Mechanism, diagnosis, and treatment of outflow tract tachycardia

Additional Lesion Sets in Ablation of Outflow Tract Premature Ventricular Contractions: A Randomized Clinical Trial

Importance

Recurrence remains a challenge after ablation of outflow tract premature ventricular contractions (OT-PVCs). Although adding additional lesions next to the index effective ablation site is sometimes performed to reinforce the ablation, it remains uncertain whether this approach is effective.

Objective

To test the hypothesis that additional ablation lesions would reduce the recurrence rate compared with single-point ablation at the index effective site for the ablation of OT-PVCs.

Design, Setting, and Participants

This study was a multicenter, prospective, randomized clinical trial. Patients receiving their first catheter ablation for OT-PVCs were enrolled from 18 hospitals in China between October 2021 and February 2023. Scheduled follow-up duration was 3 months after the procedure.

Intervention

After identifying the target point and eliminating the PVC by a single-point ablation, patients were randomized 1:1 into an additional ablation group or a control group.

Main Outcomes and Measures

The primary end point of the study was freedom from PVC recurrence (≥80% reduction of PVC burden, which is the number of PVCs in 24 hours/total heartbeats in 24 hours × 100%) from baseline to 3 months postprocedure.

Results

Of 308 patients enrolled in the study, 286 (mean [SD] age, 49.2 [14.6] years; 173 female [60.5%]) were randomized to the additional ablation or the control group. The additional ablation group had a mean (SD) of 6.3 (1.1) radiofrequency applications, whereas the control group (single-point ablation group) had a mean (SD) of 1 (0) radiofrequency application. After a median (IQR) follow-up of 3.2 (0) months, the rate of freedom from PVCs was significantly higher in the additional ablation group (139 of 142 [97.9%]) compared with the control group (115 of 139 [82.7%]; P < .001). Patients in the additional ablation group also had a more substantial reduction in PVC burden than the control group (mean [SD] reduction, 23.0% [10.5%] vs 19.0% [10.4%]; P = .002). There were no severe periprocedural complications in either group.

Conclusions and Relevance

This randomized clinical trial showed a benefit of additional ablation in reducing the recurrence of OT-PVCs compared with the single-point ablation strategy, without increased complication risk. Additional ablations surrounding the index effective ablation point should be considered in OT-PVC ablation.

Trial Registration

Chinese Clinical Trials Registry Identifier: ChiCTR2200055340.

Morphological phenotype of right ventricular outflow tract is associated with cardiovascular outcomes and premature death

Morphology of right ventricular outflow tract (RVOT) is potentially related to cardiovascular outcomes. However, this relationship still remains to be verified with direct evidence. We retrospectively reviewed cases from the autopsy specimen library in the Center of Forensic Medicine in Sun Yat-sen University from 2017 to 2023. Six RVOT morphological characteristics were measured and their association with cardiovascular diseases (CVDs), sudden cardiac death (SCD) and age at death was evaluated. Relationship between myocardial fibrosis in RVOT and CVDs was investigated. RVOT characteristics were recruited by machine learning algorithms for diagnosing CVDs. A total of 2370 cases were finally recruited. Perimeter of sub-valve plane (pSBV) in RVOT was positively associated with risk of CVDs and SCD (OR: 1.21, 95%CI: 1.07-1.37, p = 0.003; OR: 1.33, 95%CI: 1.16-1.52, p < 0.001). Compared with thickness of septum (tS) < 3.0 mm, tS ≥ 3.0 mm was associated with premature death in disease-dominant death (β=-0.16, 95%CI: -0.20 to -0.11, p < 0.001) and SCD (β=-0.15, 95%CI: -0.21 to -0.10, p < 0.001). Degree of myocardial fibrosis in the posterior septum was increased in coronary atherosclerosis (6.86%±2.48% vs. 4.91%±2.14%, p = 0.011) and cardiomyopathies (8.11%±3.24% vs. 4.88%±3.11%, p = 0.005). A logistic regression model, recruiting age, left and right ventricular wall thickness, pSBV, circumference of pulmonary annulus and aortic annulus, was elected as an optimal diagnostic model of CVDs, yielding AUC of 0.734 (95%CI: 0.705-0.763), 0.781 (0.740-0.821) and 0.763 (0.725-0.800) in training, validation and test sets. Increased pSBV significantly correlates with higher risk of CVDs and SCD. And tS ≥ 3.0 mm is an independent risk factor of premature death regardless of diseases.

Predictive value of cardiac magnetic resonance imaging for fatal arrhythmias in structural and nonstructural heart diseases

Background

The risk stratification for fatal arrhythmias remains inadequate. Cardiac magnetic resonance (CMR) imaging provides a detailed evaluation of arrhythmogenic substrates. This study investigated the predictive capacity of multiparametric CMR for fatal ventricular arrhythmias (VAs) in a heterogeneous disease cohort.

Methods

The study included 396 consecutive patients with structural heart disease (SHD, n = 248) and non-apparent SHD (n = 148) who underwent CMR scans between 2018 and 2022. The primary endpoint was fatal composite arrhythmias.

Results

Thirty-three patients (8.3 %) experienced fatal arrhythmias (25 with SHD, 8 with non-apparent SHD) over a median follow-up of 24 months. The independent risk factors for patients with SHD included syncope (hazard ratio [HR] = 5.347; P < 0.001), VA history (HR = 3.705; P = 0.004), right ventricular ejection fraction (RVEF) ≤ 45 % (HR = 2.587; P = 0.039), and the presence of late gadolinium enhancement (LGE) (HR = 4.767; P = 0.040). In the non-apparent SHD group, fatal arrhythmias were independently correlated with VA history (HR = 10.23; P = 0.005), RVEF ≤ 45 % (HR = 8.307; P = 0.015), and CMR myocardial abnormalities (HR = 5.203; P = 0.033). Patients at high risk of fatal arrhythmia in the SHD and non-apparent SHD groups exhibited 3-year event-free survival rates of 69.4 % and 83.5 %, respectively.

Conclusion

CMR provides effective prognostic information for patients with and without apparent SHD. The presence of LGE, CMR myocardial abnormalities, and right ventricular dysfunction are strong risk markers for fatal arrhythmias.

Automatic and interpretable prediction of the site of origin in outflow tract ventricular arrhythmias: machine learning integrating electrocardiograms and clinical data

The treatment of outflow tract ventricular arrhythmias (OTVA) through radiofrequency ablation requires the precise identification of the site of origin (SOO). Pinpointing the SOO enhances the likelihood of a successful procedure, reducing intervention times and recurrence rates. Current clinical methods to identify the SOO are based on qualitative analysis of pre-operative electrocardiograms (ECG), heavily relying on physician's expertise. Although computational models and machine learning (ML) approaches have been proposed to assist OTVA procedures, they either consume substantial time, lack interpretability or do not use clinical information. Here, we propose an alternative strategy for automatically predicting the ventricular origin of OTVA patients using ML. Our objective was to classify ventricular (left/right) origin in the outflow tracts (LVOT and RVOT, respectively), integrating ECG and clinical data from each patient. Extending beyond differentiating ventricle origin, we explored specific SOO characterization. Utilizing four databases, we also trained supervised learning models on the QRS complexes of the ECGs, clinical data, and their combinations. The best model achieved an accuracy of 89%, highlighting the significance of precordial leads V1-V4, especially in the R/S transition and initiation of the QRS complex in V2. Unsupervised analysis revealed that some origins tended to group closer than others, e.g., right coronary cusp (RCC) with a less sparse group than the aortic cusp origins, suggesting identifiable patterns for specific SOOs.

