Implantable Cardioverter-defibrillator Generator Replacement Research Articles

Successful defibrillation testing in patients undergoing elective subcutaneous implantable cardioverter-defibrillator generator replacement.

After implantation of a subcutaneous implantable cardioverter-defibrillator (S-ICD), a defibrillation test (DFT) is performed to ensure that the device can effectively detect and terminate the induced ventricular arrhythmia. Data on DFT efficacy at generator replacement are scarce with a limited number of patients and conflicting results. This study evaluates conversion efficacy during DFT at elective S-ICD generator replacement in a large cohort from our tertiary centre. Retrospective data of patients who underwent an S-ICD generator replacement for battery depletion with subsequent DFT between February 2015 and June 2022 were collected. Defibrillation test data were collected from both implant and replacement procedures. PRAETORIAN scores at implant were calculated. Defibrillation test was defined unsuccessful when two conversions at 65 J failed. A total of 121 patients were included. The defibrillation test was successful in 95% after the first and 98% after two consecutive tests. This was comparable with success rates at implant, despite a significant rise in shock impedance (73 ± 23 vs. 83 ± 24 Ω, P < 0.001). Both patients with an unsuccessful DFT at 65 J successfully converted with 80 J. This study shows a high DFT conversion rate at elective S-ICD generator replacement, which is comparable to conversion rates at implant, despite a rise in shock impedance. Evaluating device position before generator replacement may be recommended to optimize defibrillation success at generator replacement.

Outcome and safety of intraoperative defibrillation testing during device replacement: the Simpler trial.

Intraoperative defibrillation testing (DT) during implant or replacement of implantable cardioverter-defibrillators (ICDs) has been a matter of debate for many years. This debate was put to rest by the Simple and Nordic ICD trials, and the practice of testing during new implantations has essentially been almost abandoned. Old registries demonstrated an increased incidence of significant findings in DT during replacements. The aim of the present study was to evaluate frequency of significant findings and safety of DT in subjects undergoing device replacement. A prospective observational multi-centre study included consecutive patients undergoing ICD generator replacement. The primary outcome was a failure to terminate induced ventricular fibrillation (VF) with a single shock 10 J below the maximal capacity of the device. Secondary outcomes included complications of DT. Patients were followed-up at 1- and 6-months post-procedure. A total of 92 patients were eligible, and consented to the study, of which 84 underwent DT during battery replacement. The median age was 68 years and 79.8% were males. Induction of VF was successful in 84 patients as was a successful conversion on the first attempt in all. There were no procedure-related complications. During follow up one patient had two appropriate ICD shock events. In four patients, ICD programming was changed. None suffered inappropriate shock. There was no evidence of lead malfunction. Two deaths occurred, none of which was related to arrhythmia. The present study found DT was not associated with complications in patients undergoing ICD generator replacement but produced no clinically important information.

Defibrillator generator replacements in patients with left ventricular assist device support: The risks of hematoma and infection.

The majority (89%) of left ventricular assist device (LVAD) patients have an implantable cardioverter-defibrillator (ICD) in place. Due to the advances of modern-day LVAD therapy, more patients are on support for longer. This inevitably leads to more LVAD patients facing ICD generator battery depletion. Until now, there are insufficient data regarding periprocedural risks of generator replacements in a high-risk group like the LVAD cohort. A retrospective, single-center analysis of pocket-related outcomes of all ICD generator replacements in LVAD and Non-LVAD patients between January 2014 and December 2018. The primary outcome was the combined endpoint of clinically significant pocket hematoma and/or cardiac implantable electronic device (CIED) infection in the first 6 months after ICD generator exchange. The clinically significant hematoma was defined as hematoma requiring reoperation, prolongation of hospitalization, or interruption of anticoagulation. The cumulative incidence function was calculated for the primary endpoint. Two hundred seventy-seven patients underwent ICD generator exchange in our clinic in this time. Of these, 251 patients had a complete 6-month follow-up regarding clinically significant pocket hematomas and pocket infections. One hundred ninety patients had no LVAD, and 61 patients were on LVAD support. The rate of the primary combined endpoint clinically significant pocket hematoma and/or CIED infection was 3.5 times higher in LVAD patients compared to the non-LVAD cohort (event rate 39.14 vs 11.07 per 100 patient-years, p=0.048). Clinically significant pocket hematomas necessitating revision occurred nearly 4 times more often in the LVAD group (p=0.042). Pocket device infection rates were around 16 times higher in LVAD patients compared to non-LVAD patients (p=0.002). Compared to Non-LVAD patients, LVAD patients exhibit a relevant higher rate of clinically significant pocket hematoma and CIED infection after ICD generator exchange. This information should additionally be considered in the decision-making process regarding the indication for ICD generator exchange.

