Does Bachmann's bundle pacing prevent atrial fibrillation in myotonic dystrophy type 1 patients? A 12 months follow-up study

Comprehensive Cardiovascular Management of Myotonic Dystrophy Type 1 Patients: A Report from the Italian Neuro-Cardiology Network

Myotonic dystrophy is a hereditary disorder with systemic involvement. The Italian Neuro-Cardiology Network-"Rete delle Neurocardiologie" (INCN-RNC) is a unique collaborative experience involving neurology units combined with cardio-arrhythmology units. The INCN facilitates the creation of integrated neuro-cardiac teams in Neuromuscular Disease Centers for the management of cardiovascular involvement in the treatment of myotonic dystrophy type 1 (MD1).

Alternative atrial pacing site to improve cardiac function: focus on Bachmann's bundle pacing

Pacing from the right atrial appendage (RAA) prolongs the P wave duration and can induce interatrial and especially left-sided atrio-ventricular dyssynchrony. Pacing from Bachmann's bundle closely reproduces normal physiology and has the potential to avoid the electromechanical dysfunction associated with conventional RAA pacing. Interatrial conduction delay is associated with an increased risk of stroke, heart failure, and death. In addition to a reduction in atrial fibrillation, Bachmann's bundle pacing has emerging applications as a hemodynamic pacing modality. This review outlines the pathophysiology of atrial conduction disturbances and their potential remedies and provides the reader with a practical guide to implementing Bachmann's bundle pacing with an emphasis on the recapitulation of normal electrical and mechanical function.

Sinus Rhythm Conduction Properties across Bachmann's Bundle: Impact of Underlying Heart Disease and Atrial Fibrillation

Valvular heart disease (VHD) is a common risk factor for atrial fibrillation (AF). Conduction abnormalities (CA) during sinus rhythm (SR) across Bachmann’s bundle (BB) are associated with AF development. The study goal is to compare electrophysiological characteristics across BB during SR between patients with ischemic (IHD) and/or VHD either with or without ischemic heart disease ((I)VHD), with/without AF history using high-resolution intraoperative epicardial mapping. In total, 304 patients (IHD: n = 193, (I)VHD: n = 111) were mapped; 40 patients (13%) had a history of AF. In 116 patients (38%) there was a mid-entry site with a trend towards more mid-entry sites in patients with (I)VHD vs. IHD (p = 0.061), whereas patients with AF had significant more mid-entry sites than without AF (p = 0.007). CA were present in 251 (95%) patients without AF compared to 39 (98%) with AF. The amount of CA was comparable in patients with IHD and (I)VHD (p > 0.05); AF history was positively associated with the amount of CA (p < 0.05). Receiver operating characteristic (ROC) curve showed 85.0% sensitivity and 86.4% specificity for cut-off values of CA lines of respectively ≤ 6 mm and ≥ 26 mm. Patients without a mid-entry site or long CA lines (≥ 12 mm) were unlikely to have AF (sensitivity 90%, p = 0.002). There are no significant differences in entry-sites of wavefronts and long lines of CA between patients with IHD compared to (I)VHD. However, patients with AF have more wavefronts entering in the middle of BB and a higher incidence of long CA lines compared to patients without a history of AF. Moreover, in case of absence of a mid-entry site or long line of CA, patients most likely have no history of AF.

SERUM cardiac-specific biomarkers and atrial fibrillation in myotonic dystrophy type I

INTRODUCTION

The aim of the present study was to evaluate the role of high-sensitivity cardiac troponin I, N terminal pro-B-type natriuretic peptide (NT-proBNP), creatine kinase-MB mass concentration (CK-MB mass) and copeptin (CP) in predicting incident atrial fibrillation (AF) in myotonic dystrophy type 1 (DM1) patients.

MATERIALS AND METHODS

The study enrolled 60 consecutive DM1 patients (age 50.3 ± 7.3 years, 34 male) who underwent pacemaker (PM) implantation for cardiac rhythm abnormalities and 60 PM recipients whose age and sex matched served as control group. All DM1 patients underwent a 12-lead electrocardiogram, 2D color Doppler echocardiogram, biomarkers measurements and device interrogation at implantation, 1 month after and every 6 months thereafter for a minimum of 2-year follow-up.

RESULTS

The study population was divided into two groups according to the presence of AF (AF group vs non-AF group). The AF group was older (47.3 ± 8 vs 38.6 ± 7 years, P = .03) and showed higher serum levels of NT-proBNP (151 ± 38.4 vs 107.3 ± 24.2 pg/mL, P < .001) and CP (18.9 ± 4.5 vs 7 ± 2.3 P < .001) than non-AF Group. NT-proBNP (P < .001) and CP (P < .001) were found to be an independent predictor of AF. Based on the receiver-operating characteristics curve analysis, the cut-off value for NT-proBNP that best predicted AF event in DM1 patients was 123 pg/ml (sensitivity of 83.3% and specificity of 86.5%); the cut-off value for CP that best predicted AF event in DM1 patients was 9 pmol/L (sensitivity of 89% and specificity of 87%).

