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

Predicting long-term survival after de novo cardioverter-defibrillator implantation for primary prevention: A population based study

Background

Implantable cardioverter-defibrillators (ICDs) reduce the risk of sudden cardiac death in patients with left ventricular dysfunction. While short-term mortality benefit of ICD insertion has been established in landmark randomized controlled trials, little is known about the long-term outcomes of patients with ICDs in clinical practice. In this paper, we describe the long-term survival of patients following de novo ICD implantation for primary prevention in clinical practice and determine the factors which help predict survival after ICD implant.

Methods

Retrospective population-based study of all patients receiving a de novo ICD for primary prevention in Ontario, Canada from 2007 to 2011 using the Ontario ICD Database housed within ICES. Simple random selection was used to split the population into a derivation and internal validation cohort in a ratio of 2:1. Cox proportional hazards regression was used to determine predictors of interest and predict 10-year survival, model performance was assessed using calibration and validation.

Results

In the derivation cohort (n = 3399), mean age was 65.3 years (standard deviation [SD] = 11.0), 664 patients were female (19.5 %) and 2344 patients (69.0 %) had ischemic cardiomyopathy. Ten year survival was 45.7 % (95 % confidence interval [CI] 44.0 %-47.4 %). The final prediction model included age, sex, disease factors (ischemic vs nonischemic cardiomyopathy, left ventricular ejection fraction) and patient factors (symptoms, comorbidities), and biomarkers at the time of ICD assessment. This model had good discrimination and calibration in derivation (0.79, 95 % CI 0.77, 0.81) and validation samples (0.78, 95 % CI 0.76, 0.79).

Conclusions

A combination of demographic and clinical factors determined at baseline can be used to predict 10-year survival in patients with implantable cardioverter-defibrillators with good accuracy. Our findings help to identify individuals at risk of long-term mortality and may be useful in targeting future prevention strategies to enhance longevity in this high-risk population.

CE: Guideline-Directed Cardiac Devices for Patients with Heart Failure

ABSTRACT

Heart failure affects over 6.2 million adults in the United States and is expected to affect over 8 million by 2030. The U.S. one-year mortality rate is almost 30% among Medicare beneficiaries. Technological advances have produced several new cardiac devices that are available for therapy and symptom management. This article reviews current device therapies for heart failure and uses a composite case to demonstrate how bedside nurses can help patients understand treatment options related to their disease process and care for them through this experience.

Myocardial ATP depletion detected noninvasively predicts sudden cardiac death risk in heart failure patients

BACKGROUND

Sudden cardiac death (SCD) remains a worldwide public health problem in need of better noninvasive predictive tools. Current guidelines for primary preventive SCD therapies, such as implantable cardioverter defibrillators (ICDs), are based on left ventricular ejection fraction (LVEF), but these guidelines are imprecise: fewer than 5% of ICDs deliver lifesaving therapy per year. Impaired cardiac metabolism and ATP depletion cause arrhythmias in experimental models, but to our knowledge a link between arrhythmias and cardiac energetic abnormalities in people has not been explored, nor has the potential for metabolically predicting clinical SCD risk.

METHODS

We prospectively measured myocardial energy metabolism noninvasively with phosphorus magnetic resonance spectroscopy in patients with no history of significant arrhythmias prior to scheduled ICD implantation for primary prevention in the setting of reduced LVEF (≤35%).

RESULTS

By 2 different analyses, low myocardial ATP significantly predicted the composite of subsequent appropriate ICD firings for life-threatening arrhythmias and cardiac death over approximately 10 years. Life-threatening arrhythmia risk was approximately 3-fold higher in patients with low ATP and independent of established risk factors, including LVEF. In patients with normal ATP, rates of appropriate ICD firings were several-fold lower than reported rates of ICD complications and inappropriate firings.

CONCLUSION

To the best of our knowledge, these are the first data linking in vivo myocardial ATP depletion and subsequent significant arrhythmic events in people, suggesting an energetic component to clinical life-threatening ventricular arrhythmogenesis. The findings support investigation of metabolic strategies that limit ATP loss to treat or prevent life-threatening cardiac arrhythmias and herald noninvasive metabolic imaging as a complementary SCD risk stratification tool.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00181233.

FUNDING

This work was supported by the DW Reynolds Foundation, the NIH (grants HL61912, HL056882, HL103812, HL132181, HL140034), and Russell H. Morgan and Clarence Doodeman endowments at Johns Hopkins.

