Clinical predictors of heart block during atrioventricular nodal reentrant tachycardia ablation: A multicenter 18-year experience.

BACKGROUND: Catheter ablation is considered the first-line treatment of symptomatic atrioventricular nodal reentrant tachycardia (AVNRT). It has been associated with a risk of heart block (HB) requiring a pacemaker. This study aims to determine potential clinical predictors of complete heart block as a result AVNRT ablation. METHODS: Consecutive patients undergoing catheter ablation for AVNRT from January 2001 to June 2019 at two tertiary hospitals were included. We defined ablation-related HB as the unscheduled implantation of pacemaker within a month of the index procedure. Use of electroanatomic mapping (EAM), operator experience, inpatient status, age, sex, fluoroscopy time, baseline PR interval, and baseline HV interval was included in univariate and multivariate models to predict HB post ablation. RESULTS: In 1708 patients (56.4 ± 17.0 years, 61% females), acute procedural success was 97.1%. The overall incidence of HB was 1.3%. Multivariate analysis showed that age more than 70 (odds ratio [OR] 7.907, p ≤ .001, confidence interval [CI] 2.759-22.666), baseline PR ≥ 190 ms (OR 2.867, p = .026, CI 1.135-7.239) and no use of EAM (OR 0.306, p = .037, CI 0.101-0.032) were independent predictors of HB. CONCLUSION: Although the incidence of HB post AVNRT ablation is generally low, patients can be further stratified using three simple predictors.

A Hidden Recess of Atrial Tachycardia.

We present a case of regular narrow complex tachycardia in a 59-year-old woman with frequent paroxysmal palpitations, a normal electrocardiogram (ECG) in sinus rhythm, and a structurally normal heart. During electrophysiology study, a long R-P tachycardia was present at baseline, with P-waves superimposed on the T-waves and appearing to be positive in the inferior leads. Intracardiac recordings showed the atrial activation to be early in the para-Hisian region. The diagnosis of atrial tachycardia was confirmed by ventricular overdrive pacing, which showed ventriculoatrial dissociation without perturbing the atrial rate. The precise P-wave morphology was brought out in the pause, which followed rapidly delivered ventricular extrastimuli during tachycardia. Based on this information, activation mapping was conducted in the para-Hisian region, high atrial septal regions on the right and left sides, and aortic sinuses. Tachycardia was successfully ablated at one of these sites.

Surface unipolar electrogram characteristics to predict site of origin of outflow tract arrhythmias using noninvasive mapping.

BACKGROUND: Noninvasive electroanatomic mapping (NIEAM) demonstrate patterns of depolarization that are useful in identifying the chamber of origin (COO) in outflow tract ventricular arrhythmias (OTVA). However, its use in predicting exact site of origin (SOO) has not yet been validated. METHODS: NIEAMs (CardioInsight, Medtronic) from 40 patients (age 62.5 ± 2.6) undergoing ablation for OTVA were reviewed for diagnostic accuracy in predicting the SOO. Earliest arrhythmia breakout and directionality of earliest instantaneous unipolar electrograms (uEGMs) on NIEAMs were evaluated subjectively by two observers for quality and amplitude. Sites with most negative earliest uEGMs on right and left ventricular outflow tracts, as well as epicardial surface were manually identified. Using NIEAM-based activation timing of the lateral mitral annulus and basal septum COO was identified for each OTVA. Predictions of SOO using NIEAMs was compared with true SOO from invasive study. NIEAMs SOO predictions were compared with subjective 12 lead electrocardiogram (ECG) review by two observers. RESULTS: Review of arrhythmia breakout and signal directionality had poor diagnostic value in predicting SOO in OTVA (50.6% and 49.4%, 56.6% and 43.4%, respectively) and underperformed compared with ECG interpretation (59.1% and 80.5%). After excluding uEGMs with poor characteristics, the uEGM with most negative amplitude at the COO was predictive of the true SOO with 96.4% sensitivity and specificity. CONCLUSION: We propose a stepwise approach when interpreting NIEAMs for OTVA where patterns of activation are evaluated first to determine the COO, followed by identification of the site with most negative amplitude instantaneous uEGM to determine SOO.

Non-invasive electroanatomic mapping to reduce mapping time during catheter ablation of outflow tract ventricular premature depolarizations.

