Combined endo- and epicardial pace-mapping to localize ventricular tachycardia isthmus in ischaemic and non-ischaemic cardiomyopathy.

AIMS: A high-density pace-mapping can depict an abrupt transition in paced QRS morphology from a poor to excellent match, unmasking the critical component of ventricular tachycardia (VT) isthmus from the entrance to exit. We sought to assess pace-mapping at multiple sites within the endo- and epicardial scars to identify the VT isthmus in patients with ischaemic (ICM) and non-ischaemic cardiomyopathy (NICM). METHODS AND RESULTS: Colour-coded maps correlating to the percentage matches between 12-lead electrocardiograms during VT and pace-mapping [referred to as correlation score maps (CSMs)] were analysed. We studied 115 CSMs (80 endo- and 35 epicardial CSMs) in 37 patients (17 ICM, 20 NICM). The CSM with an abrupt change (AC) in pacemap score (AC-type) on the endocardium was more frequently observed in ICM than in NICM [11/39 (28%) vs. 1/41 (2%); P = 0.001]. Among 35 CSMs that were analysed by the combined endo- and epicardial mapping, 10 (29%) CSMs exhibited non-AC-type on the endocardium; however, AC-type was present on the opposite epicardium. Although 24 (69%) CSMs did not show AC-type on both the endocardium and epicardium, 16 of them had either an excellent (>90%) or poor (<0%) correlation score on either side, associated with isthmus exit or entrance, respectively. However, the remaining eight CSMs had neither excellent nor poor scores. CONCLUSION: The CSM may provide electrophysiological information to localize the endo- and epicardial VT isthmus. The absence of AC-type CSM on the endocardium, which is frequently observed in NICM, appears to indicate the sub-epicardial or intramural course of the critical isthmus.

Closed-loop stimulation as a physiological rate-modulated pacing approach based on intracardiac impedance to lower the atrial tachyarrhythmia burden in patients with sinus node dysfunction and atrial fibrillation.

INTRODUCTION: The effectiveness of rate-modulated pacing for the suppression of atrial fibrillation (AF) is controversial. Closed-loop stimulation (CLS) is a heart rate modulation technique based on the contractility of the right ventricle estimated by sensing myocardial impedance, and CLS can still adapt to the heart rate in conditions where there are no significant changes in acceleration or ventilation, such as emotional stress. We elucidated the association between CLS and atrial tachyarrhythmia (AT) burden in patients with sinus node dysfunction and paroxysmal AF history before pacemaker implantation. METHODS AND RESULTS: We retrospectively reviewed all consecutive patients who underwent pacemaker implantation for sinus node dysfunction with an AF history before implantation. Overall, 146 patients were analyzed, with fixed-rate pacing (FP) in 82, CLS in 31, and non-CLS rate modulation in 33 patients. The AF/AT episodes were detected in 98 patients during a 12-month period. The median AF/AT burden was 1.6% (interquartile: 0.0%, 11.0%) in FP; 0% (0.0%, 2.5%) in CLS, and 1.0% (0.1%, 9.3%) in non-CLS. The AF/AT burden was significantly lower for CLS than for FP and non-CLS rate modulation (P < .01 and P = .04, respectively). CLS was associated with lower risks of AF/AT occurrence (hazard ratio [HR], 0.31; P = .02) and AF/AT burden more than 5% (HR, 0.28; P = .05), even after adjusting for potential confounders. This association was independent of the percentage of atrial pacing. CONCLUSION: CLS was associated with lower AF/AT burden after pacemaker implantation in patients with sinus node dysfunction and AF history.

J Waves Are Associated With the Increased Occurrence of Life-Threatening Ventricular Tachyarrhythmia in Patients With Nonischemic Cardiomyopathy.

