Longevity of implantable cardioverter-defibrillators: implications for clinical practice and health care systems

Unanticipated subcutaneous ICD end-of-service due to premature battery depletion and occurrence of lead fracture: A single centre experience

The use of subcutaneous ICDs (S-ICD) is growing over years despite increasing alerts on premature battery depletion (PBD) and lead fractures leading to unanticipated device replacements. In our single-centre study including 192 patients, per year analysis demonstrated that incidence of PBD is higher than previously reported with overall greatest battery replacement requirements around the fifth year of follow-up. The underlying issue appears to be limited to old series devices, but only a longer follow-up will clarify the real impact of this phenomenon on patient outcomes. PBD is an underestimated S-ICDs issue and if the hereby demonstrated trend were to be confirmed in latest device series, this would bring significant concerns to patient safety and huge economic expense to health system.

"Real-world" analysis of battery longevity of implantable cardioverter-defibrillators: an in-depth analysis of a prospective defibrillator database

BACKGROUND

There is a lack of evidence regarding contemporary implantable cardioverter-defibrillator (ICD) battery longevity. Our aim was to assess battery longevity in ICDs in a real-world setting.

METHODS

Retrospective cross-sectional single center study of a prospectively collected database of consecutive patients who underwent ICD implantation from January 2010 to December 2015. Clinical data and battery longevity of all manufacturers were collected.

RESULTS

A total of 351 patients (84.6% males, mean age of 61 ± 12 years) were included in the study (292 VVI; 6 VDD; 53 DDD). All manufacturers (Abbott, Biotronik, Boston, Medtronic and Microport) were equally represented in the study (p = 0.110). Median battery longevity was 10.8 years (11 years for VVI and 8.5 for DDD). After a follow-up time of 5 years, 98% of VVI and DDD were still in service (vs. industry-projected longevity of 98%). During this time, 89 patients (25.4%) underwent device replacement - 69 patients (77.5%) due to battery depletion, 6 patients due to infection, 3 patients due to dysfunction and 13 patients due to upgrade to CRT-D. Patients with Medtronic or Biotronik ICDs had a greater probability of being replaced earlier due to battery depletion (Biotronik HR 6.87, 95% CI 2.54-18.58, p < 0.001; Medtronic HR 6.08, 95% CI 2.45-15.06 p < 0.001).

CONCLUSIONS

VVI and DDD ICD battery longevity matched industry-projected longevity after 5 years of follow-up. Medtronic and Biotronik ICDs appeared to have an earlier battery depletion. Further randomized studies are required to ensure optimal care.

Predictors of appropriate shock after generator replacement in patients with an implantable cardioverter defibrillator

BACKGROUND

Implantable cardioverter defibrillators (ICDs) are indicated for the primary prevention of sudden cardiac death in patients with reduced left ventricular ejection fraction (LVEF). The ongoing risk/benefit profile of an ICD at generator replacement is unknown. This study aimed to identify predictors of appropriate ICD shocks and therapies after first ICD generator replacement, and its procedure-related complications.

METHODS

We conducted a multicenter, retrospective cohort study including patients with primary prevention ICDs who underwent generator replacement between April 2005 and July 2015 at three Canadian centers. The primary and secondary outcomes were appropriate ICD shock and any appropriate ICD therapy, respectively. Procedure-related complication rates were also reported.

RESULTS

Of the 219 patients in the cohort, 61 (28%) experienced an appropriate shock while 40 (18%) experienced appropriate antitachycardia pacing over a median follow up of 2.2 years. Independent predictors of appropriate ICD shocks included: LVEF at time of replacement (adjusted odds ratio [OR] 0.4 per 10% increase in LVEF, P < .001), a history of appropriate ICD shocks prior to replacement (OR 4.9, P < .001), and a history of inappropriate ICD shocks (OR 4.2, 95%, P < .002). Similar predictors were identified for the secondary outcome of any appropriate ICD therapy. Device-related complications were reported in 25 (11%) patients, with 1 (0.5%) resulting in death, 14 (6.3%) requiring site re-operation, and 6 (2.7%) requiring cardiac surgical management.

CONCLUSION

Not all primary prevention ICD patients undergoing generator replacement will require appropriate device therapies afterwards. Generator replacement is associated with several risks that should be weighed against its anticipated benefit. A comprehensive assessment of the risk-benefit profile of patients undergoing generator replacement is warranted.