PURPOSE: Ventricular premature depolarizations (VPD) commonly arise from the septal anterior right ventricular outflow tract (sRVOT), the left coronary cusp (LCC), and the distal great cardiac vein (dGCV), and share common ECG characteristics. To assess the diagnostic accuracy of non-invasive electroanatomic mapping (NIEAM) in differentiating VPD origin between sRVOT, LCC and dGCV and quantify its clinical utility in eliminating unnecessary mapping and ablation. METHODS: ECGs and NIEAMs (CardioInsight, Medtronic) from 32 patients (56.3 ± 15.2 years) undergoing ablation for VPDs originating from sRVOT, LCC, or dGCV were blindly reviewed for their diagnostic accuracy in predicting the SOO. A 2-step algorithm using NIEAM-based activation timing of the superior basal septum of < 22.5 ms and lateral mitral annulus of > 60.5 ms was compared with subjective ECG evaluation, the maximum deflection index (MDI), and the V2 transitional ratio in predicting SOO. We calculated the mapping and ablation time that could have been avoided had the operators relied on activation timing by NIEAM in designing their mapping and ablation strategy. RESULTS: NIEAM was superior to subjective ECG evaluation, MDI, and V2 transition ratio in predicting the SOO yielding a sensitivity and specificity of 96.9% and 98.4% respectively. Using NIEAM in determining the SOO would have obviated 22 ± 4.5 min of mapping in the wrong chamber and prevented unnecessary ablation of 4.5 ± 1.8 min. CONCLUSION: NIEAM has high diagnostic accuracy in differentiating between sRVOT, LCC, and dGCV VPDs, and can significantly reduce mapping time, obviating the need for unnecessary access and ablation.

Anatomic predictors of recurrence after cryoablation for atrial fibrillation: a computed tomography based composite score.

BACKGROUND: Effective pulmonary vein isolation (PVI) with cryoablation depends on adequate occlusion of pulmonary veins (PV) by the cryoballoon and is therefore likely to be affected by PV and left atrial (LA) anatomical characteristics and variants. Thus, the objective of this study was to investigate the effect of LA and PV anatomy, evaluated by computed tomography (CT), on acute and long-term outcomes of cryoablation for atrial fibrillation (AF). METHODS: Fifty-eight patients (64.72 + 9.44 years, 60.3% male) undergoing cryoablation for paroxysmal or early persistent AF were included. Pre-procedural CT images were analyzed to evaluate LA dimensions and PV anatomical characteristics. Predictors of recurrence were identified using regression analysis. RESULTS: 60.3% of patients had two PVs on each side with separate ostia, whereas 29.3% and 10.3% had right middle and left common PVs, respectively. The following anatomic characteristics were found to be independent predictors of recurrence: right superior PV ostial max:min diameter ratio > 1.32, left superior PV ostial max:min diameter ratio > 1.2, right superior PV antral circumference > 69.1 mm, right inferior PV antral circumference > 61.38 mm, right superior PV angle > 22.7°. Using these factors, LA diameter and right middle PV, a scoring model was created for prediction of "unfavorable" LA-PV anatomy (AUC = 0.867, p = 0.000009, score range = 0-7). Score of ≥ 4 predicted need for longer cryoenergy ablation (p = 0.039) and more frequent switch to radiofrequency energy (p = 0.066) to achieve PVI, and had a sensitivity of 83.3% and specificity of 82.5% to predict clinical recurrence. CONCLUSION: CT-based scoring system is useful to identify "unfavorable" anatomy prior to cryo-PVI, which can result in procedural difficulty and poor outcomes.

Intracardiac echocardiography guided nonocclusive balloon cryothermal applications to achieve antral isolation during pulmonary vein isolation.

OBJECTIVE: Ablation for atrial fibrillation (AF) requires electrical isolation of the pulmonary veins (PV) by wide-area circumferential PV antral isolation (PVAI). Cryoballoon ablation delivers cryoenergy circumferentially after occlusion of the PV by the cryoballoon; thus, it is likely that the level of isolation, determined by adequate balloon-tissue contact, depends on PV anatomy. We sought to examine the need for nonocclusive segmental cryoballoon ablation in achieving antral isolation, describe methods of accurate visualization of the cryoballoon using intracardiac echocardiography (ICE), and provide data on biophysical characteristics of an effective nonocclusive cryothermal lesion. METHODS: Forty consecutive patients undergoing catheter ablation with a second-generation 28-mm cryoballoon and electroanatomic mapping (EAM) were included. Balloon was visualized with ICE, and its location was registered in EAM using available technology (CARTOSOUND, Biosense Webster). Need for delivery of nonocclusive lesions was based on level of isolation post occlusive lesions. RESULTS: Nonocclusive lesions to PVAI was required in 26 of 40 patients (65%) or 46 out of 148 veins (31%). Left PVs > 19.4 ± 2.9 mm, right superior PV > 20.2 ± 4.7mm, funnel-shaped PVs, and right PVs not converging to a carina were more likely to require nonocclusive lesions to achieve an antral level of isolation. Projection of balloon contour on EAM using CARTOSOUND successfully predicted level of isolation by voltage mapping. CONCLUSION: Nonocclusive cryoballoon applications are commonly required to achieve antral isolation. Use of ICE can be helpful in determining the accurate location of the balloon and in predicting the level of isolation by voltage map.