INTRODUCTION: Recent studies showed that J waves were associated with higher incidence of ventricular tachyarrhythmia (VT/VF) in patients with idiopathic ventricular fibrillation (VF) and myocardial infarction. We sought to assess the association between J waves and VT/VF in patients with nonischemic cardiomyopathy (NICM). METHODS AND RESULTS: We retrospectively enrolled 109 patients (79 men; mean age, 60 ± 15 years) with NICM who underwent implantable cardioverter defibrillator (ICD) implantation. The primary endpoint of this study was the occurrence of appropriate device therapy due to sustained VT/VF. The J wave was electrocardiographically defined as an elevation of the terminal portion of the QRS complex of >0.1 mV in at least 2 contiguous inferior or lateral leads. Among the 109 patients, 37 (34%) experienced an episode of appropriate device therapy during a median follow-up period of 25.9 (IQR 11.5-54.3) months. Kaplan-Meier curves showed that the presence of J waves on the 12-lead ECG obtained before device implantation was associated with an increased occurrence of appropriate device therapy (P < 0.001). Multivariate Cox proportional regression analysis revealed that the presence of J waves (HR 2.95; 95% CI 1.31-6.64; P = 0.009) was an independent predictor for the occurrence of appropriate device therapy. In the subgroup analysis of the patients with dilated or hypertrophic cardiomyopathy, J wave tended to increase the occurrence of appropriate device therapy (P = 0.056 and P = 0.092, respectively). CONCLUSIONS: The presence of J waves was an independent predictor for the occurrence of appropriate device therapy in patients with NICM who underwent ICD implantation.

Positive QRS complex in lead i as a malignant sign in right ventricular outflow tract tachycardia: comparison between polymorphic and monomorphic ventricular tachycardia.

BACKGROUND: Idiopathic ventricular fibrillation (VF) or polymorphic ventricular tachycardia (PVT) arising from the right ventricular outflow tract (RVOT) is occasionally observed. The difference in the initial ventricular premature contraction (VPC) between VF/PVT and monomorphic VT (MVT) from the RVOT, however, has not yet been fully investigated. METHODS AND RESULTS: The electrocardiogram findings and the clinical characteristics were compared between 14 patients with PVT and 77 with MVT. The episodes of syncope were more frequent in the VF and/or PVT group (57%) than in the MVT group (10%). An initial VPC with a positive QRS complex in lead I was observed in 10 (71%) of 14 patients with VF/PVT, and in 27 (35%) of 77 patients with MVT (P<0.05). Although radiofrequency (RF) catheter ablation targeting the trigger VPC often produced a morphological change, VF/PVT was eliminated in 13 (93%) of 14 patients after additional RF applications. CONCLUSIONS: Malignant arrhythmias from the RVOT, although rare, should be considered when the patient has a syncopal episode and VPC with a positive QRS complex in lead I.

[Open heart surgery using cardiopulmonary bypass in a patient with heparin-induced thrombocytopenia(HIT)].

Heparin-induced thrombocytopenia (HIT) is a life-threatening side effect of heparin therapy. We report an open heart surgery with cardiopulmonary bypass( CPB) using argatroban as an anticoagulant for a patient with HIT. A 72-year-old male with a history of percutaneous coronary intervention 5 years ago, was admitted to our hospital due to congestive heart failure and heparin 10,000 units/day was administered. At 10th hospital day, his platelet count was significantly decreased and antibodies positive for type II HIT was found, so he was diagnosed HIT. Echocardiogram and coronary angiography revealed severe functional mitral regurgitation and coronary stenosis. At 24th hospital day we performed coronary artery bypass grafting( CABG) and mitral valve replacement (MVR) with CPB using argatroban as an anticoagulant. During CPB, we monitored the activated clotting time (ACT) to adjust the dose of argatroban. Though the surgical procedure itself was uneventful. We required about 4 hours to achieve adequate hemostasis after CPB. Postoperative course was uneventful.

Electrocardiographic determinants of the polymorphic QRS morphology in idiopathic right ventricular outflow tract tachycardia.