Device runtime and costs of cardiac resynchronization therapy pacemakers - a health claims data analysis

Introduction: This study investigates the runtime and costs of biventricular defibrillators (CRT-D) and biventricular pacemakers (CRT-P). Accurate estimates of cardiac resynchronization therapy (CRT) device runtime across all manufactures are rare, especially for CRT-P. Methods: Health claims data of a large nationwide German health insurance was used to analyze CRT device runtime. We defined device runtime as the time between the date of implantation and the date of generator change or removal. The median costs for implantation, change, and removal of a CRT device were calculated accordingly. Results: In total, the data set comprises 17,826 patients. A total of 4,296 complete runtimes for CRT-D devices and 429 complete runtimes for CRT-P devices were observed. Median device runtime was 6.04 years for CRT-D devices and 8.16 years for CRT-P devices (log-rank test p<0.0001). The median cost of implantation for a CRT-D device was 14,270 EUR, and for a CRT-P device 9,349 EUR. Conclusions: Compared to CRT-P devices, CRT-D devices had a significantly shorter device runtime of about two years. Moreover, CRT-D devices were associated with higher cost. The study provides important findings that can be utilized by cost-effectiveness analyses.

Cardiac Implantable Electronic Devices: Reoperations and the Competing Risk of Death

BACKGROUND

The use of cardiac implantable electronic devices (CIED), which includes pacemakers, implantable cardioverter-defibrillators (ICD), cardiac resynchronisation therapy pacemakers (CRT-P) and cardiac resynchronisation therapy defibrillators (CRT-D) has increased over the past 20 years, but there is a lack of real world evidence on the longevity of these devices in the older population which is essential to inform health care delivery and support clinical decisions.

METHODS AND RESULTS

We conducted a retrospective cohort study using data from the Australian Government Department of Veterans' Affairs database. The cohort consisted of people who had a CIED procedure between 2005 and 2015. The cumulative risk of generator replacement/reoperations was estimated accounting for the competing risk of death. A total of 16,662 patients were included. In pacemaker recipients with an average age of 85 years, the 5-year risk of reoperation ranged from 2.8% in single chamber, 3.6% in dual chamber to 7.6% in CRT-P recipients, while the 5-year risk of dying with the index pacemaker in situ was 63% in single chamber, 46% in dual chamber and 56% in CRT-P recipients. In defibrillator recipients with an average age of 80 years, the 5-year risk of reoperation ranged from 11% in single chamber, 13% in dual chamber to 24% in CRT-D recipients, while the 5-year risk of dying with the index defibrillator in situ was 46% in single chamber, 40% in dual chamber and 41% in CRT-D recipients.

CONCLUSION

In this cohort of older patients the 5-year risk of generator reoperation was low in pacemaker recipients whereas up to one in four CRT-D recipients would have a reoperation within 5 years.

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.

Reliability and longevity of implantable defibrillators

Purpose

We hypothesized that data in manufacturers’ product performance reports (PPRs) can provide clinically valuable ICD and cardiac resynchronization defibrillator (CRT-D) reliability and longevity information.

Methods

Data were obtained from 2019 PPRs. Kaplan-Meier (K-M) probabilities of freedom from malfunction, normal battery depletion (NBD), and NBD + malfunction were calculated for ICD and CRT-D pulse generators (PGs) with LiMnO2 or LiSVO/CFx batteries marketed in the USA from 2010 to 2019 and compared using the log-rank test. Malfunctions (MAL) included PGs that were found outside specifications.

Results

Study population included 1,149,803 ICD and CRT-D PGs: Abbott (ABT; 35.1%), Biotronik (BIO; 4.6%), Boston Scientific (BSC; 23.5%), and Medtronic (MDT; 36.9%). Significant differences in reliability (p < 0.001), defined by freedom from MAL, were found between manufacturers; the majority of 6808 MAL occurred in ABT devices (n = 4045; 59.4%), followed by BSC (n = 2384; 35.0%), MDT (n = 338;5.0%), and BIO (n = 41; 0.6%). Battery failure (n = 890; 57.9%) was the most common cause of MAL compromising therapy; analysis of unique ABT battery MAL–indicated problem appeared a year prior to advisory. Significant differences (p < 0.001) in battery longevity, as defined by freedom from NBD, were found between manufacturers. Overall performance (freedom from NBD + MAL) favored BSC for CRT-D PGs and MDT and BIO for ICDs. BSC subcutaneous ICD reliability was inferior to its transvenous ICD (p < 0.001).

Conclusion

PPRs contain valuable data that can be aggregated and analyzed to inform physicians. Differences in product reliability exist between manufacturers. Battery longevity has improved, but MAL have significantly impacted performance. PPR data may be useful for assessing product problems and new technology.