Ventricular Tachycardia Due to Triggered Activity: Role of Early and Delayed Afterdepolarizations

Most forms of sustained ventricular tachycardia (VT) are caused by re-entry, resulting from altered myocardial conduction and refractoriness secondary to underlying structural heart disease. In contrast, VT caused by triggered activity (TA) is unrelated to an abnormal structural substrate and is often caused by molecular defects affecting ion channel function or regulation of intracellular calcium cycling. This review summarizes the cellular and molecular bases underlying TA and exemplifies their clinical relevance with selective representative scenarios. The underlying basis of TA caused by delayed afterdepolarizations is related to sarcoplasmic reticulum calcium overload, calcium waves, and diastolic sarcoplasmic reticulum calcium leak. Clinical examples of TA caused by delayed afterdepolarizations include sustained right and left ventricular outflow tract tachycardia and catecholaminergic polymorphic VT. The other form of afterpotentials, early afterdepolarizations, are systolic events and inscribe early afterdepolarizations during phase 2 or phase 3 of the action potential. The fundamental defect is a decrease in repolarization reserve with associated increases in late plateau inward currents. Malignant ventricular arrhythmias in the long QT syndromes are initiated by early afterdepolarization-mediated TA. An understanding of the molecular and cellular bases of these arrhythmias has resulted in generally effective pharmacologic-based therapies, but these are nonspecific agents that have off-target effects. Therapeutic efficacy may need to be augmented with an implantable defibrillator. Next-generation therapies will include novel agents that rescue arrhythmogenic abnormalities in cellular signaling pathways and gene therapy approaches that transfer or edit pathogenic gene variants or silence mutant messenger ribonucleic acid.

The significance of heart rate variability in patients with frequent premature ventricular complex originating from the ventricular outflow tract

BACKGROUND

As an indicator of cardiac autonomic nervous activity, heart rate variability (HRV) is closely linked to premature ventricular complexes (PVCs). However, its role in patients with frequent PVCs originating from the ventricular outflow tract remains unclear.

HYPOTHESIS

Here, we hypothesize that there may be alterations in HRV among patients with frequent PVCs originating from the ventricular outflow tract, which could play significant roles in the management of such patients.

METHODS

A retrospective study was conducted, including 106 patients with frequent outflow tract PVCs and 106 healthy participants as controls. HRV was assessed based on the 24-hour Holter recording. The originating foci of PVCs were identified during radiofrequency catheter ablation.

RESULTS

Patients with frequent outflow tract PVCs exhibited decreased levels of high frequency (HF), standard deviation of all NN intervals, and standard deviation of the average NN intervals, but increased ratios of low frequency to HF (LF/HF ratio), even after propensity score-matched analysis. Further investigation revealed that patients with PVCs originating from right ventricular outflow tract (RVOT) had much higher LF/HF ratios. Multivariate logistic regression analysis demonstrated that the LF/HF ratio was independently associated with PVCs originating from RVOT. Receiver operating characteristics curve indicated that the LF/HF ratio effectively determined the origin of PVCs (the area under the curve = 0.75, p < .001).

CONCLUSIONS

Patients with frequent outflow tract PVCs exhibited impaired HRV. Additionally, the LF/HF ratio played a significant role in determining the origin of outflow tract PVCs.

Interpretation and management of premature ventricular beats in athletes: An expert opinion document of the Italian Society of Sports Cardiology (SICSPORT)

Premature ventricular beats (PVBs) are recorded in a sizeable proportion of athletes during pre-participation screening, especially if the evaluation includes both resting and exercise ECG. While in the majority of cases no underlying heart disease is present, in others PVBs may be the sign of a condition at risk of sudden cardiac death, including cardiomyopathies, congenital, coronary artery, heart valves and ion channels diseases. In this expert opinion document of the Italian Society of Sports Cardiology, we propose a multiparametric interpretation approach to PVBs in athletes and a stepwise diagnostic algorithm. The clinical work-up should include the assessment of the probable site of origin based on the ECG pattern of the ectopic QRS and of the arrhythmia behavior (including the number of different PVB morphologies, complexity, response to exercise and reproducibility), as well as first-line tests such as echocardiography. Based on this initial evaluation, most athletes can be reassured of the benign nature of PVBs and cleared for competition under periodical follow-up. However, when the clinical suspicion is high, further investigations with non-invasive (e.g. cardiac magnetic resonance, cardiac computed tomography, genetic testing) and, in very selected cases, invasive (e.g. endocardial voltage mapping and endomyocardial biopsy) tests should be carried out to rule out a high-risk condition. Importantly, such advanced tests should be performed in centers with a consolidated experience not only in the technique, but also in evaluation of athletes.

Lead I R-wave indexes: A novel electrocardiographic criterion for distinguishing the origin of idiopathic premature ventricular contractions from the three subregions of the aortic sinus cusps

PURPOSE

The current study was conducted to investigate the electrocardiographic (ECG) characteristics of idiopathic premature ventricular contractions (PVCs) originating from the aortic sinus cusp (ASC) and establish a novel ECG criterion to discriminate PVCs originating from the right coronary cusp (RCC), left coronary cusp (LCC), and the left and right coronary cusp junction (LRJ).

METHODS

A retrospective analysis was performed on a total of 133 patients with idiopathic PVCs who underwent successful mapping and ablation. The sites of origin (SOO) were confirmed using fluoroscopy and a three-dimensional mapping system during radiofrequency catheter ablation (RFCA). Among the patients, 69 had PVCs originating from the LCC, 39 from the RCC, and 25 from the LRJ. Characteristics of surface 12‑lead electrocardiograms (ECGs) recorded during PVCs were analyzed. Q-, R-, S, and R'-wave amplitudes were measured in lead I, and the lead I R-wave indexes (IRa, IRb, IRc, IRd, and IRe) were derived by employing multiplication, subtraction, sum, and division operations on these ECG measurements. Notably, IRb and IRe demonstrated usefulness as ECG indexes for discriminating PVCs originating from RCC, LCC, and LRJ in the ASC.

RESULTS

The R- and S-wave amplitudes in lead I exhibited statistically significant differences among the three groups (P < 0.001 and P < 0.001, respectively). In discriminating PVCs originating from the RCC from the other two groups, IRb showed the largest area under the curve (AUC) of 0.813, as assessed by receiver operating characteristic (ROC) analysis, with a cutoff value of ≤0.5 indicating PVCs of RCC origin. The sensitivity and specificity were 80.3% and 78.7%, respectively. For discriminating PVCs arising from the LCC from those in the LRJ group, IRe exhibited the largest AUC of 0.801, with an optimal cutoff value of 0. An IRe value >0 indicated PVCs originating from the LRJ, while an IRe value ≤0 indicated PVCs originating from the LCC. The sensitivity and specificity of the IRe index were 84.0% and 70.7%, respectively.

CONCLUSION

Lead I R-wave indexes provided simple and useful ECG criteria for discriminating PVCs originating from the LCC, RCC, and LRJ in the left ventricular outflow tract (LVOT).

