atrial appendage thrombus 2.3%. Reduced complications were noted using micropuncture needles (2.20% vs. 10.14%; p < .0001), a longer duration pericardial drainage, and use of anti-inflammatory medications (1.58% vs. 8.4%). Oral anticoagulation use decreased from 44.7% to 22.9% post device implantation, and to 8.5% on last clinical follow up. CONCLUSIONS: The LARIAT device is effective in epicardial closure of the left atrial appendage. Improvement in device techniques such as use of micropuncture needle, prophylactic colchicine, and maintenance of a pericardial drain have helped improve safety over time.

Interatrial septal tachycardias following atrial fibrillation ablation or cardiac surgery: Electrophysiological features and ablation outcomes.

BACKGROUND: Interatrial septal tachycardias (IAS-ATs) following atrial fibrillation (AF) ablation or cardiac surgery are rare, and their management is challenging. OBJECTIVE: The purpose of this study was to investigate the electrophysiological features and outcomes associated with catheter ablation of IAS-AT. METHODS: We screened 338 patients undergoing catheter ablation of ATs following AF ablation or cardiac surgery. Diagnosis of IAS-AT was based on activation mapping and analysis of response to atrial overdrive pacing. RESULTS: Twenty-nine patients (9%) had IAS-AT (cycle length [CL] 311 ± 104 ms); 16 (55%) had prior AF ablation procedures (median 3; range 1-5), 3 (10%) had prior surgical maze, and 12 (41%) had prior cardiac surgery (including atrial septal defect surgical repair in 5 and left atrial myxoma resection in 1). IAS substrate abnormalities were documented in all patients. Activation mapping always demonstrated a diffuse early IAS breakout with centrifugal biatrial activation, and atrial overdrive pacing showed a good postpacing interval (equal or within 25 ms of the AT CL) only at 1 or 2 anatomically opposite IAS sites in all cases. Ablation was acutely successful in 27 patients (93%) (from only the right IAS in 2, only the left IAS in 9, both IAS sides with sequential ablation in 13, and both IAS sides with bipolar ablation in 3). After median follow-up of 15 (6-52) months, 17 patients (59%) remained free from recurrent arrhythmias. CONCLUSION: IAS-ATs are rare and typically occur in patients with evidence of IAS substrate abnormalities and prior cardiac surgery. Catheter ablation can be challenging and may require sequential unipolar ablation or bipolar ablation.