Prediction of sinus node dysfunction in patients with long-standing persistent atrial fibrillation using the atrial fibrillatory cycle length

Patch augmentation vs. valve replacement for patients with atrial functional mitral regurgitation and long-standing atrial fibrillation

BACKGROUND

Long-standing atrial fibrillation is associated with atrial functional mitral regurgitation (AFMR) with atriogenic tethering. We compared the outcomes of patch augmentation (PA) and valve replacement (VR) for AFMR.

METHODS

We retrospectively compared the data of 16 patients who underwent PA for AFMR with the data of 15 patients who underwent VR between 2008 and 2021. Patients with a left ventricular ejection fraction (LVEF) of <50% were excluded. We also performed atrial plication and left appendage closure if the patients had no weak atrial wall that led to severe bleeding.

RESULTS

The median age was 72.5 and 76.0 years in the PA and VR groups, respectively. The PA group had a longer cardiopulmonary bypass time (206 vs. 172 min, P=0.012). Although there were no differences in hospital morbidity and mortality between the PA and VR groups, one patient underwent reoperation for patch perforation in the PA group. The overall 3-year survival rate was 93.8% and 100% in the PA and VR groups, respectively (P=0.878). The 3-year rate of freedom from major adverse cardiac events was 75.0% and 53.6% in the PA and VR groups, respectively (P=0.181). Three and six patients were readmitted for congestive heart failure in the PA and VR groups, respectively. Two patients in the PA group developed severe recurrent regurgitation, including one patient who required reoperation. No patients in the VR group required reoperation. The postoperative left atrial volume index (LAVI) was associated with thromboembolic events (P=0.016).

CONCLUSIONS

PA may achieve comparable outcomes to those of VR for AFMR. Operative procedures should be chosen based on each patient's background. Atrial reduction could be considered to prevent thromboembolic events.

Genetic Complexity of Sinoatrial Node Dysfunction

The pacemaker cells of the cardiac sinoatrial node (SAN) are essential for normal cardiac automaticity. Dysfunction in cardiac pacemaking results in human sinoatrial node dysfunction (SND). SND more generally occurs in the elderly population and is associated with impaired pacemaker function causing abnormal heart rhythm. Individuals with SND have a variety of symptoms including sinus bradycardia, sinus arrest, SAN block, bradycardia/tachycardia syndrome, and syncope. Importantly, individuals with SND report chronotropic incompetence in response to stress and/or exercise. SND may be genetic or secondary to systemic or cardiovascular conditions. Current management of patients with SND is limited to the relief of arrhythmia symptoms and pacemaker implantation if indicated. Lack of effective therapeutic measures that target the underlying causes of SND renders management of these patients challenging due to its progressive nature and has highlighted a critical need to improve our understanding of its underlying mechanistic basis of SND. This review focuses on current information on the genetics underlying SND, followed by future implications of this knowledge in the management of individuals with SND.

The incidence, indications and predictors of acute pacemaker implantation after ablation of persistent atrial fibrillation

INTRODUCTION

Patients with persistent atrial fibrillation (AF) may additionally suffer from a concealed sinus node disease. We sought to determine the incidence, indications and predictors of acute pacemaker [PM] implantation within 1 week after the ablation of persistent AF.

METHODS AND RESULTS

We performed a retrospective analysis of patients, who had had an ablation of persistent AF at our center. Between 01/2011 and 08/2016, 1234 patients (mean age 65 ± 10 years, 66.7% male) without prior PM implantation underwent an ablation of persistent AF. Pulmonary vein isolation (PVI) was performed in 1158 (93.8%), the additional ablation of complex fractionated atrial electrograms (CFAE) in 1109 (89.9%) and linear ablation in 524 (42.5%) patients. Temporary cardiac pacing was necessary in 27 (2.2%) patients. The temporary PM was removed in 15 patients (1.2%) because sinus node recovered after a median of 1.0 (minimum 0.1-maximum 2.0) day. The remaining 12 (1.0%) patients required the implantation of a permanent PM. Another 13 (1.1%) patients required permanent PM implantation without prior temporary pacing. In a multivariable regression model, age [OR 1.07 (1.02-1.12), p = 0.006], sinus pauses prior to ablation [OR 7.97 (2.36-26.88), p = 0.001] and atria with low voltage [OR 2.83 (1.31-6.11), p = 0.008] were identified as significant predictors for acute cardiac pacing.

