Development of atrial fibrillation in patients with atrioventricular block after atrioventricular synchronized pacing

Single-lead VDD pacing: a literature review on short-term and long-term performance

INTRODUCTION

VDD pacing system was introduced more than 30 years ago. Its use is considered by the 2021 European Society of Cardiology guidelines on cardiac pacing as a potential alternative to dual chambers system for patients with atrioventricular block and normal sinus node function.

AREAS COVERED

In this article, we performed a narrative review of current literature in order to identify the strengths and weaknesses of this pacing system. VDD system allows the maintenance of AV synchronous pacing and its hemodynamic advantages. Some disadvantages may be related to the non-negligible incidence of atrial undersensing and the possible subsequent need for upgrade to DDD system. On the other hand, shorter implantation time and lower complications rate may be advantages.

EXPERT OPINION

In the modern pacing era, VDD pacing system struggles to find its own space. However, it may still be considered as a valuable alternative to a dual-chamber pacemaker for selected patients, in specific clinical scenarios.

Avoiding inappropriate therapy of single-lead implantable cardioverter-defibrillator by using atrial-sensing electrodes

INTRODUCTION

The single-chamber implantable cardioverter-defibrillator (ICD) can be associated with more frequent inappropriate therapies compared with dual-chamber ICDs, when they are accompanied by a simpler implantation procedure. The aim of this study was to investigate whether the use of a single-lead ICD system with atrial-sensing electrodes results in a reduction of inappropriate ICD therapy.

METHODS AND RESULTS

The study population consisted of 212 consecutive patients, who underwent primary prophylactic single-lead ICD implantation at our institute. A ventricular lead with atrial-sensing electrodes was implanted in 77 patients (36%; Group-VDD) and a ventricular lead without atrial-sensing electrodes was implanted in 135 patients (64%; Group-VVI). Procedural and follow-up data were collected in a prospective registry. A higher prevalence of atrial fibrillation was present in Group-VDD. There were no other significant differences in patient baseline characteristics (age, sex, and other comorbidities) or follow-up period between the two groups. The operative parameters including fluoroscopic burden showed no significant differences between Group-VDD and Group-VVI. During a mean follow-up period of 697 ± 392 days, 26 patients (12%) experienced appropriate ICD therapies and 13 patients (6%) suffered inappropriate ICD therapies. The incidence of inappropriate ICD therapies in Group-VDD was significantly lower as compared to that of Group-VVI (1/77 [1%] vs 12/135 [9%]; log-rank, P = 0.028). The incidence of appropriate ICD therapies and the occurrence of device-related complications showed no significant difference between the two groups.

CONCLUSION

Single-lead ICD with atrial-sensing electrodes shows a lower incidence of inappropriate ICD therapy compared with the absence of atrial-sensing electrodes, without additional operative burden or increased complications.

Long-term outcome in patients receiving permanent pacemaker implantation for atrioventricular block: Comparison of VDD and DDD pacing

A permanent pacemaker (PPM) with dual chamber pacing (DDD) offers atrioventricular synchronization for patients with atrioventricular block (AVB). Single lead atrial synchronous ventricular pacing mode (VDD) is an alternative, but there are concerns about its efficacy and risk of atrial undersensing. Whether VDD can be a good alternative in patients with AVB remains unknown. The aim of the present study was to compare the long-term risk of mortality of VDD with DDD pacing.A total of 207 patients undergoing PPM implantations for AVB with VDD mode were enrolled from 2000 to 2013. Another 828 age- and sex-matched patients undergoing DDD implantations during the same period of time were selected as the control group in a 1 to 4 ratio. The study endpoint was mortality.A total of 1035 patients (64.3% male) were followed up for 46.5 ± 43.2 months. The mean ages were 75.0 years for VDD, and 74.9 years for DDD. The Kaplan-Meier survival analysis showed no significant difference in long-term survival between the VDD and DDD groups (log-rank P = 0.313). After adjustment for baseline characteristics, the VDD and DDD groups had a similar long-term prognosis with an adjusted hazard ratio of 0.875 (P = 0.445). Further analyses for the risk of cardiovascular and noncardiovascular deaths also showed no significant differences between the 2 groups.The long-term prognosis of VDD mode is comparable to that of DDD mode. Single lead VDD can be considered as an alternative choice in patients with AVB without sinus nodal dysfunction.