Zero x-rays radiofrequency catheter ablation for ventricular premature contraction originating from the left coronary cusp during pregnancy: a case report

Pregnancy predisposes to arrhythmias in females due to physiological changes in the cardiovascular system, enhanced activity of the sympathetic nervous system (SNS), and changes in the endocrine system, regardless of whether there exist cardiovascular diseases before the pregnancy. Tachyarrhythmias may present for the first time or worsen persistently during pregnancy, potentially leading to maternal heart failure and sudden death, as well as some adverse fetal outcomes such as growth restriction, distress, premature birth, and stillbirth. Radiofrequency ablation (RFA) is one of the most important therapeutic methods for tachyarrhythmias. According to the 2019 European Society of Cardiology (ESC) guidelines, RFA in pregnant women should preferably be performed without x-rays. Since the 2000s, 3D mapping technique has rapidly developed, laying the foundation for cardiac electrophysiology examination free from x-rays. Ventricular arrhythmia originating from the left coronary cusp (LCC) is not common in clinic. RFA is challenging in the treatment of this type of disease due to the anatomical feature that the opening of the left main coronary artery is localized in the LCC.

Twenty-five years of catheter ablation of ventricular tachycardia: a look back and a look forward

This article will discuss the past, present, and future of ventricular tachycardia ablation and the continuing contribution of the Europace journal as the platform for publication of milestone research papers in this field of ventricular tachycardia ablation.

Effect of β1-adrenergic receptor gene polymorphism on ventricular arrhythmia and prognosis after myocardial infarction

BACKGROUND

Ventricular arrhythmia is a common complication of acute myocardial infarction (AMI). The Arg389Gly polymorphism of the β1-adrenergic receptor genotype may affect AMI patients.

METHOD

Patients diagnosed with AMI were included in this study. Clinical data were obtained from the patient's medical history, and genotypes were retrieved from laboratory test reports. ECG data were recorded daily. Data analysis was performed using SPSS 20.0, and differences were deemed statistically significant at P  < 0.05.

RESULT

In the final study, 213 patients were included. The proportions of the Arg389Arg, Arg389Gly, and Gly389Gly genotypes were 65.7%, 21.6%, and 12.7%, respectively. Patients with the Arg389Arg genotype exhibited significantly elevated cardiac troponin T (cTnT) and pro-BNP levels compared to the Arg389Gly and Gly389Gly genotypes [cTnT: 4.00 ± 2.43 ng/ml versus 2.82 ± 1.82 ng/ml, P  = 0.012; pro-BNP: 1942.37 (1223.194, 206.59) pg/ml versus 1604.57 (798.05, 1884.79) pg/ml, P  = 0.005]. Patients with the Arg389Arg genotype exhibited a lower ejection fraction than those with the Gly389Gly genotype (54.13 ± 4.94% vs. 57.11 ± 2.87%, P  < 0.001). Patients homozygous for Arg389Arg exhibited a higher incidence of ventricular tachycardia and a greater proportion of premature ventricular contraction (PVC) compared to patients homozygous for Gly389Gly (ventricular tachycardia: 19.29% vs. 0.00%, P  = 0.009; PVC: 70.00% vs. 40.74%, P  = 0.003).

CONCLUSION

The Arg389Arg genotype is associated with greater myocardial damage, impaired cardiac function, and an increased probability of ventricular arrhythmia in AMI patients.

Electrical and Structural Insights into Right Ventricular Outflow Tract Arrhythmogenesis

The right ventricular outflow tract (RVOT) is the major origin of ventricular arrhythmias, including premature ventricular contractions, idiopathic ventricular arrhythmias, Brugada syndrome, torsade de pointes, long QT syndrome, and arrhythmogenic right ventricular cardiomyopathy. The RVOT has distinct developmental origins and cellular characteristics and a complex myocardial architecture with high shear wall stress, which may lead to its high vulnerability to arrhythmogenesis. RVOT myocytes are vulnerable to intracellular sodium and calcium overload due to calcium handling protein modulation, enhanced CaMKII activity, ryanodine receptor phosphorylation, and a higher cAMP level activated by predisposing factors or pathological conditions. A reduction in Cx43 and Scn5a expression may lead to electrical uncoupling in RVOT. The purpose of this review is to update the current understanding of the cellular and molecular mechanisms of RVOT arrhythmogenesis.

Image-Based Tools and Analysis for Human RVOT/RV Structures

The right-ventricular (RV) outflow tract (RVOT) and the transition to the RV free wall are recognized sources of arrhythmia in human hearts. However, we do not fully understand myocardial tissue structures in this region. Human heart tissue was processed for optical clarity, labelled with wheat-germ agglutin (WGA) and anti-Cx43, and imaged on a custom-built line scanning confocal microscope. The 3D images were analyzed for myocyte gross structures and cell morphology. There were regions of high organization as well as rapid changes to more heterogeneous regions. Preliminary cell segmentations were used to estimate cell morphology. Observed RVOT/RV structure is consistent with known arrhythmic substrates.Clinical Relevance- New views of human tissue structure enable clearer clinical understanding of arrhythmogenic activation pathways and targets for invasive treatment such as RF ablation.

Prognostic impact of morphology and duration of premature ventricular contractions in a population without structural heart disease

BACKGROUND

Premature ventricular contractions (PVCs) are a common form of arrhythmia associated with an unfavorable prognosis in patients with structural heart disease. It is unclear whether PVCs site of origin and QRS-width has a prognostic significance in patients without structural heart disease. The aim of this study was to assess the prognostic importance of PVCs morphology and duration in this patient group.

METHODS

We included 511 consecutive patients without a history of previous heart disease. They were examined with echocardiography and exercise test with normal findings. We categorized the PVCs from a 12 lead ECG according to morphology and width of the QRS-complex and analyzed the outcome in terms of a composite endpoint of total mortality and cardiovascular morbidity.

RESULTS

During a median follow-up time of 5.3 years, 19 patients (3.5%) died and 61 (11.3%) met the composite outcome. Patients with PVCs originating from the outflow tracts had a significantly lower risk for the composite outcome compared to patients with non-OT-PVCs. Similarly, patients with PVC originating from the right ventricle had a better outcome than patients with left ventricular PCVs. No difference in outcome depending on QRS-width during PVCs was noticed.

CONCLUSION

In our cohort of consecutively included PVC patients without structural heart disease PVCs from the outflow tracts were associated with a better prognostic outcome than non-OT PVCs; the same was true for right ventricular PVCs when compared to left ventricular ones. The classification of the origin of the PVCs was based on 12-lead ECG morphology. QRS-width during PVC did not seem to have prognostic significance.

Comparing the Efficacy of Carvedilol and Flecainide on the Treatment of Idiopathic Premature Ventricular Complexes from Ventricular Outflow Tract: A Multicenter, Randomized, Open-Label Pilot Study

The mechanism of premature ventricular complexes (PVC) occurring in the ventricular outflow tract (OT) is related to an intracellular calcium overload and delayed afterdepolarizations that lead to triggered activity. The guidelines recommend using beta-blockers and flecainide for idiopathic PVCs, but they also acknowledge the limited evidence supporting this recommendation. We conducted a multicenter, randomized, open-label pilot study comparing the effect of carvedilol and flecainide on OT PVC, which are widely used to treat this arrhythmia. Patients with a 24 h Holter recording a PVC burden ≥ 5%, which showed positive R waves in leads II, III, and aVF, and without structural heart disease were enrolled. They were randomly assigned to the carvedilol or flecainide group, and the maximum tolerated dose was administered for 12 weeks. A total of 103 participants completed the protocol: 51 with carvedilol and 52 with flecainide. After 12 weeks of treatment, the mean PVC burden significantly decreased in both groups: 20.3 ± 11.5 to 14.6 ± 10.8% with carvedilol (p < 0.0001) and 17.1 ± 9.9 to 6.6 ± 9.9% with flecainide (p < 0.0001). Both carvedilol and flecainide effectively suppressed OT PVCs in patients without structural heart disease, with flecainide showing a superior efficacy compared to carvedilol.