Intraoperative defibrillation testing during replacements of implantable cardioverter-defibrillators: The Simpler trial

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Maurice Kahn Foundation via the Mayo- Sheba Collaboration Fund. Background The need for intraoperative defibrillation testing (DFT) during implant and/or replacement of implantable cardioverter-defibrillators (ICDs) has been a matter of debate for many years. This debate was put to rest by the Simple and the Nordic ICD trials, and the practice of testing during new implantations has practically been nearly abandoned. Nevertheless, induction of VF for testing purposes (VFT) may still have an important role in selective populations at risk for defibrillation failure, who were not included in the SIMPLE and Nordic trials. One such population includes those who undergo device replacements. Old registries demonstrated an increased incidence of significant findings in VFT during replacements. In the present study, we sought to test this observation. Objectives Evaluate frequency of significant findings and the safety of VFT in subjects undergoing device replacement. Methods A prospective observational multi-center study of VFT included consecutive patients undergoing ICD generator replacement in 5 centers in Israel, Europe, and the US. All centers followed the same VFT protocol. The primary outcome was defined as failure to terminate induced VF with a single shock at 10 Joules below the maximal capacity of the device. Secondary outcomes included complications of VFT. Patients were followed-up at 1 month and 6 months post-procedure. Data collection included documentation of any peri-operative complications and clinical endpoints (occurrence of appropriate shock, inappropriate shocks, lead failure, need for re-intervention, and infection). Results A total of 92 patients were eligible, and consented for the study, of which 84 underwent DFT during battery replacement. The median age was 68 years and 79.8% were male subjects. Induction of VF was successful in all 84 patients as well as VFT with a successful conversion on first attempt. During follow up one patient had two appropriate ICD shock events. In four patients, the ICD programming was changed. None suffered an inappropriate shock. There was no evidence of lead malfunction. A total of two deaths occurred, none of which were related to the device. Conclusion The present study found VFT was not associated with complications in patients undergoing ICD/CRTD generator replacement but produced no clinically important information.

Implantable cardioverter-defibrillators and the older patient: the Dutch clinical practice

Balance between benefit and burden of implantable cardioverter-defibrillator (ICD) therapy is more debatable in older patients, compared to younger patients. Of around 6000 yearly implanted ICDs in the Netherlands, 1:4 is received by patients ≥75 years. We aimed to evaluate the current clinical practice in the Netherlands for ICD implants and generator replacements, with a special focus on the older ICD patients. Cardiologists from all Dutch ICD implanting centres (n = 28) were interviewed. Questions aimed to evaluate outpatient care, pre-operative patient assessment, end-of-life-care counselling, evaluation of social and cognitive wellbeing, clinical evaluation of all patients prior to ICD replacement, and the consideration of the option to downgrade or not replace a device. Implanting cardiologists from all 28 implanting centres were approached for an interview. Response rate was 86%. Management appeared diverse. An age ≥80 years was consistently reported as incentive for more extensive patient evaluation. Patients were invited for counselling prior to device replacements in only the minority (46%) of hospitals. Downgrade or non-replacement was performed in rare cases. End-of-life care discussions were not standard procedure in 67% of the hospitals. Evaluation of social and cognitive wellbeing of patients was based solely on the general clinical impression of the physician in 83%, or not at all assessed in 8% of the centres. A structured framework for care and evaluation of cognitive and/or physical limitations is currently absent in most hospitals. At time of ICD (re-)evaluation, several factors may be considered before deciding on (continuation of) ICD therapy: patient preferences and comorbidity, the need for pacemaker therapy, primary vs. secondary prevention, procedural risks, and patient preferences.