Cardiac resynchronization therapy with or without defibrillation: a long-standing debate

Cardiac resynchronization therapy (CRT) was shown to improve cardiac function, reduce heart failure hospitalizations, improve quality of life and prolong survival in patients with severe left ventricular dysfunction and intraventricular conduction disturbances, mainly left bundle branch block, on optimal medical therapy with ACE-inhibitors, β-blockers and mineralocorticoid receptor antagonists up-titrated to maximum tolerated evidence-based doses. CRT can be achieved by means of pacemaker systems (CRT-P) or devices with defibrillation capabilities (CRT-D). CRT-Ds offer an undoubted advantage in the prevention of arrhythmic death, but such an advantage may be of lesser degree in non-ischemic heart failure aetiologies. Moreover, the higher CRT-D hardware complexity compared to CRT-P may predispose to device/lead malfunctions and the higher current drainage may cause a shorter battery duration with consequent premature replacements and the well-known incremental complications. In a period of financial constraints, also device costs should be carefully evaluated, with recent reports suggesting that CRT-Ps may be favoured over CRT-Ds in patients with non-ischemic cardiomyopathy and no prior history of cardiac arrhythmias from a cost-effectiveness point of view. The choice between a CRT-P or a CRT-D device should be patient-tailored whenever straightforward defibrillator indications are not present. The Goldenberg score may facilitate this decision-making process in ambiguous settings. Age, comorbidities, kidney disease, atrial fibrillation, advanced functional class, inappropriate therapy risk, implantable device infections and malfunctions are factors potentially reducing the expected benefit from defibrillating capabilities. Future prospective, randomized controlled trials are warranted to directly compare the efficacy and safety of CRT-Ps and CRT-Ds.

Important Parameters for Implantable Cardioverter Defibrillator Selection

The efficacy of implantable cardioverter defibrillators in reducing the risk of sudden cardiac death has been well established by several clinical trials. Several factors relating to device characteristics, patient attributes, and comorbidities should be considered when selecting the appropriate implantable cardioverter defibrillators for each patient. This review examines some of these issues.

Cardiac resynchronization therapy (CRT) device replacement considerations: upgrade or downgrade? A complex decision in the current clinical setting

There are limited data about the management of patients presenting for elective generator replacements in the setting of previously implanted cardiac resynchronization therapy (CRT) devices that are nearing end-of-life. The individual patient's clinical status and concomitant morbidities may evolve so that considerations may include not only replacement of the pulse generator, but also potentially changing the type of device [e.g. downgrading CRT-defibrillator (CRT-D) to CRT-pacemaker (CRT-P) or ICD or upgrading of CRT-P to CRT-D]. Moreover, the clinical evidence for CRT-D/CRT-P implantation may change over time, with ongoing research and availability of new trial data. In this review we discuss the ethical, clinical and financial implications related to CRT generator replacements and the need for additional clinical trials to better understand which patients should undergo CRT device downgrading or upgrading at the time of battery depletion.

Electrical cardioversion of patients with implanted pacemaker or cardioverter-defibrillator: results of a survey of german centers and systematic review of the literature

AIMS

A relevant number of patients presenting for electrical cardioversion carry a pacemaker (PM) or ICD. Case reports suggest a potential hazard of external cardioversion/defibrillation. The incidence of shock related device complications is unknown. No guidelines or recommendations by international medical societies for a cardioversion protocol of cardiovascular implantable electronic device (CIED) patients exist. We conducted a nationwide survey to gather real-world clinical data on the current clinical approach towards these patients during electrical cardioversion and to estimate the incidence of shock-related complications.

METHODS AND RESULTS

Ninety hospitals with > 380 ECV in 2014 were identified from mandatory hospital quality reports and 60 were randomly selected. All centers were provided with a standardized questionnaire on the general proceedings and complications during electrical cardioversion of pacemaker, ICD and CRT patients (CIED patients). Thirty-two centers (53%) participated in the survey. In total, 16,554 ECV were reported (534 ± 314 per center). Biphasic cardioversion with a first shock energy of ≥ 150 J via adhesive patches in antero-posterior orientation was preferred by most centers (78%). Eleven percent (n = 1809) of pts were reported to carry a PM/ICD. The ECV protocol was heterogeneous among centers. Complications associated with electrical cardioversion were reported in 11/1809 patients (0.6%), all were transitory elevations of pacing thresholds.

CONCLUSIONS

In this nationwide snapshot survey of cardioversion procedures in Germany, approximately 11% of patients presenting for elective electrical cardioversion were pacemaker or ICD carriers. Cardioversion protocols in these patients are heterogeneous throughout centers and mostly not in accordance with recommendation of the German Cardiac Society. Complications associated with external electrical cardioversion are rare. Controlled trials and large registries are necessary to provide evidence for future recommendations.

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.

"Real life" longevity of implantable cardioverter-defibrillator devices

BACKGROUND

Manufacturers of implantable cardioverter-defibrillators (ICDs) promise a 5- to 9-year projected longevity; however, real-life data indicate otherwise. The aim of the present study was to assess ICD longevity among 685 consecutive patients over the last 20 years.

HYPOTHESIS

Real-life longevity of ICDs may differ from that stated by the manufacturers.

