Artificial intelligence to detect noise events in remote monitoring data.

Background: Remote monitoring (RM) of cardiac implantable electrical devices (CIEDs) can detect various events early. However, the diagnostic ability of CIEDs has not been sufficient, especially for lead failure. The first notification of lead failure was almost noise events, which were detected as arrhythmia by the CIED. A human must analyze the intracardiac electrogram to accurately detect lead failure. However, the number of arrhythmic events is too large for human analysis. Artificial intelligence (AI) seems to be helpful in the early and accurate detection of lead failure before human analysis. Objective: To test whether a neural network can be trained to precisely identify noise events in the intracardiac electrogram of RM data. Methods: We analyzed 21 918 RM data consisting of 12 925 and 1884 Medtronic and Boston Scientific data, respectively. Among these, 153 and 52 Medtronic and Boston Scientific data, respectively, were diagnosed as noise events by human analysis. In Medtronic, 306 events, including 153 noise events and randomly selected 153 out of 12 692 nonnoise events, were analyzed in a five-fold cross-validation with a convolutional neural network. The Boston Scientific data were analyzed similarly. Results: The precision rate, recall rate, F1 score, accuracy rate, and the area under the curve were 85.8 ± 4.0%, 91.6 ± 6.7%, 88.4 ± 2.0%, 88.0 ± 2.0%, and 0.958 ± 0.021 in Medtronic and 88.4 ± 12.8%, 81.0 ± 9.3%, 84.1 ± 8.3%, 84.2 ± 8.3% and 0.928 ± 0.041 in Boston Scientific. Five-fold cross-validation with a weighted loss function could increase the recall rate. Conclusions: AI can accurately detect noise events. AI analysis may be helpful for detecting lead failure events early and accurately.

Risk stratification for the occurrence of ventricular fibrillation in patients with early repolarization syndrome.

BACKGROUND: Several signs of malignant early repolarizations have been proposed in patients with early repolarization syndrome (ERS). However, reports have challenged the efficacy of these signs in predicting future ventricular fibrillation (VF) in patients with ERS. OBJECTIVE: This study aimed to assess the predictive value of various electrocardiogram (ECG) markers for future VF events in patients with ERS. METHODS: We retrospectively evaluated the clinical characteristics of 44 patients with ERS to identify risk factors for VF during follow-up. RESULTS: After the initial event, 16 patients experienced VF (VF group), whereas 28 did not (non-VF group). The VF group had a longer QRS interval, more fragmented QRS (fQRS), and a higher T/R voltage ratio than the non-VF group. Wide J waves were more prevalent in the VF group; however, other J-wave markers did not differ between the groups. Positive late potentials recorded on signal-averaged ECGs were more frequent in the VF group. Whereas none of the patients showed spontaneous Brugada syndrome on ECG, the VF group frequently exhibited pilsicainide-induced ST-segment elevation. These ECG markers were significantly associated with the occurrence of VF during follow-up. Patients with multiple ECG factors, including QRS abnormalities (wide QRS or fQRS), wide J waves, and a high T/R ratio, had a worse prognosis than patients without multiple factors, effectively stratifying patient risk. CONCLUSION: The occurrence of VF in patients with ERS may be associated with conduction abnormalities such as QRS widening, fQRS, high T/R ratio, positive late potentials, and pilsicainide test results. Therefore, ECG factors could be useful in identifying high-risk patients.

Clinical characteristics of electrical storm in patients with early repolarization syndrome.

BACKGROUND: Early repolarization syndrome (ERS) is an idiopathic ventricular fibrillation (VF) associated with inferolateral J waves. While electrical storm (ES) in ERS is not rare, their characteristics and risk factors are not fully understood. OBJECTIVE: This study aimed to clarify the significance of ES in ERS. METHODS: We evaluated 44 patients with ERS who experienced VF/sudden cardiac death or arrhythmic syncope. We assessed clinical characteristics to identify the risk factors for ES. RESULTS: In total, 13 patients (30%) experienced ES (ES group). Of these, 11 patients (85%) experienced ES during the acute phase of initial VF episodes and 2 patients (2%) experienced ES during follow-up. VF associated with ES occurred during therapeutic hypothermia in 6 of 13 patients (46%). The J-wave voltage during therapeutic hypothermia was higher in the ES group than that in the patients without ES. Isoproterenol was used in 5 patients (38%), which decreased J-wave voltage and relieved ES. Among the clinical markers, shorter QT and QTp intervals (the interval from QRS onset to the peak of T wave), pilsicainide-induced ST elevation, and high scores on the Shanghai Score System were associated with ES. Although pilsicainide induced ST elevation in 6 of 34 patients (18%), spontaneous Brugada electrocardiographic patterns did not appear to be associated with VF. Therapeutic hypothermia was also a risk factor for acute phase ES. CONCLUSION: Patients with ERS in the ES group frequently had short QT and QTp intervals, pilsicainide-induced ST elevations, and high Shanghai Score System scores. Therapeutic hypothermia was also associated with acute phase ES.

