Posteroseptal Accessory Pathway Research Articles

Efficacy and safety of pulsed field ablation for accessory pathways: a pilot study.

Radiofrequency ablation (RFA) is used as a first-line therapy for accessory pathways (APs). However, data regarding the effects of pulsed field ablation (PFA) on APs are limited. We sought to evaluate the acute procedural and 6-month success and safety of PFA in a cohort of patients with APs. A focal contact-force sensing PFA catheter was used for patients with APs. PFA generator generated a bipolar and biphasic waveform (± 1000 V) with a duration of 100 ms from the tip of PFA catheter. 100% acute procedural success was achieved in 10 conscious patients with APs (7 left anterolateral, 2 left inferolateral, and 1 right posteroseptal APs) including 6 (60%) patients after an initial application. The average total ablation time was 6.3 ± 4.9 seconds for 4.7 ± 1.8 ablation sites (ASs), including 3.1 ± 2.4 seconds at targets and 3.2 ± 2.9 seconds at 3.2 ± 2 bolus ASs. The mean skin-to-skin time was 59.3 ± 15.5 minutes, and PFA catheter dwell time was 29.4 ± 7.8 minutes. One patient encountered transient sinus arrest during PFA due to parasympathetic overexcitation. Sinus rhythm was restored in all patients without any significant adverse events during short-term follow-up. PFA of APs was feasible, effective, and safe. Its efficiency was remarkable for its ultrarapid termination of AP conduction. Further studies are warranted to prove whether utilization of PFA with current parameters can extend to manifold APs ablation.

Differential right apical and left basal pacing: a new maneuver that rules out the presence of a left accessory pathway with retrograde conduction

Abstract Background Differential apex-base pacing or entrainment is a very useful maneuver in patients with concealed septal accessory pathways. This study evaluates for the first time the diagnostic value of differential right apical pacing (aRV) and basal left ventricular pacing (bLV) in patients with left accessory pathways before and after ablation. Purpose To determine the value of differential aRV and bLV pacing as a simple maneuver to assess the successful ablation of left accessory pathways. Methods Successive patients with preexcitation or concealed left accessory pathways were prospectively included. Baseline pre-ablation (PRE) 1:1 retrograde conduction was evaluated by the S-A interval during pacing at the aRV (PREaRV) and at the bLV (PREbLV) measured to the earliest atrial electrogram detected by a decapolar catheter placed in the coronary sinus. The S-A interval resulting from direct atrial capture during high outputpacing at the bLV at (PREdir) was also measured. The same S-A intervals, pacing at the same locations and measured to the same dipole in the coronary sinus were reassessed after ablation (POSaRV, POSbLV, POSdir) in order to compare the total values and their differences. Results 47 patients were included (age 31 yo [range 4 – 76 yo], 70% male sex, transeptal approach used in 62%). Ablation of the accessory pathway was successful in all patients. 5 patients could not be analyzed due to absence of 1:1 retrograde conduction before ablation, 27/43 (63%) patients had 1:1 retrograde nodal conduction after ablation. A significant prolongation of the S-A intervals were observed after ablation during pacing at the aRV (POSaRV – PREaRV = 43±38 ms, IC95% 27-59 ms, p<0,001) and from the bLV (POSbVI – PREbVI = 126±53 ms, IC95% 105-147 ms, p<0,001). As expected, the S-A interval during direct atrial capture from the bLV did not prolong (POSdir – PREdir = 2±10 ms, IC95% -2 – 6 ms, p=0,41). The difference PREaRV – PREbLV before ablation (difPRE) was 80±26 ms (IC95% 72-88 ms) and never overlapped with the difference POSaRV – POSbLV after ablation (-6 ±33 ms, IC95% -19 – 8 ms) (difPOS) except in one case of left posteroseptal accessory pathway. The δ value (difPRE – difPOS) was 83±40 ms (IC95% 67-100 ms, p<0,001). A difPOS value <20 ms discriminated all successful ablations of non posteroseptal accesory pathways. Conclusion The S-A values obtained during differential RV apical and LV basal pacing before and after ablation are valid to discriminate the efficacy of the procedure. The POSaVD – POSbVI value is always <20 ms after successful ablation and excludes retrograde conduction over any left non-posteroseptal accesory pathway. This same value is ≤0 ms in 72% of cases of successful ablation.Figure.