Confusion in a patient with premature ventricular complexes originating in the left ventricular summit

Background

Premature ventricular complexes (PVCs) originating in the ventricular outflow tracts are mostly of benign character.

Case Summary

We describe a rare case of pulmonary hypertension with severe hypoxaemia and confusion caused by a significant mitral regurgitation (MR) during PVC originating in the left ventricle summit. After successful PVC ablation, all above-mentioned clinical parameters had normalized.

Discussion

Premature ventricular complexes originating in the outflow tracts should be considered as a potential though rare cause of severe MR and pulmonary hypertension.

Revisiting the Anatomy of the Left Ventricular Summit

The left ventricular summit corresponds to the epicardial side of the basal superior free wall, extending from the base of the left coronary aortic sinus. The summit composes the floor of the compartment surrounded by the aortic root, infundibulum, pulmonary root, and left atrial appendage. The compartment is filled with thick adipose tissue, carrying the coronary vessels. Thus, the treatment of ventricular tachycardia originating from the summit is challenging, and three-dimensional understanding of this complicated region is fundamental. We revisit the clinical anatomy of the left ventricular summit with original images from the Wallace A. McAlpine collection.

The predictive value of Tp-Te interval, Tp-Te/QT ratio, and QRS-T angle of idiopathic ventricular tachycardia in patients with ventricular premature beats

BACKGROUND

Identify idiopathic ventricular tachycardia in patients with ventricular premature beats was required to have effectively treatment.

HYPOTHESIS

The aim of this study is to investigate the predictive value of Tp-Te interval, Tp-Te/QT ratio, and QRS-T angle of idiopathic ventricular tachycardia in patients with idiopathic ventricular premature beats.

METHODS

One hundred and seventy-eight patients who had undergone premature ventricular complex/ventricular tachycardia (PVC/VT) ablation between January 1, 2020 and August 30, 2022 constituted our study population as ventricular arrhythmia group. Seventy-five healthy people were selected as control group. Patients with no episode of VT were classified as PVC group, while with any episode of VT that has the same morphology with PVC were classified as PVC with VT group. Patients in PVC with VT group were divided into two groups: nonsustained VT group (duration of any episode of VT below 30 s) and sustained VT group (duration of any episode of VT over 30 s). Tp-Te interval, Tp-Te/QT ratio and QRS-T angle were compared in groups.

RESULTS

Tp-Te interval, Tp-Te/QT ratio and patients with increased QRS-T angle in PVC with VT group were higher or more than those in PVC group (p < .001). The value of combined diagnosis of these indexes was higher. Tp-Te interval was longer in the sustained VT group compared to the nonsustained VT group (p = .009).

CONCLUSION

Tp-Te interval, Tp-Te/QT ratio, and QRS-T angle may have a predictive value of presence of idiopathic VT in patients with premature beats and the combined prediction of these indexes is more valuable. Tp-Te interval maybe helpful for prediction of sustained idiopathic VT.

Mechanisms of Ventricular Arrhythmias and Implications for Catheter Ablation

Ventricular arrhythmias present with a wide spectrum of clinical manifestations, from mildly symptomatic frequent premature ventricular contractions to life-threatening events. Pathophysiologically, idiopathic ventricular arrhythmias occur in the absence of structural heart disease or ion channelopathies. Ventricular arrhythmias in the context of structural heart disease are usually determined by scar-related reentry and are associated with increased mortality. Catheter ablation is safe and highly effective in treating ventricular arrhythmias. The proper characterization of the arrhythmogenic substrate is essential for accurate procedural planning. We provide an overview on the main mechanisms of ventricular arrhythmias and their implications for catheter ablation.

Quality of life and symptoms in patients selected for ablation of ventricular extrasystoles: a prospective study

PURPOSE

Evaluation of the impact of catheter ablation for ventricular extrasystoles (VES) in structurally normal hearts on quality of life (QOL) and symptomatology.

METHODS

Symptom analysis assessed with a disease-specific questionnaire, EHRA score for AF, and QOL analysis at baseline and 1 year after ablation.

RESULTS

The study enrolled 39 patients between April 2016 and November 2019. Two patients were excluded from further analysis. At baseline, palpitations were reported in 31/37 (84%); syncope in 12/37 (32%); other cardiac symptoms in 33/37 (89%) of patients. The EHRA score was 3 or 4 in 13 patients (35%). With the modified arrhythmia-specific questionnaire (MASQ) psychological and physical scores were 46 and 39%. The overall perception of health in the SF-36 was 56 ± 16%. Ablation was performed in 35/37 (95%). At regular follow-up, symptoms were reported in 14/37 (38%) patients. ECG suggested a good procedural outcome in 65% with VES burden on Holter < 1% in 68%. At follow-up, palpitations were reported in 61% (P < 0.07); syncope in only 1 patient (P < 0.05). The EHRA score was 3 or 4 in only one patient (P < 0.05). MASQ scores improved to 62 and 60% (both p < 0.001). The overall perception of health in the SF-36 became 64 ± 17% (P < 0.02).

CONCLUSIONS

Patients with VES suffer from a wide variety of symptoms and have a low quality of life, as demonstrated by the EHRA score and conventional questionnaires. After catheter ablation, palpitations are still reported, but become less frequently present. Syncope becomes rare. Quality of life improves significantly from all perspectives.

Post-ablation augmentation of skin sympathetic nerve activity predicts a poor outcome of idiopathic ventricular arrhythmias

BACKGROUND

The neuromodulation effect after ventricular arrhythmia (VA) ablation is unclear. The study aimed to investigate skin sympathetic nerve activity (SKNA) changes in patients receiving catheter ablations for idiopathic VA.

METHODS

Of 43 patients with drug-refractory symptomatic VA receiving ablation, SKNA was continuously recorded for 10 min during resting from electrocardiogram lead I configuration and bipolar electrodes on the right arm 1 day before and 1 day after ablation.

RESULTS

Twenty-two patients with acute procedure success and no recurrence during follow-ups were classified as sustained success group (group 1). Other 21 patients were classified as failed ablation group (group 2). Baseline SKNA showed no significant difference between the two groups. Post-ablation SKNA in group 2 was significantly higher than in group 1. In patients with ablation involved right ventricular outflow tract (RVOT), the post-ablation SKNA was also significantly higher in group 2. In contrast, there was no difference in post-ablation SKNA between groups in patients receiving non-RVOT ablation.

CONCLUSION

The neuromodulation response after RVOT ablation may correspond to the sympathetic nerve distribution at RVOT. Augmentation of sympathetic activity after VA ablation indicates an unsuccessful VA suppression, especially in patients receiving ablation of RVOT VA.