INTRODUCTION: Premature ventricular contractions (PVCs) arising from the right ventricular outflow tract (RVOT) can trigger polymorphic ventricular tachycardia (PVT) or ventricular fibrillation (VF) in patients with no structural heart disease. We aimed to clarify the ECG determinants of the polymorphic QRS morphology in idiopathic RVOT PVT/VF. METHODS AND RESULTS: The ECG parameters were compared between 18 patients with idiopathic PVT/VF (PVT-group) and 21 with monomorphic VT arising from the RVOT (MVT-group). The coupling interval (CI) of the first VT beat was comparable between the 2 groups. However, the prematurity index (PI) of the first VT beat was smaller in the PVT-group than in the MVT-group (P < 0.001). Furthermore, the QT index, defined as the ratio of the CI to the QT interval of the preceding sinus complex, was also smaller for the PVT/VF in the PVT-group than that for the VT in the MVT-group (P < 0.01). In the PVT-group, the CI of the first VT beat was comparable between that of VT and isolated PVCs, but the PI of the first VT beat was shorter for VT than isolated PVCs (P < 0.05). The PI was the only independent determinant of the polymorphic QRS morphology (odd ratio = 2.198; 95% confidence interval = 1.321-3.659; P = 0.002). CONCLUSION: The smaller PIs of the first VT beat may result in a polymorphic QRS morphology.

Acute and long-term results of bipolar radiofrequency catheter ablation of refractory ventricular arrhythmias of deep intramural origin.

BACKGROUND: Successful bipolar radiofrequency catheter ablation (RFCA) of refractory ventricular arrhythmias (VAs) has been reported. However, the efficacy, safety, and long-term outcomes of bipolar RFCA of VAs are not fully determined. OBJECTIVE: The purpose of this study was to evaluate the effectiveness and safety of bipolar RFCA in treating refractory VAs during long-term follow-up. METHODS: Eighteen patients who underwent bipolar RFCA for ventricular tachycardia (VT) at 7 institutions were retrospectively investigated. Underlying heart diseases included remote myocardial infarction (n = 3 [17%]) and nonischemic cardiomyopathy (n = 15 [83%]). Although unipolar RFCA was performed in all patients, either it failed to suppress VT or VT recurred. The interventricular septum, left ventricular free wall, and left ventricular summit were targeted for bipolar RFCA. RESULTS: Acute success (VT termination and/or noninducibility) was achieved with bipolar RFCA in 16 patients (89%). Complications during the procedure included complete atrioventricular block (n = 2) and coronary artery stenosis (n = 1). One patient underwent chemical ablation after bipolar RFCA failure. At 12-month follow-up, VT reoccurred in 8 patients (44%). However, in patients with recurrence, VT burden had decreased: only 4 patients underwent re-RFCA, and only 1 of the 4 required chemical ablation. In the remaining 4 patients, re-RFCA was not required, as VT was controlled by medication or an implantable cardioverter-defibrillator. CONCLUSION: Bipolar RFCA is useful for acute suppression of refractory VT. Although VT recurrence rates during long-term follow-up were relatively high, we observed a significant reduction in VT burden.

Automated template matching to pinpoint the origin of right ventricular outflow tract tachycardia.

BACKGROUND: Template matching, a technique that examines the similarity between two QRS complexes, has not been broadly applied clinically. METHODS: The 16 patients enrolled in this study underwent radiofrequency catheter ablation (RFCA) at the site of five ventricular tachycardias (VT) and of premature ventricular contractions (PVC) arising from 25 sites in the right ventricular outflow tract (RVOT), under the guidance of conventional pace and activation mapping. After RFCA, (a) a template-matching score using a correlation coefficient, and (b) a pace-map score were calculated at 30 successful and 48 unsuccessful ablation sites. RESULTS: The template-matching score at successful ablation sites (94 +/- 4%) was significantly higher than at unsuccessful (85 +/- 9%) ablation sites (P < 0.001). A > or = 90% average matching score identified successful ablation sites with a sensitivity of 90% and specificity of 69%. While there was a significant correlation between the template-matching score and visually judged pace-map score (r = 0.63, P < 0.0001), the area under the receiver operating characteristic curve of the template matching score was larger than that of the pace-map score (0.80 vs. 0.67). CONCLUSIONS: Automated template matching was useful for localizing the optimal ablation site during RFCA of RVOT-VT/PVC.

