Machine Learning-Based Clustering Using a 12-Lead Electrocardiogram in Patients With a Implantable Cardioverter Defibrillator to Identify Future Ventricular Arrhythmia.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) reduce mortality associated with ventricular arrhythmia in high-risk patients with cardiovascular disease. Machine learning (ML) approaches are promising tools in arrhythmia research; however, their application in predicting ventricular arrhythmias in patients with ICDs remains unexplored. We aimed to predict and stratify ventricular arrhythmias requiring ICD therapy using 12-lead electrocardiograms (ECGs) in patients with an ICD. METHODS AND RESULTS: This retrospective analysis included 200 adult patients who underwent ICD implantation at a single center. Patient demographics, clinical features, and 12-lead ECG data were collected. Unsupervised learning techniques, including K-means and hierarchical clustering, were used to stratify patients based on 12-lead ECG features. Dimensionality reduction methods were also used to optimize clustering accuracy. The silhouette coefficient was used to determine the optimal method and number of clusters. Of the 200 patients, 59 (29.5%) received appropriate therapy. The mean age of patients was 62.3 years, and 81.0% were male. The mean follow-up period was 2,953 days, with no significant intergroup differences. Hierarchical clustering into 3 clusters proved to be the most accurate (silhouette coefficient=0.585). Kaplan-Meier curves for these 3 clusters revealed significant differences (P=0.026). CONCLUSIONS: We highlight the potential of ML-based clustering using 12-lead ECGs to help in the risk stratification of ventricular arrhythmia. Future research in a larger multicenter setting may provide further insights and refine ICD indications.

Left ventricular end-systolic contractile entropy can predict cardiac prognosis in patients with complete left bundle branch block.

BACKGROUND: Several patients with complete left bundle branch block (CLBBB) show left ventricular (LV) dyssynchrony and poor cardiac prognosis. However, the prognostic value of LV end-systolic contractile entropy which was measured by single-photon emission computer tomography (SPECT) has not been elucidated in patients with CLBBB. METHODS AND RESULTS: We recruited consecutive 115 sinus-rhythm patients with CLBBB who underwent ECG-gated 201TlCl-SPECT. After 30 days of observation, finally 102 patients (75.2 ± 9.5 years, 62 male) were enrolled and observed retrospectively for a median of 671 days. Twenty-five patients fell into major cardiac events. Multivariate Cox regression analysis showed estimated glomerular filtration rate (eGFR) ≤ 39.35 mL/min and entropy ≥ 79% were significant and independent predictors for major cardiac events (hazard ratio: 4.256 and 7.587, P value = 0.006 and < 0.001, respectively). Machine learning (Random Forest method) revealed eGFR and entropy had higher feature importance than other predictors (0.140 and 0.138, respectively). Kaplan-Meyer curve analysis demonstrated that the group with entropy ≥ 79% and eGFR ≤ 39.36 mL/min had the worst cardiac prognosis (Logrank: P = 0.002). CONCLUSIONS: Left ventricular end-systolic contractile entropy predicts poor cardiac prognosis in patients with CLBBB, which may be more valuable than the other parameters of SPECT.

Characteristics of ventricular intracardiac electrograms of ventricular tachycardias originating from the epicardia in patients with an implantable cardioverter defibrillator.

INTRODUCTION: While characteristic waveforms of 12-lead electrocardiograms have been reported to predict the epicardial origin of ventricular tachycardia (VT), it has not been fully examined whether ventricular intracardiac electrograms (VEGMs) recorded from the implantable cardioverter defibrillator (ICD) via telemetry can determine the origin of VT or not. The aim of this study was to investigate the VEGM characteristics of VT originating from the epicardia. METHOD AND RESULTS: Intracardiac VEGMs of the induced VTs, with detected sites of origin during the VT study, were recorded in 15 (23 VTs) of the 46 patients. The characteristics of the 23 VTs were evaluated using far-field and near-field VEGMs recorded via telemetry. Five of 23 VTs were found to be focused on the epicardial site (epi group) and 18 VTs were focused on the endocardium (endo group). VTs of the epi group had longer VEGM duration in far-field EGM than those of the endo group (epi group: 240 ± 49 ms vs endo group: 153 ± 45 ms; P = 0.002) and the duration from the onset to the peak of VEGM was also longer than that of the endo group (epi group: 153 ± 53 ms vs endo group: 63 ± 28 ms; P < 0.001). There was no difference in the V wave duration in tip-ring EGM between both groups (epi group: 122 ± 52 ms vs endo group: 98 ± 6 ms; P = 0.377). CONCLUSION: Evaluation of intracardiac VEGM before VT ablation may be helpful to predict the epicardial origin of VT in patients with an ICD.