Evaluation of T-wave memory after accessory pathway ablation in pediatric patients with Wolff-Parkinson-White syndrome.

T-wave memory (TWM) is a rare cause of T-wave inversion (TWI). Alterations in ventricular activation due to abnormal depolarization may cause repolarization abnormalities on the ECG, even if myocardial conduction returns to normal. These repolarization changes are defined as TWM. In our study, we aimed to determine the frequency of TWM development and the predictors affecting it in the pediatric population who underwent accessory pathway (AP) ablation due to Wolff-Parkinson-White (WPW) syndrome. The data of patients with manifest AP who underwent electrophysiological studies and ablation between 2015 and 2021 were retrospectively analyzed. The study included 180 patients who were under 21 years of age and had at least one year of follow-up after ablation. Patients with structural heart disease, intermittent WPWs, recurrent ablation, other arrhythmia substrates, and those with less than one-year follow-up were excluded from the study. The ECG data of the patients before the procedure, in the first 24h after the procedure, three months, and in the first year were recorded. The standard ablation technique was used in all patients. Postprocedure TWM was observed in 116 (64.4%) patients. Ninety-three patients (51.7%) had a right-sided AP, and 87 patients (48.3%) had a left-sided AP. The presence of posteroseptal AP was found to be significantly higher in the group that developed TWM. Of these patients, 107 (93.1%) patients showed improvement at the end of the first year. Preprocedural absolute QRS-T angle, postprocedural PR interval, and right posteroseptal pathway location were identified as predictors of TWM. The development of TWM is particularly associated with the right-sided pathway location, especially the right posteroseptal pathway location. The predictors of TWM are the preprocedural QRS-T angle, the postprocedural PR interval, and the presence of the right posteroseptal AP.

Recurrent Orthodromic SVT AVRT with Multiple Accessory Pathway in WPW Syndrome: Ablate All or Not?

Background: Patients diagnosed with Wolff-Parkinson-White syndrome (WPW) have a relatively low, nevertheless persistent risk of unexpected mortality. However, this risk can be effectively mitigated by applying radiofrequency catheter ablation targeting the accessory pathway. It is difficult to accurately study predictors because only a minority of patients develop potentially malignant arrhythmias (MA) or passed away, despite essential risk variables being relatively well-known.1 This study aimed to describe ablation in WPW syndrome. Case presentation: A 16-year-old male presents with symptoms characterized by palpitations during intense physical exertion, followed by chest pain episodes. The physical examination, CXR, laboratorium, and echocardiography were all within the normal range; his ECG showed shortened PR interval and a delta wave with a positive delta wave at V1 and mostly positive at the inferior lead. He also has recorded ECG when the patient has a tachycardia event with SVT AVRT orthodromic pattern. He underwent EP Study and had several accessory pathways at the posteroseptal mitral annulus and anteroseptal tricuspid. The decision was made to perform ablation on the posteroseptal accessory pathway located at the mitral annulus. An electrophysiology (EP) investigation was conducted at the anteroseptal tricuspid annulus, which did not induce tachyarrhythmia. Conclusion: Wolff-Parkinson-White syndrome is a congenital cardiac pathway formation, with not all accessory pathways causing tachyarrhythmias. Ablation therapy is necessary for patients with multiple pathways, with pathways with an ERP less than 250 being the only option. Keyword: Ablation, Multiple Accessories Pathway, SVT AVRT Orthodromic, WPW Syndrome.