METHODS

The study included 601 men and 84 women (mean age, 63.1 ± 13.3 years). The underlying disease was coronary (n = 396) or valvular (n = 15) disease, cardiomyopathy (n = 220), or electrical disease (n = 54). The mean ejection fraction was 35%. Devices were implanted for secondary (n = 562) or primary (n = 123) prevention. Single- (n = 292) or dual-chamber (n = 269) or cardiac resynchronization therapy (CRT) devices (n = 124) were implanted in the abdomen (n = 17) or chest (n = 668).

RESULTS

Over 20 years, ICD pulse generator replacements were performed in 238 patients (209 men; age 63.7 ± 13.9 years; ejection fraction, 37.7% ± 14.0%) who had an ICD for secondary (n = 210) or primary (n = 28) prevention. The mean ICD longevity was 58.3 ± 18.7 months. In 20 (8.4%) patients, devices exhibited premature battery depletion within 36 months. Most (94%) patients had none, minor, or modest use of ICD therapy. Longevity was longest for single-chamber devices and shortest for CRT devices. Latest-generation devices replaced over the second decade lasted longer compared with devices replaced during the first decade. When analyzed by manufacturer, Medtronic devices appeared to have longer longevity by 13 to 18 months.

CONCLUSIONS

ICDs continue to have limited longevity of 4.9 ± 1.6 years, and 8% demonstrate premature battery depletion by 3 years. CRT devices have the shortest longevity (mean, 3.8 years) by 13 to 17 months, compared with other ICD devices. These findings have important implications, particularly in view of the high expense involved with this type of electrical therapy.

Significant Discrepancy Between Estimated and Actual Longevity in St. Jude Medical Implantable Cardioverter-Defibrillators

BACKGROUND

Real-time estimated longevity has been reported in pacemakers for several years, and was recently introduced in implantable cardioverter-defibrillators (ICDs).

OBJECTIVE

We sought to evaluate the accuracy of this longevity estimate in St. Jude Medical (SJM) ICDs, especially as the device battery approaches depletion.

METHODS

Among patients with SJM ICDs who underwent generator replacements due to reaching elective replacement indicator (ERI) at our institution, we identified those with devices that provided longevity estimates and reviewed their device interrogations in the 18 months prior to ERI. Significant discrepancy was defined as a difference of more than 12 months between estimated and actual longevity at any point during this period.

RESULTS

Forty-six patients with Current/Promote devices formed the study group (40 cardiac resynchronization therapy [CRT] and 6 single/dual chamber). Of these, 34 (74%) had significant discrepancy between estimated and actual longevity (28 CRT and all single/dual). Longevity was significantly overestimated by the device algorithm (mean maximum discrepancy of 18.8 months), more in single/dual than CRT devices (30.5 vs. 17.1 months). Marked discrepancy was seen at voltages ≥2.57 volts, with maximum discrepancy at 2.57 volts (23 months). The overall longevity was higher in the discrepant group of CRT devices than in the nondiscrepant group (67 vs. 61 months, log-rank P = 0.03).

CONCLUSIONS

There was significant overestimation of longevity in nearly three-fourths of Current/Promote SJM ICDs in the last 18 months prior to ERI. Longevity estimates of SJM ICDs may not be reliable for making clinical decisions on frequency of follow-up, as the battery approaches depletion.

Device Longevity in a Contemporary Cohort of ICD/CRT-D Patients Undergoing Device Replacement

INTRODUCTION

The longevity of defibrillators (ICD) is extremely important from both a clinical and economic perspective. We studied the reasons for device replacement, the longevity of removed ICD, and the existence of possible factors associated with shorter service life.

METHODS AND RESULTS

Consecutive patients who underwent ICD replacement from March 2013 to May 2015 in 36 Italian centers were included in this analysis. Data on replaced devices were collected. A total of 953 patients were included in this analysis. In 813 (85%) patients the reason for replacement was battery depletion, while 88 (9%) devices were removed for clinical reasons and the remaining 52 because of system failure (i.e., lead or ICD generator failure or a safety advisory indication). The median service life was 5.9 years (25th-75th percentile, 4.9-6.9) for single- and dual-chamber ICD and 4.9 years (25th-75th percentile, 4.0-5.7) for CRT-D. On multivariate analysis, the factors CRT-D device, SC/DC ICD generator from Biotronik, percentage of ventricular pacing, and the occurrence of a system failure were positively associated with a replacement procedure. By contrast, the device from Boston Scientific was an independent protective factor against replacement. Considerable differences were seen in battery duration in both ICD and CRT-D. Specifically, Biotronik devices showed the shortest longevity among ICD and Boston Scientific showed the longest longevity among CRT-D (log-rank test, P < 0.001 for pairwise comparisons).

