Ampere Hour as a Predictor of Cardiac Resynchronization Defibrillator Pulse Generator Battery Longevity: A Multicenter Study

Real-world evidence in health technology assessment of high-risk medical devices: Fit for purpose?

Health technology assessment (HTA) of medical devices (MDs) increasingly rely on real-world evidence (RWE). The aim of this study was to evaluate the type and the quality of the evidence used to assess the (cost-)effectiveness of high risk MDs (Class III) by HTA agencies in Europe (four European HTA agencies and EUnetHTA), with particular focus on RWE. Data were extracted from HTA reports on the type of evidence demonstrating (cost-)effectiveness, and the quality of observational studies of comparative effectiveness using the Good Research for Comparative Effectiveness principles. 25 HTA reports were included that incorporated 28 observational studies of comparative effectiveness. Half of the studies (46%) took important confounding and/or effect modifying variables into account in the design and/or analyses. The most common way of including confounders and/or effect modifiers was through multivariable regression analysis. Other methods, such as propensity score matching, were rarely employed. Furthermore, meaningful analyses to test key assumptions were largely omitted. Resulting recommendations from HTA agencies on MDs is therefore (partially) based on evidence which is riddled with uncertainty. Considering the increasing importance of RWE it is important that the quality of observational studies of comparative effectiveness are systematically assessed when used in decision-making.

Estimate and reporting of longevity for cardiac implantable electronic devices: a proposal for standardized criteria

BACKGROUND

Cardiac implantable electronic devices (CIEDs) are widely used according to consensus guidelines in various patient categories. The longevity of CIED is a major determinant of the frequency with which patients require device replacement. Given the mismatch between the useful life of the devices and patient survival, device replacement is often needed. There is a great variability in the criteria used by manufacturers to determine the longevity of pacemakers (PM), implantable defibrillators (ICDs), and devices for cardiac resynchronization therapy (CRT). Thus, a fair comparison and an effective device evaluation is often difficult.

METHODS

The objective of this paper is to provide standardized criteria based on typical clinical settings for estimating the longevity of single and dual chamber ICDs, cardiac resynchronization defibrillators (CRT-D), single and dual chamber PMs, and cardiac resynchronization PMs (CRT- P) to be used in health technology assessment for an appropriate comparison among different devices.

RESULTS

The proposed parameters, if applied to the current marketed devices, provide longevity values in the range 5-17.2 years.

CONCLUSION

The values of longevity with the non-standardized criteria used by the manufacturers result in higher maximum values respect to the proposed standardized criteria for CRT-D, CRTD-MPP, CRT-P, and Dual-chamber PM.

First Demonstration of Cardiac Resynchronization Therapy Defibrillator Service Life Exceeding Patient Survival in a Heart Failure with Reduced Ejection Fraction Cohort

The occurrence of patient longevity exceeding implantable cardioverter-defibrillator (ICD) service life has important implications for patient outcomes and the cost of care. Battery capacity as measured in ampere-hours (Ah) is a strong predictor of survival to an elective replacement indicator (ERI) point and 2.1 Ah is the largest-capacity ICD battery in use at our facility. This was a long-term study of ICDs out of service (OOS) in patients with heart failure with reduced ejection fraction who received a 2.1-Ah cardiac resynchronization therapy defibrillator (CRT-D). All 2.1-Ah CRT-D systems implanted (n = 418) from August 1, 2008 through August 31, 2016 were included in this retrospective chart review. The primary endpoint was device OOS due to the battery reaching an ERI point, patient death, infection/erosion, advisory/recall, heart transplant, or unspecified. The maximum follow-up period was 10.3 years, with a mean follow-up length of 4.7 years. The most common reason for device OOS was patient death (65.6%), with only 5.7% of devices reaching the ERI point during the study. There was a period of OOS acceleration driven numerically by patient death in the sixth to ninth years of follow-up. Male sex, ischemic cardiomyopathy, elevated creatinine level, advanced age, and reduced ejection fraction were associated with OOS (p < 0.05). To our knowledge, this is the first study to report ICD battery life exceeding patient survival in a chronic heart failure cohort. During an accelerated time of CRT-D OOS (when it is expected that ~98% of 1.0-Ah and 1.4-Ah CRT-D systems reach an ERI point), patient death resulted in substantially more device OOS than battery replacement and avoided costs of complications and generator changes. These results help to explain the elevated risks of CRT-D generator changes in shorter-longevity devices.