Prognostic impact of lead tip position confirmed via computed tomography in patients with right ventricular septal pacing.

BACKGROUND: Although fluoroscopy-guided right ventricular (RV) lead placement in the ventricular septum is a widely performed procedure, variation in true RV lead tip position confirmed via computed tomography (CT) and its prognostic implications in patients with atrioventricular block (AVB) are not well understood. OBJECTIVE: The purpose of this study was to evaluate the prognostic impact of CT-confirmed RV lead tip position. METHODS: We retrospectively enrolled 228 consecutive patients (age 77 ± 10 years; 125 men) with AVB who underwent fluoroscopy-guided RV septal lead implantation and thoracic CT after pacemaker implantation. Patients were classified into septal and free-wall groups according to RV lead tip position. The primary endpoint was the composite outcome of cardiac death and heart failure hospitalization. RESULTS: The RV lead tip was located at the free wall in 18 patients (8%). The primary endpoint occurred in 37 patients (16%) over median follow-up of 41 months. Electrocardiographic analysis found that R amplitude >0.53 mV in lead I was significantly predictive of free-wall pacing, with sensitivity of 70% and specificity of 77%. Multivariate Cox regression analysis demonstrated that the lead tip in the free wall (hazard ratio 2.93; 95% confidence interval 1.21-7.11; P = .018) was an independent predictor of the primary endpoint. CONCLUSION: Fluoroscopy-guided RV lead placement carries potential risk of unexpected RV free-wall pacing and may increase the risk of cardiac death and heart failure-related hospitalization in patients undergoing RV septal pacing due to AVB and receiving thoracic CT for medical reasons.

Effect of cardiac resynchronization therapy in isolated ventricular noncompaction in adults: follow-up of four cases.

BACKGROUND: An isolated ventricular noncompaction (IVNC) is an unclassified cardiomyopathy and, despite the increasing awareness of and interest in this disorder, the role of cardiac resynchronization therapy (CRT) remains obscure. OBJECTIVE: The purpose of this study was to clarify the long-term effect of CRT on IVNC in adult patients. METHODS: Four cases of IVNC were included in this study. Before the CRT device was implanted, all four patients (54 +/- 16-year-old, 4 males) presented with symptomatic congestive heart failure. Echocardiography revealed their systolic dysfunction and their left ventricular ejection fraction (LVEF) was 21 +/- 8%. There was also mechanical dyssynchrony observed between the LV septum and free wall area. The QRS duration was "narrow" (112 and 120 ms) in two patients. One patient had been resuscitated from ventricular fibrillation (VF) and two had nonsustained ventricular tachycardia (VT). A CRT defibrillator (CRT-D) was implanted in three patients with VT/VF and a CRT pacemaker (CRT-P) in a patient without VT/VF. The LV lead was positioned in a lateral branch of the coronary sinus where a thickened noncompacted wall existed. RESULTS: During the follow-up period (28 +/- 23 months), their congestive heart failure had improved in terms of the cardiothoracic ratio on the chest X-ray, B-type natriuretic peptide level, LV systolic dimension, and LVEF. No episodes of defibrillation shocks were observed. CONCLUSION: CRT may improve the prognosis and quality-of-life in patients with an IVNC with mechanical dyssynchrony.

Changes in the isolated delayed component as an endpoint of catheter ablation in arrhythmogenic right ventricular cardiomyopathy: predictor for long-term success.

