Long-term RV threshold behavior by automated measurements: safety is the standpoint of pacemaker longevity!

Autothreshold algorithm feasibility and safety in left bundle branch pacing

AIMS

Autothreshold algorithms enable remote monitoring of patients with conventional pacing, but there is limited information on their performance in left bundle branch pacing (LBBP). Our objective was to analyse the behaviour of the autothreshold algorithm in LBBP and compare it with conventional pacing and manual thresholds during initial device programming (acute phase), after 1-7 days (subacute), and 1-3 months later (chronic).

METHODS AND RESULTS

A prospective, non-randomized, single-centre comparative study was conducted. Consecutive patients with indication for cardiac pacing were enrolled. Implants were performed in the left bundle branch area or the right ventricle endocardium at the discretion of the operator. Left bundle branch pacing was determined according to published criteria. Autothreshold algorithm was activated in both groups whenever allowed by the device. Seventy-five patients were included, with 50 undergoing LBBP and 25 receiving conventional pacing. Activation of the autothreshold algorithm was more feasible in later phases, showing a favourable trend towards bipolar pacing. Failures in algorithm activation were primarily due to insufficient safety margins (82.8% in LBBP and 90% in conventional pacing). The remainder was attributed to atrial tachyarrhythmias (10.3% and 10%, respectively) and electrical noise (the remaining 6.9% in the LBBP group). In the LBBP group, there were not statistically significant differences between manual and automatic thresholds, and both remained stable during follow-up (mean increase of 0.50 V).

CONCLUSION

The autothreshold algorithm is feasible in LBBP, with a favourable trend towards bipolar pacing. Automatic thresholds are similar to manual in patients with LBBP, and they remain stable during follow-up.

Is Less Always More? A Prospective Two-Centre Study Addressing Clinical Outcomes in Leadless versus Transvenous Single-Chamber Pacemaker Recipients

(1) Background: Leadless (LL) stimulation is perceived to lower surgical, vascular, and lead-related complications compared to transvenous (TV) pacemakers, yet controlled studies are lacking and real-life experience is non-conclusive. (2) Aim: To prospectively analyse survival and complication rates in leadless versus transvenous VVIR pacemakers. (3) Methods: Prospective analysis of mortality and complications in 344 consecutive VVIR TV and LL pacemaker recipients between June 2015 and May 2021. Indications for VVIR pacing were “slow” AF, atrio-ventricular block in AF or in sinus rhythm in bedridden cognitively impaired patients. LL indication was based on individualised clinical judgement. (4) Results: 72 patients received LL and 272 TV VVIR pacemakers. LL pacemaker indications included ongoing/expected chronic haemodialysis, superior venous access issues, active lifestyle with low pacing percentage expected, frailty causing high bleeding/infectious risk, previous valvular endocarditis, or device infection requiring extraction. No significant difference in the overall acute and long-term complication rate was observed between LL and TV cohorts, with greater mortality occurring in TV due to selection of older patients. (5) Conclusions: Given the low complication rate and life expectancy in this contemporary VVIR cohort, extending LL indications to all VVIR candidates is unlikely to provide clear-cut benefits. Considering the higher costs of LL technology, careful patient selection is mandatory for LL PMs to become advantageous, i.e., in the presence of vascular access issues, high bleeding/infectious risk, and long life expectancy, rendering lead-related issues and repeated surgery relevant in the long-term perspective.

Individual programming of current multiprogrammable pacemakers : Still unsatisfactory?

BACKGROUND

Pacemaker (PM) technology has developed tremendously in recent decades. We evaluated the extent of individual programming in current PMs.

METHODS

Over a 7-month period in 2016, all deceased persons taken to the Rostock crematorium were prospectively screened for cardiac implantable electronic devices (CIEDs) and these were interrogated in situ. Programming of patient data, leads, and study parameters including mode, lower rate, upper tracking or sensor rate (UTSR), ventricular refractory time, sleeping function, hysteresis, and PM-mediated tachycardia intervention were analyzed and compared with delivery settings. Alterations in atrial/ventricular capture management and atrial/ventricular sensing assurance as well as changes in sensitivity and lead output were evaluated.

