The impact of pulse generator longevity on the long-term costs of cardiac pacing

MEDICAL DEVICE PRICES IN ECONOMIC EVALUATIONS

Objectives: Economic evaluations, although not formally used in purchasing decisions for medical devices in Canada, are still being conducted and published. The aim of this study was to examine the way that prices have been included in Canadian economic evaluations of medical devices.

Methods: We conducted a review of the economic concepts and implications of methods used for economic evaluations of the eleven most implanted medical devices from the Canadian perspective.

Results: We found Canadian economic studies for five of the eleven medical devices and identified nineteen Canadian studies. Overall, the device costs were important components of total procedure cost, with an average ratio of 44.1 %. Observational estimates of the device costs were obtained from buyers or sellers in 13 of the 19 studies. Although most of the devices last more than 1 year, standard costing methods for capital equipment was never used. In addition, only eight studies included a sensitivity analysis for the device cost. None of the sensitivity analyses were based on actual price distributions.

Conclusions: Economic evaluations are potentially important for policy making, but although they are being conducted, there is no standardized approach for incorporating medical device prices in economic analyses. Our review provides suggestions for improvements in how the prices are incorporated for economic evaluations of medical devices.

Are elderly patients at increased risk of complications following pacemaker implantation? A meta-analysis of randomized trials

BACKGROUND

Patients over the age of 75 represent more than half the recipients of permanent pacemakers. It is not known if they have a different risk of complications than younger patients.

METHODS

Patient-level data were pooled from the CTOPP, UKPACE, and Danish pacing trials. These three randomized trials of pacing mode systematically captured early and late complications following pacemaker insertion. Early postimplant complications included lead dislodgement or loss of capture, cardiac perforation, pneumothorax, hematoma, infection, and death. Lead fracture was considered a late complication.

RESULTS

A total of 4,814 patients were included in this analysis, with an average follow-up of 5.1 years. The average age was 76 years and 43% were female. Any early complication occurred in 5.1% of patients ≥75 years of age compared to 3.4% of patients aged <75 years (P = 0.006). This was driven by an increased risk of pneumothorax (1.6% vs 0.8%, P = 0.07) and both atrial and ventricular lead dislodgement/loss of capture (2.0% vs 1.1%, P = 0.07). Early complications were higher in patients receiving atrial-based pacemakers in both age groups (<75 years: 4.6% vs 2.4%; ≥75 years: 6.6% vs 3.7%); however, the relative risk was not influenced by age group. Older patients had a lower risk of lead fracture (3.6% vs 2.7%, P = 0.08).

CONCLUSION

Elderly patients (≥75 years of age) are at increased risk of early postimplant complications but are at lower risk for lead fracture.

Pacemaker longevity: the world's longest-lasting VVI pacemaker

OBJECTIVE

To describe VVI-pacemaker longevity by model type at our institution and report on a long-lasting model and the longest-lasting pacemaker to be described in the literature.

BACKGROUND

Cardiac pacemakers are becoming increasingly common in the United States. Presently their batteries are expected to last up to 12 years. Pacemaker generator change is associated with increased cost to the health care system and is inconvenient for patients.

METHODS

After identifying a group of very long-lasting CPI Microlith 605 VVI pulse generators, we reviewed records on all patients who had either Guidant or Medtronic pulse generator explantation at our institution over a 10-year period. Average longevities were calculated for all VVI pacemakers, four common VVI models, and the CPI Microlith 605.

RESULTS

A total of 105 VVI-programmed pacemakers were identified. Their average longevity was 7.2 years. The two most common Medtronic VVI-programmed pacemakers explanted were the Thera (7.1 years) and Kappa (7.3 years). The two most common Guidant/CPI models were the Vigor (4.2 years) and Discovery (5.7 years). The CPI Microlith 605 (19.2 years) lasted more than 26 years in one patient before being explanted.

