Single-Chamber Leadless Cardiac Pacemaker in Patients Without Atrial Fibrillation: Findings From Campania Leadless Registry

Introduction:Little is known about the clinical performance of single-chamber leadless pacemaker (LLPM) in patients without atrial fibrillation (AF) as pacing indication. The aim of this study was to describe the clinical characteristics of patients who underwent single chamber LLPM implantation at three tertiary referral centers and to compare the safety and effectiveness of the single-chamber LLPM among patients with or without AF.Materials and Methods:All the consecutive patients who underwent LLPM implantation at three referral centers were analyzed. The indications to LLPM in a real-world setting were described. The study population was divided into two groups according to AF as pacing indication. We assessed the procedure-related complications; moreover, we compared syncope, cardiac hospitalization, pacemaker syndrome, and all-cause death recurrence during the follow-up between patients with and without AF as pacing indication.Results:A total of 140 consecutive patients (mean age, 76.7 ± 11.24 years, men 64.3%) were included in the study. The indication to implantation of LLPM was permanent AF with slow ventricular response (n: 67; 47.8%), sinus node dysfunction (n: 25; 17.8%), third atrioventricular block (AVB) (n: 20; 14.2%), second-degree AVB (n: 18; 12.8%), and first degree AVB (n: 10; 7.1%). A total of 7 patients (5%) experienced perioperative complications with no differences between the AF vs. non-AF groups. During a mean follow-up of 606.5 ± 265.9 days, 10 patients (7.7%) died and 7 patients (5.4%) were reported for cardiac hospitalization; 5 patients (3.8%) experienced syncope; no patients showed pacemaker syndrome. No significant differences in the clinical events between the groups were shown. The Kaplan–Meier analysis for the combined endpoints did not show significant differences between the AF and non-AF groups [hazard ratio (HR): 0.94, 95% CI: 0.41–2.16; p = 0.88].Conclusion:Our real-world data suggest that LLPM may be considered a safe and reasonable treatment in patients without AF in need of pacing. Further studies are needed to confirm these preliminary results.

Dual Atrial Rhythms: A Case Report Of An Unusual Cause Of Pacemaker Syndrome

Background Atrial dissociation (AD) is described as the existence of two simultaneous electrically isolated atrial rhythms. Theoretically, detection of dual atrial rhythms with a sufficiently high rate by pacemaker can lead to automatic mode switching and associated pacemaker syndrome. Such a clinical observation has not been reported before in the literature. Case Summary An 87-year-old female with Ebstein’s anomaly status post tricuspid valve annuloplasty and tricuspid valve replacement and a dual chamber pacemaker presented with congestive heart failure one week after undergoing atrial lead revision. Interrogation of her dual chamber pacemaker revealed two atrial rhythms: sinus or atrial-paced rhythm and electrically isolated atrial tachycardia (AT). Sensing of both atrial rhythms by the pacemaker led to automatic mode switching, which manifested as ventricular paced rhythm with retrograde P waves on electrocardiogram (ECG). Adjusting the atrial lead sensitivity to a level higher than the sensing amplitude of AT restored atrial paced and ventricular sensed rhythm, which resulted in resolution of heart failure symptoms. Discussion Regardless of the cause of AD, there must be electrical insulation between the two rhythms for their independent coexistence in the atria. AD can lead to pacemaker syndrome from automatic mode switching. If the sensing amplitude during sinus rhythm is significantly larger than that of AT, adjusting the atrial lead sensitivity would solve the issue, as in the present case. Otherwise, atrial lead revision, pharmacotherapy or AT ablation should be considered.