Usefulness of epicardial impedance evaluation for epicardial mapping and determination of epicardial ablation site for ventricular tachycardia: A pilot study.

BACKGROUND: During epicardial mapping, determination of appropriate ablation sites in low voltage areas (LVA) is challenging because of large epicardial areas covered by adipose tissue. OBJECTIVE: To evaluate the impedance difference between epicardial fat and the epicardial LVA using multiple detector computed tomography (MDCT). METHODS: We enrolled patients who underwent ventricular tachycardia (VT) ablation via the epicardial approach after endocardial ablation failure. After the procedure, MDCT-derived images of epicardial fat were loaded to the mapping system. Then, all points acquired during sinus rhythm were retrospectively superimposed and analyzed. RESULTS: This study included data from 7 patients (62.5 ± 3.9 years old) who underwent eight epicardial VT ablation procedures. After the procedure, MDCT-derived images of epicardial fat were registered in eight procedures. Retrospective analysis of 1,595 mapping and 236 ablation points was performed. Of the 1,595 mapping points on the merged electroanatomical and epicardial fat maps, normal voltage area (NVA) and low voltage area (LVA) without fat had lower impedance than those with fat (NVA without fat 182 ± 46 Ω vs. NVA with fat 321 ± 164.0 Ω, P  =  0.001, LVA without fat 164 ± 69 Ω vs. LVA with fat 248 ± 89 Ω, P  =  0.002). Of the 236 ablation points, initial impedance before ablation was higher on epicardial fat than on epicardial LVA without fat (134 ± 16 Ω vs. 156 ± 28 Ω, P  =  0.01). CONCLUSIONS: Real time epicardial impedance evaluation may be useful to determine effective epicardial ablation sites and avoid adipose tissue. However, the number of patients in the present study is limited. Further investigation with a large number of patients is needed to confirm our result.

PR deviation as a risk marker for cardiac events in patients with Takotsubo syndrome.

BACKGROUND: PR segment deviation (PRD: defined as PR elevation in aVR and PR depression in lead II/III) on electrocardiography is frequently observed in patients with acute pericarditis; however, there have been few studies that explore the occurrence of PRD in patients with Takotsubo syndrome (TTS). The clinical significance of PRD in TTS is not clearly elucidated. METHODS & RESULTS: A total of 52 consecutive patients with TTS in sinus rhythm (73.9 ± 13.8 years, nine males) were enrolled in the study. The major cardiac events were defined as sustained ventricular tachycardia or ventricular fibrillation, Killip class 4 heart failure, and cardiac death within 30 days. PRD in the hyperacute phase (within 48 h from the onset of TTS) was observed in 15 patients (29%), and all PRDs disappeared or diminished at 1 week later. The PRD (+) group had a higher value of C-reactive protein level (median: 1.80 mg/dL [0.31-3.26] vs 0.20 mg/dL [0.06-0.81], P  =  0.013) and creatine kinase-muscle/brain isoenzyme (median: 60 IU/L [28-75] vs 17 IU/L [13-26], P < 0.001) and a lower level of left ventricular ejection fraction (42.7 ± 7.2% vs 48.8 ± 9.4%, P  =  0.041) than the PRD (-) group. Multivariate analysis showed that PRD was a significant and independent predictor for major cardiac events (odds ratio  =  21.0, 95% confidence interval  =  1.18-273). CONCLUSIONS: TTS patients with PRD in the hyperacute phase showed a high incidence of major cardiac events. Therefore, PRD may help to identify TTS patients at high risk for cardiac event.

Life-Threatening Ventricular Arrhythmia and Brugada-Type ST-Segment Elevation Associated With Acute Ischemia of the Right Ventricular Outflow Tract.

