Accessory pathway localization with probabilistic density maps generated by a mobile application: Assessment of a full pre-excitation net-vector method.

INTRODUCTION: Precise electrocardiographic localization of accessory pathways (AP) can be challenging. Seminal AP localization studies were limited by complexity of algorithms and sample size. We aimed to create a nonalgorithmic method for AP localization based on color-coded maps of AP distribution generated by a web-based application. METHODS: APs were categorized into 19 regions/types based on invasive electrophysiologic mapping. Preexcited QRS complexes were categorized into 6 types based on polarity and notch/slur. For each QRS type in each lead the distribution of APs was visualized on a gradient map. The principle of common set was used to combine the single lead maps to create the distribution map for AP with any combination of QRS types in several leads. For the validation phase, a separate cohort of APs was obtained. RESULTS: A total of 800 patients with overt APs were studied. The application used the exploratory data set of 553 consecutive APs and the corresponding QRS complexes to generate AP localization maps for any possible combination of QRS types in 12 leads. Optimized approach (on average 3 steps) for evaluation of preexcited electrcardiogram was developed. The area of maximum probability of AP localization was pinpointed by providing the QRS type for the subsequent leads. The exploratory data set was validated with the separate cohort of APs (n = 256); p = .23 for difference in AP distribution. CONCLUSIONS: In the largest data set of APs to-date, a novel probabilistic and semi-automatic approach to electrocardiographic localization of APs was highly predictive for anatomic localization.

Malignant ventricular arrhythmias and other complications of untreated accessory pathways: an analysis of prevalence and risk factors in over 600 ablation cases.

BACKGROUND: The presence of accessory pathways (APs) is a risk factor for sudden cardiac death and other clinical complications. AIMS: We aimed to characterize all adverse events likely related to the presence of APs in patients referred for AP ablation and to identify risk factors for malignant arrhythmias. METHODS: We performed a retrospective analysis of consecutive patients referred for AP ablation from 2002 to 2017. Electrocardiograms, electrophysiological system records, and hospital discharge notes were reviewed. We collected data concerning symptoms before ablation, occurrence of ventricular fibrillation or malignant atrial fibrillation (AF), as well as other complications related to APs. RESULTS: We identified 602 patients with APs. Serious AP­related events were observed in 41 patients, including 14 sudden cardiac arrests (1 death) and 16 pre­cardiac arrest events. Other complications included strokes, pulmonary edema, heart failure, and unnecessary device implantation. The risk of malignant arrhythmias decreased with a longer shortest preexcited RR interval (per 10 ms: odds ratio [OR], 1.3; 95% CI, 1.16­1.47) and increased with age (per 10 years: OR, 1.29; 95% CI, 1.06­1.57). The presence of inducible AF, but not sole atrioventricular reentrant tachycardia, increased the risk for malignant arrhythmias when compared with patients without any inducible arrhythmias. CONCLUSIONS: Patients with APs referred for ablation commonly present with various adverse events. The predictive value of clinical risk factors for malignant arrhythmias is too low to prevent devastating consequences. When high safety and efficacy of AP ablation are ensured, even a low risk of sudden death is unacceptable and a lower threshold for prophylactic ablation should be used to prevent AP­related adverse events.

Contemporary outcomes of catheter ablation of accessory pathways: complications and learning curve.

BACKGROUND AND AIM: The aim of this study was to examine contemporary results of accessory pathway (AP) ablation in a sizeable number of patients, focusing on periprocedural complications and the learning curve. METHODS: We performed a retrospective cohort study of consecutive AP ablation procedures at three centresby the same operator. In total 629 electrophysiological studies and 610 AP ablation procedures were performed in 570 patients (age: 33 ± 18.9 years). RESULTS: There was one (0.16%) serious and there were 14 (2.3%) minor periprocedural complications. Five hundred and ninety APs were successfully ablated: single/multiple procedure success was 93.4%/96.7%, while the average fluoroscopy time was 13.5 min. There was significantly higher success and less fluoroscopy use with increased experience, while periprocedural complications seemed evenly distributed over the years. The learning was most pronounced for the first 120 cases. However, the learning curve fully flattened only after approximately 400 ablations. CONCLUSIONS: This study suggests that in the modern era AP ablation is safer than it was in the first two decades after the introduction of catheter ablation of APs. Perhaps, in experienced centres there should be a lower threshold for referring asymptomatic/mildly symptomatic patients with pre-excitation for electrophysiological study.