CONCLUSION

At a time when pacemakers are being used more frequently, pacemaker longevity may decrease as a result of the use of dual-chamber pacing systems. In our study, the CPI Microlith 605 had an average longevity more than twice that of all other VVI pacemakers. We also report on a pulse generator that lasted 26.3 years.

Pacemaker Longevity: Are We Getting What We Are Promised?

BACKGROUND

Although pacemaker manufacturers provide projections on longevity, these projections cannot be relied upon due to the assumptions of output parameters being far in excess of those programmed in clinical practice.

OBJECTIVE

The purpose of this review was to compare the actual longevity to the calculated longevity of pacemakers based on battery cell characteristics taking into account individual programmed parameters, mode, degree of usage, and percent pacing. This was also compared to the manufacturers' own projected longevities.

METHODS

Patients who had a pacemaker replaced between 1998 and 2003 were included (n = 124). Cell characteristics were obtained from manufacturers and programmed parameters were obtained at each visit. Stepwise calculations were done for each visit to find current drain during each interval, and then were used in a weighted average to find the total average lifetime current drain. This was subsequently used to find a calculated longevity for each pacemaker to be compared to the actual longevity observed.

RESULTS

The pacemakers lasted 491+/-92 days (mean+/-SEM) less than calculated. There was also a difference between dual- and single-chamber devices (though not statistically significant). Moreover, it was found that there were significant differences between manufacturers.

CONCLUSIONS

There appears to be a significant discrepancy between calculated and actual longevities, confirming that battery depletion occurs earlier than expected. This suggests that current drain expended for ancillary functions may be considerable. Another factor may be pre-implantation drain. Vigilance with programming of outputs, modes, sensors, heart rates, and ancillary functions could potentially extend longevity and postpone/obviate the need for costly repeat surgery with its attended risk of complications. Furthermore, the differences between manufacturers seem to parallel the clinical impressions.

Cardiovascular outcomes with atrial-based pacing compared with ventricular pacing: meta-analysis of randomized trials, using individual patient data

BACKGROUND

Several randomized trials have compared atrial-based (dual-chamber or atrial) pacing with ventricular pacing in patients with bradycardia. No trial has shown a mortality reduction, and only 1 small trial suggested a reduction in stroke. The goal of this review was to determine whether atrial-based pacing prevents major cardiovascular events.

METHODS AND RESULTS

A systematic review was performed of publications since 1980. For inclusion, trials had to compare an atrial-based with a ventricular-based pacing mode; use a randomized, controlled, parallel design; and have data on mortality, stroke, heart failure, or atrial fibrillation. Individual patient data were obtained from 5 of the 8 identified studies, representing 95% of patients in the 8 trials, and a total of 35 000 patient-years of follow-up. There was no significant heterogeneity among the results of the individual trials. There was no significant reduction in mortality (hazard ratio [HR], 0.95; 95% confidence interval [CI], 0.87 to 1.03; P=0.19) or heart failure (HR, 0.89; 95% CI, 0.77 to 1.03; P=0.15) with atrial-based pacing. There was a significant reduction in atrial fibrillation (HR, 0.80; 95% CI, 0.72 to 0.89; P=0.00003) and a reduction in stroke that was of borderline significance (HR, 0.81; 95% CI, 0.67 to 0.99; P=0.035). There was no convincing evidence that any patient subgroup received special benefit from atrial-based pacing.

CONCLUSIONS

Compared with ventricular pacing, the use of atrial-based pacing does not improve survival or reduce heart failure or cardiovascular death. However, atrial-based pacing reduces the incidence of atrial fibrillation and may modestly reduce stroke.

