Modern mapping and ablation of idiopathic outflow tract ventricular arrhythmias

Outflow tract (OT) premature ventricular complexes (PVCs) are being recognized as a common and often troubling, clinical electrocardiographic finding. The OT areas consist of the Right Ventricular Outflow Tract (RVOT), the Left Ventricular Outflow Tract (LVOT), the Aortomitral Continuity (AMC), the aortic cusps and the Left Ventricular (LV) summit. By definition, all OT PVCs will exhibit an inferior QRS axis, defined as positive net forces in leads II, III and aVF. Activation mapping using the contemporary 3D mapping systems followed by pace mapping is the cornerstone strategy of every ablation procedure in these patients. In this mini review we discuss in brief all the modern mapping and ablation modalities for successful elimination of OT PVCs, along with the potential advantages and disadvantages of each ablation technique

Incorporating latent variables using nonnegative matrix factorization improves risk stratification in Brugada syndrome

Background: A combination of clinical and electrocardiographic risk factors is used for risk stratification in Brugada syndrome. In this study, we tested the hypothesis that the incorporation of latent variables between variables using nonnegative matrix factorization can improve risk stratification compared with logistic regression. Methods and Results: This was a retrospective cohort study of patients presented with Brugada electrocardiographic patterns between 2000 and 2016 from Hong Kong, China. The primary outcome was spontaneous ventricular tachycardia/ventricular fibrillation. The external validation cohort included patients from 3 countries. A total of 149 patients with Brugada syndrome (84% males, median age of presentation 50 [38–61] years) were included. Compared with the nonarrhythmic group (n=117, 79%), the spontaneous ventricular tachycardia/ ventricular fibrillation group (n=32, 21%) were more likely to suffer from syncope (69% versus 37%, P=0.001) and atrial fibrillation (16% versus 4%, P=0.023) as well as displayed longer QTc intervals (424 [399–449] versus 408 [386–425]; P=0.020). No difference in QRS interval was observed (108 [98–114] versus 102 [95–110], P=0.104). Logistic regression found that syncope (odds ratio, 3.79; 95% CI, 1.64–8.74; P=0.002), atrial fibrillation (odds ratio, 4.15; 95% CI, 1.12–15.36; P=0.033), QRS duration (odds ratio, 1.03; 95% CI, 1.002–1.06; P=0.037) and QTc interval (odds ratio, 1.02; 95% CI, 1.01–1.03; P=0.009) were significant predictors of spontaneous ventricular tachycardia/ventricular fibrillation. Increasing the number of latent variables of these electrocardiographic indices incorporated from n=0 (logistic regression) to n=6 by nonnegative matrix factorization improved the area under the curve of the receiving operating characteristics curve from 0.71 to 0.80. The model improves area under the curve of external validation cohort (n=227) from 0.64 to 0.71. Conclusions: Nonnegative matrix factorization improves the predictive performance of arrhythmic outcomes by extracting latent features between different variables

Predictors of ventricular arrhythmias in patients with mitral valve prolapse: A meta-analysis

Mitral valve prolapse (MVP) has an estimated prevalence of 2-3% in the general population. Patients with MVP have an increased risk of ventricular arrhythmic events. The aim of this meta-analysis was to identify easily obtained markers that can be used for the arrhythmic risk stratification of MVP patients. This meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA Statement). The search strategy identified 23 studies that were finally included in the study. The quantitative synthesis showed that late gadolinium enhancement (LGE) [RR 6.40 (2.11-19.39), I2 77%, P = 0.001], longer QTc interval [mean difference: 14.2 (8.92-19.49) I2 0%, P < 0.001], T-wave inversion in inferior leads [RR 1.60 (1.39-1.86), I2 0%, P < 0.001], mitral annular disjunction (MAD) [RR 1.77 (1.29-2.44), I2 37%, P = 0.0005], lower left ventricular ejection fraction (LVEF) [mean difference: -0.77 (-1.48, -0.07) I2 0%, P = 0.03], bileaflet MVP [RR 1.32 (1.16-1.49), I2 0%, P < 0.001], increased anterior [mean difference: 0.45 (0.28, 0.61), I2 0%, P < 0.001] and posterior [mean difference: 0.39 (0.26, 0.52), I2 0%, P < 0.001] mitral leaflet thickness were significantly associated with ventricular arrhythmias in MVP patients. On the other hand, gender, QRS duration, anterior, and posterior mitral leaflet length were not associated with increased risk of arrhythmias. In conclusion, inferior T-wave inversions, QTc interval, LGE, LVEF, MAD, bileaflet MVP, anterior, and posterior mitral leaflet thickness are easily obtained markers that can be used for the risk stratification of patients with MVP. Prospective studies should be designed for the better stratification of this population. [Abstract copyright: Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.