Successful high-resolution three-dimensional electroanatomical mapping and radiofrequency catheter ablation of a posteroseptal accessory pathway in a dog using CARTO 3

A one-year-and-seven-month-old, 28 kg, male castrated crossbreed dog was presented for supraventricular tachycardia causing recurrent episodes of anorexia and lethargy. Sotalol (2.2 mg/kg q12 h) reduced the frequency of symptomatic episodes but did not provide full relief. Three-dimensional electroanatomical mapping was performed at the Ghent University Small Animal Teaching hospital using the CARTO 3. Right atrial activation mapping identified the earliest atrial activation right posteroseptal, near the tricuspid annulus. Fast retrograde ventriculoatrial conduction during tachycardia and extrastimulus testing confirmed the presence of a concealed right posteroseptal accessory pathway. Six radiofrequency catheter ablation applications were delivered, and tachycardia remained uninducible. The dog recovered well from the procedure. Sotalol was stopped three weeks later, and no more clinical signs were noted by the owner. Repeated 24-hour electrocardiography monitoring on day one and at one, three, and 12 months after the procedure showed no recurrence of tachycardia.

Comparison between conventional approach and three-dimensional mapping system in the catheter ablation of accessory pathway associated with coronary sinus diverticulum: A single-center experience.

Posteroseptal accessory pathways (APs) associated with coronary sinus (CS) diverticulum present a rare and challenge for ablation. This study aimed to compare the safety and efficacy of conventional approach and three-dimensional (3D) mapping system in the catheter ablation. This was a retrospective study of all patients (from January 2013 to July 2022) who underwent catheter ablation of posteroseptal AP associated with CS diverticula in our center. Patients who underwent catheter ablation using the traditional fluoroscopy method were included in the conventional method group (n = 13). Patients who underwent catheter ablation using the 3D mapping method were included in the 3D mapping group (n = 11). Clinical characteristics, ablation procedure, and outcomes were recorded and analyzed between the two groups. Out of 669 patients with posteroseptal APs, 24 of them (3.6%) were associated with CS diverticula. All patients in both groups successfully completed the electrophysiological study. In the conventional method group, two patients experienced complications (one patient with pericardial effusion and the other patient with femoral arterial hematoma), and two patients had recurrence. However, no patients suffered from complications or recurrence during follow-up. The procedure time and fluoroscopy time in the conventional method group were significantly longer than those in the 3D mapping method group. The utilization of 3D mapping led to reduced fluoroscopy time, shorter procedure duration, enhanced acute success rates, and decreased incidence of complications.

Coronary sinus ablations in pediatric patients with supraventricular arrhythmias.

Intracoronary sinus ablations have been performed for various arrhythmical substrates. The aim of this study is to report our experience on pediatric patients of the safety and efficacy of ablations in the coronary sinus. This is a retrospective study of all patients who underwent ablations in the coronary sinus from October 2013 to October 2021 at a single center. Clinical presentation, type of arrhythmia causing tachycardia, ablation procedure, and outcome were recorded. A total of 27 patients were included in the study. Nineteen (69%) of those followed up received a diagnosis of Wolff-Parkinson-White syndrome (WPW), 4 (15%) were cases of supraventricular tachycardia with concealed accessory pathway (AP), 2 (8%) were cases of focal atrial tachycardia, and 2 (8%) were cases of permanent junctional reciprocating tachycardia. Negative delta wave was noteworthy especially in lead II in 11/19 (58%) cases and coronary sinus diverticulum was detected in the WPW cases. Of those with manifest AP (19 cases), 15 (79%) had a high-risk AP and the AP in all WPW cases was adenosine unresponsive. Radiofrequency (RF) catheter ablation was performed in 25/27 (93%) cases during the procedure, and 16/25 (64%) of these were irrigated RF catheters. No complications were observed in the follow-up, including coronary artery injury. Catheter ablation of supraventricular tachyarrhythmias can be accomplished effectively and potentially safely within the coronary sinus. Coronary sinus diverticula should be suspected in patients with manifest posteroseptal APs who have a previous failed ablation and typical electrocardiographic signs.