Defibrillation success after subcutaneous implantable cardioverter-defibrillator generator replacement is not affected by impedance increase

Abstract Funding Acknowledgements Type of funding sources: None. Background Routine defibrillation testing during implant and replacement of the subcutaneous implantable cardioverter-defibrillator (S-ICD) is recommended per current guidelines. Recently, concerns have been raised about an increase in shock impedance and consequent shock failure during defibrillation testing in S-ICD patients undergoing a generator replacement. Purpose We aim to describe the defibrillation success rate in relation to the shock impedance in patients undergoing S-ICD generator replacement in our large tertiary center. Methods In this retrospective analysis, data from replacement procedures were collected from all patients who underwent an S-ICD generator replacement in our center from June 2014 to December 2020. Defibrillation testing was performed with at least one shock of ≤65J, and a successful shock was defined as terminating the ventricular arrhythmia within 5 seconds after the shock. Results A total of 133 patients underwent an S-ICD generator replacement, 5.8 ± 0.9 years after initial implant. Reasons for replacement were: reaching of elective replacement indicator (n = 119), early battery depletion (n = 9), complaints of generator pocket (n = 3) and device malfunction (n = 2). Defibrillation testing was performed in 111 patients (86.5%) undergoing a replacement procedure. Shock impedance data from both the implant and replacement procedure were available in 101 patients. The median shock impedance of these patients during their replacement procedure was significantly higher than during their implant, 79Ω (IQR 66-94) and 66Ω (IQR 57.5-81) respectively (Z = -5.552, p &amp;lt; 0.001). Despite the higher shock impedance, first shock during defibrillation testing was successful in 105/111 patients (94.6%), with a success rate of 97.3% after two attempts. In the remaining three patients, the ventricular arrhythmia could only be terminated with a 80J shock. This was the case during both their initial implant and their replacement procedure. Shock impedance increase between implant and replacement was not significantly higher in patients with a successful first shock compared to patients with an unsuccessful first shock (Δ+11.1 ± 20.0Ω versus Δ+12.7 ± 27.6Ω, p = 0.86). Conclusion In this large retrospective analysis, we have shown a first shock success rate during S-ICD generator replacement of 94.6%, which is similar to the success rate of defibrillation testing after initial implant. After multiple attempts, defibrillation testing success rate was 100%. Even though the median shock impedance during replacement was significantly higher than during the initial implant, there was no difference in impedance increase in patients with a successful shock compared to patients with an unsuccessful shock. Abstract Figure. Defibrillation success

Electromagnetic interference from left ventricular assist device in patients with transvenous implantable cardioverter-defibrillator.

Many advanced heart failure patients have both a left ventricular assist device (LVAD) and an implantable cardioverter-defibrillator (ICD). This study examines incidence, clinical impact, and management of LVAD-related EMI. We performed a three-center retrospective analysis of transvenous ICD implanted patients with LVAD implanted between January 1, 2005 and December 31, 2020. The primary outcome was EMI after LVAD implantation, categorized as LVAD-related noise or telemetry interference. The rate of LVAD-related EMI among the 737 patients (mean age 58.6 ± 12.8 years) studied was 5.0%. Telemetry interference (1.5%) compromised ICD interrogation in all patients. This was resolved successfully with use of a metal shield, encased wand, radiofrequency tower, different ICD programmer or by increasing distance between ICD programmer and LVAD (n=6). ICD replacement was required to reestablish successful communication in three patients. LVAD-related noise (3.5%) led to oversensing (n=4), inappropriate mode switches (n=4), noise reversion (n=3), inhibition of pacing (n=2), inappropriate detection as atrial fibrillation (AF) (n=2) and inappropriate detection as ventricular tachycardia (VT) and/or ventricular fibrillation (VF) (n=2). This noise interference persisted (n=3), resolved spontaneously (n=16), resolved with programming change (n=6) or required lead revision (n=1). EMI from LVAD impacts ICD function, although, the incidence rate is low. Physicians implanting both, LVAD in patients with ICD (more common) or ICD in patients with LVAD, should be aware of possible interferences. Telemetry failure not resolved by metal shielding was overcome by ICD generator replacement to a different manufacturer. In most cases, LVAD-related noise resolves spontaneously.