Predictors of ventricular arrhythmias in patients with Mitral valve prolapse: A meta-analysis.

Mitral valve prolapse (MVP) has an estimated prevalence of 2-3% in the general population. Patients with MVP have an increased risk of ventricular arrhythmic events. The aim of this meta-analysis was to identify easily obtained markers that can be used for the arrhythmic risk stratification of MVP patients. This meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA Statement). The search strategy identified 23 studies that were finally included in the study. The quantitative synthesis showed that late gadolinium enhancement (LGE) [RR 6.40 (2.11-19.39), I2 77%, P = 0.001], longer QTc interval [mean difference: 14.2 (8.92-19.49) I2 0%, P < 0.001], T-wave inversion in inferior leads [RR 1.60 (1.39-1.86), I2 0%, P < 0.001], mitral annular disjunction (MAD) [RR 1.77 (1.29-2.44), I2 37%, P = 0.0005], lower left ventricular ejection fraction (LVEF) [mean difference: -0.77 (-1.48, -0.07) I2 0%, P = 0.03], bileaflet MVP [RR 1.32 (1.16-1.49), I2 0%, P < 0.001], increased anterior [mean difference: 0.45 (0.28, 0.61), I2 0%, P < 0.001] and posterior [mean difference: 0.39 (0.26, 0.52), I2 0%, P < 0.001] mitral leaflet thickness were significantly associated with ventricular arrhythmias in MVP patients. On the other hand, gender, QRS duration, anterior, and posterior mitral leaflet length were not associated with increased risk of arrhythmias. In conclusion, inferior T-wave inversions, QTc interval, LGE, LVEF, MAD, bileaflet MVP, anterior, and posterior mitral leaflet thickness are easily obtained markers that can be used for the risk stratification of patients with MVP. Prospective studies should be designed for the better stratification of this population. [Abstract copyright: Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.

Right ventricular outflow tract electroanatomical abnormalities in asymptomatic and high-risk symptomatic patients with Brugada syndrome: Evidence for a new risk stratification tool?

Introduction: Microstructural abnormalities at the epicardium of the right ventricular outflow tract (RVOT) may provide the arrhythmia substrate in Brugada syndrome (BrS). Endocardial unipolar electroanatomical mapping allows the identification of epicardial abnormalities. We evaluated the clinical implications of an abnormal endocardial substrate as perceived by high-density electroanatomical mapping (HDEAM) in patients with BrS. Methods: Fourteen high-risk BrS patients with aborted sudden cardiac death (SCD) (12 males, mean age: 41.9 ± 11.8 years) underwent combined endocardial-epicardial HDEAM of the right ventricle/RVOT, while 40 asymptomatic patients (33 males, mean age: 42 ± 10.7 years) underwent endocardial HDEAM. Based on combined endocardial-epicardial procedures, endocardial HDEAM was considered abnormal in the presence of low voltage areas (LVAs) more than 1 cm2 with bipolar signals less than 1 mV and unipolar signals less than 5.3 mV. Programmed ventricular stimulation (PVS) was performed in all patients. Results: The endocardial unipolar LVAs were colocalized with epicardial bipolar LVAs (p = .0027). Patients with aborted SCD exhibited significantly wider endocardial unipolar (p < .01) and bipolar LVAs (p < .01) compared with asymptomatic individuals. A substrate size of unipolar LVAs more than 14.5 cm2 (area under the curve [AUC]: 0.92, p < .001] and bipolar LVAs more than 3.68 cm2 (AUC: 0.82, p = .001) distinguished symptomatic from asymptomatic patients. Patients with ventricular fibrillation inducibility (23/54) demonstrated broader endocardial unipolar (p < .001) and bipolar LVAs (p < .001) than noninducible patients. The presence of unipolar LVAs more than 13.5 cm2 (AUC: 0.95, p < .001) and bipolar LVAs more than 2.97 cm2 (AUC: 0.78, p < .001) predicted a positive PVS. Conclusion: Extensive endocardial electroanatomical abnormalities identify high-risk patients with BrS. Endocardial HDEAM may allow risk stratification of asymptomatic patients referred for PVS