CONCLUSION

Several factors were associated with shorter service life of ICD devices: CRT-D, occurrence of system failure and percentage of ventricular pacing. Our results confirmed significant differences among manufacturers.

Battery drain in daily practice and medium-term projections on longevity of cardioverter-defibrillators: an analysis from a remote monitoring database

AIMS

The longevity of generators is a crucial determinant of the cost-effectiveness of therapy with implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-D). We evaluated the trend of device-measured residual battery capacity and longevity projections over 5-year follow-up. We also investigated possible factors associated with battery drain.

METHODS AND RESULTS

Data from 4851 patients in the European LATITUDE(®) database who were followed up for a minimum of 3 years were analysed. The factors associated with battery drain (i.e. year-to-year decrease in residual battery capacity), and thus potentially impacting on device longevity, were mainly the pacing parameters in CRT-D devices and the number of shocks delivered and diverted in both ICD and CRT-D (all P < 0.01 on linear regression analysis). Over the first 5 years, the longevity estimates provided by devices showed low intra-patient variability and increased with time. The estimates exceeded 10 years for CRT-D and 13 and 12 years for single- and dual-chamber ICDs, respectively. In CRT-D patients, the expected patient age on replacement was 80 ± 12 years, and the expected probability of undergoing device replacement was 63 ± 13% for New York Heart Association (NYHA) II patients and 37 ± 16% for NYHA III patients. For comparison, the probabilities of replacing a CRT-D lasting 5 years were 78 ± 8 and 59 ± 13%, respectively (both P < 0.001).

CONCLUSION

Battery drain was mainly associated with pacing output in CRT-D devices and with the number of capacitor charges in both ICD and CRT-D devices. The longevity estimates provided by the devices were consistent and conservative. According to these estimates, among CRT-D recipients a low proportion of patients should require device replacement.

Longevity of implantable cardioverter defibrillators: a comparison among manufacturers and over time

Aims

Longevity of implantable cardioverter defibrillators (ICDs) is crucial for patients and healthcare systems as replacements impact on infection rates and cost-effectiveness. Aim was to determine longevity using very large databases of two teaching hospitals with a high number of replacements and a rather homogeneous distribution among manufacturers.

Methods and results

The study population consists of all patients in whom an ICD was inserted in. All ICD manufacturers operating in Switzerland and the Netherlands and all implanted ICDs were included. Implantable cardioverter defibrillator replacements due to normal battery depletion were considered events, and other replacements were censored. Longevity was assessed depending on manufacturers, pacing mode, implant before/after 2006, and all parameters combined. We analysed data from 3436 patients in whom 4881 ICDs [44.2% VVI-ICDs, 27.4% DDD-ICDs, 26.3% cardiac resynchronization therapy (CRT)-ICDs, 2.0% subcutaneous ICDs] were implanted. The four major manufacturers had implant shares between 18.4 and 31.5%. Replacement due to battery depletion (27.4%) was performed for 1339 ICDs. Patient survival at 5 years was 80.1%. Longevity at 5 years improved in contemporary compared with elderly ICDs [63.9–80.6% across all ICDs, of 73.7–92.1% in VVIs, 58.2–76.1% in DDDs, and of 47.1–66.3% in CRT defibrillators, all P value < 0.05]. Remarkable differences were seen among manufacturers, and those with better performance in elderly ICDs were not those with better performance in contemporary ones.

Conclusion

Implantable cardioverter defibrillator longevity increased in contemporary models independent of manufacturer and pacing mode. Still, significant differences exist among manufacturers. These results might impact on device selection.

Longevity of implantable cardioverter-defibrillators for cardiac resynchronization therapy in current clinical practice: an analysis according to influencing factors, device generation, and manufacturer

Aims

Device replacement at the time of battery depletion of implantable cardioverter-defibrillators (ICDs) may carry a considerable risk of complications and engenders costs for healthcare systems. Therefore, ICD device longevity is extremely important both from a clinical and economic standpoint. Cardiac resynchronization therapy defibrillators (CRT-D) battery longevity is shorter than ICDs. We determined the rate of replacements for battery depletion and we identified possible determinants of early depletion in a series of patients who had undergone implantation of CRT-D devices.

Methods and results

We retrieved data on 1726 consecutive CRT-D systems implanted from January 2008 to March 2010 in nine centres. Five years after a successful CRT-D implantation procedure, 46% of devices were replaced due to battery depletion. The time to device replacement for battery depletion differed considerably among currently available CRT-D systems from different manufacturers, with rates of batteries still in service at 5 years ranging from 52 to 88% (log-rank test, P < 0.001). Left ventricular lead output and unipolar pacing configuration were independent determinants of early depletion [hazard ratio (HR): 1.96; 95% 95% confidence interval (CI): 1.57–2.46; P < 0.001 and HR: 1.58, 95% CI: 1.25–2.01; P < 0.001, respectively]. The implantation of a recent-generation device (HR: 0.57; 95% CI: 0.45–0.72; P < 0.001), the battery chemistry and the CRT-D manufacturer (HR: 0.64; 95% CI: 0.47–0.89; P = 0.008) were additional factors associated with replacement for battery depletion.