BACKGROUND: Brugada-type ECG (Br-ECG) is occasionally observed during acute myocardial ischemia of the right ventricular outflow tract (RVOT). No studies have explored, however, the association of ventricular tachyarrhythmia and development of Br-ECG due to acute ischemia of the RVOT.Methods and Results:The study included 13 consecutive patients with acute ischemia of the RVOT during coronary catheterization. Patients were divided into 2 groups: those with Br-ECG (group B) and those without (group N). The proportion of male patients was higher in group B than in group N (100% vs. 25%, P<0.01), and VT/VF developed in only patients with Br-ECG (group B). In group B, VT/VF was observed in patients without pre-existing organic change in the conus/right ventricular (RV) branch of the right coronary artery and no VT/VF was seen in patients with organic coronary stenosis despite Br-ECG. CONCLUSIONS: Acute myocardial ischemia of the RVOT caused Br-ECG predominantly in male patients and subsequent development of VT/VF in some patients. VT/VF was seen in patients without any obstructive lesion but arrhythmic events were not observed in RVOT ischemia in the case of pre-existing coronary occlusion or stenosis of the conus or RV branch, suggesting the effects of precondition.

Early repolarization pattern and its day-to-day dynamic change as markers for ventricular fibrillation in patients with vasospastic angina.

AIMS: An early repolarization (ER) pattern is a risk factor for ventricular fibrillation (VF) in certain diseases. However, it is unclear whether this association holds for patients with vasospastic angina (VSA). Moreover, the reported long-term follow-up of implantable cardioverter defibrillator (ICD) therapy for VSA patients is limited to 3 years. This study aimed to clarify the relation between ER and VF in patients with VSA and to investigate the long-term outcomes of ICD therapy. METHODS AND RESULTS: This retrospective, observational survey evaluated 265 consecutive VSA patients, including 21 with VF. Their electrocardiogram findings and clinical course were analysed over a mean follow-up of 5.5 ± 3.3 years. Early repolarization was observed in 64 patients (24.2%) and was more frequent in patients with VF history than those without (P = 0.001). Early repolarization was independently associated with VF history. During follow-up, four patients had VF recurrences. Ventricular fibrillation recurrence was higher in patients with ER (log-rank, P = 0.018) or VF history (log-rank, P < 0.001) than those without. Among patients with ER, day-to-day variations in ER (P = 0.003) and notching of ER pattern (P = 0.03) were associated with VF history. Cases with day-to-day variation showed a higher incidence of VF recurrence during follow-up (log-rank, P = 0.007). During long-term follow-up, 23.5% of patients with an ICD received appropriate shock therapy. CONCLUSION: The presence of ER, especially with day-to-day variation, can help predict VF recurrence in VSA patients. Implantable cardioverter defibrillator implantation is a reasonable approach for the secondary prevention of VF in high-risk VSA patients.

Cardiac function changes with switching from the supine to prone position: analysis by quantitative semiconductor gated single-photon emission computed tomography.

BACKGROUND: Prone positioning is required in certain operations such as spinal surgery. Changes in cardiac function in the prone position have been studied with various methodologies. Few studies have investigated changes in left ventricular diastolic function and rhythm in subjects turned prone. METHODS AND RESULTS: Cardiac function was evaluated in the supine and prone positions in 90 patients without atrial fibrillation who underwent (99m)Tc-tetrofosmin quantitative gated single-photon emission computed tomography. Three groups of 30 patients each were classified as "no history of myocardial ischemia or cardiomyopathy" (Group A), "history of myocardial infarction" (Group B), and "ischemic heart disease without myocardial infarction history" (Group C). Upon assuming the prone position, the cardiac index and any dyssynchrony worsened in all groups. Ejection fraction changes occurred only in Group B, and diastolic function changes occurred in Groups B and C, but not in Group A. The changes caused by prone positioning were more severe in the patients with poor cardiac function. CONCLUSIONS: Prone positioning induces significant changes in systolic and diastolic function, as well as dyssynchrony. The negative effects of prone positioning are more severe in patients with poor baseline cardiac function.

Unmasking Brugada-type electrocardiogram on deep inspiration.