Intermittent preexcitation indicates "a low-risk" accessory pathway: Time for a paradigm shift?

We report three patients with intermittent loss of the preexcitation pattern in the ECG that had undergone an electrophysiological study. Despite apparently poorly conducting accessory pathway (AP), in each case a fast anterograde conduction, either during spontaneous atrial fibrillation or during incremental atrial pacing (on isoproterenol) was documented; shortest preexcited RR intervals of 200-240 ms were observed. We review the literature and conclude that intermittent preexcitation observed on resting 12-lead ECG lacks sufficient specificity for the diagnosis of an AP with long refractory period and cannot be considered a substitute for electrophysiological study in patients with this electrocardiographical phenomenon.

Validation of Standard and New Criteria for the Differential Diagnosis of Narrow QRS Tachycardia in Children and Adolescents.

To establish an appropriate treatment strategy and determine if ablation is indicated for patients with narrow QRS complex supraventricular tachycardia (SVT), analysis of a standard 12-lead electrocardiogram (ECG) is required, which can differentiate between the 2 most common mechanisms underlying SVT: atrioventricular nodal reentry tachycardia (AVNRT) and orthodromic atrioventricular reentry tachycardia (OAVRT). Recently, new, highly accurate electrocardiographic criteria for the differential diagnosis of SVT in adults were proposed; however, those criteria have not yet been validated in a pediatric population.All ECGs were recorded during invasive electrophysiology study of pediatric patients (n = 212; age: 13.2 ±â€Š3.5, range: 1-18; girls: 48%). We assessed the diagnostic value of the 2 new and 7 standard criteria for differentiating AVNRT from OAVRT in a pediatric population.Two of the standard criteria were found significantly more often in ECGs from the OAVRT group than from the AVNRT group (retrograde P waves [63% vs 11%, P < 0.001] and ST-segment depression in the II, III, aVF, V1-V6 leads [42% vs 27%; P < 0.05]), whereas 1 standard criterion was found significantly more often in ECGs from the AVNRT group than from the OAVRT group (pseudo r' wave in V1 lead [39% vs 10%, P < 0.001]). The remaining 6 criteria did not reach statistical significance for differentiating SVT, and the accuracy of prediction did not exceed 70%. Based on these results, a multivariable decision rule to evaluate differential diagnosis of SVT was performed.These results indicate that both the standard and new electrocardiographic criteria for discriminating between AVNRT and OAVRT have lower diagnostic values in children and adolescents than in adults. A decision model based on 5 simple clinical and ECG parameters may predict a final diagnosis with better accuracy.

[Pseudo-PJRT in an 8 year-old boy with severe decompensated heart failure and recurrent episodes of ventricular fibrillation]. / Pseudo-PJRT u 8-letniego chlopca z ciezka zdekompensowana niewydolnoscia serca i nawracajacym migotaniem komór.

We present a case of 8 year-old boy with several episodes of ventricular fibrillation in the course of tachycardia-mediated cardiomyopathy and severe decompensated heart failure. The cardiomyopathy was caused by incessant long-RP tachycardia that was resistant to pharmacotherapy. Despite initial suspition that the arrhythmia was permanent junctional reciprocating tachycardia (PJRT) electrophysiology study revealed atypical atrioventricular nodal reentrant tachycardia. Due to clinical and electrocardiographical presentation mimicking PJRT such arrhythmia merits the name 'pseudo PJRT'.

[Focal atrial tachycardia originating in the right atrial appendage]. / Czestoskurcz ogniskowy z uszka prawego przedsionka.

We present a case of 14-year-old boy with incessant atrial tachycardia from right atrial appendage, resistant to pharmacotherapy and with early signs of the left ventricle tachyarrhythmic dysfunction. The P-wave was positive in leads I, II, III, aVF, negative in aVR, aVL. Moreover, P waves configuration specific for this localization: negative in V1-V2 that become positive in V3-V6 was present. After first ablation session a recurrence was observed after 3 weeks, due to inadequate power delivery resulting from trabeculation/anatomy that limited conventional ablation catheter cooling. Second ablation session with the use of an active electrode cooling and 3D mapping system was successful.