INTRODUCTION: Although successful ablation of ventricular tachycardia (VT) is feasible in arrhythmogenic right ventricular cardiomyopathy (ARVC), long-term recurrence is common. The aim of this study was to assess the usefulness of a change in the isolated delayed component (IDC) as an endpoint of the catheter ablation in ARVC. METHODS AND RESULTS: Eighteen patients (48 +/- 11 years) with ARVC were studied. Detailed endocardial mapping of the right ventricle (RV) was performed during sinus rhythm. IDCs were recorded in 16 patients and the latest IDCs were related to the VT circuit. Catheter ablation was carried out in the areas with the IDCs. At the end of the session, the IDC was electrically dissociated in one, disappeared in five, exhibited second-degree block in one, was significantly delayed (>or=50 ms) in three, and remained unchanged in six. The change in the IDC was correlated with the change in the type II/III late potentials in the signal-averaged electrocardiography (ECG) and the inducibility of the clinical VT after the ablation. During a follow-up of 61 +/- 38 months, VT recurred in six. The patients with a changed IDC had a significantly lower VT recurrence than those with no IDC or an unchanged IDC (P < 0.02). CONCLUSION: In patients with ARVC, (1) the IDCs during sinus rhythm are related to the clinical VT and can be a target for the ablation, (2) a change in the IDC can be used as an endpoint, and (3) qualitative analyses of the serial signal-averaged ECGs may be useful for the long-term follow-up.

Idiopathic ventricular arrhythmias arising from the pulmonary artery: prevalence, characteristics, and topography of the arrhythmia origin.

BACKGROUND: The characteristics of idiopathic ventricular tachycardias (VTs) or idiopathic premature ventricular contractions (PVCs) arising from the pulmonary artery (PA) have not been sufficiently clarified. OBJECTIVE: The purpose of this study was to clarify the prevalence, characteristics, and preferential sites of idiopathic VT/PVCs arising from the PA (PA-VT/PVCs). METHODS: Data obtained from 276 patients with idiopathic VT/PVCs who underwent radiofrequency (RF) catheter ablation were analyzed. RESULTS: Twelve VT/PVCs (4%) were PA-VT/PVCs, and their onset (34 +/- 14 years) was the youngest among all subgroups. Because those QRS morphologies were similar to VT/PVCs arising from the right ventricular outflow tract (RVOT-VT/PVC) and the earliest ventricular activation was from the RVOT, an initial ablation was performed in the RVOT in all patients. However, RF catheter ablation at the RVOT resulted in a QRS morphology change in all patients, so thereafter PA mapping and ablation was performed. A characteristic potential during sinus rhythm and/or the arrhythmia was recorded at the successful PA ablation site in all patients. A perfect or good pace map was obtained in 7 (70%) of 10 patients. The successful ablation site was the septal side of the PA close to the posterolateral attachment in 9 patients (75%) and the septal side close to the anterior attachment in the remaining 3 (25%). No PA-VT/PVCs recurred during follow-up of 27 +/- 13 months. CONCLUSION: PA-VT/PVCs should always be considered when the ECG suggests RVOT-VT/PVCs and RF catheter ablation in the RVOT results in both a failed ablation and a change in QRS morphology. PA-VT/PVCs often originate from the septal side of the PA.

New Substrate-Guided Method of Predicting Slow Conducting Isthmuses of Ventricular Tachycardia: Preliminary Analysis to the Combined Use of Voltage Limit Adjustment and Fast-Fourier Transform Analysis.