Early recurrence of atrial fibrillation after pulmonary vein isolation: a comparative analysis between cryogenic and contact force radiofrequency ablation.

BACKGROUND: Early recurrence (ER) of atrial fibrillation (AF) within 90 days post-ablation is observed in up to 50% of patients and has been attributed to transient inflammation. The importance of ER in current era of pulmonary vein isolation (PVI) with cryoballoon ablation (CBA) and contact-force catheter radiofrequency ablation (cfRFA) has not been clearly reported. In addition, it is not known whether there are differences between types of ablation energy used during PVI. METHODS: Study population was drawn from a prospective multicenter database of AF ablation. Consecutive patients undergoing first-time ablation with PVI alone, using either second-generation CBA or cfRFA catheters were included. Patients were followed at 0.5, 3, 6, and 12 months to assess recurrence. Predictors of late recurrence (LR), defined as recurrence outside the blanking period, were assessed by Cox proportional hazards regression models. Freedom from LR was calculated and compared between two groups using the Kaplan-Meier method and log-rank test. RESULTS: Study cohort included 300 patients (1:1 CBA:RFA, age 63.6 ± 10.3 years, 67% male). There were no baseline characteristic differences between the CBA and cfRFA groups. ER occurred in 23.3% and 16.7% of patients in the CBA and cfRFA groups, respectively (p = 0.149). One-year freedom from LR was similar for both groups (72.7% CBA vs. 78% cfRFA, p = 0.287). Fifty-two patients (25 CBA and 27 cfRFA) underwent repeat ablation and no difference in durability of PVI was found. ER was the only common independent predictor of LR for either group and for the entire cohort (HR 2.3). CONCLUSIONS: In our series of AF ablation using second-generation cryoballoon and contact-force RFA catheters, recurrence in the "blanking period" is seen in 20% and remains predictive of late recurrence irrespective of the energy used.

Conduction patterns of idiopathic arrhythmias from the endocardium and epicardium of outflow tracts: New insights with noninvasive electroanatomic mapping.

BACKGROUND: Idiopathic arrhythmias commonly arise from the septal right ventricular outflow tract (RVOT), sinuses of Valsalva (SoV), and great cardiac vein (GCV). Predicting the exact site of origin is important for preparation for catheter ablation. OBJECTIVE: The purpose of this study was to examine the diagnostic value of noninvasive electroanatomic mapping (NIEAM) to differentiate between septal RVOT, SoV, and GCV origin and compare it to that of 12-lead electrocardiography (ECG). METHODS: NIEAM maps (CardioInsight, Medtronic) were generated during spontaneous ventricular premature depolarizations (VPDs) and threshold pacing from septal RVOT, SoV, and GCV. Origin prediction using NIEAM was compared to algorithmic ECG criteria (maximal deflection index; V2 transition ratio) and subjective ECG evaluation. RESULTS: Sixty NIEAMs (18 spontaneous VPDs and 42 pace-maps) from 31 patients (age 56 ± 16 years) were analyzed. NIEAM showed distinct conduction patterns, best visualized at the base of the heart: septal RVOT VPDs propagate toward the tricuspid annulus, depolarizing the septum from inferior to superior; SoV VPDs engage the superior septum early; and GCV VPDs move laterally along the mitral annulus, depolarizing the heart from left to right. Activation of the lateral mitral annulus >60.50 ms and the superior basal septum <22.5 ms from onset predicts RVOT and SoV origin, respectively, in 100% of cases. NIEAM was superior to maximum deflection index in predicting GCV origin (100% vs 42.2% accuracy) and superior to V2 transition ratio in predicting SoV origin (100% vs 75.9% accuracy). CONCLUSION: Arrhythmias arising from the outflow tracts follow distinct propagation patterns depending on the origin. A 2-step algorithm using activation timing by NIEAM yields 100% diagnostic accuracy in predicting origin.

Paroxysmal Atrial Fibrillation With Both Triggers and Rotational Drivers Within the Right Atrial Appendage.

A 48-year-old woman with paroxysmal atrial fibrillation (AF) underwent an electrophysiology study after 2 previous failed ablations. Noninvasive mapping suggested AF initiation from the right atrial appendage (RAA) with rotational drivers of AF in the RAA. Invasive mapping confirmed these findings. The patient was successfully treated with cryoballoon RAA isolation. (Level of Difficulty: Intermediate.).