BACKGROUND: Electrocardiogram (ECG) recorded at the upper intercostal lead positions is recommended as an additional diagnostic clue for Brugada syndrome (BrS), but similar recording conditions to unmask ECG signs have not been explored. METHODS AND RESULTS: We evaluated the diagnostic usefulness for unmasking ECG signs of BrS using recordings at the upper intercostal lead position, on deep inspiration and on standing. In 34 patients (mean age, 49±14 years; 30 male) with diagnosed and suspected BrS, ECG type and ST-elevation in leads V1-V3 recorded at a higher position by 1 rib from the standard position (3ICS), and at standard lead positions (4ICS) on deep inspiration (DI test) and on standing (Stand test) were compared with the conventional lead positions (baseline). While type 1 ECG had been documented in 17 of 34 patients on at least 1 occasion in the past, only 4 had the sign at baseline during the study. Twenty patients had type 1 on 3ICS recording, 18 on DI test, and 6 on Stand test. Among 17 patients without previous documentation of spontaneous type 1, 7 had type 1 on 3ICS recording, 6 on DI test, and 1 on Stand test. CONCLUSIONS: ECG recording on deep inspiration is useful to unmask diagnostic signs of BrS and has similar accuracy to 3ICS recording.

J wave and fragmented QRS formation during the hyperacute phase in Takotsubo cardiomyopathy.

BACKGROUND: The J wave and fragmented QRS (fQRS) on electrocardiography are suggested to be closely related to cardiac arrhythmogenesis. Takotsubo cardiomyopathy (TTC) occasionally causes fatal cardiac conditions including life-threatening ventricular arrhythmia. There has been, however, only 1 case report describing the J wave in TTC, and fQRS has not been reported thus far in relation to clinical courses and prognosis. METHODS AND RESULTS: J wave and fQRS formation were investigated in 31 consecutive patients with TTC. Nine patients (29%) had J waves and/or fQRS (group A), whereas the remaining 22 did not (group B). The J wave (4 patients), fQRS (4 patients), or both (1 patient) appeared transiently during the hyperacute phase. Left ventricular ejection fraction was significantly lower in group A. Summed defect score of single-photon emission computed tomography using iodine 123 beta-methyl-p-iodophenyl-pentadecanoic acid, and creatine kinase MB isozyme (CKMB) were significantly higher in group A. On multivariate analysis CKMB was a significant indicator of J wave or fQRS. Moreover, the J wave was a significant indicator for cardiac death and/or ventricular tachyarrhythmia (odds ratio, 11.5; P=0.026). CONCLUSIONS: Patients with TTC frequently had J waves and/or fQRS during the hyperacute phase, and which were associated with myocardial damage. J wave was also an indicator for cardiac death and/or ventricular tachyarrhythmia. J waves and fQRS may be useful markers for myocardial damage.

Macroreentrant atrial tachycardia in patients without previous atrial surgery or catheter ablation: clinical and electrophysiological characteristics of scar-related left atrial anterior wall reentry.

INTRODUCTION: Macroreentrant atrial tachycardia (MRAT) has been described most frequently in patients with prior cardiac surgery. Left atrial tachycardia and flutter are common in patients who undergo atrial fibrillation ablation; however, few reports describe left atrial MRAT involving the regions of spontaneous scarring. Here, we describe left atrial MRAT in patients without prior cardiac surgery or catheter ablation (CA) and discuss the clinical and electrophysiological characteristics of tachycardia and outcome of CA. METHODS AND RESULTS: An electrophysiological study and CA were performed in 6 patients (3 men; age 76 ± 6 years) with MRAT originating from the left atrial anterior wall (LAAW). No patient had a history of cardiac surgery or CA in the left atrium. Spontaneous scars (areas with bipolar voltage ≤ 0.05 mV) were observed in all patients. The activation map showed a figure-eight circuit with loops around the mitral annulus (4 counterclockwise and 2 clockwise) and a low-voltage area with LAAW scarring. The mean tachycardia cycle length was 303 ± 49 milliseconds. The conduction velocity was significantly slower in the isthmus between the scar in the LAAW and the mitral annulus than in the lateral mitral annulus (0.17 ± 0.05 m/s vs 0.94 ± 0.35 m/s; P = 0.003). Successful ablation of the isthmus caused interruption of the tachycardia and rendered it noninducible in all patients. CONCLUSION: Spontaneous LAAW scarring is an unusual cause of MRAT, showing activation patterns with a figure-eight configuration. Radiofrequency CA is a feasible and effective treatment in such cases.

Prevalence and electrophysiological characteristics of typical atrial flutter in patients with atrial fibrillation and chronic obstructive pulmonary disease.