The R-S difference index: A new electrocardiographic method for differentiating idiopathic premature ventricular contractions originating from the left and right ventricular outflow tracts presenting a left bundle branch block pattern

Introduction: Differentiating idiopathic premature ventricular contractions (PVCs) originating from the right and left ventricular outflow tracts with a left bundle branch block (LBBB) morphology is relevant to catheter ablation planning and important for lowering the risk of complications. This study established a novel electrocardiographic (ECG) criterion to discriminate PVCs originating from the septum of the right ventricular outflow tract (s-RVOT) and those originating from the aortic sinus cusp of the left ventricular outflow tract (LVOT-ASC).

Methods: A total of 259 patients with idiopathic PVCs originating from ventricular outflow tract with a LBBB pattern who underwent successful catheter ablation were retrospectively included. Among them, the PVCs originated from the s-RVOT in 183 patients and from the LVOT-ASC in 76 patients. The surface ECGs of the PVCs and sinus beats were analyzed using an electronic caliper. The R-S difference index in the precordial leads was calculated as V2R + V3R + V4R − V1S.

Results: PVCs originating from both the s-RVOT and LVOT-ASC displayed an inferior axis (dominant R waves in leads II, III, and aVF). Compared with the s-RVOT group, the R-wave amplitudes on leads II, III, and aVF were significantly larger in the LVOT-ASC group (p < 0.001, p < 0.003, and p < 0.001, respectively). Compared to the LVOT-ASC group, the s-RVOT group showed smaller R-wave amplitudes on leads V1–V6 (p = 0.021, p < 0.001, p < 0.001, p < 0.001, p < 0.001, and p < 0.001, respectively) and larger S-wave amplitudes on leads V1–V3 (p < 0.001, p < 0.001, and p < 0.001, respectively). Lead V3 was the most common transitional lead in both groups. Analysis of the receiver operating characteristic curve showed that the R-wave amplitude on lead V3 had the largest area under the curve (AUC) of 0.856 followed by the R-wave amplitudes on leads V4 (0.834) and V2 (0.806). The AUC of the R-S difference index was 0.867. An R-S difference index greater than 20.9 predicted an LVOT-ASC origin with 73.7% sensitivity and 86.3% specificity. This index is superior to previous criteria in differentiating PVCs with LBBB morphology and inferior axis originating from s-RVOT vs. LVOT-ASC.

Conclusions: The R-S difference index in precordial leads is a useful new ECG criterion for distinguishing LVOT-PVCs from RVOT-PVCs with LBBB morphology.

Training machine learning models with synthetic data improves the prediction of ventricular origin in outflow tract ventricular arrhythmias

In order to determine the site of origin (SOO) in outflow tract ventricular arrhythmias (OTVAs) before an ablation procedure, several algorithms based on manual identification of electrocardiogram (ECG) features, have been developed. However, the reported accuracy decreases when tested with different datasets. Machine learning algorithms can automatize the process and improve generalization, but their performance is hampered by the lack of large enough OTVA databases. We propose the use of detailed electrophysiological simulations of OTVAs to train a machine learning classification model to predict the ventricular origin of the SOO of ectopic beats. We generated a synthetic database of 12-lead ECGs (2,496 signals) by running multiple simulations from the most typical OTVA SOO in 16 patient-specific geometries. Two types of input data were considered in the classification, raw and feature ECG signals. From the simulated raw 12-lead ECG, we analyzed the contribution of each lead in the predictions, keeping the best ones for the training process. For feature-based analysis, we used entropy-based methods to rank the obtained features. A cross-validation process was included to evaluate the machine learning model. Following, two clinical OTVA databases from different hospitals, including ECGs from 365 patients, were used as test-sets to assess the generalization of the proposed approach. The results show that V2 was the best lead for classification. Prediction of the SOO in OTVA, using both raw signals or features for classification, presented high accuracy values (>0.96). Generalization of the network trained on simulated data was good for both patient datasets (accuracy of 0.86 and 0.84, respectively) and presented better values than using exclusively real ECGs for classification (accuracy of 0.84 and 0.76 for each dataset). The use of simulated ECG data for training machine learning-based classification algorithms is critical to obtain good SOO predictions in OTVA compared to real data alone. The fast implementation and generalization of the proposed methodology may contribute towards its application to a clinical routine.

An Overview of Parkinson's Disease: Curcumin as a Possible Alternative Treatment

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra of the midbrain and basal ganglia, followed by dopamine deficiency in the brain. Dopamine plays a crucial role in motor coordination, memory, and cognition; its decrease in PD leads to dyskinesia, cognitive deficits, and depression. In addition, the formation of alpha-synuclein protein aggregates (Lewy bodies) causes further damage to the CNS. Current treatment options include dopamine precursors, inhibitors of dopamine metabolism, upregulation of autophagy, adenosine A2A antagonists, and surgical intervention as a last resort. A challenge arises from a progressive decrease in treatment efficacy as the disease progresses and this necessitates exploration of adjunctive treatments. Epidemiological studies suggest that the prevalence of PD varies between ethnic groups of Caucasians, Asians, and African Americans. Notably, the prevalence of PD is lower in countries of Southeastern Asia including India. The differences in the diet of various ethnic groups may suggest an origin for this difference in the prevalence of PD. One staple ingredient in traditional Asian cuisine is turmeric. Curcuma longa, popularly known as turmeric, is an orange tuberous rhizome that has been used for centuries in traditional Indian cuisine and traditional medicine. Turmeric contains curcumin, a potent antioxidant that scavenges reactive oxygen species and chelates toxic metals. Curcumin has been proposed to be a neuroprotective agent due to its potent antioxidative properties. Though preliminary studies in animal model systems have suggested a protective effect of curcumin on dopaminergic neurons, the direct benefits of curcumin on the progress of PD remains poorly understood. In this review, we explore the promising use of curcumin as an adjunct to conventional PD treatments in order to enhance treatment and improve outcomes.

Feasibility of electroanatomic mapping and radiofrequency catheter ablation in Boxer dogs with symptomatic ventricular tachycardia

Background

Treatment for Boxers with ventricular tachycardia (VT) is limited. Electroanatomic mapping (EAM) facilitates identification of arrhythmogenic substrate for radiofrequency catheter ablation (RFCA).

Objective

Describe the use of EAM to guide RFCA in Boxers with VT.

Animals

Five client‐owned Boxers with symptomatic VT or persistent VT despite antiarrhythmic medications.

Methods

Case series evaluating clinical, EAM, and before and after RFCA Holter data.

Results

Sustained VT was inducible in 3 dogs, but required aggressive stimulation protocols. Low‐voltage areas consistent with electroanatomic scar were found in 2 dogs, located at the right ventricular (RV) outflow tract and cranial RV. Two dogs had a focal activation pattern of VT and 1 dog had a reentrant mechanism. After RFCA, all dogs no longer collapsed and had fewer runs of VT, 3 of which had 0 runs of VT. Number of ventricular premature beats increased in 3 dogs and decreased in 2 dogs, 1 of which had nearly complete resolution of all arrhythmias. Procedural complications included ventricular fibrillation (n = 2) with successful defibrillation, bruising or hemorrhage at the vascular access site (n = 4), retroperitoneal hemorrhage (n = 1), aortic and mitral regurgitation (n = 1), onset of frequent supraventricular tachycardia (n = 1), and persistent right pelvic limb lameness (n = 1).