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

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. 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. 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. 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.

Comparison of left ventricular lead upgrade vs continued medical care among patients eligible for cardiac resynchronization therapy at the time of defibrillator generator replacement: Predictors of left ventricular lead upgrade and associations with long-term outcomes

Randomized trials evaluating cardiac resynchronization therapy (CRT) have excluded patients with a pre-existing implantable cardioverter-defibrillator (ICD). The association of CRT upgrade with clinical outcomes in patients with a pre-existing ICD is unclear. The purpose of this study was to examine a CRT-eligible population to evaluate clinical outcomes associated with CRT upgrade compared to patients who did not undergo CRT. Using the National Cardiovascular Data Registry (NCDR) ICD Registry between April 2010 and December 2014, we created a hierarchical logistic regression model to identify predictors of CRT upgrade in a CRT-eligible ICD population. In the subpopulation of patients with Medicare-linked claims data, differential outcomes were determined with censoring at 3 years. The primary endpoint of this study was all-cause mortality, with secondary endpoints of rates of hospitalization and procedural complications. CRT upgrade was performed in 75.5% of CRT-eligible patients with pre-existing ICD (n = 15,803). Presence of left bundle branch block conduction was the strongest predictor of CRT upgrade (odds ratio [OR] 4.56; 95% confidence interval [CI] 4.08-5.11; P<.0001). In both unadjusted and adjusted analyses, CRT upgrade was associated with a reduction in mortality at 3 years (unadjusted hazard ratio [HR] 0.80; 95% CI 0.70-0.92; P = .001; adjusted HR 0.84; 95% CI 0.72-0.98; P = .02, respectively). Compared to patients with ICD generator replacement only, patients who underwent CRT upgrade experienced no different 3-year rates of hospitalization (adjusted HR 1.01; 95% CI 0.91-1.12; P = .81) or 1-year periprocedural complication rates (adjusted HR 1.07; 95% CI 0.79-1.45; P = .66). In a national registry of CRT-eligible patients with pre-existing ICD, upgrade to CRT was associated with lower rates of mortality than continued medical management.

Outcomes following implantable cardioverter–defibrillator generator replacement in adults: A systematic review

Randomized trials inform the use of implantable cardioverter-defibrillators (ICDs) for prevention of sudden cardiac death, yet management of patients considering ICD generator replacement procedures remains largely dependent on clinical judgment. Thus, we performed a systematic review of all studies evaluating outcomes associated with ICD generator replacement. We queried PubMed, Embase, Web of Science, and the Cochrane Database of Systematic Reviews for relevant studies with a prespecified search and adjudication strategy (PROSPERO registration number CRD42018100818) to evaluate outcomes including (1) survival; (2) clinical complications (eg, infection, hematoma); or (3) incidence of ICD therapy. From 1607 unique titles, 37 studies met inclusion criteria, describing outcomes for 238,949 patients. Procedural mortality was rare, but complications including reoperation (median 4.57%; range 0.38%-10.31%), infections (median 2.01%; range 0.03%-9.27%), and hematoma (median 1.22%, range 0.17%-2.53%) were observed in a small fraction of patients. Appropriate ICD therapy after generator replacement was common (median rate 23.03%; range 10.9%-31.4%), with an overall annualized event rate of 8.52% at median duration of follow-up of 32.4 months. Appropriate ICD therapy continued to occur at a significant annual rate even in patients who no longer met implantation criteria (5.27%) and in patients who never previously received ICD therapy (4.87%). This analysis of published observational data regarding ICD generator replacement procedures identifies relatively low risks of procedural complications and clinically meaningful rates of appropriate ICD therapies. These estimates may guide clinical decisions and inform the design of definitive trials.

Association between the Charlson comorbidity index and outcomes after implantable cardioverter defibrillator generator replacement.