Precordial reverse pattern break on ECG: could it be a discriminator endo/epicardial ablation site of left posteroseptal accessory pathways

Abstract Funding Acknowledgements Type of funding sources: None. Backrounds The posteroseptal (PS) region may pose difficulty in WPW ablation due to its complex anatomical structure. The posteroseptal region may require the need for a transeptal puncture, CS venogram or coronary angiography due to its right and left endocardial and epicardial proximity. ECG prediction may prevent unnecessary procedures. Negative V1 double QRS transition pattern in the precordial leads is highly specific and validated for a right endocardial AP Purpose To investigate the presence of a reverse pattern break in the left posteroseptal [V1 (+) V3 (+)] WPW patient and compare between endocardial-epicardial ablation localization. Methods We retrospectively included 338 WPW patients into the study. 97 of them successfully ablated with posteroseptal area. Results Thirty-two of the total PS patient (33%) patients had a reverse pattern break or double transition pattern. A total of 4 patients with the middle cardiac vein (MCV) and diverticulum origin were identified. The left pattern break predicts endocardial localization 75% of the time while the right pattern predicts it 95% of the time. Conclusion Double transition and reverse pattern break are common in posteroseptal AP’s ECG. Left reverse pattern break is also highly predictive of endocardial ablation, similar to the right.

Successful catheter ablation of the accessory pathway in an unusual location in a 13-year-old girl with a coronary sinus diverticulum and Wolff-Parkinson-White syndrome.

Wolff-Parkinson-White syndrome is a congenital cardiac pre-excitation syndrome that is effectively treated by ablating the accessory pathway. However, accessory pathways located in the posteroseptal region can sometimes be challenging. In this paper, we present the successful ablation of the epicardial posteroseptal accessory pathway through the middle cardiac vein in a 13-year-old girl with a coronary sinus diverticulum and Wolff-Parkinson-White syndrome, after unsuccessful ablation attempts at different locations. If the ablation procedure fails, the possibility of the posteroseptal pathway should be kept in mind, and coronary sinus angiography should be performed. In cases with a coronary sinus diverticulum where ablation is not successful, other coronary sinus structures, for example, the middle cardiac vein should be considered as potential accessory pathways.

PO-03-142 ABLATION OF EPICARDIAL POSTEROSEPTAL ACCESSORY PATHWAYS IN CHILDREN

Epicardial posteroseptal accessory pathways (Epi-PSAPs) within the coronary sinus (CS) are a rarely reported ablation target in children. They are often associated with abnormal CS anatomy as well as risk of coronary artery (CA) injury. To assess characteristics associated with successful outcome of Epi-PSAP ablation in children. Retrospective cohort study at a tertiary care institution including all patients aged ≤18 years who underwent ablation of Epi-PSAP from 2000-2022. Clinical/electrophysiological characteristics and outcomes were analyzed. Epi-PSAP was targeted in 19 patients. Mean age at procedure was 13.4 (12.1-14.7) years, mean weight was 62.5 (47-78) kg. Prior ablations had been attempted in 7/19 patients. Ventricular preexcitation was present in 12/19 (63%) patients, with steep negative delta wave in lead II in all cases, and 8/12 (67%) demonstrating high risk antegrade conduction. CS angiogram to define the anatomy was performed in all patients. In 5/5 (100%) of cases where CS diverticulum was identified by CS angiogram, it proved to be the ablation target. CA angiogram to define arterial proximity (5mm cutoff) was obtained in 17/19 (90%). CA system was right dominant in 10/17 (59%), and closest arteries were ≥5mm away from the target in 11/17 (65%). Primary energy was RF in 12/19 (63%, artery ≥5mm) and cryo in 7/19 (37%, artery <5mm). Ablation was acutely successful in 18/19 (95%) patients, chronically successful in 15/18 (83%) of patients, over 98.2 (57.8-138.7) months of follow up.There was no apparent difference in outcome between ablation sites in 1) coronary vein; 2) CS diverticulum; or 3) floor of CS (FIG1.A.). The presence of a sharp unipolar accessory pathway potential (FIG1.B.) at the target site was significantly associated with acute (p=0.003) and chronic (p=0.005) success. Choice of energy was not significantly associated with outcome. Performance of CS angiogram (FIG1.C) was significantly associated with acute (p=0.04) and chronic (p=0.03) success when all ablation attempts were analyzed. There was no incidence of major adverse events. Majority of Epi-PSAP in children are manifest with high risk antegrade conduction properties. They can be ablated with RF energy when the coronary arteries are ≥5mm from ablation target, or alternatively with cryoablation. Localizing a sharp unipolar AP potential, identification of CS anatomy by CS angiogram, and delineation of arterial proximity by CA angiogram are associated with successful ablation.