Do all patients with implantable cardioverter defibrillator need a generator change? A health service evaluation of patients who underwent generator changes from a single tertiary center

BACKGROUND

The patient characteristics, therapy received and outcomes after one or more implantable cardioverter defibrillator (ICD) generator changes from contemporary practice is not well known.

METHODS

We conducted a health service evaluation of patients who underwent ICD implantation and generator change. Patients who had generator changes from February 2016 to October 2019 were identified from our database and electronic records were reviewed for patient characteristics, number of generator changes, receipt of therapy and death.

RESULTS

Our database included 88 patients with a generator change. A total of 22 patients (25.0%) received dual chamber ICD, 10 patients (11.4%) received single chamber ICD, 54 patients (61.3%) received cardiac resynchronization therapy defibrillator and 2 patients (2.3%) received subcutaneous ICD. A second generator change occurred in 18 patients and a third generator changes was performed in 6 patients. There were 29 deaths and a follow up period of 9.4 ± 2.9 years. From implant to initial generator change 39 patients had appropriate antitachycardia pacing (ATP), 6 patient had inappropriate ATP, 29 patients had appropriate shocks and 5 patients had an inappropriate shock. Between the 1st and 2nd generator change and the 2nd and 3rd there were no cases of inappropriate ATP or shock. Overall, 42 patients out of the 88 had appropriate therapy (47.7%) and 7 patients had inappropriate therapy (8.0%).

CONCLUSIONS

Most patients with ICDs do not receive therapy and a minority have inappropriate therapy which typically occur before the first generator change as we observed no inappropriate therapy beyond the first generator change.

Multifunctional Pacemaker Lead for Cardiac Energy Harvesting and Pressure Sensing

Biomedical self-sustainable energy generation represents a new frontier of power solution for implantable biomedical devices (IMDs), such as cardiac pacemakers. However, almost all reported cardiac energy harvesting designs have not yet reached the stage of clinical translation. A major bottleneck has been the need of additional surgeries for the placements of these devices. Here, integrated piezoelectric-based energy harvesting and sensing designs are reported, which can be seamlessly incorporated into existing IMDs for ease of clinical translation. In vitro experiments validate the energy harvesting process by simulating the bending and twisting motion during heart cycle. Clinical translation is demonstrated in four porcine hearts in vivo under various conditions. Energy harvesting strategy utilizes pacemaker leads as a means of reducing the reliance on batteries and demonstrates the charging ability for extending the lifetime of a pacemaker battery by 20%, which provides a promising self-sustainable energy solution for IMDs. The additional self-powered blood pressure sensing is discussed, and the reported results demonstrate the potential in alerting arrhythmias by monitoring the right ventricular pressure variations. This combined cardiac energy harvesting and blood pressure sensing strategy provides a multifunctional, transformative while practical power and diagnosis solution for cardiac pacemakers and next generation of IMDs.

Appropriate Implantable Cardioverter-Defibrillator Therapies Delivered 5 Years After End of Service

We present the case of a 57-year-old man with a primary prevention internal cardioverter-defibrillator for severe nonischemic cardiomyopathy. At the time of elective replacement indicator, systolic function had fully recovered, and his generator was not changed. Nearly 5 years post–elective replacement indicator he received appropriate internal cardioverter-defibrillator therapies during a myocardial infarction. (Level of Difficulty: Intermediate.)