Recipients of implantable cardioverter defibrillator (ICD) generator replacement with multiple medical comorbidities may be at higher risk of adverse outcomes that attenuate the benefit of ICD replacement. The aim of this investigation was to study the association between the Charlson comorbidity index (CCI) and outcomes after ICD generator replacement. All patients undergoing first ICD generator replacement at Mayo Clinic, Rochester and Beth Israel Deaconess Medical Center, Boston between 2001 and 2011 were identified. Outcomes included: (a) all-cause mortality, (b) appropriate ICD therapy, and (c) death prior to appropriate therapy. Multivariable Cox regression analysis was performed to assess association between CCI and outcomes. We identified 1421 patients with mean age of 69.6 ± 12.1 years, 81% male and median (range) CCI of 3 (0-18). During a mean follow-up of 3.9 ± 3 years, 52% of patients died, 30.6% experienced an appropriate therapy, and 23.6% died without experiencing an appropriate therapy. In multivariable analysis, higher CCI score was associated with increased all-cause mortality (Hazard ratio, HR 1.10 [1.06-1.13] per 1 point increase in CCI, P<.001), death without prior appropriate therapy (HR 1.11 [1.07-1.15], P<.0001), but not associated with appropriate therapy (HR 1.01 [0.97-1.05], P=.53). Patients with CCI ≥5 had an annual risk of death of 12.2% compared to 8.7% annual rate of appropriate therapy. CCI is predictive of mortality following ICD generator replacement. The benefit of ICD replacement in patients with CCI score ≥5 should be investigated in prospective studies.

Incidence of appropriate implantable cardioverter-defibrillator therapy and mortality after implantable cardioverter-defibrillator generator replacement: results from a real-world nationwide cohort.

The safety of omitting implantable cardioverter-defibrillator (ICD) generator replacement in patients with no prior appropriate therapy, comorbid conditions, and advanced age is unclear. The aim was to investigate incidence of appropriate ICD therapy after generator replacement. We identified patients implanted with a primary prevention ICD (n = 4630) from 2007 to 2016, who subsequently underwent an elective ICD generator replacement (n = 670) from the Danish Pacemaker and ICD Register. The data were linked to other databases and evaluated the outcomes of appropriate therapy and death. Predictors of ICD therapy were identified using multivariate Cox regression analyses. A total of 670 patients underwent elective ICD generator replacement. Of these, 197 (29.4%) patients had experienced appropriate therapy in their 1st generator period. During follow-up of 2.0 ± 1.6 years, 95 (14.2%) patients experienced appropriate therapy. Predictors of appropriate therapy in 2nd generator period was low initial left ventricular ejection fraction (≤25%) [hazard ratio (HR) 1.87, confidence interval (CI) 1.13-1.95] and appropriate therapy in 1st generator period (HR 3.95, CI 2.57-6.06). For patients with appropriate therapy in 1st generator period, 4-year incidence of appropriate therapy was 50.6% vs. 16.4% in those without (P < 0.001). Among patients >80 years with no prior appropriate therapy 8.8% of patients experienced appropriate therapy after replacement. Comorbidity burden and advanced age were associated with reduced device utilization after replacement and a high competing risk of death without preceding appropriate therapy. A significant residual risk of appropriate therapy in the 2nd generator was present even among patients with advanced age and with a full prior generator period without any appropriate ICD events.

Outcomes following implantable cardioverter-defibrillator generator replacement in patients with recovered left ventricular systolic function: The National Cardiovascular Data Registry

