Pacing on the tail of paced QRS: What is the mechanism?

An electrocardiogram on the day following the implantation of a dual-chamber pacemaker revealed two closely coupled pacing spikes at 100ms intervals with the latter being on the trailing edge of the paced QRS complex. Differential diagnoses of such closely coupled pacing pulses include atrial lead displacement, lead reversal on the pulse generator, a ventricular premature complex in the post-atrial ventricular blanking period, and backup pacing pulse following a loss of capture. The critical analysis of the pacemaker timing intervals led to the mechanism and aetiology of the problem.

Management of patients with an electrical storm or clustered ventricular arrhythmias: a clinical consensus statement of the European Heart Rhythm Association of the ESC-endorsed by the Asia-Pacific Heart Rhythm Society, Heart Rhythm Society, and Latin-American Heart Rhythm Society.

Electrical storm (ES) is a state of electrical instability, manifesting as recurrent ventricular arrhythmias (VAs) over a short period of time (three or more episodes of sustained VA within 24 h, separated by at least 5 min, requiring termination by an intervention). The clinical presentation can vary, but ES is usually a cardiac emergency. Electrical storm mainly affects patients with structural or primary electrical heart disease, often with an implantable cardioverter-defibrillator (ICD). Management of ES requires a multi-faceted approach and the involvement of multi-disciplinary teams, but despite advanced treatment and often invasive procedures, it is associated with high morbidity and mortality. With an ageing population, longer survival of heart failure patients, and an increasing number of patients with ICD, the incidence of ES is expected to increase. This European Heart Rhythm Association clinical consensus statement focuses on pathophysiology, clinical presentation, diagnostic evaluation, and acute and long-term management of patients presenting with ES or clustered VA.

Feasibility of cardiac magnetic resonance imaging in temporary permanent pacemaker implants in pediatric myocarditis and complete atrioventricular block.

Background: Diagnosing myocarditis in children presenting with complete AV block (CAVB) is challenging. Temporary permanent pacing support using standard transvenous active fixation lead can be inserted percutaneously until recovery. However, access to cardiac magnetic resonance (CMR) imaging may be limited due to safety concerns. Cases: We report three cases where CMR was performed using temporary permanent pacemaker in situ. We evaluated the effect of device artefacts on image quality and examined any instances of device malfunction. Conclusion: In children with CAVB and myocarditis, a temporary permanent pacemaker can provide reliable pacing until recovery, and CMR can be safely performed with the implanted pacemaker without compromising image quality.

Predicting stroke in Asian patients with atrial fibrillation using machine learning: A report from the KERALA-AF registry, with external validation in the APHRS-AF registry.

Atrial fibrillation (AF) is a significant risk factor for stroke. Based on the higher stroke associated with AF in the South Asian population, we constructed a one-year stroke prediction model using machine learning (ML) methods in KERALA-AF South Asian cohort. External validation was performed in the prospective APHRS-AF registry. We studied 2101 patients and 83 were to patients with stroke in KERALA-AF registry. The random forest showed the best predictive performance in the internal validation with receiver operator characteristic curve (AUC) and G-mean of 0.821 and 0.427, respectively. In the external validation, the light gradient boosting machine showed the best predictive performance with AUC and G-mean of 0.670 and 0.083, respectively. We report the first demonstration of ML's applicability in an Indian prospective cohort, although the more modest prediction on external validation in a separate multinational Asian registry suggests the need for ethnic-specific ML models.

Bump termination of an atriofascicular tachycardia. Where is the level of block?

This electrophysiological tracing localizes the level of block distal to the recorded Mahaim potential during bump termination mapping of an atriofascicular pathway at the tricuspid annulus.

Response to spontaneous and induced His refractory ventricular premature beats during long RP tachycardia: What is the mechanism?

This electrophysiology tracing demonstrates a graded postexcitation response of the retrograde limb of an orthodromic reentrant tachycardia circuit with varying His refractory VPB coupling intervals, which reiterates the decrementally conducting retrograde limb of the tachycardia circuit.