Conclusion

The device longevity at 5 years was 54%. High left ventricular lead output and unipolar pacing configuration were associated with early battery depletion, while recent-generation CRT-Ds displayed better longevity. Significant differences emerged among currently available CRT-D systems from different manufacturers.

Seven years of use of implantable cardioverter-defibrillator therapies: a nationwide population-based assessment of their effectiveness in real clinical settings

Background

The efficacy of implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy-defibrillator (CRT-D) therapy has already been established in clinical trials but their effectiveness in several clinical settings remains undetermined. This study aimed to assess the effectiveness of ICD and CRT-D therapies within the Brazilian National Health System (SUS).

Methods

All patients who underwent ICD or CRT-D implantation within the SUS from 2001 to 2007 were included in the study. We compared estimated Kaplan-Meier survival curves using the Peto’s test. Prognostic factors were selected using Cox’s models.

Results

There were included 3,295 patients in the ICD group and 681 patients in the CRT-D group. Cardiac causes accounted for 79% of all deaths in both groups and Chagas’ heart disease accounted for 31% of these deaths. In the CRT-D group, survival significantly decreased around the fourth year of follow-up, with a decrease from 59.5% to 38.3% in 5.5 months. Transvenous implantation technique was used in 62% of CRT-D patients. In-hospital case-fatality rates were higher in those undergoing surgical implantation (5.3%) than those undergoing transvenous implantation (1.6%) (p = 0.02).

Conclusions

The results show that short-term, medium-term and long-term effectiveness of ICD therapy appears to be similar to that evidenced in clinical trials. In the CRT-D group, in-hospital case-fatality and 30-day case-fatality were higher than those reported in other studies. Surgical epicardial implantation technique was performed in this group at a higher frequency than that reported in the literature and was associated with poorer short-term prognosis.

The mismatch between patient life expectancy and the service life of implantable devices in current cardioverter-defibrillator therapy: a call for larger device batteries

In 2005, Bob Hauser published a paper in the Journal of the American College of Cardiology entitled "The growing mismatch between patient longevity and the service life of Implantable Cardioverter-Defibrillators". Now, nearly a decade later, I would like to perform a second look on the problem of a mismatching between ICD device service life and the survival of ICD recipients. Since 2005, the demographics of the ICD population has changed significantly. Primary prevention has become the dominant indication in defibrillator therapy and device implantation is indicated more and more in earlier stages of cardiac diseases. In former larger scale ICD trials, the patient average 5-year survival probability was in a range of 68-71%; in newer CRT-D trials in a range of 72-88%. Due to a progressively widened ICD indication and implantation preferentially performed in patients with better life expectancy, the problem of inadequate device service life is of growing importance. The early days of defibrillator therapy started with a generator volume of 145 ccm and a device service life <18 months. In this early period, the device miniaturization and extension of service life were similar challenges for the technicians. Today, we have reached a formerly unexpected extent of device miniaturization. However, technologic improvements were often preferentially translated in further device miniaturization and not in prolonging device service life. In his analysis, Bob Hauser reported a prolonged device service life of 2.3 years in ICD models with a larger battery capacity of 0.54 up to 0.69 Ah. Between 2008 and 2014, several studies had been published on the problem of ICD longevity in clinical scenarios. These analyses included "older" and currently used single chamber, dual chamber and CRT devices. The reported average 5-year device service life ranged from 0 to 75%. Assuming today technology, larger battery capacities will only result in minimal increase in device volume. Selected ICD patients may further benefit from device miniaturization-but the vast majority may much more benefit from a significant prolongation in device service life. All published cost-effectiveness analyses in ICD therapy show that device costs and device service life are the dominant determinants of the results. The performed "second look-nearly a decade later" revealed that there are still relevant limitations regarding the device service life in current defibrillator therapy. Technical improvements were preferentially transformed into device miniaturization but not into prolonging device service life. But this optimization is strongly enforced. The most feasible solution might be the use of device batteries with larger capacities. The economic burden, mainly caused by non-adequate device service life, may limit the future realization of ICD therapy in a progressively growing patient population. In the former years, physicians and device manufacturers have ignored the patient perspective in defibrillator therapy. However, it is the patient viewpoint that prolonged device service life is much more important than smaller generator size.