[Efficiency potential in the pacemaker/implantable cardioverter defibrillator outpatient clinic]

The aim of the present study was to elucidate whether the duration of a technical follow-up (FU) of a pacemaker (PM)/implantable cardioverter defibrillator (ICD) has an impact on cost-effectiveness in the outpatient clinic. We determined the time required for a complete FU of devices from three different manufacturers. In 130 patients (70 VVI/DDD-PM, 60 VVI/DDD-ICD) with either a PM (Phylos, Chorum/Talent, Kappa, EnPulse) or an ICD (Belos, Alto or GEM) the time was recorded for a complete FU including determination of lead impedance, sensing and pacing threshold. The time for activation of individual menue buttons was excluded. On the basis of time required for FU, cost-units (CU) were calculated for 2000 FU/year and for a presumed device longevity (PM 7 years, ICD 5 years). For VVI-PM, the duration of FU was almost identical for devices from different manufacturers (105+/-11 s to 125+/-8 s; p=n.s.). However, analysis of DDD-PM revealed marked differences (140+/-25 s vs 282+/-23 s, p<0.05). Time for FU of ICDs varied between 108+/-5 s and 207+/-21 s (p<0.05) in VVI-ICDs and between 129+/-8 ms and 225+/-23 s (p<0.05) in DDD-ICDs. The total savings could be 55 000 CU in VVI- and 53 333 CU in DDD-ICDs. For full automatic DDD-pacemakers (EnPulse) time for FU could be reduced to 58+/-3 s (p<0.05). Differences in FU times were caused by problems with telemetry, delay during booting of the programmer, interrogation at the beginning and at the end of FU and for sensing tests. Improving not only programmers and devices but also test automaticity could significantly increase cost-efficiency in the outpatient clinic.

Pacemaker selection: time for a rethinking of complex pacing systems?The opinions expressed in this article are not necessarily those of the Editors of the European Heart Journal or of the European Society of Cardiology

Evidence from randomized trials indicates that the clinical benefits of dual-chamber (DDD) pacing are modest: (i) no significant differences exist between physiological pacing and single-chamber pacing in mortality and stroke; (ii) ventricular desynchronization resulting from chronic right-ventricular pacing in DDD mode, induces a significantly increased incidence of atrial fibrillation (AF) and heart failure hospitalizations; (iii) AF pacing prevention and therapy algorithms have shown a modest to minimal or absent efficacy; (iv) the widespread use of physiological pacemakers is not an economically attractive strategy. Thus, these data provide a reliable body of evidence on which to make more rationale clinical decisions for individual patients and policy decisions for health costs saving. The cheaper single-chamber AAI(R) or VVI(R) has been shown to satisfy both conditions in most cases of sinus node disease and AV block.

Cost-effectiveness of physiologic pacing: Results of the Canadian Health Economic Assessment of Physiologic Pacing

OBJECTIVES

The purpose of this study was to determine the cost-effectiveness of physiologic pacemakers.

BACKGROUND

The Canadian Trial of Physiologic Pacing (CTOPP) was a large randomized trial that evaluated the efficacy of physiologic pacing compared with ventricular pacing. CTOPP also included a prospective cost-effectiveness substudy.

METHODS

Resource usage and costs were collected from a subset of 472 patients (of 1,094) who received a physiologic pacemaker and 586 (of 1,474) who received a ventricular pacemaker. Costs included initial pacemaker implantation and all health care follow-up costs over a follow-up of 5.2 years. Costs are reported in 2004 Canadian dollars (1 Canadian dollar = 0.76 US dollars), with adjustments for censoring. Incremental cost-effectiveness was estimated as the ratio of the difference (treatment-control) in mean cost to the difference in life expectancy (mean survival), with costs and effects discounted at 3% per year.

RESULTS

Over a mean follow-up of 3.1 years, physiologic pacing was associated with a gain of 0.01 life-years. This benefit increases to 0.25 life-years in the subgroup of patients with an intrinsic (unpaced) heart rate < or =60 bpm. Physiologic pacing was more expensive than ventricular (16,833 Canadian dollars vs 13,857 US dollars), largely because of the increased cost of dual-chamber devices. Among all substudy patients, the incremental cost-effectiveness of physiologic pacing is 297,600 Canadian dollars per life-year gained; however, this value falls to 16,343 Canadian dollars in patients with an intrinsic heart rate >60.