Some patients with heart failure (HF) experience recovery of left ventricular (LV) systolic function by the end of their implantable cardioverter-defibrillator (ICD) generator battery life. Outcomes following generator replacement in this setting are poorly understood. We sought to describe outcomes following ICD generator replacement associated with recovery of LV systolic function. We evaluated 26,197 Medicare beneficiaries enrolled in the American College of Cardiology's National Cardiovascular Data Registry ICD Registry who underwent primary prevention ICD generator replacement between 2006 and 2009, stratified by LV ejection fraction (LVEF): reduced (LVEF ≤35%), partially recovered (LVEF >35% and ≤50%), and recovered (LVEF >50%). At the time of generator replacement, 1915 (7.3%) patients had recovered LVEF and 4576 (17.5%) had partially recovered LVEF. Periprocedural events were rare (<1%) in all patients. In patients with reduced LVEF, the incidence of HF readmission and mortality at 3 years was 27.5% and 32.7%, respectively. In comparison, the rates of HF readmission and mortality were lower for patients with partially recovered LVEF (readmission: 15.9%; hazard ratio [HR] 0.66; 95% confidence interval [CI] 0.61-0.72; mortality: 23.0%; HR 0.82; 95% CI 0.76-0.87) and those with recovered LVEF (readmission: 12.2%; HR 0.55; 95% CI 0.48-0.63; mortality: 18.2%; HR 0.72; 95% CI 0.64-0.80). Patients with partially recovered and recovered LVEF have lower risks of mid-term adverse outcomes than do those with reduced LVEF following ICD generator replacement. Approximately 3 in 4 patients continue to have reduced LVEF at the time of generator replacement and are at high risk of HF readmission and mortality. These data highlight the prognostic associations of LVEF in patients undergoing generator replacement as well as the clinical encounter for generator replacement as an opportunity to identify those at increased risk of adverse outcomes.

Risk of Appropriate Therapy and Death Before Therapy After Implantable Cardioverter-Defibrillator Generator Replacement.

Background The decision to initially implant an implantable cardioverter-defibrillator (ICD) is informed by robust randomized controlled trials, but no such data exist to guide the decision to replace an ICD generator. In this study, we aimed to determine outcomes after ICD generator replacement. Methods All patients with ischemic or nonischemic cardiomyopathy who underwent ICD generator replacement from 2001 to 2011 at Mayo Clinic, MN, or Beth Israel Deaconess Medical Center, MA, were included. Outcomes included (1) appropriate therapy after generator replacement and (2) death before appropriate therapy after generator replacement. Cox proportional hazards modeling was used to determine the associations between patient characteristics and outcomes. Results In 1421 patients undergoing ICD generator replacement (mean±SD age 69.6±12.1 years, 81% male), appropriate therapy occurred after replacement in 435 patients (30.6%) over a mean follow-up of 2.7±2.6 years. Associated factors included lower left ventricular ejection fraction and history of appropriate therapy before generator replacement. Death before appropriate ICD therapy occurred in 336 (23.7%) patients. Older age, lower left ventricular ejection fraction, and noncardiac comorbidities, including diabetes mellitus, chronic lung disease, peripheral vascular disease, lower hemoglobin, and lower glomerular filtration rate, were associated with greater risk of death before appropriate therapy. A progressive increase in mortality was observed with aggregation of these noncardiac comorbidities. Conclusions The decision to replace the ICD should take into consideration not only left ventricular ejection fraction and history of ventricular arrhythmias, but also comorbid illnesses that may impact the duration and the quality of life.

Benefit of Implantable Cardioverter-Defibrillator Generator Replacement in a Primary Prevention Population-Based Cohort.

This study investigated the benefit of an implantable cardioverter-defibrillator (ICD) generator replacement in patients who did not have an ongoing theoretical indication for ICD therapy at time of replacement. Primary prevention ICD therapy is known to reduce mortality in patients with cardiomyopathy andreduced left ventricular systolic function. The data describing outcomes after generator replacement arelimited. This was a retrospective cohort study following patients implanted with primary prevention ICD therapy from 2002 until 2015 who subsequently received a generator replacement. Patients with an ongoing theoretical indication for ICD therapy were defined as either left ventricular ejection fraction≤35% or having had prior appropriate ICD therapy. Outcomes were mortality, appropriate ICD therapy and shock, inappropriate shock, and device and lead complications. A total of 614 patients were identified; 173 (28.2%) underwent a generator replacement and were followed for a mean of 2.9 years after replacement; 144 (83.2%) had an ongoing theoretical indication. Patients with no ongoing theoretical indication (n= 29, 16.7%) had lower mortality (hazard ratio [HR]: 0.39, 95% confidence interval [CI]: 0.15-1.00; p= 0.0495), appropriate shock rate (HR: 0.29, 95% CI: 0.09 to 0.96; p= 0.04), and appropriate ICD therapy rate (HR: 0.30, 95% CI: 0.12 to 0.77; p= 0.012) when compared with patients with ongoing theoretical indication. In theentire cohort, there were low rates of inappropriate shock (4.0%), device complication (5.1%), and lead complication(2.3%). In patients with primary prevention ICD therapy who underwent generator replacement, improved leftventricular ejection fraction and lack of prior appropriate ICD therapy at time of replacement were associated with alower risk of mortality and incident ventricular arrhythmia.