Prophylactic Lead Extraction at Implantable Cardioverter-Defibrillator Generator Change

Background—

Current implantable cardiac devices have a finite battery life of ≈3 to 7 years for implantable cardioverter-defibrillators. It is current practice to reuse all properly functioning intravascular leads. We tested the hypothesis that a strategy of prophylactic lead removal at the time of device change would be superior under some conditions to the current practice of lead reuse.

Methods and Results—

Using currently available data and a Monte Carlo microsimulation trial, we calculated the risks of leaving an indwelling lead until extraction is indicated because of malfunction versus an aggressive management strategy of prophylactic serial extraction at time of generator change. With a serial lead exchange strategy of leads at generator change, there is reduced overall extraction-related mortality because of fewer late complications attributable to extraction of leads with high dwell time because of infection, recall, or subsequent lead failure. This finding is limited to young patients or those with high expected indwell time of lead. This trend reverses for leads with <40 years expected dwell time. Sensitivity analysis shows high dependence on extraction performance and device longevity. In all cases, serial extraction would be expected to lead to increased adverse events related to the more complex procedure.

Conclusions—

A strategy of serial lead extraction, given best available current parameters, yields a lower procedural mortality risk in the long-term management of indwelling implantable cardioverter-defibrillator leads in young patients (>40-year estimated dwell time) driven by high aggregate anticipated risk of lifetime lead complication.

Battery longevity in cardiac resynchronization therapy implantable cardioverter defibrillators

AIMS

Cardiac resynchronization therapy (CRT) implantable cardioverter defibrillators (ICDs) deliver high burden ventricular pacing to heart failure patients, which has a significant effect on battery longevity. The aim of this study was to investigate whether battery longevity is comparable for CRT-ICDs from different manufacturers in a contemporary cohort of patients.

METHODS AND RESULTS

All the CRT-ICDs implanted at our institution from 1 January 2008 to 31 December 2010 were included in this analysis. Baseline demographic and clinical data were collected on all patients using the electronic medical record. Detailed device information was collected on all patients from scanned device printouts obtained during routine follow-up. The primary endpoint was device replacement for battery reaching the elective replacement indicator (ERI). A total of 646 patients (age 69 ± 13 years), implanted with CRT-ICDs (Boston Scientific 173, Medtronic 416, and St Jude Medical 57) were included in this analysis. During 2.7 ± 1.5 years follow-up, 113 (17%) devices had reached ERI (Boston scientific 4%, Medtronic 25%, and St Jude Medical 7%, P < 0.001). The 4-year survival rate of device battery was significantly worse for Medtronic devices compared with devices from other manufacturers (94% for Boston scientific, 67% for Medtronic, and 92% for St Jude Medical, P < 0.001). The difference in battery longevity by manufacturer was independent of pacing burden, lead parameters, and burden of ICD therapy.

CONCLUSION

There are significant discrepancies in CRT-ICD battery longevity by manufacturer. These data have important implications on clinical practice and patient outcomes.

Development of implantable medical devices: from an engineering perspective

From the first pacemaker implant in 1958, numerous engineering and medical activities for implantable medical device development have faced challenges in materials, battery power, functionality, electrical power consumption, size shrinkage, system delivery, and wireless communication. With explosive advances in scientific and engineering technology, many implantable medical devices such as the pacemaker, cochlear implant, and real-time blood pressure sensors have been developed and improved. This trend of progress in medical devices will continue because of the coming super-aged society, which will result in more consumers for the devices. The inner body is a special space filled with electrical, chemical, mechanical, and marine-salted reactions. Therefore, electrical connectivity and communication, corrosion, robustness, and hermeticity are key factors to be considered during the development stage. The main participants in the development stage are the user, the medical staff, and the engineer or technician. Thus, there are three different viewpoints in the development of implantable devices. In this review paper, considerations in the development of implantable medical devices will be presented from the viewpoint of an engineering mind.

Cost-utility analysis of the EVOLVO study on remote monitoring for heart failure patients with implantable defibrillators: randomized controlled trial

BACKGROUND

Heart failure patients with implantable defibrillators place a significant burden on health care systems. Remote monitoring allows assessment of device function and heart failure parameters, and may represent a safe, effective, and cost-saving method compared to conventional in-office follow-up.

OBJECTIVE

We hypothesized that remote device monitoring represents a cost-effective approach. This paper summarizes the economic evaluation of the Evolution of Management Strategies of Heart Failure Patients With Implantable Defibrillators (EVOLVO) study, a multicenter clinical trial aimed at measuring the benefits of remote monitoring for heart failure patients with implantable defibrillators.

METHODS

Two hundred patients implanted with a wireless transmission-enabled implantable defibrillator were randomized to receive either remote monitoring or the conventional method of in-person evaluations. Patients were followed for 16 months with a protocol of scheduled in-office and remote follow-ups. The economic evaluation of the intervention was conducted from the perspectives of the health care system and the patient. A cost-utility analysis was performed to measure whether the intervention was cost-effective in terms of cost per quality-adjusted life year (QALY) gained.