CONCLUSIONS

In the short term, a strategy of routine implantation of physiologic pacemakers is not cost-effective by currently accepted standards. The selective use of these devices in patients likely to be pacemaker dependent appears to be cost-effective. Further studies with longer follow-up and which consider the benefit of reducing nonfatal cardiac events would be valuable.

Cost-effectiveness of dual-chamber pacing compared with ventricular pacing for sinus node dysfunction

BACKGROUND

Compared with single-chamber ventricular pacing, dual-chamber pacing can reduce adverse events and, as a result, improve quality of life in patients paced for sick sinus syndrome. It is not clear, however, how these benefits compare with the increased cost of dual-chamber pacemakers.

METHODS AND RESULTS

We used 4-year data from a 2010-patient, randomized trial to estimate the incremental cost-effectiveness of dual-chamber pacing compared with ventricular pacing and then projected these findings over the patients' lifetimes by using a Markov model that was calibrated to the first 5 years of in-trial data. To assess the stability of the findings, we performed 1000 bootstrap analyses and multiple sensitivity analyses. During the first 4 years of the trial, dual-chamber pacemakers increased quality-adjusted life expectancy by 0.013 year per subject at an incremental cost-effectiveness ratio of 53,000 dollars per quality-adjusted year of life gained. Over a lifetime, dual-chamber pacing was projected to increase quality-adjusted life expectancy by 0.14 year with an incremental cost-effectiveness ratio of approximately 6800 dollars per quality-adjusted year of life gained. In bootstrap analyses, dual-chamber pacing was cost-effective in 91.9% of simulations at a threshold of 50,000 dollars per quality-adjusted year of life and in 93.2% of simulations at a threshold of 100,000 dollars. Its cost-effectiveness ratio was also below this threshold in numerous sensitivity analyses that varied key estimates.

CONCLUSIONS

For patients with sick sinus syndrome requiring pacing, dual-chamber pacing increases quality-adjusted life expectancy at a cost that is generally considered acceptable.

Pacemakers and Implantable Cardioverter Defibrillators:. Device Longevity Is More Important Than Smaller Size: The Patient's Viewpoint

The size of pacemakers and implantable cardioverter defibrillators (ICDs) has been diminishing progressively. If two devices are otherwise identical in components, features and technology, the one with a larger battery should have a longer service life. Therefore, patients who receive smaller devices may require more frequent surgery to replace the devices. It is uncertain whether this tradeoff for smaller size is desired by patients. We surveyed 156 patients to determine whether patients prefer a larger, longer-lasting device, or a smaller device that is less noticeable but requires more frequent surgery. The effects of subgroups were evaluated; these included body habitus, age, gender, and patients seen at time of pulse generator replacement (PGR), initial implant, or follow-up. Among 156 patients surveyed, 151 expressed a preference. Of these, 90.1% preferred the larger device and 9.9% the smaller device (P <0.0001). Among thin patients, 79.5% preferred a larger device. Ninety percent of males and 89.2% of females selected the larger device. Among younger patients (< or =72 years), 89.6% preferred the larger device, as did 90.5% of older patients (>72 years). Of patients undergoing PGR or initial implants, 95% favored the larger device, as did 86% of patients presenting for follow-up. The vast majority of patients prefer a larger device to reduce the number of potential replacement operations. This preference crosses the spectrum of those with a previously implanted device, those undergoing initial implants, those returning for routine follow-up, and patients of various ages, gender, and habitus.

Cost-utility analysis of pacemakers for the treatment of vasovagal syncope

Dual-chamber pacing is a promising treatment for patients with very frequent vasovagal syncope, but its cost utility is unknown. We report that the incremental cost per quality-adjusted life-year gained is $13,159 Canadian dollars (about $8,600 US dollars), and therefore this pacemaker therapy for vasovagal syncope has a favorable cost-utility ratio.