CONCLUSION

NT-proBNP and CP represent two independent predictors of AF onset in DM1 population with conduction disturbances underwent PM implantation.

Cardiovascular manifestations of myotonic dystrophy

Patients with myotonic dystrophy, the most common neuromuscular dystrophy in adults, have a high prevalence of arrhythmic complications with increased cardiovascular mortality and high risk for sudden death. Sudden death prevention is central and relies on annual follow-up and prophylactic permanent pacing in patients with conduction defects on electrocardiogram and/or infrahisian blocks on electrophysiological study. Implantable cardiac defibrillator therapy may be indicated in patients with ventricular tachyarrhythmia.

Interatrial block to predict atrial fibrillation in myotonic dystrophy type 1

Paroxysmal atrial fibrillation frequently occurs in Myotonic dystrophy type 1 (DM1) patients. Interatrial block is recognized as predictor of atrial arrhythmias, particularly atrial fibrillation (AF). The aim of this study was to evaluate the role of interatrial block in predicting the onset of atrial fibrillation during 2-year follow-up in DM1 patients who underwent pacemaker implantation for conduction system disorders. The study prospectively enrolled 70 DM1 patients (aged 36-69; 31 M) who underwent pacemaker implantation for cardiac rhythm abnormalities in accordance with the current guidelines. All DM1 patients underwent 12-lead surface ECG, 2D color Doppler echocardiogram and device interrogation at implantation, one month after and every six months thereafter for a minimum of 2-year follow-up. 12-lead surface ECGs were analyzed to diagnose interatrial block (IAB), defined as a P-wave duration ≥120 ms without (partial IAB) or with (advanced IAB) biphasic morphology (±) in the inferior leads. Device interrogation was performed to evaluate the development of new onset atrial high rate electrograms compatible with paroxysmal atrial fibrillation episodes. Interatrial block was detected in 22 patients (31.4%): 18 partial (25.7%) and 4 advanced (5.7%). During follow-up, AF episodes were detected in 18 DM1 patients (25.7%). The study population was divided into 2 groups according to the presence of AF (AF+ Group vs AF- Group). The AF+ Group was older and showed higher prevalence of IAB than the AF- Group. IAB was found to be independent predictor of AF in DM1 population (P < 0.001). A cut-off value of 121 ms for IAB had a sensitivity of 83.3% and specificity of 90.3% in identifying DM1 patients at high risk of developing AF. Interatrial block represents an independent predictor of AF occurrence in our DM1 population with conduction disturbances who had previously undergone pacemaker implantation.

Effect of dual-chamber minimal ventricular pacing on paroxysmal atrial fibrillation incidence in myotonic dystrophy type 1 patients: A prospective, randomized, single-blind, crossover study

BACKGROUND

Atrial fibrillation (AF) is a common finding in the myotonic dystrophy type 1 (DM1) population. Pacemakers (PMs) may facilitate the diagnosis and management of frequent subclinical asymptomatic AF episodes.

OBJECTIVE

The purpose of this study was to evaluate the effect of minimal ventricular pacing on paroxysmal AF incidence in DM1 patients during a 24-month follow-up period.

METHODS

We enrolled 70 DM1 patients (age 43.4 ± 13.8 years; 39 women) who underwent dual-chamber PM implantation. Patients were randomized to minimizing ventricular pacing features (ON) or not (OFF). Patients crossed over to the opposite pacing programming 12 months later. We counted the number of DM1 patients with at least 1 episode of AF, the AF total duration, and the burden recorded by PM diagnostics during the MVP ON and OFF phases.

RESULTS

Twenty-five DM1 patients (41.7%) showed at least 1 AF episode. Seven patients (11.7%) demonstrated AF episodes during MVP ON phase and 25 patients (41.7%) during MVP OFF phase (P <.001). Thirty-five patients had no AF during MVP ON or OFF phase, 3 patients had AF episodes only during MVP ON phase, 21 patients had AF episodes only during MVP OFF phase, and 4 patients had AF episodes during MVP ON and OFF phases. Activation of the MVP algorithm was associated with a 44% reduction in relative risk of developing AF. Furthermore, during the MVP ON phases, the study population showed a shorter total AF duration and a lower AF burden.

CONCLUSION

MVP is an efficacy strategy for reducing the risk of AF in DM1 patients who have undergone PM implantation.