AIMS: Chronic obstructive pulmonary disease (COPD) is one of the important underlying diseases of atrial fibrillation (AF). However, the prevalence and electrophysiological characteristics of typical atrial flutter (AFL) in patients with AF and COPD remain unknown. The purpose of the present study was to investigate those characteristics. METHODS AND RESULTS: We investigated 181 consecutive patients who underwent catheter ablation of AF. Twenty-eight patients were diagnosed with COPD according to the Global Initiatives for Chronic Obstructive Lung Disease (GOLD) criteria. Forty patients with no lung disease served as a control group. We analysed the electrophysiological characteristics in these groups. Typical AFL was more common in the COPD group (19/28, 68%) than in the non-COPD group (13/40, 33%; P = 0.006). The prevalence of AFL increased with the severity of COPD: 4 (50%) of 8 patients with GOLD1, 13 (72%) of 18 patients with GOLD2, and 2 (100%) of 2 patients with GOLD3. Atrial flutter cycle length and conduction time from the coronary sinus (CS) ostium to the low lateral right atrium (RA) during CS ostium pacing before and after the cavotricuspid isthmus ablation were significantly longer in the COPD group than in the non-COPD group (285 vs. 236, 71 vs. 53, 164 vs. 134 ms; P = 0.009, 0.03, 0.002, respectively). CONCLUSION: In COPD patients with AF, conduction time of RA was prolonged and typical AFL was commonly observed.

Prophylactic catheter ablation for induced monomorphic ventricular tachycardia in patients with implantable cardioverter defibrillators as primary prevention.

AIMS: Prophylactic catheter ablation (CA) has been established to reduce the incidence of appropriate implantable cardioverter-defibrillator (ICD) therapy (anti-tachycardia pacing or shock) in secondary prevention patients. The aim of this study was to determine whether prophylactic CA for induced ventricular tachycardia (VT) reduces the incidence of appropriate ICD therapy in primary prevention patients. METHODS AND RESULTS: We retrospectively investigated 66 consecutive patients with structural heart disease who had undergone ICD implantation as primary prevention and electrophysiological study. Patients with hypertrophic cardiomyopathy or no inducible monomorphic VT had been excluded, and the remaining 38 patients were divided into two groups; those who had undergone prophylactic CA for induced monomorphic VT (the CA group, n = 18), and those who had not undergone CA (the non-CA group, n = 20). During a mean follow-up of 50 ± 38 months, 1 patient (5%) received appropriate ICD therapy in the CA group and 13 (65%) in the non-CA group. Kaplan-Meier survival analysis revealed a significantly higher event-free survival rates for appropriate ICD therapy in the CA group compared with the non-CA group (P = 0.003). Among the patients, one patient (5%) in the CA group and nine patients (45%) in the non-CA group suffered appropriate shock (P = 0.018). CONCLUSIONS: Prophylactic CA for induced monomorphic VT reduces the incidence of appropriate ICD therapy including shock in primary prevention patients. These results indicate that prophylactic CA may be considered for structural heart disease patients who are candidates for ICD implantation as primary prevention.

Fragmented QRS predicts cardiovascular death of patients with structural heart disease and inducible ventricular tachyarrhythmia.

BACKGROUND: Fragmented QRS (fQRS) can predict cardiac events, and inducible ventricular tachycardia/fibrillation (VT/VF) is a known high-risk factor for arrhythmic death. However, whether fQRS is a predictor of cardiac events in patients with inducible VT/VF is unknown. We aimed to evaluate whether fQRS is a predictor of cardiac events in patients with structural heart disease and inducible VT/VF. METHODS AND RESULTS: We retrospectively investigated 98 patients with structural heart disease who had a defibrillator device implanted. All patients underwent electrophysiological testing prior to or after device implantation and VT/VF was induced. fQRS was present in 30 patients. Appropriate defibrillator therapies were similar between the fQRS and non-fQRS groups (47% vs. 47%). In total, 25 patients (26%) died during a mean follow-up period of 87±43 months. All-cause mortality (12 [40%] vs. 13 [19%]) and cardiovascular deaths (9 [30%] vs. 4 [6%]) were significantly higher in the fQRS group than non-fQRS group, respectively; Kaplan-Meier analysis revealed significantly lower event-free survival for all-cause mortality (P=0.012) and cardiovascular deaths (P=0.001) for fQRS patients. A multivariable Cox regression model revealed that fQRS was an independent predictor of cardiovascular death (hazard ratio, 4.58; 95% confidence interval, 1.34-15.64; P=0.015). CONCLUSIONS: fQRS is a predictor of cardiovascular death in patients with structural heart disease and inducible VT/VF.