Left cardiac sympathetic denervation in children with Jervell Lange-Nielsen syndrome and drug refractory torsades - A case series.

INTRODUCTION: Long QT syndrome is an inherited malignant channelopathy which leads to life-threatening arrhythmia, with multiple genotypes. Jervell and Lange-Nielsen syndrome (JLNS) is an autosomal recessive subtype of this disease, characterized by congenital sensorineural deafness and a high incidence of sudden cardiac death (SCD). METHODOLOGY: We prospectively followed up six children who underwent left cardiac sympathetic denervation (LCSD) for JLNS in view of high-risk features despite being on maximally tolerated doses of oral propranolol. RESULTS: Mean age at diagnosis was 2.75 ± 0.39 years, with a significant delay between onset of symptoms and diagnosis (mean 7.2 ± 3.5 months). All had sensorineural hearing loss, conforming to the JLNS phenotype. Mean QTc interval was 603 ± 93 ms, with T wave alternans (TWA) seen in all cases. All were started on propranolol and subsequently subjected to LCSD, and 3 underwent AAI permanent pacemaker implantation. Over a mean follow-up of 20 months, there was a significant reduction in QTc (603 ± 93 ms to 501 ± 33 ms, p = .04), which was persistent on follow-up (525 ± 41 ms) and only two out of six had persistent T wave alternans on ECG (p < .01). None of these children had presyncope, syncope, seizures, torsades de pointes, cardiac arrest or death on follow up following LCSD. CONCLUSION: Jervell Lange-Nielsen syndrome is a subtype of LQTS with high-risk features. LCSD, an effective therapeutic option for those having symptoms despite being on propranolol, results in significant reduction of QTc interval and amelioration of symptoms.

Utility of late gadolinium enhancement on magnetic resonance imaging in hypertrophic cardiomyopathy patients in an Indian cohort.

This prospective observational study sought to correlate segmental late gadolinium enhancement (LGE) seen in cardiac magnetic resonance imaging with occurrence of ventricular arrhythmias (VAs) in patients with hypertrophic cardiomyopathy. LGE was assessed in a 17-segmental model of heart. Of 57 patients, VAs were present in 26.3% of patients and 10.5% had sustained ventricular tachycardia. LGE was present in 43.9% of patients. Presence of LGE in 4 or more segments was associated with VAs with a sensitivity of 73% and specificity of 76% with area under curve of 0.733 in C-statistics.

Is COVID-19 another case of the obesity paradox? Results from an international ecological study on behalf of the REPROGRAM Consortium Obesity study group.

Introduction: Obesity has emerged as one of the major risk factors of severe morbidity and cause-specific mortality among severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infected individuals. Patients with obesity also have overlapping cardiovascular diseases and diabetes, which make them increasingly vulnerable. This novel ecological study examines the impact of obesity and/or body mass index (BMI) on rates of population-adjusted cases and deaths due to coronavirus disease 2019 (COVID-19). Material and methods: Publicly available datasets were used to obtain relevant data on COVID-19, obesity and ecological variables. Group-wise comparisons and multivariate logistic regression analyses were performed. The receiver operating characteristic curve (ROC) was plotted to compute the area under the curve. Results: We found that male BMI is an independent predictor of cause-specific (COVID-19) mortality, and not of the caseload per million population. Countries with obesity rates of 20-30% had a significantly higher (approximately double) number of deaths per million population to both those in < 20% and > 30% slabs. We postulate that there may be a U-shaped paradoxical relationship between obesity and COVID-19 with the cause-specific mortality burden more pronounced in the countries with 20-30% obesity rates. These findings are novel along with the methodological approach of doing ecological analyses on country-wide data from publicly available sources. Conclusions: We anticipate, in light of our findings, that appropriate targeted public health approaches or campaigns could be developed to minimize the risk and cause-specific morbidity burden due to COVID-19 in countries with nationwide obesity rates of 20-30%.