BACKGROUND: Several conducting channels of ventricular tachycardia (VT) can be identified using voltage limit adjustment (VLA) of substrate mapping. However, the sensitivity or specificity to predict a VT isthmus is not high by using VLA alone. This study aimed to evaluate the efficacy of the combined use of VLA and fast-Fourier transform analysis to predict VT isthmuses. METHODS AND RESULTS: VLA and fast-Fourier transform analyses of local ventricular bipolar electrograms during sinus rhythm were performed in 9 postinfarction patients who underwent catheter ablation for a total of 13 monomorphic VTs. Relatively higher voltage areas on an electroanatomical map were defined as high voltage channels (HVCs), and relatively higher fast-Fourier transform areas were defined as high-frequency channels (HFCs). HVCs were classified into full or partial HVCs (the entire or >30% of HVC can be detectable, respectively). Twelve full HVCs were identified in 7 of 9 patients. HFCs were located on 7 of 12 full HVCs. Five VT isthmuses (71%) were included in the 7 full HVC+/HFC+ sites, whereas no VT isthmus was found in the 5 full HVC+/HFC- sites. HFCs were identical to 9 of 16 partial HVCs. Eight VT isthmuses (89%) were included in the 9 partial HVC+/HFC+ sites, whereas no VT isthmus was found in the 7 partial HVC+/HFC- sites. All HVC+/HFC+ sites predicted VT isthmus with a sensitivity of 100% and a specificity of 80%. CONCLUSIONS: Combined use of VLA and fast-Fourier transform analysis may be a useful method to detect VT isthmuses.

Radiofrequency Catheter Ablation of Ventricular Tachycardia in Patients With Hypertrophic Cardiomyopathy and Apical Aneurysm.

OBJECTIVES: This study evaluated the characteristics and results of radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) in patients with hypertrophic cardiomyopathy (HCM) and left ventricular apical aneurysm (AA). BACKGROUND: Monomorphic VT in patients with HCM and left ventricular AA has been reported. However, outcome data of RFCA are insufficient. METHODS: Fifteen patients with HCM and AA who underwent RFCA for VT at 5 different institutions were included in this study. The data were evaluated retrospectively. RESULTS: Endocardial voltage mapping showed a low-voltage area (LVA), and late potential in the AA was recorded in 12 patients (80%). Although epicardial or intramural origin of VT was suspected in 7 patients, endocardial RFCA successfully suppressed the VT at the LVA border (n = 10) or within the LVA (n = 2). In 2 of 3 patients without LVA at the endocardial site, linear RFCA at the anterior wall of the aneurysmal neck side was successful. In the remaining patient, endocardial RFCA of AA was not effective, and epicardial RFCA site was needed. In all patients, clinical VT became noninducible after RFCA. VT recurrence was observed in 2 patients (13.3%) during the 12-month follow-up period. One patient underwent a second endocardial RFCA, and no VT recurrence was noted. In the other patient, VT recurred 3 months after RFCA and was successfully terminated by antitachycardia pacing of the implantable cardioverter-defibrillator. CONCLUSIONS: In patients with HCM and AA, endocardial RFCA of AA effectively suppressed monomorphic VT which was related to AA and resulted in satisfactory outcomes.

Efficacy of Endocardial Ablation of Drug-Resistant Ventricular Fibrillation in Brugada Syndrome: Long-Term Outcome.

Background Both endocardial trigger elimination and epicardial substrate modification are effective in treating ventricular fibrillation (VF) in Brugada syndrome. However, the primary approach and the characteristics of patients who respond to endocardial ablation remain unknown. Methods Among 123 symptomatic Brugada syndrome patients (VF, 63%; syncope, 37%), ablation was performed in 21 VF/electrical storm patients, the majority of whom were resistant to antiarrhythmic drugs. Results Careful endocardial mapping revealed that 81% of the patients had no specific findings, whereas 19% of the patients, who experienced the most frequent VF episodes with notching of the QRS in lead V1, had delayed low-voltage fractionated endocardial electrograms. Ablation of VF triggers followed by endocardial substrate modification was performed in the right ventricular outflow tract in 85% of the cases and in the right ventricle in 15%. VF triggers could not be completely eliminated in 1 patient and VF became noninducible in 14 (88%) patients among 16 patients who underwent VF induction with normalization of Brugada-type ECG in 3. During follow-up (56.14±36.95 months), VF recurrence was observed in 7 patients. Importantly, all patients who had nothing of QRS in lead V1 did not respond to endocardial ablation despite presence of VF-triggering ectopic beats during ablation. Conclusions With careful documentation of VF-triggering ectopic beats and detailed endocardial mapping, endocardial VF trigger elimination followed by endocardial substrate modification has an excellent long-term outcome, whereas presence of QRS notching in lead V1 was associated with high VF recurrence suggesting epicardial substrate ablation as effective initial approach.