Significant delayed conduction and characteristic ventricular tachycardias in patients with cardiac sarcoidosis and electrical storm.

INTRODUCTION: Electrical storm (ES) of ventricular tachyarrhythmias (VTAs) is an important cause of sudden death in patients with cardiac sarcoidosis (CS). VTAs in CS are associated with myocardial scarring and inflammation. However, little is known about the risk factors of ES in patients with CS and VTAs. The objective of this study is to clarify the characteristics and risk factors for the development of ES in patients with CS. METHODS: The study population included consecutive 52 patients with CS and sustained VTA. Twenty-five out of 52 patients experienced ES. We evaluated clinical characteristics, imaging modalities, and electrocardiogram (ECG) parameters to determine the risk factors associated with ES. RESULTS: Half of the patients experienced VTAs as the initial symptom of sarcoidosis, and eight patients had ES as the initial VTA episode. There were no differences in cardiac imaging abnormalities between patients with and without ES. Among ECG markers, significant QRS fragmentation (odds ratio [OR]: 7.9, p = .01) and epsilon waves (OR: 12.24, p = .02) were associated with ES. Among the ventricular tachycardia (VT) characteristics, multiple morphologies of monomorphic VTs (OR: 10.9, p < .01), short VT cycle lengths (OR: 12.5, p < .01), and polymorphic VT (OR: 13.5, p < .01) were associated with ES. Bidirectional VTs were detected in 10 patients with ES and one patient without ES. Immunosuppressive therapy relieved ES in some patients. CONCLUSIONS: ES was common in patients with CS and VTAs. Significant depolarization abnormalities that appeared as QRS fragmentation, epsilon waves, and specific VT characteristics were associated with ES.

Syncope and loss of consciousness after implantation of a cardioverter-defibrillator in patients with Brugada syndrome: Prevalence and characteristics in long-term follow-up.

Background: Syncope is a significant prognostic factor in patients with Brugada syndrome (BrS). However, the risk of ventricular arrhythmia in patients with nonarrhythmic loss of consciousness (LOC) is similar to that in asymptomatic patients. LOC events after implantable cardioverter-defibrillator (ICD) implantation may provide insights into underlying causes of the initial LOC episode. Objective: The purpose of this study was to examine LOC characteristics following ICD implantation. Methods: We retrospectively analyzed 112 patients with BrS (mean age 47 years; 111 men) who were treated with an ICD. The patients were classified into 3 groups based on symptoms at implantation: asymptomatic (35 patients); LOC (46 patients); and ventricular tachyarrhythmia (VTA) (31 patients). We evaluated the incidence and cause of LOC during long-term follow-up after ICD implantation. Results: During mean follow-up of 12.2 years, 41 patients (37%) experienced LOC after ICD implantation. Arrhythmic LOC occurred in 5 asymptomatic patients, 14 LOC patients, and 16 patients with VTA. Nonarrhythmic LOC, similar to the initial episode, occurred after ICD implantation in 6 patients with prior LOC (2 with neurally mediated syncope and 4 with epilepsy). Most epileptic patients experienced LOC during rest or sleeping, and did not show an abnormal encephalogram during initial evaluation of the LOC episodes. Conclusion: After ICD implantation, 13% of patients had nonarrhythmic LOC similar to the initial episode. Accurate classification of LOC based on a detailed medical history is important for risk stratification, although distinguishing arrhythmic LOC from epilepsy-related LOC episodes can be challenging depending on the circumstances and characteristics of the LOC event.