CONCLUSION

Acute cardiac pacing within 1 week after the ablation of persistent AF was necessary in 40 (3.2%) patients. Age, sinus pauses in history prior to ablation and the existence of low-voltage areas in the atria were identified as relevant risk factors.

Acute Sinus Node Dysfunction after Atrial Ablation: Incidence, Risk Factors, and Management

BACKGROUND

Many patients with atrial fibrillation (AF) or atrial flutter (Aflutter) have concomitant sinus node dysfunction (SND). Ablation may result in injury to the sinus node complex or its blood supply resulting in sinus arrest and need for temporary pacing. We sought to characterize patients who develop acute SND (ASND) during/immediately after AF/Aflutter ablation.

METHODS

We performed a retrospective analysis of AF/Aflutter ablation patients between January 1, 2010 and February 28, 2015 to characterize those who required temporary pacemaker (TPM) implantation due to ASND (sinus arrest, sinus bradycardia <40 beats/min, or junctional rhythm with hemodynamic compromise) following atrial ablation.

RESULTS

Of 2,151 patients, eight patients (<0.5%) with ASND manifesting as sinus arrest (n = 2), severe sinus bradycardia (n = 2), and junctional rhythm with hemodynamic compromise (n = 4) were identified (all male, age 66 ± 9.9 years, 4/8 [50%] persistent AF). AF ablation was performed in four, atypical Aflutter in one, and AF/Aflutter in three patients. The ablation set consisted of: pulmonary vein (PV) isolation (n = 6), roof line ablation (n = 6), mitral annulus-left inferior PV line ablation (n = 5), left atrial appendage-mitral annulus ablation (n = 1), cavotricuspid isthmus ablation (n = 5), and isolation or ablation near the superior vena cava (SVC, n = 4). Patients with peri-SVC ablation were more likely to develop ASND (P = 0.03). All patients received TPM; six received permanent pacemaker before discharge, performed 3.5 days postablation (range 2-6 days). At 3-month device interrogation, all patients were atrially paced >50%.

CONCLUSION

ASND is a rare complication of atrial ablation. It may be more common when peri-SVC ablation is performed and may necessitate permanent pacemaker implantation.

A low fibrillatory wave amplitude predicts sinus node dysfunction after catheter ablation in patients with persistent atrial fibrillation

BACKGROUND

Concealed sinus node dysfunction (SND) may become manifest after restoration of sinus rhythm by ablation in patients with persistent atrial fibrillation (AF). The purpose of this study was to investigate the predictors of SND after catheter ablation of persistent AF.

METHODS

Two hundred two consecutive patients who underwent ablation for persistent AF were enrolled. Ipsilateral pulmonary vein isolation followed by, if necessary, electrical cardioversion were performed in all patients. SND was defined when temporary and/or permanent pacemakers were needed due to sinus bradycardia after ablation.

RESULTS

SND developed in 12 (5.9 %) patients. There was no difference between the patients with and without SND in terms of the age (with SND, 67 ± 9 and without, 66 ± 10 years old, P = 0.599) and sex (male; 58 vs. 79 %, P = 0.186). However, the patients with SND had a lower amplitude of the fibrillatory waves (0.115 ± 0.086 vs. 0.176 ± 0.077 mV, P = 0.009) and larger left atrial volume index (LAVI; 66 ± 31 vs. 34 ± 13, P = 0.007) than those without. A receiver operating characteristic curve identified a fibrillatory wave amplitude of 0.145 mV (AUC = 0.742; sensitivity = 65 %; specificity = 83 %) and LAVI of 47.5 ml/m(2) (AUC = 0.837; sensitivity = 82 %; specificity = 87 %) as the optimal cutoff values for predicting SND. A multivariate analysis revealed that the amplitude of the fibrillatory waves (odds ratio = 0.84 for 0.010 mV increase, 95 % CI = 0.71-0.98, P = 0.031) and LAVI (odds ratio = 1.08 for 1.0 cm(3)/m(2) increase, 95 % CI = 1.04-1.12, P < 0.001) were independent risk factors for SND.

CONCLUSIONS

A low amplitude of the fibrillatory waves and a large LAVI were predictors of SND after restoration of sinus rhythm by ablation in patients with persistent AF.

Predictors of sick sinus syndrome in patients after successful radiofrequency catheter ablation of atrial flutter

PURPOSE

The identification of sick sinus syndrome (SSS) in patients with atrial flutter (AFL) is difficult before the termination of AFL. This study investigated the patient characteristics used in predicting a high risk of SSS after AFL ablation.