Pacing threshold trends and variability in modern tined leads assessed using high resolution automatic measurements: conversion of pulse width into voltage thresholds

With the aid of an algorithm for automatic pacing threshold (T) measurement in the atrium and ventricle, downloadable into implanted Thera pacemakers (Medtronic Inc.), we studied T evolution during lead maturation, T variation during activities of daily living, and various types of beat-to-beat T variations in three tined bipolar leads: 5.6-mm2 steroid-eluting (Medtronic Inc. models 4524 atrial-J [n = 8] and 4024 ventricular [n = 8]), 1.2-mm2 steroid-eluting (Medtronic Inc. models 5534 atrial-J [n = 9] and 5034 ventricular [n = 9]), and 8-mm2 without steroid (Intermedics models 432-04 atrial-J [n = 7] and 430-10 ventricular [n = 7]). The leads were implanted in 24 consecutive patients with intact AV conduction (required by the algorithm) and followed for up to 13-25 months after implantation. Since the algorithm determined pulse width Ts at different amplitudes that, depending upon T level, could range from 0.5 to 5.0 V, we invented a methodology for conversion of pulse width Ts into voltage Ts at 0.5 ms, to pool and present T data on a universal scale. Frequent, high resolution T measurements revealed details on the lead maturation process that we divided into three stages: initial T subsiding, first wave of T peaking, and a new, quicker or slower, T rise. Although there were notable differences in duration and magnitude of T peaking on the individual basis, differences between the three lead types and between the atrium and ventricle were demonstrable. The 1.2-mm2 leads exhibited less T peaking than their predecessors 5.6-mm2 leads and excellent positional stability, whereas 8-mm2 leads demonstrated the most intensive T peaking and highest mean chronic T values. T changes during activities of daily living showed some tendencies-higher T during night and lower T during exercise--yet with a number of exceptions. The overall magnitude of daily T fluctuations was < 0.2 V in all but one lead, and 50% daily voltage safety margin would be sufficient. A 100% voltage safety margin may be inadequate for a 1-year period during the chronic phase (after 6 months of implantation). A scheme for calculation of pulse width safety margins equivalent to voltage safety margins is given. Some leads can exhibit very large beat-to-beat T variations before, during, and after T peaking, and prospective algorithms for automatic T measurement should verify T values through more than 1-2 captured beats to obviate a great underestimation of the T providing consistent capture. T dependence upon pacing rate was negligible. Consistent-capture hysteresis may, in conjunction with lead instability, be as much as 0.25 V. Therefore, it is better to use an incremental approach from below to T level during automatic T measurements.

Clinical use of low output settings in 1.2-mm2 steroid eluting electrodes: three years of experience

A new generation of tined steroid-eluting leads featuring 1.2-mm2 distal electrodes (CapSure Z, Medtronic Inc., Minneapolis MN, USA) has the potential to reduce battery current drain and enhance pulse generator longevity by means of high pacing impedance and low pacing threshold. Forty patients aged 50-87 years (mean 72.4 years) were implanted with 33 ventricular (models 4033 and 5034) and 30 atrial-J (models 4533 and 5534) leads with 1.2-mm2 electrodes. Low pacing outputs, mainly in the range from 1 V/0.20 ms to 1.6 V/0.36 ms with > or = 3:1 pulse width safety margins (PWSM) applied, were instituted at 3-6 months of implantation and adjusted at subsequent follow-up controls according to changes in thresholds. Cumulative follow-up period of low outputs was 1,512 months (24 months per lead, range 9-36 months), which involved 3.43 follow-up controls per lead (range 2-5). During follow-up, pulse width thresholds (PWTs) at the used amplitudes did not change in 55.5% of the leads; PWTs increased by < or = 100% in 36.5%, by 101%-200% in 1.6%, and by > 200% in 6.3% of the leads. Changes in PWT that would apparently exceed 3:1 PWSM over a 1-year period occurred in one atrial lead where even the nominal 3.5 V/0.4-ms output would not be effective and in one ventricular lead in the aftermath of an acute myocardial infarction (300% PWT rise at 1.6 V). Based on the present observations, pacemaker dependent patients require > or = 4:1 PWSM and other patients > or = 3:1 PWSM with output pulse widths < or = 0.60 ms and annual pacemaker clinic visits. Calculated battery current drain and anticipated longevity associated with a variety of pacing outputs and impedances are provided, compared, and discussed. Correlation between acute and chronic pacing impedances and pacing thresholds was weak, implying that a systematic intraoperative pacing site optimization cannot contribute significantly to the extension of average battery longevity.