Abstract 16643: Pacemaker For First Degree AV Block Without Bradycardia: Pseudo-pacemaker Syndrome

Case Presentation: An 86 year old man underwent PCI of distal LAD for severe single vessel coronary artery disease identified after a high risk pharmacologic nuclear stress test (evaluation of exertional fatigue prior to abdominal aortic aneurysm surgical repair). ECHO was consistent with preserved LVEF (60-65%), moderate concentric LVH and mild left atrial enlargement. Less than a week after PCI, he presented to the emergency department for NYHA III dyspnea and fatigue. The patient was not taking any negative chronotropic medications. CT angiography of the chest excluded pulmonary edema, pneumonia and pulmonary embolism; repeat limited ECHO was unchanged. EKG showed first degree AV block (PR 400ms, figure 1). Severely prolonged PR interval with otherwise-unexplained exertional symptoms raised suspicion for pseudo-pacemaker syndrome. In the absence of an alternative cause of declining exertional tolerance, a dual chamber pacemaker with short programmed AV delay (<200ms) was implanted. The patient reported resolution of exertional fatigue and dyspnea on one-month followup. Discussion: Pseudo-pacemaker syndrome is a rare, infrequently reported, complication of first degree AV block with severely prolonged PR>300ms. P-wave at the end of the preceding T-wave suggests AV dyssynchrony (arrowhead, figure 1). Left atrial contraction against a closed mitral valve led to loss of atrial contribution to cardiac output, and elevated left atrial pressure. These changes, accentuated by physiologic increase in heart rate on exertion, most likely caused symptoms in this patient. It is interesting that AV dyssynchrony in pacemaker syndrome is caused by the pacemaker (VVI pacing) whereas the AV dyssynchrony in pseudo-pacemaker syndrome from severely prolonged PR interval is treated with a pacemaker. In the appropriate clinical picture, it is an indication for dual-chamber pacemaker implantation for first degree AV block without bradycardia or pauses.

Late Retrieval of the Leadless Micra Transcatheter Pacemaker System

Aim: We report our single-center experience with the retrieval and replacement of the chronically implanted Micra transcatheter pacing system (TPS). Material and Methods: We included 6 patients with an implanted the Micra TPSs who subsequently underwent transvenous method of retrieval at our institution. The indication for device retrieval was pacemaker syndrome in two patients, battery depletion in three patients, and need for upgrade to biventricular pacing in one patient. Results: After an implantation duration of 555 ± 373 days, the overall retrieval success rate was 83.3%, 5 of 6 patients. No procedure-related adverse device events occurred. In the single patient with unsuccessful retrieval, intracardiac echocardiography revealed that the Micra TPS was embedded within the cardiac wall and surrounding tissue. After retrieval, four patients received a new Micra TPS. Conclusions: Late retrieval of an implanted Micra TPS was safe and feasible, which indicates the possibility for their safe and elective replacement with a new leadless pacing device.

Abstract 14856: Leadless Pacemaker Implantation in Patients With Paroxysmal Complete Atrioventricular Block

Introduction: Transcatheter pacing systems have recently emerged as a safe and effective alternative in treating patients who require right ventricular pacing therapy. Traditionally, patients with atrial fibrillation with slow ventricular response had been benefit from this therapy. More recent, patients with symptomatic paroxysmal complete AV block had been receiving these devices. At this moment there is no data available about the feasibility , safety or outcomes of leadless pacemaker in this subgroup of patients Objective: The aim of this study was to assess the feasibility safety and 1 year follow up of the transcatheter leadless pacemaker device in patients with paroxysmal complete AV block . Methods: One hundred and ten (110 ) consecutive patients who underwent implantation of a Micra transcatheter leadless pacemaker (LPM)and have been follow up for at least a year were evaluated . Forty one (41) of these patients had the device implanted after experiencing symptomatic paroxysmal complete AV block. A t-test analysis was used to compare patient demographics, total procedure times, complication rates and recaptures necessary during the procedure. Results: All the patients with symptomatic paroxysmal complete AV block were implanted successfully with the leadless pacemaker system ( LPN ) . None of the patients suffered complications during the procedures. Fifty three percent ( 53%) were female , mean age of 77 , mean procedure time was 21.1 min. The mean number of recaptures required were 0.48 . None of the patient experienced pacemaker syndrome or progress to complete AV block after 1 year of follow up Conclusion: Leadless pacemaker implantation appears to be a safe and feasible alternative for subjects with symptomatic paroxysmal complete AV block . Further studies are required in these subgroup of patients