Long-term prognosis of patients older than ninety years after permanent pacemaker implantation: does the procedure save the patients?

BACKGROUND

The implantation of a permanent pacemaker (PPM) is life-saving for patients with life-threatening bradycardia. However, the effectiveness and prognosis of PPM implantations for extremely old patients (≥ 90 years old) have not been investigated.

METHODS

From 2001-2012, a total of 108 patients older than 90 years were identified from 2630 consecutive patients receiving PPM implantations in our hospital as the study group. For each study patient, 4 age-, sex-, and comorbidity-matched subjects who did not have the diagnoses of bradyarrhythmias indicated for PPM implantations were selected from the "Taiwan National Health Research Database" to constitute the control group (n = 432). The study end point was all-cause mortality.

RESULTS

The median age of the study population was 91 (interquartile range, 90-93) years. Among the PPM group, 45 patients died during the follow-up with an annual mortality rate of 18.7%. The risk of mortality did not differ significantly between the study and control groups with a hazard ratio of 1.020 (95% confidence interval, 0.724-1.437; P = 0.912) after the adjustment for age and sex. Procedure-related complications occurred in 7.4% of the patients receiving PPM implants, and pocket hematoma was the most common. The preimplantation history of heart failure and cerebrovascular accident, rather than age, were significant predictors of mortality among PPM recipients.

CONCLUSIONS

Nonagenarians with severe bradyarrhythmias could retain the same life expectancies as those without bradyarrhythmias through PPM implantations. Extremely old age (≥90 years) should not be a barrier for PPM implants when indications are present.

Persistent atrial fibrillation is associated with a poor prognosis in patients with atrioventricular block and dual-chamber pacemaker

BACKGROUND

The prognostic significance of development of persistent atrial fibrillation (AF) in patients with atrioventricular (AV) block and dual chamber (DDD) pacemakers has not been separately investigated. We sought to determine whether persistent AF influences clinical outcome in these patients.

METHODS

Three hundred-eight consecutive patients with second- or third-degree AV block and implanted a DDD pacemaker were followed for 36 ± 20 months and retrospectively divided into two groups. Thirty-four patients who developed persistent AF formed persistent AF group, and 278 patients who remained free of this arrhythmia control group. Clinical and outcome data of the two groups were compared. The primary outcome was cardiovascular death.

RESULTS

The primary outcome occurred more often among the patients in the persistent AF group (6.8% per year) than among those in the control group (2.9% per year; P = 0.028). This difference was primarily because of higher rate of heart failure-related deaths in the persistent AF group (P = 0.009). Secondary outcomes, hospitalization for heart failure and paroxysmal AF episode ≥5 minutes, occurred also more often among the patients in the persistent AF group (P = 0.008 and P < 0.001, respectively), although the risk of nonfatal stroke was similar in both groups (P = 0.628).

CONCLUSION

In patients with second- or third-degree AV block and DDD pacemaker, the development of persistent AF is associated with an increased risk of cardiovascular death and heart failure.

[Atrial sensing with fixed and floating electrodes at identical activities]

Despite advantages of single-lead VDD systems, the frequency of implantation of these pacemakers in patients with symptomatic atrioventricular block and normal sinus rhythm continues to decline. Therefore, data comparing the atrial sensing performance of floating and fixed electrodes at identical activities are rare. The aim of the study was to investigate atrial sensing via floating and fixed atrial electrodes at identical activity levels (supine position, left side position, seated position, hyperventilation, standing, walking, fast walking, walking up and down stairs, for 1.5 min each) by beat-to-beat analysis in 24 h Holter ECG. A total of 42 patients were included in the study (22 patients with a DDD system; 20 patients with a VDD system). In 45% of the DDD systems and only in 20% of the VDD systems an intermittent atrial undersensing during activity was recorded (p = 0.0024). The intermittent atrial undersensing in both groups was detected significantly more often in the first 15 s of an activity (p < 0.001). Floating sensing reduced the frequency of atrial undersensing in the initial phase of the activity significantly compared to atrial sensing by a fixed electrode (p = 0.0347). This advantage of floating electrodes and the significant earlier atrial signal recognition by floating electrodes might be useful in future DDD pacemakers by combining a VDD electrode with a fixed atrial electrode.