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.

Characteristics and Outcomes of Pediatric Patients Who Undergo Placement of Implantable Cardioverter Defibrillators: Insights From the National Cardiovascular Data Registry

Background Implantable cardioverter defibrillators (ICDs) are an important part of therapy for many patients, yet there is little data on population characteristics, complications, or system survival in pediatric patients. Methods A retrospective review of ICD recipients in the National Cardiovascular Data Registry ICD Registry was performed from 2010 to 2016. Patient characteristics and complications between pediatric (≤21 years) and adult populations (>21 years) were compared. Variables associated with complications and early device interventions within the pediatric cohort were evaluated using multivariate modeling. Results There were 562 209 total ICD implants, of which 3461 occurred in the pediatric cohort. Among the pediatric patients, 60% of implants were for primary prevention, and nonischemic cardiomyopathy was the most common underlying disease (60%). Over time, there was an increasing trend of both primary and secondary prevention ICD implantations ( P<0.05). Compared with adults, pediatric patients were more likely to have structural heart disease, hypertrophic cardiomyopathy, and channelopathy, and to receive a single-chamber device (all P<0.001). There was no difference in inhospital complications between the adult and pediatric cohorts (2.4% versus 2.6%, P=0.3). However, among the pediatric patients, lower weight, Ebstein anomaly, worse New York Heart Association class, dual chamber, and cardiac resynchronization therapy-defibrillator were associated with greater risk of complications. Although reintervention for generator replacement or upgrade was more common in adults, the time to reintervention was shorter in the pediatric cohort. Conclusions We observed an increasing trend in ICD device implantation among pediatric patients. The pediatric cohort had similar inhospital complication rates compared with adults but had a shorter time to reintervention.

Implantable Cardioverter-Defibrillators and Cardiac Resynchronization Therapy in Older Adults With Heart Failure

BACKGROUND/OBJECTIVES

Implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy (CRT) are cardiac implantable electronic devices that may improve morbidity and mortality in select patients with heart failure. Although the benefits of these devices have been well defined, competing mortality risks, comorbid conditions, and frailty pose difficulty in determining risk-benefit trade-offs when these options are considered for older adults.

CONCLUSION

In this review, we focus on the benefit, risk, and use of ICD and CRT in older adults, particularly because the goals of care for many older adults include a shift away from life-prolonging interventions. Additionally, we discuss periprocedural risk, cost, and maintenance in older populations. Finally, we introduce a framework for helping clinicians and older adults make these challenging decisions collectively. J Am Geriatr Soc 67:2193-2199, 2019.

Favorable Trend of Implantable Cardioverter-Defibrillator Service Life in a Large Single-Nation Population: Insights From 10-Year Analysis of the Italian Implantable Cardioverter-Defibrillator Registry

Background Implantable cardioverter-defibrillators (ICDs) are widely employed for the prevention of sudden cardiac death. Despite technological improvements, patients often need to undergo generator replacement, which entails the risk of periprocedural complications. Our aim was to estimate the service life of ICDs over a 10-year interval and to assess the main causes of replacement on the basis of data from the National ICD Registry of the Italian Society of Arrhythmology and Cardiac Pacing (AIAC). Methods and Results The registry includes data from over 400 hospitals in Italy. We included all patients who underwent device replacement from calendar years 2007 to 2016. The median service life of the ICDs and its trend over the years was estimated across the 3 types of devices (single-chamber, dual-chamber, cardiac resynchronization therapy defibrillator) and the indication to implantation. The causes of replacement were also analyzed. We included 29 158 records from 27 676 patients (80.9% men; mean age at device replacement 65.8±12.0 years). The median service life was 57.3 months (interquartile range 27.8 months). Over the years, service life showed an increasing trend. The majority of patients underwent elective replacement because of battery end of life, and over the years there was a significant reduction of replacement for recalls, erosion/infections, and cardiac resynchronization therapy upgrading. Conclusions Our data from a large single-nation population showed that the trend of ICD service life, independently from ICD type, indication, and settings, significantly improved over time. Moreover, there was a striking reduction of interventions for upgrading and infection/erosion. This favorable trend has important clinical, organizational, and financial implications.

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.

The subcutaneous implantable cardioverter defibrillator--review of the recent data

The subcutaneous implantable cardioverter defibrillators (SICD) is an alternative to the transvenous ICD for the prevention of sudden cardiac death (SCD). Multiple studies have shown that the SICD is safe and effective in treating ventricular arrhythmias. While earlier studies mainly enrolled younger patients with channelopathies, more recent reports included patients with “typical” indications for ICD therapy for the prevention of SCD. In this review we summarize the data available to date on the SICD while highlighting its pros and cons.