Conclusions and Clinical Importance

Electroanatomic mapping and RFCA are feasible in Boxers with VT. Based on this small cohort, RFCA may help decrease runs of VT and improve clinical signs. The anatomic substrate and electrophysiologic mechanisms are variable and require further study.

Epicardial Adipose Tissue Thickness is Higher in Right Ventricular Outflow Tract Tachycardia

Introduction: Idiopathic ventricular arrhythmias, which occur in the absence of structural heart disease, are commonly originating from the outflow tract, and 80% of the them arise from the right ventricle. Epicardial adipose tissue (EAT), which originates from the splanchnopleuric mesoderm, has been shown to be an important source of inflammatory mediators and plays an important role in cardiac autonomic function by epicardial ganglionated plexuses. EAT may potentially contribute to the pathophysiology of idiopathic right ventricular outflow tract (RVOT) tachycardia by different mechanisms. In this study, we aimed to investigate the relationship between EAT thickness and RVOT tachycardia. Methods: This study included 55 patients (32 male, 23 female) with RVOT tachycardia and 60 control subjects (38 male, 22 female). Patients who had more than three consecutive ventricular beats over 100 bpm with specific morphological features on the electrocardiogram (ECG) were diagnosed with RVOT tachycardia. EAT thickness was measured by transthoracic echocardiography. Results: EAT thickness was significantly higher in the RVOT tachycardia group (p <0.05). Ejection fraction (EF), and the thickness of the posterior wall of the left ventricle and of the interventricular septum were significantly lower, and left ventricular end-diastolic diameter, left ventricular end-systolic diameter, and left atrial diameter were significantly higher in patients who had RVOT tachycardia compared to normal subjects (p <0.05). Conclusion: Patients who were diagnosed with RVOT tachycardia had increased EAT thickness compared to normal subjects. The underlying mechanism of the condition could be mechanical, metabolic, infiltrative, or autonomic effects of the EAT.

S-R index in V1/V3 serves as a novel criterion to discriminate idiopathic premature ventricular contractions originating from posteroseptal right ventricular outflow tract versus right coronary cusp

AIM

The current study aimed to establish a novel electrocardiographic (ECG) criterion for discrimination of idiopathic premature ventricular contractions (PVCs) originating from posteroseptal right ventricular outflow tract (sRVOT-p) versus right coronary cusp (RCC).

METHODS

A total of 76 patients with idiopathic PVCs who underwent mapping and successful ablation were retrospectively included. Among them, 37 patients had PVCs from sRVOT-p origin and 39 patients from RCC origin. The surface ECGs during PVCs were recorded. S-R different index in V1/V3 was calculated with the following formula of 0.134*V3R-0.133*V1S.

RESULTS

ECG characteristics showed wider total QRS duration, smaller R-wave amplitude on lead V2-V5, and larger S-wave amplitude on lead V1-V3 in sRVOT-p origin than RCC origin. Lead V3 was the most common transitional lead in two groups. Receiver operating characteristic (ROC) curve analysis showed that S-wave amplitude on lead V1 exhibited the largest AUC of 0.772, followed by the AUC of R-wave amplitude on lead V3 of 0.771. Subsequently, 0.134*V3R-0.133*V1S index was obtained by multiplication, subtraction, sum, and division of these ECG measurements, which exhibited the largest AUC of 0.808. The optimal cut-off value was -0.26 for differentiating RCC from sRVOT-p origin, with the sensitivity of 78.4% and specificity of 77.8%. Moreover, 0.134*V3R-0.133*V1S index was superior to previous criteria in analysis of PVCs originating from sRVOT-p and RCC.

CONCLUSIONS

0.134*V3R-0.133*V1S is a novel ECG criterion to discriminate sRVOT-p from RCC origin in patients with idiopathic PVCs, which may provide guidance for approach of radiofrequency catheter ablation.

Ventricular tachycardia originating from the His bundle: A case report

BACKGROUND

Ventricular tachycardia (VT) commonly occurs among patients with heart failure and can even cause sudden cardiac death. VT originating from the His bundle branch has been rarely reported. We present the case of a patient with VT from the His bundle branch.

CASE SUMMARY

A 58-year-old female complained of paroxysmal palpitations and dizziness for approximately 6 mo. She had a history of fatty liver and cholecystitis, and carotid atherosclerosis could not be excluded from the ultrasound results. An evaluation of the electrocardiogram obtained after admission showed spontaneous conversion between two different morphologies. The possible electrophysiologic mechanism suggested that the dual-source VT originated from the same source, the His bundle branch. Finally, the His bundle branch was ablated, and a dual-chamber pacemaker was inserted into the patient’s heart. No further VT occurred during the 3-year follow-up after hospital discharge.

CONCLUSION

The diagnosis of VT originating from the His bundle is rare and difficult to establish. The results of this study showed VT originating from the His bundle based on a careful evaluation of the electrocardiogram, and the diagnosis was confirmed by an intracardiac electrophysiologic examination.

Diagnosis and Treatment of Idiopathic Premature Ventricular Contractions: A Stepwise Approach Based on the Site of Origin

Premature ventricular contractions in the absence of structural heart disease are among the most common arrhythmias in clinical practice, with well-defined sites of origin in the right and left ventricle. In this review, starting from the electrocardiographic localization of premature ventricular contractions, we investigated the mechanisms, prevalence in the general population, diagnostic work-up, prognosis and treatment of premature ventricular contractions, according to current scientific evidence.

Constitutively Activating GNAS Somatic Mutation in Right Ventricular Outflow Tract Tachycardia

[Figure: see text].

Wide Complex Tachycardia in a Young Woman

A 27-year-old woman presented with palpitations and was found to have episodes of a non-sustained wide complex tachycardia. In this report, we discuss a differential diagnosis for the patient’s wide complex tachycardia and the important ECG findings which lead to her diagnosis. (Level of Difficulty: Advanced.)

Tp-Te interval and Tp-Te/QT ratio may be predictive of idiopathic ventricular tachycardia in patients with frequent outflow tract premature ventricular complexes

BACKGROUND

The aim of present study is to evaluate the predictive value of QTc dispersion, Tp-Te interval and Tp-Te/QT ratio for idiopathic monomorphic outflow tract ventricular tachycardia (VT) occurrence in patients with frequent idiopathic outflow tract premature ventricular complexes (PVCs).

METHODS

A total of 180 patients (49.2 ± 13.6 years, 74 male) who had undergone outflow tract PVC ablation between 01 January 2015 and 01 November 2018 constituted our study population. Patients with isolated outflow tract PVC without any VT recording on Holter recordings and without any inducible VT at EPS were classified as isolated PVC group. Patients with any episode of VT that has the same morphology with outflow tract PVC were classified as nonsustained or sustained VT groups based on the duration of VT episode. QTc dispersion, Tp-Te and Tp-Te/QT ratio values were calculated and compared between groups.

RESULTS

There were 116 patients with isolated PVC, 35 patients with nonsustained VT and 29 patients with sustained VT. QTc dispersion, Tp-Te and Tp-Te/QT ratio values were significantly lower in patients with isolated PVC compared to patients with nonsustained or sustained VT episodes. Tpeak to Tend interval greater than 110.5 msec on derivation V6 predicted VT occurrence with 93.8% sensitivity and 82.8% specificity. Tpeak to Tend/QT interval greater than 0.27 on derivation V6 predicted VT occurrence with 93.8% sensitivity and 0.81% specificity.