RESULTS

Overall, remote monitoring did not show significant annual cost savings for the health care system (€1962.78 versus €2130.01; P=.80). There was a significant reduction of the annual cost for the patients in the remote arm in comparison to the standard arm (€291.36 versus €381.34; P=.01). Cost-utility analysis was performed for 180 patients for whom QALYs were available. The patients in the remote arm gained 0.065 QALYs more than those in the standard arm over 16 months, with a cost savings of €888.10 per patient. Results from the cost-utility analysis of the EVOLVO study show that remote monitoring is a cost-effective and dominant solution.

CONCLUSIONS

Remote management of heart failure patients with implantable defibrillators appears to be cost-effective compared to the conventional method of in-person evaluations.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00873899; http://clinicaltrials.gov/show/NCT00873899 (Archived by WebCite at http://www.webcitation.org/6H0BOA29f).

Significant differences in the expected versus observed longevity of implantable cardioverter defibrillators (ICDs)

BACKGROUND

Implantable cardioverter defibrillator (ICD) is a life-saving therapy for patients at risk of ventricular arrhythmias. Due to its high cost, its cost-effectiveness is highly dependent on its longevity, which is currently only based upon the manufacturer's predicted device life span.

AIM

We sought to assess the ICDs' longevity and the factors influencing it, and to compare the observed (real life) to the expected (manufacturer's prediction) life span at a device level.

METHODS

We retrospectively identified all patients who underwent an ICD implantation in a tertiary care medical center. For each device, an expected longevity was assigned based on the manufacturer/model, pacing percentage, and number of shocks per year. We defined device failure if the observed survival was shorter than 80 % of the expected. Only devices with follow-up time that exceeded the expected longevity were included.

RESULTS

Of the 275 devices in the cohort, 79 (29 %) failed. Median device longevity was 5 years and varied markedly between manufacturers (4.3, 4.8, 5.1, and 6.3 years for Biotronik, St. Jude Medical, Boston Scientific, and Medtronic, respectively). There were significant differences among the manufacturers in device failure rates: 48, 17, 22, and 14 % for Biotronik, St. Jude Medical, Boston Scientific, and Medtronic, respectively). In multivariate analysis, manufacturer, earlier year of implantation, congestive heart failure and chronic renal failure significantly predicted device failure.

CONCLUSIONS

In conclusion, there is a significant device failure rate among ICDs, with variability among manufacturers, impacting both patients and the medical economic systems.

How to truly value implantable cardioverter-defibrillators technology: up-front cost or daily cost?

BACKGROUND

We calculated the daily cost of implantable cardioverter-defibrillators (ICDs) based on their actual longevity to prove whether the up-front cost is a reliable parameter for the ICD purchasing-process. METHODS. Longevity of single chamber (SC), double chamber (DC), and biventricular (BiV) ICDs from Medtronic (MDT), Guidant (GDT), and St. Jude Medical (SJM) was measured in all the patients implanted in years 2000, 2001, 2002 who reached device replacement within December 31, 2009. The cost of each ICD (device + lead/s) was normalized for its own longevity. Data are expressed as median (25th-75th percentile).

RESULTS

A total of 123/153 patients completed the study, 70 percent being alive 8 years after implantation. MDT devices had a superior longevity compared with GDT and SJM (p < .001). Fifty-eight percent of replaced ICDs had a service life at least 1 year shorter than the manufacturers' prediction. Longer-lasting devices had a significantly lower daily cost: €4.8 (4.6-5.7) versus €6.8 (6.2-9.2) and €6.9 (6.2-7.6) for SC (p < .001); €6.9 (6.8-7.7) versus €12.6 (11.8-13.3) and €13.4 (10.3-16.1) for DC; €8.5 (8.3-10.3) versus €15.4 (15.1-15.8) and €14.6 (14.1-14.9) for BiV (p < .005).

CONCLUSIONS

The true cost of ICD treatment is strictly dependent on device longevity, whereas device up-front cost is unreliable. This aspect should be valued in the technology purchasing process, and could set the basis for an outcome-based reimbursement system. Our observations may be the benchmark respectively for ICD longevity and daily ICD cost in future comparisons. Independent observations in the real-life scenario are needed to properly value newer technologic improvements.

Characterization and financial impact of implantable cardioverter-defibrillator patients without interventions 5 years after implantation

BACKGROUND

Implantable cardioverter defibrillators (ICD's) are increasingly used for primary and secondary prevention of sudden cardiac death. However, data on how many ICD patients indeed receive appropriate ICD therapy during long-term follow-up is scarce.