Machine Learning for Multi-Vessel Coronary Artery Disease Prediction on Electrocardiogram Gated Single-Photon Emission Computed Tomography.

Background: Single-photon emission computed tomography (SPECT) encounters difficulties in diagnosing severe multi-vessel coronary artery disease (svMVD) because of balanced ischemia. We estimated the predictive value of electrocardiogram-gated SPECT for svMVD and improved it using machine learning (ML). Methods and results: We enrolled consecutive 335 patients (median age, 74 years; 255 men) who underwent adenosine stress-gated SPECT (99mTechnesium) and coronary angiography. svMVD was defined as three-vessel disease or left main tract stenosis. Predictive models were constructed using statistical and ML methods. Eighteen cases (5%) showed svMVD, and diabetes, summed stress score (SSS), and the max difference among segmental time of stroke volume per cardiac cycle (MDSV: a parameter of left ventricular [LV] end-systolic dyssynchrony) on adenosine stress were independent significant predictors. The area under the receiver operating characteristic curve (AUC) of SSS and MDSV on stress were 0.759 and 0.763, respectively. Conversely, the extra trees classifier and light gradient boosting machine had improved AUC values of 0.826 and 0.870, respectively, and the MDSV on stress and diabetes showed high feature values in the ML models. Conclusion: ML on SPECT helped to improve the diagnostic performance of svMVD and diabetes, and the parameters of LV dyssynchrony played essential roles in the ML predictive models.

Risk prediction of inappropriate implantable cardioverter-defibrillator therapy using machine learning.

We aimed to develop machine learning-based predictive models for identifying inappropriate implantable cardioverter-defibrillator (ICD) therapy. Our study included 182 consecutive cases (average age 62.2 ± 4.5 years, 169 men) and employed 14 non-deep learning models for prediction (hold-out method). These models utilized selected electrocardiogram parameters and clinical features collected after ICD implantation. From the feature importance analysis of the best ML model, we established easily calculable scores. Among the patients, 25 (13.7%) experienced inappropriate therapy, and we identified 16 significant predictors. Using recursive feature elimination with cross-validation, we reduced the features to six with high feature importance: history of atrial arrhythmia (Atr-arrhythm), ischemic cardiomyopathy (ICM), absence of diabetes mellitus (DM), lack of cardiac resynchronization therapy (CRT), V3 ST level at J point (V3 STJ), and V5 R-wave amplitudes (V5R amp). The extra-trees classifier yielded the highest area under receiver operating characteristics curve (AUROC; 0.869 on test data). Thus, the Cardi35 score was defined as [+ 5.5*Atr-arrhythm - 1.5*CRT + 1.0*V3STJ + 1.0*V5R - 1.0*ICM - 0.5*DM], which demonstrated a hazard ratio of 1.62 (P < 0.001). A cut-off value of the score + 5.5 showed high AUROC (0.826). The ML approach can yield a robust prediction model, and the Cardi35 score was a convenient predictor for inappropriate therapy.

Clinical and electrophysiological characteristics in patients with sustained monomorphic reentrant ventricular tachycardia associated with dilated-phase hypertrophic cardiomyopathy.