CONCLUSION

Tp-Te interval and Tp-Te/QT ratio on derivation V6 may aid in prediction of presence of outflow tract VT in clinical practice.

Ventricular tachycardia of right ventricular outflow tract origin during the perioperative period: A case report

RATIONALE

Idiopathic ventricular tachycardia (VT) occurs in individuals without structural abnormalities in the heart, accounts for approximately 10% of total VTs. Furthermore, approximately 70% of idiopathic VTs originate from Right ventricular outflow tract (RVOT). However, among perioperative arrhythmias, incidence of VT after surgery is extremely rare and most arrhythmias are atrial origin.

PATIENT CONCERNS

A 69-year-old man with permanent pacemaker underwent colon surgery.

DIAGNOSES

Patient suffered from low blood pressure and dizziness, sweating at post anesthetic care unit (PACU) and heart rate (HR) increased suddenly to 200 beats/min with monomorphic VT after bolus ephedrine administration and continuous dopamine infusion.

INTERVENTIONS

Pacemaker interrogation followed by DC cardioversion was done.

OUTCOMES

Patient's vital signs became normal and symptoms are subsided.

LESSONS

RVOT VT can be caused by triggering activities, such as ephedrine, dopamine, and inadequate fluid management. These triggering activities are initiated by acceleration of HR from ventricles with infusion of catecholamine which lead monomorphic VT originating from RVOT.RVOT origin PVCs can be precipitated into monomorphic VT by administrating catecholamines such as ephedrine and dopamine even in patient with pacemaker. The mechanism of these VTs includes catecholamine induced acceleration of HR. Since RVOT PVCs can be recognize by 12 EKGs, we should be pay more attentions to the pre-operation EKG and be cautious using catecholamines.

How Cardiac Embryology Translates into Clinical Arrhythmias

The electrophysiological signatures of the myocardium in cardiac structures, such as the atrioventricular node, pulmonary veins or the right ventricular outflow tract, are established during development by the spatial and temporal expression of transcription factors that guide expression of specific ion channels. Genome-wide association studies have shown that small variations in genetic regions are key to the expression of these transcription factors and thereby modulate the electrical function of the heart. Moreover, mutations in these factors are found in arrhythmogenic pathologies such as congenital atrioventricular block, as well as in specific forms of atrial fibrillation and ventricular tachycardia. In this review, we discuss the developmental origin of distinct electrophysiological structures in the heart and their involvement in cardiac arrhythmias.

Therapeutic Inefficacy and Proarrhythmic Nature of Metoprolol Succinate and Carvedilol Therapy in Patients With Idiopathic, Frequent, Monomorphic Premature Ventricular Contractions

BACKGROUND

Antiarrhythmic drugs remain the first-line therapy for treatment of idiopathic ventricular arrhythmias.

STUDY QUESTION

The aim of this study was to assess the therapeutic efficacy of extended-release metoprolol succinate (MetS) and carvedilol for idiopathic, frequent, monomorphic premature ventricular contractions (PVCs).

STUDY DESIGN

Study population consisted of 114 consecutive patients: 71 received MetS and 43 received carvedilol.

MEASURES AND OUTCOMES

All patients underwent 24-hour Holter monitoring at baseline and during drug therapy. PVC-burden response to drug therapy was categorized as "good" (≥80% reduction), "poor" (either <80% reduction or ≤50% increase), and "proarrhythmic" responses (>50% increase) based on change in PVC burden compared with baseline.

RESULTS

Most common presenting symptom was palpitations (65.8%), followed by coincidental discovery (29%). The mean MetS and carvedilol dosages were 65.57 ± 30.67 mg/d and 23.66 ± 4.26 mg/d, respectively. "Good," "poor," and "proarrhythmic" responses were observed in 11.3% and 16.3%, 63.4% and 67.4%, and 25.3% and 16.3% of patients treated with MetS and carvedilol, respectively. In patients with relatively high (≥16%) PVC burden, the sum of "poor"/"proarrhythmic" response was observed in 95.5% and 86.4% of patients treated with MetS and carvedilol, respectively. "Proarrhythmic" response was observed in 21.9% of the patients, particularly in the presence of relatively lower (≤10%) baseline PVC burden. Patients with "good" response during beta-blocker therapy had higher baseline daily average intrinsic total heart beats compared with patients with "poor"/"proarrhythmic" response combined (96,437 ± 26,488 vs. 86,635 ± 15,028, P = 0.047, respectively). Side effects and intolerance were observed in 5.6% and 18.6% of patients treated with MetS and carvedilol, respectively.

CONCLUSIONS

MetS and carvedilol for idiopathic, frequent, monomorphic PVCs are frequently inefficient. Therapeutic efficacy decreases further in patients with relatively high (≥16%) PVC burden. Relatively higher baseline daily intrinsic total heart beats may be used to predict "good" response before beta-blocker therapy.

Electrocardiographic Criteria for Differentiating Left from Right Idiopathic Outflow Tract Ventricular Arrhythmias

Idiopathic ventricular arrhythmias are ventricular tachycardias or premature ventricular contractions presumably not related to myocardial scar or disorders of ion channels. Of the ventricular arrhythmias (VAs) without underlying structural heart disease, those arising from the ventricular outflow tracts (OTs) are the most common. The right ventricular outflow tract (RVOT) is the most common site of origin for OT-VAs, but these arrhythmias can, less frequently, originate from the left ventricular outflow tract (LVOT). OT-VAs are focal and have characteristic ECG features based on their anatomical origin. Radiofrequency catheter ablation (RFCA) is an effective and safe treatment strategy for OT-VAs. Prediction of the OT-VA origin according to ECG features is an essential part of the preprocedural planning for RFCA procedures. Several ECG criteria have been proposed for differentiating OT site of origin. Unfortunately, the ECG features of RVOT-VAs and LVOT-VAs are similar and could possibly lead to misdiagnosis. The authors review the ECG criteria used in clinical practice to differentiate RVOT-VAs from LVOT-VAs.

Acute effect of outflow tract premature ventricular complex ablation on QT dispersion, Tp-e interval and Tp-e/QT ratio

BACKGROUND

There is limited data regarding the effect of idiopathic premature ventricular complexes (PVC) on myocardial repolarisation. Most of PVC's originate from right and left ventricular outflow tracts (RVOT and LVOT).

AIM

The aim of this study is to evaluate the acute effect of outflow tract PVC ablation on electrocardiographic repolarisation markers.

METHODS

A total of 180 patients (49.2 ± 13.6 years, 74 male) without any exclusion criteria who had undergone outflow tract PVC ablation between 1 January 2015 and 1 November 2018 constituted our study population. Electrocardiographic recordings that had been obtained before and after ablation procedure on the same day were retrospectively evaluated for the QTc dispersion, Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio. Significance of difference between pre- and postablation values was tested.

RESULTS

There was no significant difference regarding QTc dispersion between pre- and post-ablation state (36.5 ± 20.9 vs. 35.3 ± 16.4 ms, p: NS). However, Tp-e and Tp-e/QT values in all lateral precordial derivations were observed to decrease significantly after PVC ablation (in the respective order on derivation V5: 104.0 ± 21.6 ms vs. 91.1 ± 14.8 ms, p<.001 and 0.26 ± 0.05 vs. 0.23 ± 0.04, p<.001).