Significance of left posterior extension of early repolarization in patients with J-wave syndrome.

BACKGROUND: J waves in the inferior or lateral leads are characteristic electrocardiographic (ECG) changes in patients with early repolarization syndrome (ERS). However, the presence of J waves in the left posterior region has not yet been evaluated. OBJECTIVE: The purpose of this study was to clarify the significance of J waves in the posterior left ventricle using leads V7-V9 and a body surface mapping (BSM) system. METHODS: Forty patients diagnosed with ERS were included. All patients exhibited J waves in either the contiguous inferior, lateral, or posterior leads. We evaluated the incidence of J waves in the inferolateral and posterior leads using a 15-lead ECG with synthesized V7-V9 and an 87-lead BSM. Additionally, we assessed the arrhythmogenicity of the posterior regions based on the morphology of the premature ventricular complexes (PVCs) associated with ventricular fibrillation (VF). RESULTS: J waves were observed in the lateral, inferior, and posterior leads of 26 (65%), 31 (78%), and 39 (97%) patients, respectively. J waves were found only in the posterior leads of 5 patients. BSM was evaluated in 9 patients, all of whom exhibited a positive area on the posterior region. PVCs associated with VF were recorded in 5 patients. Among patients with inferolateral and posterior J waves, all except 1 patient who displayed left bundle branch block morphology showed PVCs originating from the posterior left ventricular region. CONCLUSION: Posterior J waves are common in ERS patients. This abnormality can be detected using leads V7-V9 and the BSM system and may be associated with arrhythmogenesis.

Prevalence and Treatment of Arrhythmias in Patients With Transthyretin and Light-Chain Cardiac Amyloidosis.

Background: Various types of arrhythmia are observed in patients with cardiac amyloidosis, but the prevalence of arrhythmia has not been fully investigated. This study investigated the prevalence and treatment of arrhythmias in patients with cardiac amyloidosis before the introduction of new agents for amyloidosis, such as tafamidis. Methods and Results: Of 53 patients who were histologically diagnosed with cardiac amyloidosis at 10 centers in western Japan between 2009 and 2021, 43 who were diagnosed on the basis of immunohistochemical staining were evaluated in this study. Of these 43 patients, 13 had immunoglobulin light-chain (AL) amyloidosis and 30 had transthyretin (ATTR) amyloidosis; further, 27 had atrial tachyarrhythmia, 13 had ventricular tachyarrhythmia, and 17 had bradyarrhythmia. Atrial fibrillation (AF) was the most common arrhythmia in patients with cardiac amyloidosis (n=24; 55.8%), especially among those with ATTR amyloidosis (70.0% of ATTR vs. 23.1% of AL). Eleven (25.6%) patients were treated with a cardiac implantable device. All 3 patients with pacemakers were alive at the last follow-up (median 76.7 months; interquartile range [IQR] 4.8-146.4 months). Of the 8 patients who underwent AF ablation, there was no recurrence in 6 (75%) after a median of 39.3 months (IQR 19.8-59.3 months). Conclusions: The prevalence of various arrhythmias was high in patients with cardiac amyloidosis. AF occurred most frequently in patients with cardiac amyloidosis, especially among patients with ATTR.

Significant Delayed Activation on the Right Ventricular Outflow Tract Represents Complete Right Bundle-Branch Block Pattern in Brugada Syndrome.

Background The appearance of complete right bundle-branch block (CRBBB) in Brugada syndrome (BrS) is associated with an increased risk of ventricular fibrillation. The pathophysiological mechanism of CRBBB in patients with BrS has not been well established. We aimed to clarify the significance of a conduction delay zone associated with arrhythmias on CRBBB using body surface mapping in patients with BrS. Methods and Results Body surface mapping was recorded in 11 patients with BrS and 8 control patients both with CRBBB. CRBBB in control patients was transiently exhibited by unintentional catheter manipulation (proximal RBBB). Ventricular activation time maps were constructed for both of the groups. We divided the anterior chest into 4 areas (inferolateral right ventricle [RV], RV outflow tract [RVOT], intraventricular septum, and left ventricle) and compared activation patterns between the 2 groups. Excitation propagated to the RV from the left ventricle through the intraventricular septum with activation delay in the entire RV in the control group (proximal RBBB pattern). In 7 patients with BrS, excitation propagated from the inferolateral RV to the RVOT with significant regional activation delay. The remaining 4 patients with BrS showed a proximal RBBB pattern with the RVOT activation delay. The ventricular activation time in the inferolateral RV was significantly shorter in patients with BrS without a proximal RBBB pattern than in control patients. Conclusions The CRBBB morphology in patients with BrS consisted of 2 mechanisms: (1) significantly delayed conduction in the RVOT and (2) proximal RBBB with RVOT conduction delay. Significant RVOT conduction delay without proximal RBBB resulted in CRBBB morphology in patients with BrS.