Projected longevities of cardiac implantable defibrillators: a retrospective analysis over the period 2007–17 and the impact of technological factors in determining longevity

Aims

Implanters of cardiac implantable electronic devices cannot easily choose devices by longevity as usually current models only have projected longevity data since those with known performance are obsolete. This study examines how projected device longevities are derived, the influencing factors, and their roles in guiding model choice.

Methods and results

Ninety-eight implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy-defibrillator (CRT-D) models released in Europe in 2007–17 were analysed for reported battery capacities, projected longevities for standardized settings stipulated by the French Haute Autorité de Santé (HAS) and manufacturer-chosen settings. Battery capacities and HAS projected longevities increased during the study period. Based on current drain estimation, therapy functions consumed only a small portion (2–7%) of the battery energy for single- and dual-chamber ICDs, but up to 50% (from biventricular pacing) for CRT-Ds. Large differences exist between manufacturers and models both in terms of battery capacity and energy consumption.

Conclusion

Battery capacity is not the sole driver of longevity for electronic implantable cardiac devices and, particularly for ICDs, the core function consume a large part of the battery energy even in the absence of therapy. Providing standardized current drain consumption in addition to battery capacity may provide more meaningful longevity information among implantable electronic cardiac devices.

Device Therapy and Arrhythmia Management in Left Ventricular Assist Device Recipients: A Scientific Statement From the American Heart Association

Left ventricular assist devices (LVADs) are an increasingly used strategy for the management of patients with advanced heart failure with reduced ejection fraction. Although these devices effectively improve survival, atrial and ventricular arrhythmias are common, predispose these patients to additional risk, and complicate patient management. However, there is no consensus on best practices for the medical management of these arrhythmias or on the optimal timing for procedural interventions in patients with refractory arrhythmias. Although the vast majority of these patients have preexisting cardiovascular implantable electronic devices or cardiac resynchronization therapy, given the natural history of heart failure, it is common practice to maintain cardiovascular implantable electronic device detection and therapies after LVAD implantation. Available data, however, are conflicting on the efficacy of and optimal device programming after LVAD implantation. Therefore, the primary objective of this scientific statement is to review the available evidence and to provide guidance on the management of atrial and ventricular arrhythmias in this unique patient population, as well as procedural interventions and cardiovascular implantable electronic device and cardiac resynchronization therapy programming strategies, on the basis of a comprehensive literature review by electrophysiologists, heart failure cardiologists, cardiac surgeons, and cardiovascular nurse specialists with expertise in managing these patients. The structure and design of commercially available LVADs are briefly reviewed, as well as clinical indications for device implantation. The relevant physiological effects of long-term exposure to continuous-flow circulatory support are highlighted, as well as the mechanisms and clinical significance of arrhythmias in the setting of LVAD support.

Longevity decoded: Insights from power consumption analyses into device construction and their clinical implications

Introduction

The longevity of a cardiac implantable electronic device (CIED) depends on how quickly the powers consumed by the device's functions exhaust its usable battery energy. A mathematical model for CIED power consumptions was developed and validated against longevity data from manufacturers.

Methods

The programmable parameters for the Resonate X4 cardiac resynchronization therapy defibrillators (CRT‐Ds) on the Boston Scientific (St. Paul, MN, USA) online longevity calculator were designated as independent terms in the sum for the total power consumption. The reciprocal of longevity was plotted against variations in these terms. Linear and nonlinear regression analyses were used to fit the plots. The power consumed by pacing was theoretically derived and used as the calibrating tool for estimating the powers consumed by other functions and the usable battery energy. The same methodology was applied to the longevity data of other manufacturers’ CRT‐Ds.

Results

Single chamber 100% pacing at 60 beats/min, 2.5 V, 0.4 ms, 500 Ω consumes ≈ 144 J/year. Shock therapy is 45–85% energy efficient. Multichamber pacing modes and maintaining readiness to pace a chamber consume power even if no pacing is delivered. Switching voltage regulation is theoretically more energy efficient than linear voltage regulation for powering pacing.