AIM

The aim of our study was to determine the number of patients without appropriate ICD therapy 5 years after ICD implantation, to identify predicting factors, to assess the occurrence of late first ICD therapy and to quantify the financial impact of ICD therapy in a real-world setting.

DESIGN

Prospective observational study.

METHODS

We prospectively enrolled 322 consecutive ICD patients. Baseline data were collected at implantation and patients were followed for a median of 7.3 years (IQR 5.8-9.2 years). Time to first appropriate ICD therapy (either antitachycardia pacing or cardioversion) was documented.

RESULTS

Five years after implantation, 139 patients (43%) had not received appropriate ICD therapy. In multivariable analysis, a primary prevention indication and negative electrophysiological studies prior to ICD implantation were independent predictors of freedom from ICD therapy. Of the patients without ICD therapy, 5 years after implantation, 25% had experienced inappropriate ICD shocks. Two hundred and seven devices (1.5 devices per patient) were needed for the 139 patients without ICD intervention within 5 years, accounting for € 31,784 per patient. During an additional follow-up of 3 years, 12% of the patients with unused ICD received a late first appropriate ICD therapy.

CONCLUSION

About half of the ICD patients receive appropriate ICD therapy within 5 years after implantation. Furthermore, there is a significant proportion of patients receiving late first shocks after five initially uneventful years.

Long-Term Complications Related to Biventricular Defibrillator Implantation

Background—

Long-term data on device-related untoward events in patients receiving defibrillators for resynchronization therapy (CRT-D) are lacking. We quantified the frequency of repeat invasive procedures and the nature of long-term complications in current clinical practice and examined possible predictors of device-related events and their association with long-term patient outcome.

Methods and Results—

We analyzed data from 3253 patients who underwent de novo successful implantation of CRT-D and were followed up for a median of 18 months (25th to 75th percentiles: 9 to 30) in 117 Italian centers. Device-related events were reported in 416 patients, and, specifically, surgical interventions for system revision were described in 390 patients. Four years after the implantation procedure, 50% of patients underwent surgical revision for battery depletion and 14% for unanticipated events. For comparison, at 4 years battery depletion occurred in 10% and 13% of patients who received single- and dual-chamber defibrillators at the study centers, and unanticipated events were reported as 4% and 9%, respectively. In CRT-D, infections occurred at a rate of 1.0%/y, and the risk of infections increased after device replacement procedures (hazard ratio, 2.04; 95% confidence interval, 1.01 to 4.09; P =0.045). Left ventricular lead dislodgements were reported at a rate of 2.3%/y and were predicted by longer fluoroscopy time and higher pacing threshold on implantation. Device-related events were not associated with a worse clinical outcome; indeed, the risk of death was similar in patients with and without surgical revision (hazard ratio, 0.90; 95% confidence interval, 0.56 to 1.47; P =0.682).

Conclusions—

In current clinical practice device-related events are more frequent in CRT-D than in single- or dual-chamber defibrillators, and are frequently managed by surgical intervention for system revision. However, a worse clinical outcome is not associated with these events.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01007474.

Recurrent implantable cardioverter-defibrillator replacement is associated with an increasing risk of pocket-related complications

BACKGROUND

Despite beneficial effects of implantable cardioverter-defibrillator (ICD) therapy, limited service life results in replacement within the majority of patients. Data concerning the effect of replacement procedures on the occurrence of pocket-related adverse events are scarce. In this study, the requirement for pocket-related surgical re-interventions following ICD treatment and the effect of device replacement were evaluated.

METHODS

From 1992 to 2008, 2,415 patients receiving an ICD at the Leiden University Medical Center were analyzed. Pocket-related complications requiring surgical re-intervention following ICD implantation or replacement were noted. Elective device replacement, lead failure, and device malfunction were not considered pocket-related complications.

RESULTS

A total of 3,161 ICDs were included in the analysis. In total, 145 surgical re-interventions were required in 122 (3.9%) ICDs implanted in 114 (4.7%) unique patients. Three-year cumulative incidence for first surgical re-intervention in all ICDs was 4.7% (95% confidence interval [CI] 3.9-5.5%). Replacement ICDs exhibited a doubled requirement for surgical re-intervention (rate ratio 2.2, 95% CI 1.5-3.0). Compared to first implanted ICDs, the occurrence of surgical re-intervention in replacements was 2.5 (95% CI 1.6-3.7) times higher for infectious and 1.7 (95% CI 0.9-3.0) for noninfectious causes. Subdivision by the number of ICD replacements showed an increase in the annual risk for surgical re-intervention, ranging from 1.5% (95% CI 1.2-1.9%) for the first, to 8.1% (95% CI 1.7-18.3%) for the fourth implanted ICD.

CONCLUSIONS

ICD replacement is associated with a doubled risk for pocket-related surgical re-interventions. Furthermore, the need for re-intervention increases with every consecutive replacement.