Telemetry guided pacemaker programming: impact of output amplitude and the use of low threshold leads on projected pacemaker longevity

In a prospective study, a low threshold screw-in electrode (Medtronic 5078, group I, n = 9) was compared to a conventional active fixation lead (Biotronik Y60BP, group II, n = 9) to investigate whether lower pacing thresholds really translate into longer projected service life of the pacemaker. The leads were implanted in the atrium and were connected to a dual chamber pacing system which included the same ventricular lead (Medtronic 5024) and the same pulse generator model (Intermedics 294-03) in both groups. Eighteen months after implantation, atrial and ventricular pacing thresholds were measured as the charge delivered per pulse [microC] at 0.5, 1.0, 1.5, 2.0, and 3.5 V, respectively. For chronic output programming in both channels, patients capturing at 0.5 V were set to 1.0 V, those capturing at 1.5 V were permanently programmed to 2.0 V with the double of the charge threshold as the safety margin for pacing ("safety charge"). A combination of atrial and ventricular output settings was optimal, if it resulted in minimum battery current drain (microA] as measured by pacemaker telemetry. In both groups, current consumption [microA] decreased significantly as output amplitude was decreased, exhibiting its lowest value at 1.0 V in either channel. All ventricular leads could be programmed to the optimum output amplitude of 1.0 V in groups 1 and 2. As the 2:1 "safety charge" values were almost identical, the ventricular channel essential contributes the same amount to the battery drain of the pacing system in both groups. In the atrium, all patients of group 1 could be programmed to the optimum output amplitude of 1.0 V with an average pulse duration of 0.42 +/- 0.15 ms. In group 2, however, all patients had to be programmed to 2.0 V with a mean pulse width of 0.52 +/- 0.15 ms. With the atrial and ventricular output being optimized, the average battery drain of the whole pacing system was 12.19 +/- 0.63 microA in group 1 versus 14.42 +/- 0.32 microA in group 2 (P < 0.001). As patients were chronically programmed to these output settings, this difference translates into a clinically relevant gain in projected pacemaker longevity of 17 months or 18.3% (121 +/- 4 vs. 104 +/- 2 months; P < 0.001). Thus, programming a 2:1 safety margin in terms of charge and optimizing the output parameters by real-time telemetry of the battery current is a useful approach to reduce battery current drain. Making the most of modern lead technology with a different performance in only one channel of an otherwise identical DDD pacing system translates into a significant prolongation of projected pacemaker service life which is of great importance with the increasing awareness of health care expenditures. The gain in projected longevity is mainly due to the option of reducing the output amplitude which is still significantly beneficial well below the nominal voltage of the power source.

On the mechanism of ventricular defibrillation

The mechanism of ventricular defibrillation can be considered at many different levels. The highest level is considered at strength of the shock given through the defibrillation electrodes. At the next level, the mechanism of defibrillation can be examined in terms of the electrical field that the shock produces throughout the ventricles. Other levels include the effects this electric field has on the activation sequences and on the cellular action potentials that either initiate or inhibit the early sites of activation following the shock. Yet another level considers the mechanism by which the shock field initiates new action potentials or prolongs the action potential by changing the transmembrane potential during the shock. Finally, the subcellular level is considered, which involves the response of the individual ion channels to the shock. This review gives a brief overview of some salient features of defibrillation at each of these mechanistic levels.