Conclusions

The powers consumed by therapy functions are dictated by the patient's clinical needs, but healthcare professionals can extend device longevity by switching off dormant functions and simplifying the pacing mode. Choosing a device model with large usable battery energy, low background power, and energy efficient pacing and shock therapy for implantation will increase the probability of a long service lifespan.

Predicted longevity of contemporary cardiac implantable electronic devices: A call for industry-wide "standardized" reporting

BACKGROUND

Battery longevity is an important factor that may influence the selection of cardiac implantable electronic devices (CIEDs). However, there remains a lack of industry-wide standardized reporting of predicted CIED longevity to facilitate informed decision-making for implanting physicians and payers.

OBJECTIVE

The purpose of this study was to compare the predicted longevity of current generation CIEDs using best-matched CIEDs settings to assess differences between brands and models.

METHODS

Data were extracted for current model pacemakers, implantable cardioverter-defibrillators (ICDs), and cardiac resynchronization therapy-defibrillators (CRT-Ds) from product manuals and, where absent, by communication with the manufacturers. Pacemaker longevity estimations were based on standardized pacing outputs (2.5V, 0.40-ms pulse width, 500-Ω impedance) and pacing loads of 50% or 100% at 60 bpm. ICD and CRT-D longevity were estimated at 0% pacing and 15% atrial plus 100% biventricular pacing, with essential capacitor reforms and zero clinical shocks.

RESULTS

Mean maximum predicted longevity of single- and dual-chamber pacemakers was 12.0 ± 2.1 and 9.8 ± 1.9 years, respectively. Use of advanced features such as remote monitoring, prearrhythmia electrogram storage, and rate response can result in ∼1.4 years of reduction in longevity. Mean maximum predicted longevity of ICDs and CRT-Ds was 12.4 ± 3.0 and 8.8 ± 2.1 years, respectively. Of note, there were significant variations in predicted CIED longevity according to device manufacturers, with up to 44%, 42%, and 44% difference for pacemakers, ICDs, and CRT-Ds, respectively.

CONCLUSION

Contemporary CIEDs demonstrate highly variable predicted longevity according to device manufacturers. This may impact on health care costs and long-term clinical outcomes.

ENDURALIFE-Powered Cardiac Resynchronisation Therapy Defibrillator Devices for Treating Heart Failure: A NICE Medical Technology Guidance

ENDURALIFE™-powered cardiac resynchronisation therapy defibrillator (CRT-D) devices were the subject of an evaluation by the National Institute for Health and Care Excellence, through its Medical Technologies Evaluation Programme, for the treatment of heart failure. Boston Scientific (manufacturer) submitted a case for the adoption of the technology, claiming that it has a longer battery life resulting in a longer time to CRT-D replacement. Other claimed benefits were fewer complications associated with replacement procedures, fewer hospital admissions, less time spent in hospital and reduced demand on cardiology device implantation rooms. The submission was critiqued by Cedar, an external assessment centre. The submitted clinical evidence showed that ENDURALIFE-powered devices implanted during the period 2008-2010 were superior, in terms of longevity, to other devices at that time. Submitted economic evidence indicated that, because of a reduction in the need for replacement procedures, ENDURALIFE-powered devices were cost saving when compared to comparator devices. Cedar highlighted uncertainty of the applicability of the clinical evidence to devices marketed today. The Medical Technologies Advisory Committee noted that this was unavoidable due to the follow-up time required to study battery life. Clinical experts noted that increased battery life is an important patient benefit. However, centres use devices from multiple manufacturers to negate pressure on clinical services in the event of a major device recall. The clinical and economic evidence showed benefits to the patient, and further analysis requested by the committee suggested that ENDURALIFE-powered CRT-Ds may save between £2120 and £5627 per patient over 15 years through a reduction in the need for replacement procedures. ENDURALIFE-powered CRT-D devices received a positive recommendation in Medical Technologies Guidance 33.