The role of the atrial electromechanical delay in predicting atrial fibrillation in beta-thalassemia major patients

BACKGROUND

Paroxysmal atrial tachyarrhythmias frequently occur in beta-thalassemia major (β-TM) patients. The aim of the current study was to evaluate the atrial electromechanical delay (AEMD) in a large β-TM population with normal cardiac function and its relationship to atrial fibrillation (AF) onset.

METHODS

Eighty β-TM patients (44 men, 36 women), with a mean age of 36.2 ± 11.1 years, and 80 healthy subjects used as controls, matched for age and gender, were studied for the occurrence of AF during a 5-year follow-up, through 30-day external loop recorder (ELR) monitoring performed every 6 months. Intra-AEMD and inter-AEMD of both atria were measured through tissue Doppler echocardiography. P-wave dispersion (PD) was carefully measured using 12-lead electrocardiogram (ECG).

RESULTS

Compared to the healthy control group, the β-TM patients showed a statistically significant increase in inter-AEMD, intra-left AEMD, maximum P-wave duration, and PD. Dividing the β-TM group into two subgroups (patients with or without AF), the inter-AEMD, intra-left AEMD, maximum P-wave duration, and PD were significantly higher in the subgroup with AF compared to the subgroup without AF. There were significant good correlations of intra-left AEMD and inter-AEMD with PD. A cut-off value of 40.1 ms for intra-left AEMD had a sensitivity of 76.2% and a specificity of 97.5% in identifying β-TM patients with AF risk. A cut-off value of 44.8 ms for inter-AEMD had a sensitivity of 81.2% and a specificity of 98.7% in identifying this category of patients.

CONCLUSIONS

Our results showed that the echocardiographic atrial electromechanical delay indices (intra-left and inter-AEMD) and the PD were significantly increased in β-TM subjects with normal cardiac function. PD and AEMD represent non-invasive, inexpensive, useful, and simple parameters to assess the AF risk in β-TM patients.

A simple method for Bachmann's bundle pacing with indigenous modification of J-stylet

Background

Pacing in the Bachmann's bundle (BB) area (upper atrial septum) appears superior to right atrial appendage or free wall stimulation for the prevention of paroxysmal atrial fibrillation in patients with atrial conduction delay. However, insertion of active fixation lead in the upper atrial septal position is difficult and time consuming with conventional stylet, inhibiting application of this pacing method in routine practice.

Methods

The technique of positioning the atrial lead in BB with hand-made stylet is presented with emphasis on electrocardiographic P-wave pattern and fluoroscopic landmarks.

Results

The results demonstrate an acute implantation and short-term success of BB pacing of 14 patients out of 15 patients without major complications. Pacing parameters at implantation and 3 months postprocedure were noted which were within normal limits.

Conclusion

These favorable initial results indicate that the positioning of active fixation atrial lead in BB with fluoroscopic landmarks is feasible and reproducible with a simple technique.

Atrial flutter or fibrillation is the most frequent and life-threatening arrhythmia in myotonic dystrophy

BACKGROUND

Several arrhythmias were reported in myotonic dystrophy (MD).

OBJECTIVES

To evaluate the prevalence of atrial fibrillation (AF) and atrial flutter (AFL) in MD and the clinical consequences.

METHODS

One hundred sixty-one patients, mean age 41 ± 14 years, were referred for a type 1 MD. All patients were asymptomatic except four patients and followed during 5 ± 4 years. Electrocardiogram (ECG), echocardiography assessing left ventricular ejection fraction, and Holter monitoring were obtained and repeated.

RESULTS

Twenty-seven patients (17%) presented sustained (>1 hour) AF (n = 15) or AFL (n = 12); two of them presented syncope-related 1/1 AFL. In one of them, 16 years of age, cardiac defibrillator was implanted for a diagnosis of ventricular tachycardia, but the true diagnosis was established after inappropriate shocks. AFL ablation was performed in five patients, but four developed AF. The other seven patients with AFL developed AF. During the follow-up, 22 patients died (14%) from cardiac and respiratory failure; eight patients with AF/AFL died (30%) while only 14 without AF/AFL died (10%; P < 0.01). Univariate analysis indicated that age >40 years (death: 48 ± 14 vs 40 ± 8 in alive patients), abnormal ECG, and occurrence of AF/AFL were significant factors of death. At multivariate analysis, AF at ECG (odds ratio: 3.12) and age >40 (odds ratio: 3.14) were the sole independent variables predicting death.

CONCLUSIONS

AF and AFL were frequent in MD and increased mortality. AFL could present as 1/1 AFL with a poor tolerance and a risk of misdiagnosis despite frequent conduction disturbances. This arrhythmia could explain wide QRS tachycardia occurring in MD and interpreted as VT.

[Advances in cardiac pacing]

This article contains a review of the current status of remote monitoring and follow-up involving cardiac pacing devices and of the latest developments in cardiac resynchronization therapy. In addition, the most important articles published in the last year are discussed.