Worldwide survey on implantation of and outcomes for conduction system pacing with His bundle and left bundle branch area pacing leads.

BACKGROUND: Adoption and outcomes for conduction system pacing (CSP), which includes His bundle pacing (HBP) or left bundle branch area pacing (LBBAP), in real-world settings are incompletely understood. We sought to describe real-world adoption of CSP lead implantation and subsequent outcomes. METHODS: We performed an online cross-sectional survey on the implantation and outcomes associated with CSP, between November 15, 2020, and February 15, 2021. We described survey responses and reported HBP and LBBAP outcomes for bradycardia pacing and cardiac resynchronization CRT indications, separately. RESULTS: The analysis cohort included 140 institutions, located on 5 continents, who contributed data to the worldwide survey on CSP. Of these, 127 institutions (90.7%) reported experience implanting CSP leads. CSP and overall device implantation volumes were reported by 84 institutions. In 2019, the median proportion of device implants with CSP, HBP, and/or LBBAP leads attempted were 4.4% (interquartile range [IQR], 1.9-12.5%; range, 0.4-100%), 3.3% (IQR, 1.3-7.1%; range, 0.2-87.0%), and 2.5% (IQR, 0.5-24.0%; range, 0.1-55.6%), respectively. For bradycardia pacing indications, HBP leads, as compared to LBBAP leads, had higher reported implant threshold (median [IQR]: 1.5 V [1.3-2.0 V] vs 0.8 V [0.6-1.0 V], p = 0.0008) and lower ventricular sensing (median [IQR]: 4.0 mV [3.0-5.0 mV] vs. 10.0 mV [7.0-12.0 mV], p < 0.0001). CONCLUSION: In conclusion, CSP lead implantation has been broadly adopted but has yet to become the default approach at most surveyed institutions. As the indications and data for CSP continue to evolve, strategies to educate and promote CSP lead implantation at institutions without CSP lead implantation experience would be necessary.

Three-dimensional electroanatomical mapping guided right bundle branch pacing in congenitally corrected transposition of great arteries.

AIMS: The ideal pacing strategy has been the Achilles' heel for patients with congenitally corrected transposition of great arteries (ccTGA) with bradycardia. Various pacing modalities were documented in the literature. This article describes a novel pacing strategy and its feasibility in ccTGA with an intact ventricular septum. METHODS AND RESULTS: We prospectively recruited three patients with ccTGA who presented with symptomatic complete heart block to our institute and were evaluated. All patients were planned for conduction system pacing. Those who had more than moderate or severe systemic atrioventricular regurgitation and systemic ventricular dysfunction were planned for conduction system pacing with an additional lead in the coronary sinus (CS) tributary, i.e. bundle branch pacing optimized cardiac resynchronization therapy with the intention to achieve incremental benefit. Since right bundle pacing is not described previously and in view of anatomical complexity in location, three-dimensional (3D) anatomical mapping was done with the EnSite system and later right bundle capture is identified conventionally as that of a left bundle in a normal heart. All three patients have stable lead positions and adequate thresholds at short-term follow-up. CONCLUSION: In this report, we demonstrated the feasibility of permanent physiological pacing of the systemic ventricle by capturing the right bundle with 3D anatomical mapping guidance, which results in physiological activation of the systemic ventricle.

Programmed ventricular stimulation in structural heart disease: Implications of patterns of ventricular arrhythmias induced to long-term outcomes.