Longevity of Cardiovascular Implantable Electronic Devices

Battery depletion is the most common reason for device reoperation, which is associated with significant patient morbidity and mortality. This article describes the history of pacing and defibrillation power supplies and the factors that determine the longevity of pacing and defibrillator generators with a special emphasis on factors that can be adjusted or controlled by the implanting and following physician. Optimization of longevity is attained through device selection; shock minimization; avoidance of prolonged radiofrequency telemetry; selection of higher impedance vectors; avoidance of long pulse duration when possible; and avoidance of unnecessary feature activation, such as continuous electrogram storage.

The economic impact of battery longevity in implantable cardioverter-defibrillators for cardiac resynchronization therapy: the hospital and healthcare system perspectives

Aims

Patients receiving cardiac resynchronization therapy defibrillators (CRT-Ds) are likely to undergo one or more device replacements, mainly for battery depletion. We assessed the economic impact of battery depletion on the overall cost of CRT-D treatment from the perspectives of the healthcare system and the hospital. We also compared devices of different generations and from different manufacturers in terms of therapy cost.

Methods and results

We analysed data on 1792 CRT-Ds implanted in 1399 patients in 9 Italian centres. We calculated the replacement probability and the total therapy cost over 6 years, stratified by device generation and manufacturer. Public tariffs from diagnosis-related groups were used together with device prices and hospitalization costs. Generators were from 3 manufacturers: Boston Scientific (667, 37%), Medtronic (973, 54%), and St Jude Medical (152, 9%). The replacement probability at 6 years was 83 and 68% for earlier- and recent-generation devices, respectively. The need for replacement increased total therapy costs by more than 50% over the initial implantation cost for hospitals and by more than 30% for healthcare system. The improved longevity of recent-generation CRT-Ds reduced the therapy cost by ∼6% in both perspectives. Among recent-generation CRT-Ds, the replacement probability of devices from different manufacturers ranged from 12 to 70%. Consequently, the maximum difference in therapy cost between manufacturers was 40% for hospitals and 19% for the healthcare system.

Conclusions

Differences in CRT-D longevity strongly affect the overall therapy cost. While the use of recent-generation devices has reduced the cost, significant differences exist among currently available systems.

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.

Economic impact of longer battery life of cardiac resynchronization therapy defibrillators in Sweden

OBJECTIVE

The objective of this study was to quantify the impact that longer battery life of cardiac resynchronization therapy defibrillator (CRT-D) devices has on reducing the number of device replacements and associated costs of these replacements from a Swedish health care system perspective.

METHODS

An economic model based on real-world published data was developed to estimate cost savings and avoided device replacements for CRT-Ds with longer battery life compared with devices with industry-standard battery life expectancy. Base-case comparisons were performed among CRT-Ds of three manufacturers - Boston Scientific Corporation, St. Jude Medical, and Medtronic - over a 6-year time horizon, as per the available clinical data. As a sensitivity analysis, we evaluated CRT-Ds as well as single-chamber implantable cardioverter defibrillator (ICD-VR) and dual-chamber implantable cardioverter defibrillator (ICD-DR) devices over a longer 10-year period. All costs were in 2015 Swedish Krona (SEK) discounted at 3% per annum.

RESULTS

Base-case analysis results show that up to 603 replacements and up to SEK 60.4 million cumulative-associated costs could be avoided over 6 years by using devices with extended battery life. The pattern of savings over time suggests that savings are modest initially but increase rapidly beginning in the third year of follow-up with each year's cumulative savings two to three times the previous year. Evaluating CRT-D, ICD-VR, and ICD-DR devices together over a longer 10-year period, the sensitivity analysis showed 2,820 fewer replacement procedures and associated cost savings of SEK 249.3 million for all defibrillators with extended battery life.

CONCLUSION

Extended battery life is likely to reduce device replacements and associated complications and costs, which may result in important cost savings and a more efficient use of health care resources as well as a better quality of life for heart failure patients in Sweden.