PO-05-147 RIGHT ON Q: WIDE-COMPLEX TACHYCARDIA IN SETTING OF DEXTROPOSITION

Dextroposition is a rare cardiac malformation defined as rightward cardiac displacement with leftward apex, vs. dextrocardia, which is rightward base-axis orientation. We report the second known case of dextroposition with accessory pathway, presenting as preexcited atrial tachycardia. Abnormal anatomy complicates ECG localization and pathway ablation. N/A N/A A 50-year-old woman was admitted with respiratory distress due to EBV infection. Chest X-ray showed right-sided heart. A month later, she presented in wide-complex tachycardia, rate 205 bpm. She was cardioverted after minimal response to procainamide/adenosine. Post-cardioversion ECG showed short PR interval and preexcitation, confirming presence of accessory pathway. However, the wide-complex tachycardia had morphology identical to baseline, supporting preexcited atrial tachycardia over AVRT. Despite X-ray findings and reverse R-wave progression in precordial leads, presence of left axis deviation and initial negative deflection in aVR argued against dextrocardia. Moreover, aVR had negative T- and P-waves, findings associated with levocardia. Thus, dextroposition was suspected. Millstein and Arruda criteria suggested posteroseptal accessory pathway, but no data on their applicability in right-sided heart exist. EP study was performed. Eccentric VA conduction was noted. Earliest activation was at proximal coronary sinus. During isoproterenol infusion, patient went into atrial tachycardia, cycle length 420ms. Multiple AT foci were identified, including at right atrial appendage and tricuspid annulus. During ablation, patient developed atrial fibrillation with preexcited RR <250ms, confirming high-risk accessory pathway. Given numerous AT foci and high risk, it was decided to focus on pathway over tachycardia sites. Pathway was successfully ablated at ostia of coronary sinus and middle cardiac vein. One prior case of accessory pathway ablation in dextroposition has been reported. This patient had left lateral pathway and multiple congenital abnormalities including lung hypoplasia. While our patient was found to have multifocal atrial tachycardia, she had no clinical or radiographic lung disease. ECG changes in dextroposition are less predictable than in dextrocardia; they vary with cardiac rotation, axis position, and lead position. Comorbid accessory pathway is rare; ECG-anatomy relationship is ill-defined. Structural abnormalities pose individual challenges during electrophysiologic procedures.