CONCLUSIONS

Based on these observations, it may be suggested that frequent outflow tract PVC's increase transmural dispersion of repolarisation and this effect is attenuated by catheter ablation in the acute phase. Results of further prospective studies are required for evaluation of the long term effects of PVC ablation on myocardial repolarisation.

Earliest activation time is a good predictor of successful ablation of idiopathic outflow tract ventricular arrhythmias

BACKGROUND

In idiopathic outflow tract ventricular arrhythmias (OT-VAs), identifying the site with the earliest activation time (EAT) using activation mapping is critical to eliminating the arrhythmogenic focus. However, the optimal EAT for predicting successful radiofrequency catheter ablation (RFCA) has not been established.

HYPOTHESIS

To evaluate the association between EAT and successful RFCA in idiopathic OT-VAs and to determine the optimal cut-off value of EAT for successful ablation.

METHODS

We retrospectively analyzed patients undergoing RFCA for idiopathic OT-VAs at a single center from January 2015 to December 2019.

RESULTS

Acute procedural success was achieved in 168 patients (87.0%). Among these patients, 158 patients (81.9%) were classified in the clinical success group according to the recurrence of clinical VAs during median (Q1, Q3) follow-up (330 days [182, 808]). EAT was significantly earlier in the clinical success group compared with the recurrence (p = .006) and initial failure (p < .0001) groups. The optimal EAT cut-off value predicting clinical success was -30 ms in the right ventricular outflow tract (RVOT) with 77.4% sensitivity and 96.4% specificity. In all cases of successful ablation in the left ventricular outflow tract (LVOT), EAT in the RVOT was not earlier than -29 ms.

CONCLUSIONS

EAT in patients with successful catheter ablation was significantly earlier than that in patients with recurrence and initial failure. EAT earlier than -30 ms could be used as a key predictor of successful catheter ablation as well as an indicator of the need to shift focus from the RVOT to the LVOT.

Adenosine-A drug with myriad utility in the diagnosis and treatment of arrhythmias

Adenosine has been used in the emergency treatment of arrhythmia for more than nine decades. However, cardiologists are often unfamiliar about its basic mechanism and various diagnostic and therapeutic uses, considering it mainly as a therapeutic drug for supraventricular tachycardia. This article discusses the role of adenosine relevant to emergency physicians, cardiologists, and electrophysiologists. Understanding of the mechanisms of adenosine and its electrophysiological effects is discussed first, followed by dosing, side effects, diagnostic, and therapeutic uses. Finally, the role of adenosine in the electrophysiology laboratory is discussed.

[Prognostic significance of premature ventricular contractions : Harmless or life-threatening?]

Premature ventricular contractions (PVC) are very common arrhythmias in cardiology. In structural normal hearts they usually represent a benign entity. If the ECG morphology is not consistent with idiopathic PVC, further diagnostic workup should be performed. They can occur due to structural heart disease and may be associated with sudden cardiac death. Polymorphic PVC or a high PVC burden should also always lead to further diagnostics and an individual risk-stratification. Therapeutic options include drug therapy and invasive catheter ablation.

Re-entrant ventricular tachycardia as a complication of ablation of idiopathic ventricular premature beats from the right outflow tract: a case report

Background

We report an unusual case of non-sustained ventricular tachycardia (NSVT) from the epicardial part of the right ventricular outflow tract (RVOT).

Case summary

A 37-year-old woman who underwent in 2006 an ablation for idiopathic ventricular premature beats (VPBs) from the RVOT presented with pre-syncopal NSVT in 2016. A cardiac workup showed no coronary disease, normal biventricular function, and no enhancement on cardiac magnetic resonance imaging. A metabolic positron emission tomography scan excluded inflammation. Biopsies revealed normal desmosomal proteins. An endocardial mapping revealed an area of low voltage potential (<0.5 mV) at the antero-septal aspect of the RVOT corresponding to the initial site of ablation from 2006. Activation mapping revealed poor prematurity and pace-mapping showed unsatisfactory morphologies in the RVOT, the left ventricle outflow tract and the right coronary cusp. An epicardial map revealed a low voltage area at the antero-septal aspect of the RVOT with fragmented potentials opposite to the endocardial scar. Pace-mapping demonstrated perfect match. An NSVT was induced and local electrocardiogram showed mid-diastolic potentials. Ablation was applied epicardially and endocardially without any complication. The patient was arrhythmia free at 4-year follow-up.

Discussion

Cardiac workup allowed to exclude specific conditions such as arrhythmogenic cardiomyopathy, tetralogy of Fallot, sarcoidosis, or myocarditis as a cause for NSVT from the RVOT. The epi and endocardial map showed residual scar subsequent to the first ablation which served as substrate for the re-entrant NSVT. This is the first case which describes NSVT from the epicardial RVOT as a complication from a previous endocardial ablation for idiopathic VPB.

Management of tachyarrhythmias in pregnancy - A review

The most common arrhythmias detected during pregnancy include sinus tachycardia, sinus bradycardia, and sinus arrhythmia, identified in 0.1% of pregnancies. Isolated premature atrial or ventricular arrhythmias are observed in 0.03% of pregnancies. Arrhythmias may become more frequent during pregnancy or may manifest for the first time.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Ventricular tachycardia as a consequence of triggered activity

One of the less frequent underlying mechanisms of ventricular tachycardia (VT) is triggered activity. Triggered activity refers to an extrasystole due to a premature depolarization that occurs when the amplitude of an early or delayed afterdepolarization brings the cardiac membrane to its threshold potential. Hydrochlorothiazide and hydroxyzine can prolong repolarization and QT interval and are associated with early afterdepolarizations. Cyclic AMP-mediated, delayed afterdepolarizations can occur as a result of catecholaminergic surge. Delayed afterdepolarization is classically associated with outflow tract (OT) tachycardia, a type of VT that is uniquely defined by its termination with adenosine. We present a case of triggered OT tachycardia for which intravenous amiodarone through its antiadrenergic effect may have been effective. Infusions of magnesium and a cardioselective, β-receptor antagonist that does not prolong repolarization may have been more appropriate given the concurrent, acquired prolonged QT syndrome. After initial stabilization, considering the underlying VT mechanism may prompt the clinician to select the most appropriate, further treatment.

Evaluation and treatment of premature ventricular contractions in heart failure with reduced ejection fraction

Premature ventricular complexes (PVCs) are often observed in patients presenting with heart failure with a reduced ejection fraction (HFrEF). PVCs may in some patients be considered to be the cause of heart failure, while in others it may be the consequence of heart failure. PVCs are important prognostic markers in HFrEF. The uncertainty whether PVCs are the cause or effect in HFrEF impacts clinical decision making. In this review, we discuss the complexity of the cause-effect relationship between PVCs and HFrEF. We demonstrate a workflow with the use of a trial period of amiodarone that may discover whether the reduced LVEF is reversible, the symptoms are due to PVCs and whether biventricular pacing can be increased by the reduction of PVCs. The use of non-invasive and invasive (high-density) mapping techniques may help to improve accuracy and efficacy in the treatment of PVC, which will be demonstrated. With these results in mind, we conclude this review highlighting the future directions for PVC research and treatment.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.