Association of statin therapy and the risk of atrial fibrillation in patients with a permanent pacemaker

BACKGROUND

Recent studies have shown conflicting results regarding a protective effect of statin therapy on atrial fibrillation (AF).

HYPOTHESIS

We sought to determine whether statins are effective in reducing the risk of developing arrhythmia in a cohort of 264 patients (49% women, mean age [+/-standard deviation] 71 [+/-12] years) with permanent pacemakers who are at high risk for AF.

METHODS

All patients who underwent implantation of a permanent pacemaker over a 3-year period were eligible for inclusion in the study. We excluded patients with AF at implantation, incomplete medication information, or less than a yearly follow-up visit. Atrial fibrillation was diagnosed by ECG documentation, pacemaker interrogation, and Holter monitoring. Statin treatment was verified through a central pharmacy-computerized database (for most patients) or by chart review. Of the 264 patients, 36% had coronary artery disease.

RESULTS

Atrial fibrillation developed in 70 patients (26%) at a median of 359 days post pacemaker implantation. The incidence rate for the first occurrence of AF post pacemaker implantation among patients treated and not treated with statins was 10.5 versus 9.8 events per 100 patient-years, respectively (p = 0.81). Even after controlling for baseline differences, the hazard ratio (HR) for developing AF among statin users did not achieve statistical significance (HR = 0.59 [0.31-1.12]).

CONCLUSIONS

We could not demonstrate that statin therapy had a protective effect against the risk of AF in patients implanted with a permanent pacemaker. The low prevalence of coronary artery disease in our patients may partly explain our results.

Retrospective analysis of mode survival, reliability of atrial sensing and incidence of atrial tachyarrhythmias in 307 single-lead VDD pacemaker patients

AIMS

The aim of this retrospective analysis was to investigate VDD mode survival, development of atrial tachyarrhythmias (AT), and long-term atrial sensing performance of VDD pacing systems.

METHODS AND RESULTS

We implanted single-lead VDD pacemakers in patients with isolated atrioventricular block and performed a retrospective analysis of 307 patients who had their devices implanted between May 1994 and September 2001. In 39 patients (12.7%), the pacing mode had to be reprogrammed to a single-chamber ventricular pacing mode, mostly due to permanent AT. In 16 of these patients, the atrial sensing safety margin was less than 150%. The atrial sensing safety margin was insufficient, i.e. less than 100% in only seven patients. Although only 12 (3.9%) of the patients had a history of paroxysmal AT at the time of pacemaker implantation, 200 (65%) patients presented with AT during follow-up. The mean AT burden at the last follow-up was 2.5%.

CONCLUSION

These data illustrate that single-lead VDD pacemakers can be applied without serious complications in a highly selected group of patients. Our main concern is the development of AT in a large part of our population. Over a 10-year period, two thirds of our patients presented with AT.

Long-term efficacy and stability of atrial sensing in VDD pacing

BACKGROUND

The efficacy and stability of atrial electrode sensing function is essential in maintaining atrioventricular (AV) synchrony and activity response in VDD pacing. Studies to evaluate the relationship between atrial sensing efficacy, stability, and implantation strategy are few.

HYPOTHESIS

This study sought to determine the possible predictors, among the recipients' underlying clinical conditions and the implantation strategies used, of achieving the most stable and effective atrial sensing.

METHODS

Eighty consecutive adults implanted with VDD pacemakers were studied retrospectively. Atrial electrodes were positioned where the optimal atrial potentials (APs) were measured during implantation. Interrogation parameters, including AV-synchrony ratio, were acquired immediately post implantation, at 1 year, and at 2 years after pacemaker implantation. Appropriate atrial sensing efficacy was defined as AV-synchrony ratio > or = 90%. The stability of atrial sensing was evaluated by the variation ranges of measured APs.

RESULTS

The measured APs showed no statistical difference when age, gender, or comorbidity was considered. However, with pacing-lead bending angles < or = 90 degrees, patients may have presented with larger APs and narrower AP variation than patients with obtuse angles. There were no clinical parameters in our study that could have predicted the proper atrial sensing efficacy with an AV-synchrony ratio > or = 90%.

CONCLUSIONS

The long-term sensing efficacy and stability of VDD pacing is reliable. More sophisticated implantation strategies may further improve the atrial sensing stability and efficacy in VDD pacing.