Transjugular approach for a difficult posteroseptal accessory pathway

Transjugular approach for a difficult posteroseptal accessory pathway

Posteroseptal Accessory Pathway Ablation Via a Left Superior Vena Cava and Retrograde Coronary Sinus Approach

Posteroseptal Accessory Pathway Ablation Via a Left Superior Vena Cava and Retrograde Coronary Sinus Approach

Accessory pathways in monozygotic twins with different clinical phenotypes: a case report

BackgroundThe atrioventricular reentrant tachycardia (AVRT) is the most common tachycardia associated with accessory pathways (APs). Although sporadic Wolff-Parkinson-White (WPW) syndrome has been well-described, AP occurrence in identical twins with WPW syndrome remains rarely reported.Case presentationWe report a case of 14-year-old monozygotic twin brothers referred for an electrophysiology (EP) study. Twin A presented with recurrent symptomatic narrow complex tachycardia after exercise, noted for 3 years. His 12-lead surface electrocardiogram (ECG) did not show ventricular pre-excitation. However, an orthodromic AVRT utilizing a concealed right posteroseptal AP was found and successfully ablated. AVRT did not recur 12 months after the procedure. Twin B was asymptomatic. During his medical examination for firefighter volunteerism, his 12-lead ECG showed a spontaneous ventricular pre-excitation. EP study revealed a short anterograde right midseptal AP, which was then successfully eliminated by catheter ablation. His 12-lead ECG showed no ventricular pre-excitation recurrence 12 months after the procedure.ConclusionsThese identical twin brothers had a right-side AP in almost the same place but showed completely different phenotypes. This case clearly illustrates the difficulty in understanding genetic contribution in the origin of atrioventricular APs. Environmental exposure could play a role in their clinical presentations and AP electrophysiological properties.

Electrocardiographic patterns of ventricular pre-excitation in dogs with right-sided accessory pathways.

The aim of the study was to describe the electrocardiographic features of ventricular pre-excitation (VPE) patterns characterized by the presence of delta (δ) wave, short P-δQRS interval, wide δQRS complexes in dogs with right-sided accessory pathways. Twenty-six dogs with a confirmed accessory pathways (AP) via electrophysiological mapping were included. All dogs underwent a complete physical examination, 12-lead ECG, thoracic radiography, echocardiographic examination and electrophysiologic mapping. The AP were located in the following regions: right anterior, right posteroseptal, right posterior. The following parameters were determined: P-δQRS interval, δQRS duration, δQRS axis, δQRS morphology, δ-wave polarity, Q-wave, R-wave, R'-wave, S-wave amplitude, and R/S ratio. In lead II, the median δQRS complex duration was 82.4 (IQR 7.2) and the median P-δQRS interval duration was 54.6 (IQR 4.2) msec. The median δQRS complex axis in the frontal plane was: + 68° (IQR 52.5) for right anterior APs, - 24 ° (IQR 24) for right postero-septal APs, - 43.5 ° (IQR 27.25) for right posterior APs (P = 0.007). In lead II, the polarity of the δ wave was positive in 5/5 right anterior APs and negative in 7/11 postero-septal APs and 8/10 in right posterior APs. In precordial leads of all dogs, R/S was ≤ 1 in V1 and > 1 in all leads from V2 to V6. Surface electrocardiogram can be used to distinguish right anterior APs from right posterior and right postero-septal ahead of an invasive electrophysiological study.

A Single-lead ECG algorithm to differentiate right from left manifest accessory pathways: A reappraisal of the P-Delta interval.

Despite numerous ECG algorithms being developed to localize the site of manifest accessory pathways (AP), they often require stepwise multiple-lead analysis with variable accuracy, limitations, and reproducibility. The study aimed to develop a single-lead ECG algorithm incorporating the P-Delta interval (PDI) as an adjunct criterion to discriminate between right and left manifest AP. Consecutive WPW patients undergoing electrophysiological study (EPS) were retrospectively recruited and split into a derivation and validation group (1:1 ratio). Sinus rhythm ECG analysis in lead V1 was performed by three independent investigators blinded to the EPS results. Conventional ECG parameters and PDI were assessed through the global cohort. A total of 140 WPW patients were included (70 for each group). A score-based, single-lead ECG algorithm was developed through derivation analysis incorporating the PDI, R/S ratio, and QRS onset polarity in lead V1. The validation group analysis confirmed the proposed algorithm's high accuracy (95%), which was superior to the previous ones in predicting the AP side (p < 0.05). A score of ≤+1 was 96.5% accurate in predicting right AP while a score of ≥+2 was 92.5% accurate in predicting left AP. The new algorithm maintained optimal performance in specific subgroups of the global cohort showing an accuracy rate of 90%, 92%, and 96% in minimal pre-excitation, posteroseptal AP, and pediatric patients, respectively. A novel single-lead ECG algorithm incorporating the PDI interval with previous conventional criteria showed high accuracy in differentiating right from left manifest AP comprising pediatric and minimal pre-excitation subgroups in the current study.