RESULTS

We examined 2297 subjects, of whom 154 (6.7%) had CIEDs, with 125 (81.2%) being PMs. Finally, 72 (57.6%) PMs were eligible for analysis with an operation time of 31.0 ± 27.0 months. We excluded 28 (18.2%) implantable cardioverter defibrillators (ICDs), 51 (41%) PMs presenting elective replacement indicator (ERI), two (1.6%) PMs with programming to insufficient function prior to death, and the left ventricle parameter of one (1.4%) cardiac resynchronization therapy pacemaker (CRT-P); further one CIED (0.6%) was not contactable. PMs offered in mean 75.2% of study parameters thereof 88.0% were to adjust manually, whereof 49.3% stayed unchanged to delivery mode. Lead output, UTSR, lower rate, and mode were the most frequently changed parameters (>85.7%, 65.3%, 54.2%, and 52.8%, respectively) compared with unmodified ventricular refractory time and hysteresis (91.7% and. 85.4%, respectively); 2.8% of PMs had out-of-the-box settings. The most frequent personalized data were last (88.9%) and first name (73.6%), while atrial and ventricular serial lead numbers were rarely entered (18.2% and 23.4%, respectively).

CONCLUSION

The programming possibilities of PMs have advanced greatly. Nonetheless, improvements in individual PM programming are still needed as demonstrated by the findings in this study, e.g., PMs with manufacturer settings and lack of individual data.

Impact of pacemaker longevity on expected device replacement rates: Results from computer simulations based on a multicenter registry (ESSENTIAL)

BACKGROUND

The rate of device replacement in pacemaker recipients has not been investigated in detail.

HYPOTHESIS

Current pacemakers with automatic management of atrial and ventricular pacing output provide sufficient longevity to minimize replacement rate.

METHODS

We considered a cohort of 542 pacemaker patients (age 78 ± 9 years, 60% male, 71% de-novo implants) and combined 1-month projected device longevity with survival data and late complication rate in a 3-state Markov model tested in several Monte Carlo computer simulations. Predetermined subgroups were: age < or ≥ 70; gender; primary indication to cardiac pacing.

RESULTS

At the 1-month follow-up the reported projected device longevity was 153 ± 45 months. With these values the proportion of patients expected to undergo a device replacement due to battery depletion was higher in patients aged <70 (49.9%, range 32.1%-61.9%) than in age ≥70 (24.5%, range 19.9%-28.8%); in women (39.9%, range 30.8%-48.1%) than in men (32.0%, range 24.7%-37.5%); in sinus node dysfunction (41.5%, range 30.2%-53.0%) than in atrio-ventricular block (33.5%, range 27.1-38.8%) or atrial fibrillation with bradycardia (27.9%, range 18.5%-37.0%). The expected replacement rate was inversely related to the assumed device longevity and depended on age class: a 50% increase in battery longevity implied a 5% reduction of replacement rates in patients aged ≥80.

CONCLUSIONS

With current device technology 1/4 of pacemaker recipients aged ≥70 are expected to receive a second device in their life. Replacement rate depends on age, gender, and primary indication owing to differences in patients' survival expectancy. Additional improvements in device service time may modestly impact expected replacement rates especially in patients ≥80 years.

Clinically guided pacemaker choice and setting: pacemaker expert programming study

Aim

The aim of this multicentre, observational, transversal study was to evaluate pacemaker (PM) choice and setting in a large number of patients, in order to understand their relationship with the patients' clinical characteristics.

Methods and results

The study enrolled a total of 1858 patients (71 ± 14 years, 54% male), consecutively evaluated during scheduled PM follow-up visits in 7 Italian cardiac arrhythmia centres. To evaluate the appropriateness of PM choice in relation to the patients' clinical characteristics, we analysed their rhythm disorders at the time of device implantation and the characteristics of the devices implanted. To evaluate the appropriateness of device setting, current rhythm disorders and device setting at the time of enrolment were analysed. In the overall study population, 64.3% of the patients received a PM with all of the features required for their rhythm disorder [80.8% in persistent atrioventricular (AV) block, 76.5% in atrial fibrillation needing pacing, 71.0% in sinus node disease, 58.7% in non-persistent atrioventricular block (AVB), 52.7% in neuro-mediated syncope]. The most frequent cause of inappropriate PM choice was the lack of an algorithm to promote intrinsic AV conduction in non-persistent AVB patients (38.1%). In 76.2% of the patients with an appropriate PM (n = 1301), the PM was optimally set for their rhythm disorder.

Conclusions

In the present 'real-world' registry, a large number of patients (35.7%) did not receive an optimal PM for their rhythm disorders. Moreover, one-fourth of appropriate PMs were not programmed according to the patients' clinical characteristics.