Ablation for unmappable ventricular tachycardia in a patient with complete transposition of the great arteries who underwent Rastelli repair.

Catheter ablation (CA) of ventricular tachycardia (VT) after repair of congenital heart disease may be difficult because of complex anatomy and sometimes unmappable VT. Here, we report a 41-year-old woman with successful CA of unmappable VT in a patient with complete transposition of the great arteries after Rastelli repair. Clinical VT was induced by programmed electrical stimulation, when the mapping catheter was placed at the high anterior right ventricular outflow tract (RVOT). During VT, the local potential at the high anterior RVOT under the right ventricle (RV) - pulmonary artery (PA) conduit was equal to that at the timing of onset of QRS. The VT was unmappable because the hemodynamics deteriorated. Pace mapping was also tried at the aortic cusp and the left ventricular outflow tract (LVOT). Fractionated potential during sinus rhythm was observed at the noncoronary cusp, and the paced QRS morphology at this site was similar to that of the clinical VT, with a delay of 55 ms from pacing to the onset of QRS. However, mapping at the LVOT was impossible due to the difficulty of catheter manipulation. Radiofrequency energy was successfully applied at the noncoronary cusp and the high anterior RVOT under the RV-PA conduit. .

Usefulness of right ventriculography compared with computed tomography for ruling out the possibility of lead perforation before lead extraction.

PURPOSE: High-risk patients can be identified by preprocedural computed tomography (CT) before lead extraction. However, CT evaluation may be difficult especially for lead tip identification due to artifacts in the leads. Selective right ventriculography (RVG) may enable preprocedural evaluation of lead perforation. We investigated the efficacy of RVG for identifying right ventricular (RV) lead perforation compared with CT in patients who underwent lead extraction. METHODS: Ninety-five consecutive patients who were examined by thin-section non-ECG-gated multidetector CT and RVG before lead extraction were investigated retrospectively. Newly recognized pericardial effusion after lead extraction was used as a reference standard for lead perforation. We analyzed the prevalence of RV lead perforation diagnosed by each method. The difference in the detection rates of lead perforation by RVG and CT was evaluated. RESULTS: Of the 115 RV leads in the 95 patients, lead perforation was diagnosed for 35 leads using CT, but the leads for 29 (83%) of those 35 leads diagnosed as lead perforation by CT were shown to be within the right ventricle by RVG. Three patients with 5 leads could not be evaluated by CT due to motion artifacts. The diagnostic accuracies of RVG and CT were significantly different (p < 0.001). There was no complication of pericardial effusion caused by RV lead extraction. CONCLUSION: RVG for identification of RV lead perforation leads to fewer false-positives compared to non-ECG-gated CT. However, even in cases in which lead perforation is diagnosed, most leads may be safely extracted by transvenous lead extraction.

Prognosis of patients with severe left ventricular dysfunction after transvenous lead extraction and the need for additional hemodynamic support in the perioperative period.