PS-R02-9: A PATIENT HAS THE ONLY CONNECTION BETWEEN THE ATRIUM AND VENTRICLE IS AN ACCESSORY PATHWAY

Case report: A 62-year-old woman without cardiovascular risk factors such as hypertension, diabetes, smoking and hyperlipidemia was admitted to our cardiology outpatient clinic with palpitations and syncope history. Her electrocardiography showed preexcitation possible posteroseptal accessory pathway. We performed electrophysiological study and found posteroseptal accessory pathway. Tachycardia was not induced in inductions. ERP detected below 240 msn. The area where the shortest V-A interval was detected. His signal was not detected in this region. We determined that it was anatomically far from the AV node. We started radiofrequency ablation and in the 5. second of ablation, we saw that the patient entered 3. degree AV block. Ablation was immediately stopped then sinus rhythm restored in patients qucikly. We search his signal with ablation catheter in right atrium but could not find the signal. We detected that the AV block and accessory pathway were found together in the patient. Since the patient had a history of syncope and ERP &lt; 250 ms was detected, we planned ablation after pacemaker implantation in the patient. We implant DDDR pacemaker and 2 weeks later we make successfully accessory pathway ablation. Discussion: In these patients, atrioventricular conduction is done only, and entirely, via the accessory route. A complete block, nodal or sub-Hissian, underlying, will only be visible on the ECG if there is concomitant blockage of the atrioventricular conduction through the accessory pathway. The appearance of atrioventricular conductive disorders after radiofrequency ablation of an accessory pathway, located at a distance from the atrioventricular junction, is not considered by some authors to be a real complication of this procedure. It would rather be a prior conductive disorder having been unmasked following the blockage of the accessory pathway thanks to ablation. It is therefore logical to review the indication for the removal of the accessory pathway in these cases, especially in asymptomatic patients who have never reported a history of palpitation attacks. The only possible tachycardia remains atrial fibrillation on WPW. Only the study of anterograde refractory periods makes it possible to specify the correct indication for ablative treatment. The indication for the implantation of a pacemaker is still appropriate given the risk of progressive and subsequent degeneration of the accessory pathway. In addition, conduction via the accessory pathway, whether continuous or intermittent, would help prolong the longevity of the pacemaker by inhibiting ventricular pacing in the event of atrioventricular conduction through the accessory pathway.

953 KEY ROLE OF GENETIC ANALYSIS IN A FAMILIAR CASE OF HYPERTROPHIC CARDIAC PHENOTYPE AND VENTRICULAR PREEXCITATION RELATED TO PRKAG2 GENE MUTATION