Fascicular Ventricular Tachycardia Originating From Papillary Muscles: Purkinje Network Involvement in the Reentrant Circuit.

BACKGROUND: Verapamil-sensitive fascicular ventricular tachycardia (FVT) has been demonstrated to be a reentrant mechanism using the Purkinje network as a part of its reentrant circuit. Although the papillary muscles (PMs) are implicated in arrhythmogenic structure, reentrant FVT originating from the PMs has not been well defined. METHODS AND RESULTS: We studied 13 patients in whom FVT was successfully eliminated by ablation at the posterior PMs (n=8; PPM-FVT) and anterior PMs (n=5; APM-FVT). Although intravenous administration of verapamil (5 mg) terminated ventricular tachycardia (VT) in 6 patients, VT was only slowed in the remaining 7 patients. PPM-FVT exhibited right bundle branch block and superior right axis (extreme right axis) or horizontal axis deviation. APM-FVT exhibited right bundle branch block configuration and right axis deviation with deep S wave in leads I, V5, and V6. VT was reproducibly induced by programmed atrial or ventricular stimulation. His-ventricular interval during VT was shorter than that during sinus rhythm. Ablation at the left posterior or anterior fascicular regions often changed the QRS morphology but did not completely eliminate it. Mid-diastolic Purkinje potentials were recorded during VT around the PMs, where ablation successfully eliminated the tachycardia. All patients have been free from recurrent VT after ablation. CONCLUSIONS: Reentrant circuit of verapamil-sensitive FVT can involve the Purkinje network lying around the PMs. PM-FVT is a distinct entity that is characterized by distinctive electrocardiographic characteristics and less sensitivity to verapamil administration compared with common type FVT. Ablation targeting the mid-diastolic Purkinje potentials around the PMs during tachycardia can be effective in suppressing this arrhythmia.

Idiopathic ventricular arrhythmia arising from the mitral annulus: a distinct subgroup of idiopathic ventricular arrhythmias.

OBJECTIVES: We sought to clarify the prevalence and characteristics of idiopathic ventricular tachycardia or premature ventricular contraction originating from the mitral annulus (MAVT/PVC). BACKGROUND: Recent case reports have presented patients with MAVT/PVC. METHODS: Electrocardiographic (ECG) characteristics and the results of electrophysiologic investigation and radiofrequency catheter ablation (RFCA) were analyzed in 352 patients with symptomatic idiopathic ventricular tachycardia (IVT)/premature ventricular contraction (PVC). RESULTS: Nineteen cases of IVT/PVC (5%) represented MAVT/PVC. Of these, 11 (58%) originated from the anterolateral portion of the mitral annulus (AL-MAVT/PVC), and 2 (11%) arose from the posterior portion (Pos-MAVT/PVC). The remaining six cases of MAVT/PVC (31%) had posteroseptal origin (PS-MAVT/PVC). In all patients, an S-wave was present in lead V(6). The QRS polarity in inferior leads and leads I and aVL was useful for differentiating AL-MAVT/PVC from Pos-MAVT/PVC or PS-MAVT/PVC. The Pos-MAVT/PVC had an Rs pattern in lead I and an R pattern in lead V(1), whereas PS-MAVT/PVC invariably had an R pattern in lead I and a negative QRS component in lead V(1). The AL-MAVT/PVC and Pos-MAVT/PVC showed a longer QRS duration than the PS-MAVT/PVC (p < 0.001), and all had late-phase "notching" of the QRS complex in inferior leads. In all patients, RFCA eliminated MAVT/PVC, with no recurrences during follow-up for 21 +/- 15 months. CONCLUSIONS: Mitral annular VT/PVC is a rare but distinct subgroup of IVT/PVC. MAVT/PVC origin could be determined by ECG analysis. The AL and PS sites of the MA were preferential.