MATERIALS AND METHODS

Out of 339 consecutive patients who had undergone radiofrequency ablation for AFL from 1991 to 2012, 27 (8%) had SSS (SSS group). We compared the clinical characteristics of patients with and without SSS (n=312, no-SSS group).

RESULTS

The SSS group was more likely to have a lower body mass index (SSS: 22.5±3.2; no-SSS: 24.0±3.0 kg/m²; p=0.02), a history of atrial septal defects (ASD; SSS: 19%; no-SSS: 6%; p=0.01), a history of coronary artery bypass graft surgery (CABG; SSS: 11%; no-SSS: 2%; p=0.002), and a longer flutter cycle length (CL; SSS: 262.3±39.2; no-SSS: 243.0±40; p=0.02) than the no-SSS group. In multivariate analysis, a history of ASD [odds ratio (OR) 3.7, 95% confidence interval (CI) 1.2-11.4, p=0.02] and CABG (7.1, 95% CI 1.5-32.8, p=0.01) as well as longer flutter CL (1.1, 95% CI 1.0-1.2, p=0.04) were independent risk factors for SSS.

CONCLUSION

A history of ASD and CABG as well as longer flutter CL increased the risk of SSS after AFL ablation. While half of the patients with SSS after AFL ablation experienced transient SSS, heart failure was associated with irreversible SSS.

Pitx2-microRNA pathway that delimits sinoatrial node development and inhibits predisposition to atrial fibrillation

The molecular mechanisms underlying atrial fibrillation, the most common sustained cardiac arrhythmia, remain poorly understood. Genome-wide association studies uncovered a major atrial fibrillation susceptibility locus on human chromosome 4q25 in close proximity to the paired-like homeodomain transcription factor 2 (Pitx2) homeobox gene. Pitx2, a target of the left-sided Nodal signaling pathway that initiates early in development, represses the sinoatrial node program and pacemaker activity on the left side. To address the mechanisms underlying this repressive activity, we hypothesized that Pitx2 regulates microRNAs (miRs) to repress the sinoatrial node genetic program. MiRs are small noncoding RNAs that regulate gene expression posttranscriptionally. Using an integrated genomic approach, we discovered that Pitx2 positively regulates miR-17-92 and miR-106b-25. Intracardiac electrical stimulation revealed that both miR-17-92 and miR-106b-25 deficient mice exhibit pacing-induced atrial fibrillation. Furthermore electrocardiogram telemetry revealed that mice with miR-17-92 cardiac-specific inactivation develop prolonged PR intervals whereas mice with miR-17-92 cardiac-specific inactivation and miR-106b-25 heterozygosity develop sinoatrial node dysfunction. Both arrhythmias are risk factors for atrial fibrillation in humans. Importantly, miR-17-92 and miR-106b-25 directly repress genes, such as Shox2 and Tbx3, that are required for sinoatrial node development. Together, to our knowledge, these findings provide the first genetic evidence for an miR loss-of-function that increases atrial fibrillation susceptibility.

Outcomes of ablation of paroxysmal atrial fibrillation in patients on chronic hemodialysis

INTRODUCTION

It is not common for patients on chronic hemodialysis (HD) to undergo catheter ablation of atrial fibrillation (AF). We aimed to show the outcomes of AF ablation in the HD patients.

METHODS AND RESULTS

Thirty HD patients who underwent pulmonary vein (PV) isolation for drug refractory paroxysmal AF were retrospectively studied, and their AF recurrence free rate and frequency of periprocedural complications were compared to 60 age- and gender-matched control patients not requiring HD. A nonirrigated ablation catheter was used in both patient groups. During a mean follow-up period of 821 ± 218 days, 16 (54%) of the HD patients remained free from AF recurrence without any antiarrhythmic agents versus 47 (78%) of the control patients with an initial ablation (P = 0.013). A second ablation procedure was performed in 12 patients with an AF recurrence, and consequently 20 (67%) of the HD patients were in sinus rhythm compared to 53 (88%) of the controls during a follow-up duration of 747 ± 221 after the last ablation (P = 0.012). Bleeding from the venipuncture site requiring a prolonged hospital stay was identified in 2 HD patients and 1 control subject, while no life-threatening complications were observed in either patient group.

CONCLUSION

Although the success rate of the PV isolation in HD patients was far from satisfactory, it may be considered as one of the therapeutic options for them.