Perez-Downes, Julio

Background: Patients with D-transposition of the great arteries and atrial switch have a high incidence of atrial arrhythmias. We sought to analyze the arrhythmia substrate, ablation strategies, and outcomes for catheter ablation in this population. Methods: An in-depth analysis of all clinical and procedural data in patients with D-transposition of the great arteries, atrial baffles, and atrial arrhythmia ablation was performed. Results: A cohort of 32 patients (72% male, mean age 38±7 years) underwent ablation for non-AV nodal reentrant tachycardia atrial arrhythmias, and 4 patients underwent AV nodal reentrant tachycardia ablation. Cavotricuspid isthmus flutter (CTI-flutter) was the most common arrhythmia, encountered in 75% of patients, followed by scar-related intraatrial reentrant tachycardia (non-CTI intraatrial reentrant tachycardia, 53%) and focal atrial tachycardia (focal atrial tachycardia, 6%). Among the 32 patients, 26 underwent 31 procedures at our institution. For patients with prior outside intervention, the index ablation at our institution revealed CTI-dependent flutter in 3/5 cases. However, redo ablation after an index ablation with demonstrated bidirectional CTI block revealed different/new arrhythmia substrates (80% non-CTI intraatrial reentrant tachycardia, 40% focal atrial tachycardia). Achieving bidirectional block across the CTI often required ablating on both sides of the baffle (retroaortic access, 81%; using a baffle leak, 11.5%; or transbaffle puncture, 7.7%). Combined approaches were necessary in 19% to reach the critical tissue. Acute procedural success was 81%, and recurrence was documented in 58% of patients. Despite recurrence, clinical arrhythmia burden was significantly reduced post-ablation ( P <0.001), with rare episodes, amenable to antiarrhythmic therapy. Redo ablation was required in 5 (19%) patients and uncovered new arrhythmia substrates. AV nodal reentrant tachycardia ablation also required transbaffle approaches in 3/4 patients. Conclusions: CTI-dependent flutter was the most common arrhythmia in patients with Dextro-Transposition of the Great Arteries and atrial switch. Transbaffle approaches were often necessary, and, provided that bidirectional CTI block was achieved at the index ablation, late recurrence was due to different arrhythmia mechanisms. Despite recurrence, ablation was associated with significant clinical improvement.

Introduction: Atrial arrhythmias are common in patients with D-TGA and atrial switch. We sought to analyze the arrhythmia substrate and catheter ablation approaches and outcomes. Methods: We performed a retrospective review of all clinical and procedural data in patients with D-TGA followed at a large tertiary care center. Results: In a cohort of 152 patients (mean age 30±11 years), atrial tachycardia was present in 69(45%) patients. Ablations were performed in 39(26%) patients: macro-reentrant atrial flutter (N=37), atrial fibrillation (N=4), and focal automatic atrial tachycardia (N=3). Detailed electrophysiology study data was available for 34 patients. At first ablation (N=28), cavo-tricuspid isthmus dependent flutter (CTI, 23(82%)) was most common, followed by right atriotomy-related flutter (IART, 16(57%)) and focal atrial tachycardia (FAT, 1(3.5%)). Bidirectional CTI block often required ablation on both sides of the baffle to complete the isthmus line. Access to the pulmonary venous atrium was obtained in 82% of first-time ablations (via retrograde aortic access, 74%, baffle puncture, 6%, or baffle fenestration, 12%) and in 100% of redo procedures. The first ablation was acutely successful in 25 (89%) patients; the other 3 patients had either partial procedural success (1), failed ablation (1), or underwent an empirical ablation (1). Long-term arrhythmia recurrence occurred in 13(46%) after the first ablation and class III antiarrhythmic medications were utilized in 12 patients. At least one long-term recurrence occurred in 11(44%) patients. Importantly, clinical arrhythmia burden was significantly reduced post-ablation, with rare and short-limited episodes amenable to antiarrhythmic drugs or cardioversion. Repeat ablation was required in 3 cases. Long-term arrhythmia recurrence after a previously completed CTI line involved different arrhythmia mechanisms: scar-related reentry (80%) and automatic atrial tachycardia (40%). Conclusions: Atrial arrhythmia in patients with D-TGA often involves the CTI and atriotomy scars. Ablation of the CTI typically requires access to the pulmonary venous atrium to achieve bidirectional block. Despite late recurrence, the clinical arrhythmic burden is substantially improved.