Implications of right ventricular septal pacing for medium-term prognosis: Propensity-matched analysis.

BACKGROUND: The effect of right ventricular (RV) septal pacing as opposed to RV apical pacing on prognosis in patients undergoing pacemaker implantation remains controversial. This study was performed to examine the clinical efficacy of RV septal pacing in a large cohort with medium-term follow-up and propensity-matched analysis. METHODS: A total of 982 consecutive patients with first pacemaker implantation between 2008 and 2013 at two centers in Japan (51.4% male, age 76.1±10.6years, 64.3% septal pacing, 94% preserved ejection fraction [EF]) were enrolled. Propensity matching successfully matched 446 patients into RV septal and apical pacing groups. The primary endpoint, a combination of all-cause death and hospitalization due to heart failure, was compared between the two groups. RESULTS: In the propensity-matched cohort, the primary endpoint was observed in 61 patients (13.7%) over a median follow-up period of 2.1years (interquartile range, 1.1-3.5years). The effects of septal pacing on prognosis were not statistically significant (hazard ratio [HR]=1.10, 95% confidence interval [CI]=0.60-2.04, P=0.752). No significant benefit of septal pacing was observed on all-cause death (HR=1.86, 95%CI=0.74-4.66, P=0.187) and heart failure hospitalization (HR=0.93, 95%CI=0.44-1.98, P=0.847) when assessed separately. CONCLUSION: Septal pacing did not show medium-term advantages in prognosis in this large-scale retrospective cohort study with propensity matching of patients with predominantly preserved EF.

Conversion to Purkinje-Related Monomorphic Ventricular Tachycardia After Ablation of Ventricular Fibrillation in Ischemic Heart Disease.

BACKGROUND: Catheter ablation is an effective therapy for ventricular fibrillation (VF) arising from the Purkinje system in ischemic heart disease. However, some patients experience newly emergent monomorphic ventricular tachycardia (VT) after the ablation of VF. We evaluated the prevalence and mechanism of monomorphic VT after VF ablation. METHODS AND RESULTS: Twenty-one consecutive patients with primary VF because of ischemic heart disease who underwent catheter ablation were retrospectively analyzed. Twenty of 21 patients were in electrical storm. Ventricular premature contractions triggering VF arose from the left Purkinje system and were targeted for ablation. Before the ablation, 14 of 21 patients had only VF, and the other 7 had VF and concomitant monomorphic VT. Four of the 14 patients with only VF (29%) exhibited newly emergent monomorphic VT after VF ablation. Three of these patients had Purkinje-related VTs, which were successfully eliminated by the ablation of a Purkinje network located in the same low-voltage area as the site of prior successful VF ablation. During a median follow-up of 28 months (interquartile range, 16-68 months), VF recurred in 6 of 21 patients (29%); however, there were neither electrical storms nor monomorphic VT, and all recurring arrhythmias were controlled by medical therapy alone. CONCLUSIONS: Over one fifth of patients with primary ischemic VF experienced newly emergent Purkinje-related monomorphic VT after VF ablation. The circuit of the monomorphic VT associated with the Purkinje network was located in the same low-voltage area as the Purkinje tissue that triggered VF and could be suppressed by additional ablation.

Kaplan-Meier survival analysis and Cox regression analyses regarding right ventricular septal pacing: Data from Japanese pacemaker cohort.

The presented data were obtained from 982 consecutive patients receiving their first pacemaker implantation with right ventricular (RV) lead placement between January 2008 and December 2013 at two centers in Japan. Patients were divided into RV apical and septal pacing groups. Data of Kaplan-Meier survival analysis and Cox regression analysis are presented. Refer to the research article "Implications of right ventricular septal pacing for medium-term prognosis: propensity-matched analysis" (Mizukami et al., in press) [1] for further interpretation and discussion.