Abstract A 38-year-old male patient (A2) was referred to our ambulatory for paroxysmal atrial fibrillation in young age and ventricular preexcitation. Echocardiographic evaluation showed left ventricle hypertrophy (localized particularly at inter-ventricular septum (SIV) and normal LV ejection fraction. He also had a positive family history of hypertrophic cardiomyopathy since the latter was already diagnosed with the maternal grandmother (M0), the mother (M1) and the two brothers (A1 and A3). His father was apparently healthy (P1- consanguineous third degree of the mother M1). Specifically, the mother (M1) was suffering from non-obstructive hypertrophic cardiomyopathy, and tachy-brady (paroxysmal atrial flutter, sinus arrest) syndrome requiring pacemaker implantation. The firstborn (A1) was affected by paroxysmal atrial fibrillation, ventricular prexcitation and mild hypertrophy of the interventricular septum (SIV). The third child (A3) had a diagnosis of hypertrophic cardiomyopathy and a history of successfully ablation of a left postero-septal accessory pathway. A3 suffered also by paroxysmal typical atrial common flutter. Genetic analysis of the proband A2 confirmed a heterozygous pathological mutation of the PRKAG2 gene. Thus, genetic analysis was extended to the other two brothers A1 and A3 and the mother. We proposed to the all three brothers electrophysiological study in order to assess arrhythmic substrate and appropriate therapy (strict FUP, PM or ICD implantation). Mutation of the PRKAG2 gene is a rare disease, classified as non-lysosomal cardiac glycogenosis with clinical onset in late adolescence or in the third decade of life and presents an autosomal dominant inheritance with complete penetrance. It is associated with cardiac arrhythmias, such as ventricular preexcitation (Wolff-Parkinson-White syndrome), sinus node disease, atrioventricular block, atrial fibrillation. Genetic analysis has a crucial role especially in the evaluation of inheritance with autosomal dominant transmission and regarding the prognostic impact, since PRKAG2 gene mutation involved a greater arrhythmic risk comparing with other subtypes of hypertrophic cardiomyopathy. Affected patients should be closely monitored to facilitate early detection of arrhythmia and conduction problems. PRKAG2 mutation should be considered in patients with LVH who develop AF or require permanent pacemakers at a young age. Early recognition is important to allow prompt identification and appropriate management of genetic carriers.

Abstract 14513: An Aberrant Friend - Using Bundle Branch Block for Septal Accessory Pathway Localization

Introduction: While changes in the ventriculoatrial (VA) time with RBBB or LBBB during ORT utilizing a free wall accessory pathway (AP) is well described, such a change in VA time can also be helpful in identifying the location of a septal AP. Objectives: To demonstrate the effect of RBBB and LBBB aberrancy on the VA time for ORT involving septal AP and thereby assist in identifying a posteroseptal AP. Results: A 51-year-old man with WPW syndrome was referred for EP study and ablation due to palpitations. With programmed atrial extrastimulation, an atypical echo beat was noted. While attempting to induce tachycardia, double atrial extrastimuli resulted in non-sustained ORT both with RBBB and LBBB aberrancies (Figure). Measurement of the VA time during non-sustained ORT demonstrated a VA time that was longer in the presence of LBBB aberrancy (110ms) than RBBB aberrancy (97ms) compared to narrow QRS (95ms). Electroanatomic mapping identified the earliest atrial activation of the echo beat on the right posteroseptum. Radiofrequency ablation at this site resulted in immediate loss of ventricular pre-excitation. Conclusions: Changes in the VA interval during AP-mediated SVT are especially important for pathway localization. As demonstrated in prior studies, for free wall APs, the difference between sinus and bundle branch block time (ΔVA) is usually &gt;35ms compared to &lt;35ms for septal APs. Furthermore, studies described that for septal APs, posteroseptal APs have a greater VA time with LBBB, anteroseptal APs with RBBB and no significant change in VA time with midseptal APs. By demonstrating both RBBB and LBBB aberrancy in this patient, this case uniquely validates the concept that the VA time with LBBB aberrancy is greater with posteroseptal APs.

Precordial reverse pattern break: A predictor of posteroseptal accessory pathways ablatable from the proximal coronary sinus.

Posteroseptal accessory pathways (PSAPs) occasionally may lie within the coronary sinus (CS) or its tributaries, in a CS diverticulum, or along the epicardial surface. Catheter ablation is challenging in this subset of patients.1 Certain electrocardiographic (ECG) characteristics have been described in patients with proximal coronary sinus (PCS)-related PSAPs.1,2 We encountered precordial