INTRODUCTION: Currently available data gives some credence to utility of VT induction studies in patients with stable ischemic cardiomyopathy, there are some unresolved questions as to define sensitive threshold for low-risk and the prognostic relevance of ill sustained or non-specific tachycardia on induction study. We evaluated potential ability of VT inducibility to predict likelihood of SHD (Structural heart disease) patients for subsequent arrhythmic or adverse cardiac events. MATERIAL AND METHODS: All consecutive patients with syncope/documented arrhythmia who had VT induction done were included and patients with VT storm, ACS,uncontrolled HF were excluded. We studied in 4 groups-monomorphic VT, sustained polymorphicVT, ill sustainedVT/VF and no VT/VF induced. The primary-endpoints were - Sudden death, all-cause mortality and secondary-endpoints were - MACE (AICD shock, death,HF, recurrence of VT). We screened 411 patients and included 169 within inducible (n = 79) and non-inducible group (n = 90). RESULTS: There were a higher number of patients with coronary artery disease, LV dysfunction, patients on amiodarone in inducible group and no difference in usage of beta-blockers. Recurrence of VT, composite of MACE was significantly higher in inducible group (p < 0.05). Mortality was not different in 3 groups compared with no VT/VF group. We found that monomorphic VT group had significantly higher MACE as compared to others and also predicted recurrence of VT and AICD shock and showed a trend towards significance for prediction of mortality. Inducible patients on AICD had mortality similar to non-inducible group. CONCLUSION: Induction of monomorphicVT/polymorphicVT with ≤3extrastimuli is associated with a higher number of MACE events on follow up. Induction of monomorphicVT predicts recurrence of VT/ICD shock.

Clinical profile and outcomes of semi-permanent pacing in a tertiary care institute in southern India.

BACKGROUND: Semi-permanent pacing (SPP) includes the placement of a permanent lead through the internal jugular vein and connection to a pulse generator on the skin outside the venous access site. AIM: To evaluate the clinical profile and outcomes of semi-permanent pacing in a tertiary care institute in Southern India. METHODS: This is a retrospective observational study. All patients admitted and requiring management with semi-permanent pacing from January 2017 to June 2020 were included. RESULTS: From January 2017 to June 2020, 20 patients underwent semi-permanent pacing (SPP) with a median age of 54 (21-74) years. Males comprised a majority of the patients (55%). Hypertension was noted in 50% of patients and 30% were diabetic. The right internal jugular vein was the most common access in 95% of patients. The most common indication for semi-permanent pacing was pocket site infection in 30% of patients. There were no procedural complications. The median duration on SPP was 7 (5-14) days and the median duration of hospital stay was 13 (8-21) days. Permanent pacemaker implantation was done in 55% of patients. Mortality in our study group was 15% with 10% dying due to cardiogenic shock (post resuscitated cardiac arrest) and 5% dying due to non-cardiac cause (Epidural hematoma). CONCLUSION: In our study, semi-permanent pacing was noted to be a safe procedure and was more commonly indicated in emergent conditions with complete heart block secondary to underlying reversible causes and in the management of pocket site infection.

2022 HRS expert consensus statement on evaluation and management of arrhythmic risk in neuromuscular disorders.

This international multidisciplinary document is intended to guide electrophysiologists, cardiologists, other clinicians, and health care professionals in caring for patients with arrhythmic complications of neuromuscular disorders (NMDs). The document presents an overview of arrhythmias in NMDs followed by detailed sections on specific disorders: Duchenne muscular dystrophy, Becker muscular dystrophy, and limb-girdle muscular dystrophy type 2; myotonic dystrophy type 1 and type 2; Emery-Dreifuss muscular dystrophy and limb-girdle muscular dystrophy type 1B; facioscapulohumeral muscular dystrophy; and mitochondrial myopathies, including Friedreich ataxia and Kearns-Sayre syndrome, with an emphasis on managing arrhythmic cardiac manifestations. End-of-life management of arrhythmias in patients with NMDs is also covered. The document sections were drafted by the writing committee members according to their area of expertise. The recommendations represent the consensus opinion of the expert writing group, graded by class of recommendation and level of evidence utilizing defined criteria. The recommendations were made available for public comment; the document underwent review by the Heart Rhythm Society Scientific and Clinical Documents Committee and external review and endorsement by the partner and collaborating societies. Changes were incorporated based on these reviews. By using a breadth of accumulated available evidence, the document is designed to provide practical and actionable clinical information and recommendations for the diagnosis and management of arrhythmias and thus improve the care of patients with NMDs.