BACKGROUND: Transvenous lead extraction (TLE) is necessary because of system infection, lead malfunction, or system upgrade. Patients with severe left ventricular dysfunction (SLVD) undergoing TLE may be at a higher risk because hemodynamic parameters may change unfavorably during or after TLE; however, this has not yet been clarified. OBJECTIVE: The purpose of this study was to examine whether patients with SLVD undergoing TLE have higher mortality. METHODS: All patients who underwent TLE were stratified as follows: patients with ejection fraction ≤ 35% (SLVD group) and those with ejection fraction > 35% (non-SLVD group). RESULTS: We assessed the data of 200 patients [SLVD group, 36 (18%); non-SLVD group, 164 (82%)]). Brain natriuretic peptide level and cardiac resynchronization therapy rate were higher in the SLVD group than in the non-SLVD group. There were no significant between-group differences in major complications and clinical success rates. Patients with SLVD were more likely to require additional hemodynamic support, such as catecholamine infusion, temporary atrium-ventricle sequential pacing, and temporary cardiac resynchronization therapy pacing (27.8% vs 1.2%; P < .001). The survival rate was not significantly different between the groups at 30 days and 1 year after TLE (SLVD vs non-SLVD: 30 days: 97.2% vs 99.4%; P = .215; 1 year: 80.6% vs 91.5%; P = .053). Multivariate Cox regression analysis revealed log brain natriuretic peptide and serum hemoglobin levels as predictors for 1-year mortality. CONCLUSION: The prognosis after TLE was comparable between patients with and without SLVD. However, additional hemodynamic support was often necessary for patients with SLVD.

Significance of Exercise-Related Ventricular Arrhythmias in Patients With Brugada Syndrome.

Background Sinus tachycardia during exercise attenuates ST-segment elevation in patients with Brugada syndrome, whereas ST-segment augmentation after an exercise test is a high-risk sign. Some patients have premature ventricular contractions (PVCs) related to exercise, but the significance of exercise-related PVCs in patients with Brugada syndrome is still unknown. The objective of this study was to determine the significance of exercise-related PVCs for predicting occurrence of ventricular fibrillation (VF) in patients with Brugada syndrome. Methods and Results The subjects were 307 patients with Brugada syndrome who performed a treadmill exercise test. We evaluated the occurrence of PVCs at rest, during exercise and at the peak of exercise, and during recovery after exercise (0-5 minutes). We followed the patients for 92±68 months and evaluated the occurrence of VF. PVCs occurred in 82 patients (27%) at the time of treadmill exercise test: PVCs appeared at rest in 14 patients (4%), during exercise in 60 patients (20%), immediately after exercise (0-1.5 minutes) in 28 patients (9%), early after exercise (1.5-3 minutes) in 18 patients (6%), and late after exercise (3-5 minutes) in 12 patients (4%). Thirty patients experienced VF during follow-up. Multivariable analysis including symptoms, spontaneous type 1 ECG, and PVCs in the early recovery phase showed that these factors were independently associated with VF events during follow-up. Conclusions PVCs early after an exercise test are associated with future occurrence of VF events. Rebound of vagal nerve activity at the early recovery phase would promote ST-segment augmentation and PVCs in high-risk patients with Brugada syndrome.

Indication and prognostic significance of programmed ventricular stimulation in asymptomatic patients with Brugada syndrome.

AIMS: To establish the indication for programmed ventricular stimulation (PVS) for asymptomatic patients with Brugada syndrome (BrS), we evaluated the prognostic significance of PVS based on abnormal electrocardiogram (ECG) markers. METHODS AND RESULTS: One hundred and twenty-five asymptomatic patients with BrS were included. We performed PVS at two sites of the right ventricle with up to three extrastimuli [two pacing cycle lengths and minimum coupling interval (MCI) of 180 ms]. We followed the patients for 133 months and evaluated ventricular fibrillation (VF) events. Fragmented QRS (fQRS) and Tpeak-Tend (Tpe) interval were evaluated as ECG markers for identifying high-risk patients. Fragmented QRS and long Tpe interval (≥100 ms) were observed in 66 and 37 patients, respectively. Ventricular fibrillation was induced by PVS in 60 patients. During follow-up, 10 patients experienced VF events. Fragmented QRS, long Tpe interval, and PVS-induced VF with an MCI of 180 ms or up to two extrastimuli were associated with future VF events (fQRS: P = 0.015, Tpe ≥ 100 ms: P = 0.038, VF induction: P < 0.001). However, PVS-induced VF with an MCI of 200 ms was less specific (P = 0.049). The frequencies of ventricular tachyarrhythmia events during follow-up were 0%/year with no ECG markers and 0.1%/year with no VF induction. The existence of two ECG factors with induced VF was strongly associated with future VF events (event rate: 4.4%/year, P < 0.001), and the existence of one ECG factor with induced VF was also associated (event rate: 1.3%/year, P = 0.011). CONCLUSION: We propose PVS with a strict protocol for asymptomatic patients with fQRS and/or long Tpe interval to identify high-risk patients.