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.

Impact of quadripolar LV leads on heart failure hospitalization rates among patients implanted with CRT-D: data from the Israeli ICD Registry

BACKGROUND

Cardiac resynchronization therapy (CRT) is an effective treatment for heart failure (HF); however, a third of patients are non-responders. The development of quadripolar left ventricular (LV) lead was shown, mainly in single manufactures' registry, to improve LV remodeling and overall mortality. However, limited reports exist on the impact of quadripolar LV leads on HF hospitalization rates in real-life cohorts. We evaluated the clinical outcomes associated with quadripolar LV leads in a large nation-wide registry including all patients implanted with a cardiac resynchronization therapy with defibrillator (CRT-D).

METHODS

Between July 2010 and October 2016, 2913 consecutive patients were implanted with a CRT-D and all were prospectively enrolled in the Israeli ICD Registry. Quadripolar LV leads were implanted in 973 (33.4%) patients during this period, and their clinical outcomes were compared to CRT-D recipients implanted with a bipolar LV lead. Primary endpoint was HF hospitalization rate.

RESULTS

Quadripolar leads were implanted more in patients with non-ischemic cardiomyopathy and for primary prevention indication and less in post-infarction patients and for secondary prevention of sudden death. Longer QRS duration was observed with quadripolar leads (147 ± 23 vs 143 ± 25; p < 0.001). Outcome event rate for 100 patient years revealed no difference in HF hospitalization rates between bipolar and quadripolar LV leads. Quadripolar lead implant led to lower cardiac mortality, with no influence on overall mortality. Multivariate analysis revealed no significant differences in study endpoints between bipolar and quadripolar LV leads.

CONCLUSION

In a large real-life registry, implantation of quadripolar LV leads in patients with CRT-D did not influence HF hospitalization rates.

Effect of battery longevity on costs and health outcomes associated with cardiac implantable electronic devices: a Markov model-based Monte Carlo simulation

Introduction

The effects of device and patient characteristics on health and economic outcomes in patients with cardiac implantable electronic devices (CIEDs) are unclear. Modeling can estimate costs and outcomes for patients with CIEDs under a variety of scenarios, varying battery longevity, comorbidities, and care settings. The objective of this analysis was to compare changes in patient outcomes and payer costs attributable to increases in battery life of implantable cardiac defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-D).

Methods and results

We developed a Monte Carlo Markov model simulation to follow patients through primary implant, postoperative maintenance, generator replacement, and revision states. Patients were simulated in 3-month increments for 15 years or until death. Key variables included Charlson Comorbidity Index, CIED type, legacy versus extended battery longevity, mortality rates (procedure and all-cause), infection and non-infectious complication rates, and care settings. Costs included procedure-related (facility and professional), maintenance, and infections and non-infectious complications, all derived from Medicare data (2004–2014, 5% sample). Outcomes included counts of battery replacements, revisions, infections and non-infectious complications, and discounted (3%) costs and life years. An increase in battery longevity in ICDs yielded reductions in numbers of revisions (by 23%), battery changes (by 44%), infections (by 23%), non-infectious complications (by 10%), and total costs per patient (by 9%). Analogous reductions for CRT-Ds were 23% (revisions), 32% (battery changes), 22% (infections), 8% (complications), and 10% (costs).

Conclusion

Based on modeling results, as battery longevity increases, patients experience fewer adverse outcomes and healthcare costs are reduced. Understanding the magnitude of the cost benefit of extended battery life can inform budgeting and planning decisions by healthcare providers and insurers.

Electronic supplementary material

The online version of this article (10.1007/s10840-017-0289-8) contains supplementary material, which is available to authorized users.

Electrophysiology Catheter-Facilitated coronary sinus cannulation and implantation of cardiac resynchronization therapy systems

BACKGROUND

Cardiac resynchronization therapy (CRT) device implantation is hampered by difficult placement of the left ventricular (LV) lead. We have routinely used a steerable electrophysiology catheter to guide coronary sinus (CS) cannulation and facilitate LV lead positioning. The aim of this prospective study is to present our results with this approach in 138 consecutive patients receiving a CRT device over 10 years.

METHODS

The study included 120 men and 18 women, aged 64.8±11.4 years, with coronary disease (n=63), cardiomyopathy (n=72), or other disease (n=3), and mean ejection fraction of 24.5±4.5%. Devices were implanted for refractory heart failure and dyssynchrony, all but 2 in the presence of left bundle branch block. Implanted devices included biventricular pacemakers (CRT-P) (n=33) and cardioverter defibrillators (CRT-D) (n=105).