Introduction: Conduction disturbance after transcatheter aortic valve replacement (TAVR) remains a common complication. Predictive tools to identify conduction disturbance requiring pacing are limited. Our main objective was to develop a deep learning model to predict the need for a permanent pacemaker. Hypothesis: An electrocardiogram (ECG) based deep learning algorithm can predict the need for permanent pacemaker post TAVR. Methods: We evaluated patients who had TAVR at Mayo Clinic between June 2010 and May 2021. Digital ECGs done on the TAVR date or within 24 hours post procedure were partitioned into training, validation, and testing datasets. We trained a deep learning algorithm on the training data and optimized hyperparameters against the validation data. All model performance metrics are based on the reserved test data that were estimated once model architecture was optimized. Need for permanent pacemaker, defined as pacemaker placement due to development of conduction disturbance post TAVR and at least 1% ventricular pacing on device interrogation done at least 2 weeks post pacemaker implantation, was the training target. Results: A total of 3021 patients were evaluated for inclusion and 2,407 cases were available for modeling (exclusions: prior pacemaker (n=419), unsuccessful TAVR (n=27) and no ECG within the pre-specified period (n=168)). Overall, the median age was 82 (Q1: 76, Q3: 86) and 41% were female. In the withheld test data, 15% had a permanent pacemaker with at least 1% ventricular pacing. The algorithm detected the need for pacemaker in the test set with an AUC of 0.83 (95% CI: 0.73 to 0.92). Accuracy, sensitivity, specificity, positive and negative predictive were 80%, 72%, 81%, 41% and 94%, respectively. Conclusions: This study demonstrates the ability of a deep learning model based on ECG data to assist in making the decision to implant a pacemaker following TAVR with a high negative predictive value. Larger validation studies are warranted.

Introduction: Patients with D-TGA palliated with atrial switch operations have the morphologic right ventricle in the systemic position. There is increased risk of atrial arrhythmias and systemic right ventricle (SRV) failure. We sought to analyze the long term outcomes of these patients. Methods: All patients with D-TGA and SRV followed in the Adult Congenital Heart Disease Clinic of a large tertiary care institution were reviewed. A comprehensive retrospective analysis of the medical record was performed, including consult notes, ECGs, echocardiograms and electrophysiology reports. Results: A total of 154 patients (63% male) aged 29±11 years were followed for a mean of 10±9 years (range 0-51). During follow-up, 3 patients underwent cardiac transplantation and 15 died; 5 had sudden death, 2 had cardiogenic shock, 5 had non-cardiac death (i.e., infective endocarditis, sepsis) and 3 had unknown causes of death. Heart failure symptoms were present in 53(34%) patients. Severe SRV systolic dysfunction occurred in 37(24%) patients, with a mean EF of 23±5.5%; moderate SRV dysfunction occurred in 67(44%) patients, mean EF 35±4%. Sinus node dysfunction was present in 75(49%) patients, complete AV block in 9(5%) patients, and a pacemaker placed in 60(39%) patients, with cardiac resynchronization therapy in 5. Atrial arrhythmias occurred in 94(61%) patients and ablations were performed in 47(31%) patients. An ICD was implanted in 37 patients; 5 patients had appropriate shocks, but 7 had inappropriate shocks due to atrial arrhythmias. Age (HR 1.07, p=001), heart failure symptoms (HR 4.9, p= 0.007), severe SRV enlargement (HR 3.7, p=0.03), severe systolic dysfunction (HR 5.4, p=0.003), severe systemic AV valve regurgitation (HR 5.2, p=0.002) and a QRS duration> 122ms (HR 3.7, p=0.02) were significant predictors of mortality. The 15 year probability of sudden death was 3.2%(95% CI 0-6.9%). Conclusions: Atrial arrhythmias are common after atrial switch operations secondary to atriotomy scars. Further studies will need to determine whether restoration of sinus rhythm or cardiac synchrony may prevent further deterioration of the systemic right ventricle. Severe SRV dysfunction and prolonged QRS duration >122ms were significantly correlated with mortality.