Technologies for Prolonging Cardiac Implantable Electronic Device Longevity

Prolonged longevity of cardiac implantable electronic devices (CIEDs) is needed not only as a passive response to match the prolonging life expectancy of patient recipients, but will also actively prolong their life expectancy by avoiding/deferring the risks (and costs) associated with device replacement. CIEDs are still exclusively powered by nonrechargeable primary batteries, and energy exhaustion is the dominant and an inevitable cause of device replacement. The longevity of a CIED is thus determined by the attrition rate of its finite energy reserve. The energy available from a battery depends on its capacity (total amount of electric charge), chemistry (anode, cathode, and electrolyte), and internal architecture (stacked plate, folded plate, and spiral wound). The energy uses of a CIED vary and include a background current for running electronic circuitry, periodic radiofrequency telemetry, high-voltage capacitor reformation, constant ventricular pacing, and sporadic shocks for the cardiac resynchronization therapy defibrillators. The energy use by a CIED is primarily determined by the patient recipient's clinical needs, but the energy stored in the device battery is entirely under the manufacturer's control. A larger battery capacity generally results in a longer-lasting device, but improved battery chemistry and architecture may allow more space-efficient designs. Armed with the necessary technical knowledge, healthcare professionals and purchasers will be empowered to make judicious selection on device models and maximize the utilization of all their energy-saving features, to prolong device longevity for the benefits of their patients and healthcare systems.

Increased hs-CRP and decreased 1,25-dihydroxyvitamin D are associated with increased left ventricle lead threshold

PURPOSE

There are not enough data about threshold changes in patients with CRT. In this study, we aimed to investigate frequency of significant threshold increase of left ventricle lead and to determine clinical, demographic, medical and laboratory parameters that associated with threshold increase in CRT implanted patients.

METHODS

We included CRT implanted 200 patients (124 males, 76 females; mean age 65.8 ± 10.3 years) to this study. Basal and third month LV R wave amplitude, electrode impedance, and threshold values were recorded. Threshold increase was accepted as ≥0.1 V and significant increase as >1 V. Patients were divided into two groups: increased threshold and non-increased threshold for LV lead.

RESULTS

Number of patients with increased LV threshold was 68 (37.6 %). Furthermore, 8 % of patients had severe increase (≥1 V) in LV threshold. We observed that serum levels of hs-CRP and 1,25 (OH)2 vitamin D were independently associated with increased LV threshold. We showed that 1 mg/dl increase in hs-CRP and the 1 mg/dl decrease in vitamin D are associated with 25.3 and 4.5 % increase in the odds of increased LV threshold, respectively.

CONCLUSIONS

Increased hs-CRP and decreased 1,25 (OH)2 vitamin D are the strongest predictors of increased LV lead thresholds. We suggest that hs-CRP and 1,25 (OH)2 vitamin D may be used as markers to predict and follow the patients with increased thresholds. It may be useful to finalize CRT procedure with more appropriate basal threshold in patients with high serum hs-CRP and low 1,25 (OH)2 vitamin D levels.

Acute performance of a right ventricular automatic pacing threshold algorithm for implantable defibrillators

INTRODUCTION

Automatic pacing threshold (AT) testing with threshold trending and output adjustment may simplify follow-up and improve cardiac rhythm device longevity. The objective of this study was to evaluate the performance of a new right ventricular (RV) AT algorithm for implantable cardioverter defibrillators (ICDs) using RVcoil to Can evoked response sensing.

METHOD

Patients undergoing ICD, with or without cardiac resynchronization therapy device, implant, replacement, or upgrade were enrolled. A pulse generator emulator (Can) was temporarily placed in the device pocket. An external pacing system (Boston Scientific, St. Paul, MN, USA) with customized software was used for performing threshold tests and data acquisition. RV manual threshold and up to four AT tests using various pacing parameters were conducted. The threshold measurement and the capture detection performance of the RV AT tests were evaluated through comparison with visual examination of surface electrocardiogram.

RESULTS

Data from 43 patients were analyzed. A total of 158 AT tests were performed, in which 144 AT tests (91.1%) measured correct threshold values. No consecutive asystolic noncaptured beats were observed in any AT tests, and none of the AT tests resulted in incorrectly low threshold measurements. The difference between manual and AT measurements was -0.05 ± 0.43 V. The accuracy for detecting capture and noncaptured beats were 95% and 99%, respectively.

CONCLUSION

The RVcoil to Can evoked response sensing based RV AT algorithm can reliably measure pacing threshold for ICDs, including CRT-Ds.