RESULTS

Using the electrophysiology catheter, the CS could be engaged in 134 (97.1%) patients. In 4 patients failing CS cannulation, a dual-chamber device was implanted in 2, and bifocal right ventricular pacing was effected in 2. Bifocal (n=2) or conventional (n=1) systems were implanted in another 3 patients, in whom the LV lead got dislodged (n=2) or removed because of local dissection (n=1). Thus, finally, a CRT system was successfully established in 131 (94.9%) patients. There were 3 patients with CS dissection, of whom 1 was complicated by cardiac tamponade managed with pericardiocentesis. There were no perioperative deaths. During follow-up (31.0±21.2 months), clinical improvement was reported by 108 (82.4%) patients.

CONCLUSION

Routine use of an electrophysiology catheter greatly facilitated CS cannulation and successful LV lead placement in ∼95% of patients undergoing CRT system implantation.

Repeated procedures at the generator pocket are a determinant of implantable cardioverter-defibrillator infection

BACKGROUND

Rates of cardiac-device infections have increased in recent years, but the current incidence and risk factors for infection in patients with implantable cardioverter-defibrillators (ICDs) are not well known.

HYPOTHESIS

The increasing number of ICD infections is related to accumulated pocket manipulations over time.

METHODS

This single-center, prospective study included patients that underwent ICD implantation from 2008 to 2015. The endpoint was time to infection. Multivariate analysis was performed to identify independent risk factors related to infection.

RESULTS

The study included a total of 570 patients, of whom 419 (73.5%) underwent a first implantation. Mean age was 59 ± 14 years, and 80% were male. During a median follow-up of 36 months (interquartile range, 18-61 months; 1887 patient-years), infection was identified in 26 patients (4.56%), an incidence of 14.9 × 1000 patient-years. Median time to infection was 9.7 months (interquartile range, 1.35-23.4 months), and 38.5% were late infections (beyond 12 months of follow-up). In patients with replacement implants, the incidence was 3-fold higher than in first implantations (27.7 vs 9.1 × 1000 patient-years; P = 0.002). Cox regression identified 2 independent predictors of ICD infection: cumulative number of interventions at the generator pocket (hazard ratio: 1.92, 95% confidence interval: 1.42-2.6, P < 0.001) and pocket hematoma (hazard ratio: 7.0, 95% confidence interval: 2.7-17.9, P < 0.0001).

CONCLUSIONS

The incidence of infection in ICD patients is greater than previously reported, largely due to late infections. Each new cumulative intervention at the same generator pocket nearly doubles the risk of infection.

"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.

Long-Term Experience with First-Generation Implantable Neurostimulation Device in Central Sleep Apnea Treatment

BACKGROUND

Sleep-disordered breathing (SDB) and Cheyne-Stokes respiration (CSR) are associated with shorter survival in patients with heart failure. A novel treatment method for this patient group is unilateral phrenic nerve stimulation by the remedē® system (Respicardia Inc., Minnetonka, MN, USA), a transvenously implantable neurostimulation device, which has recently been studied in a large randomized, controlled trial. Previous literature has shown efficacy and safety of the treatment with this first-generation device, but hardly any data are available on long-term clinical parameters, the remedē® device's battery lifetime, device exchangeability, lead position stability, surgical accessibility, and manageability.

METHODS

We performed remedē® device replacements in consecutive patients for battery depletion, and documented clinical parameters, longevity, operation procedure, complications, and difficulties.

RESULTS

All patients were on neurostimulation treatment by phrenic nerve neurostimulation when device replacement became necessary. Apnea-hypopnea index (from 45 ± 4/h to 9 ± 4/h), oxygen-desaturation index (from 35 ± 7/h to 7 ± 6/h), and time spent with oxygen saturation of <90% (T < 90% from 5 ± 7% to 0 ± 0%) were improved and improvements remained constant throughout the 4-year follow-up. Mean battery life was 4.2 ± 0.2 years and mean replacement procedure time was 25 ± 5.1 minutes. Apart from conventional X-ray documentation of stable lead positions in a long-term setting, no radiation or contrast dye usage was needed and no major complications occurred. In addition, clinical exercise capacity and sleepiness symptoms improved.

CONCLUSIONS

Novel remedē® device shows sustained therapy efficacy and safety in terms of stable lead positions over 4 years. Long-term phrenic nerve neurostimulation therapy for central SDB/CSR appears feasible in a clinical routine setting.

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.

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.