AIMS: Little is known about sustained monomorphic ventricular tachycardia (SMVT) associated with dilated-phase hypertrophic cardiomyopathy (DHCM). The purpose of this study was to clarify the clinical characteristics and effectiveness of catheter ablation for SMVTs in DHCM patients. METHODS AND RESULTS: Five patients with DHCM (mean age; 67.0 years old, five males) who underwent catheter ablation for drug-refractory SMVTs were included the study. Four of five patients suffered from electrical storm. When the endocardial ablation failed, epicardial and/or intracoronary ethanol ablation, or surgical cryoablation was performed. We reviewed all ablation procedures and electrocardiogram (ECG) of targeted SMVTs. A total of 13 SMVTs were targeted for ablation. Mechanism of all ventricular tachycardias (VTs) was diagnosed as reentry. Endocardial ablation successfully eliminated all VTs in two patients. The remaining three patients needed epicardial ablation, intracoronary ethanol ablation, and surgical cryoablation. All but one VT arose from the basal septum, basal anterior to anterolateral left ventricle (LV). Although the ECGs demonstrated similar features of idiopathic outflow or mitral annulus VTs reflecting the origins, there were characteristic multiple QRS deflections. Following the ablation, four (80%) of the five patients are free from VT recurrence during 18 months of the follow-up period. CONCLUSIONS: In DHCM patients, VT circuits predominantly distributed in the basal septum and the basal anterior to anterolateral LV. In addition to the endocardial ablation, alternative approaches were required in some patients.

Machine learning of microvolt-level 12-lead electrocardiogram can help distinguish takotsubo syndrome and acute anterior myocardial infarction.

Background: Qualitative differences in 12-lead electrocardiograms (ECG) at onset have been reported in patients with takotsubo syndrome (TTS) and acute anterior myocardial infarction (Ant-AMI). We aimed to distinguish these diseases by machine learning (ML) approach of microvolt-level quantitative measurements. Methods: We enrolled 56 consecutive patients with sinus rhythm TTS (median age, 77 years; 16 men), and 1-to-1 random matching was performed based on age and sex of the patients. The ECG in the emergency room was evaluated using an automated system (ECAPs12c; Nihon-Koden). Statistical and ML predictive models for TTS were constructed using clinical features and ECG parameters. Results: Statistically significant differences were observed in 25 parameters; the V1 ST level at the J point (V1 STJ) showed the lowest P value (P < .001). V1 STJ ≤+18 µV showed the highest accuracy for TTS (0.773). The highest area under the receiver operating characteristic curve (AUROC) was shown in the aVR ST level at 1/16th of the preceding R-R interval after the J point (aVR STmid: 0.727). Conversely, the light gradient boosting machine (model_LGBM) and extra tree classifier (model_ET) indicated higher accuracy (model_LGBM: 0.842, model_ET: 0.831) and AUROC (model_LGBM: 0.868, model_ET 0.896) than other statistical models. V1 STJ had high feature importance and Shapley additive explanation values in the 2 ML models. Conclusion: ML applied to automated microvolt-level ECG measurements showed the possibility of distinguishing between TTS and Ant-AMI, which may be a clinically useful ECG-based discriminator.

Low risk for arrhythmic events in asymptomatic patients with drug-induced type 1 ECG. Do patients with drug-induced Brugada type ECG have poor prognosis? (Con).

The type 1 ST-segment elevation is diagnostic for Brugada syndrome (BS) and its presence may sometimes be associated with a high risk of arrhythmic events. The type 1 ECG is also known to be unmasked by administration of sodium-channel blockers in equivocal or suspected cases of BS, and the drug-challenge test is frequently used in the diagnostic approach. In large cohort studies the spontaneous appearance of the type 1 ECG with symptoms of aborted sudden death or unexplained syncope are indicative of a poor prognosis for patients with BS compared with not having clinical symptoms. Therefore, the spontaneous type 1 ECG appears to represent an important predictive sign for cardiac events. It is unknown, however, whether or not the drug-induced type 1 ECG is as useful as the spontaneous type 1 for predicting cardiac events in asymptomatic subjects showing non-type 1 ECG. Review of the literature for large cohort studies indicates that there is a low incidence of arrhythmic events in asymptomatic patients with either the spontaneous or drug-induced type 1 ECG compared with symptomatic subjects, and the drug-induced type 1 ECG in asymptomatic patients does not add to an increase in arrhythmic risk. Therefore, drug testing to unmask the type 1 ECG in asymptomatic patients with a non-type 1 BS ECG does not have an additional value for risk stratification of cardiac events, although it might be useful in symptomatic patients showing only the non-type 1 ECG.

Catheter ablation of ventricular insertion of Mahaim fiber using noncontact mapping system in a patient with mirror-image dextrocardia.

We report a case of mirror-image dextrocardia with antidromic atrioventricular reciprocating tachycardia via the Mahaim fiber. Using the noncontact mapping system, arborized ventricular insertion of the Mahaim fiber was identified and successfully ablated.