Implantable cardioverter-defibrillator elective generator replacement: a procedure for all?

Six risk stratification scores have been developed to estimate mortality risk in patients receiving an implantable cardioverter-defibrillator (ICD). This study aims at validating and comparing these risk scores in patients having elective ICD generator replacement (GR) and assessing the outcome of patients submitted to this procedure. Two hundred twenty three consecutive patients with ischaemic or non-ischaemic dilated cardiomyopathy submitted to elective ICD GR and followed-up for 44 ± 19 months were included. We evaluated which of six previously developed risk scores could predict post-discharge all-cause mortality risk in this context with the highest efficacy. Comparisons between these scores were made using receiver-operating characteristic curves and the integrated discrimination improvement (IDI) index. We further assessed risk of appropriate ICD therapies and all-cause mortality following ICD GR. The prognostic utility of the six scores was assessed by calculating the AUC for follow-up all-cause mortality prediction: Goldenberg - 0.758 ± 0.042, p < 0.001; Parkash - 0.754 ± 0.042, p < 0.001; Bilchick - 0.813 ± 0.038, p < 0.001; Kraaier - 0.721 ± 0.043, p < 0.001; REPLACE DARE - 0.746 ± 0.048, p < 0.001; Providencia - 0.739 ± 0.043, p < 0.001. Through measures of risk reclassification (IDI and relative IDI), the score by Bilchick et al. was shown to outperform all other scores. Binary logistic regression identified pre-GR-appropriate ICD therapy as an independent predictor of post-GR ICD therapy (OR 6.2, CI 95% 3.0-12.7, p < 0.001), along with male gender (OR 6.6, CI 95% 0.8-55, p = 0.082) and history of atrial fibrillation (OR 2.28, CI 95% 1.1-4.5, p = 0.019). Current prediction scores are useful in predicting mortality risk of patients considered for ICD generator replacement and can potentially help identify patients who may not benefit from continuous ICD treatment due to high mortality rates regardless of the ICD.

Upgrading and replacement in CRT devices: experience counts.

Cardiac resynchronisation therapy has proven to be highly effective in patients with heart failure and an asynchronous contraction pattern of the left ventricle, due to late activation of the posterolateral wall with left bundle branch block configuration on the ECG of more than 150 ms [1]. In pacemaker patients with a high percentage of right ventricular pacing, pacing-induced left ventricular (LV) dysfunction can appear. This newly developing heart failure is most probably the result of pacing-induced LV asynchrony. These patients with pacing-induced heart failure and ICD patients with heart failure who develop a wide QRS complex during follow-up account for the majority of patients who are eligible for an upgrade to a CRT device. In an European survey, up to 25 % of CRT implants were upgrading procedures [2]. The REPLACE registry demonstrated a high percentage of complications in upgrade and revision procedures in 434 CRT patients from 71 centres. It was not stated how many centres actually contributed to this total number of CRT upgrades [3]. Their conclusion ‘pacemaker and implantable cardioverter-defibrillator generator replacements are associated with a notable complication risk, particularly those with lead additions’ made cardiologists somewhat cautious and even reluctant to perform a therapeutic upgrade to CRT. These REPLACE data support careful decision making before device replacement when managing device advisories and when considering upgrades to more complex systems, concluded the authors [3]. And indeed, an upgrade procedure can be complicated and is in need of an experienced skilled operator or at least her or his direct supervision during the procedure. As experience is a major factor in reducing complications during and after device implantation [4], it is reasonable that experience is an even stronger denominator in complicated procedures as primary CRT implants and CRT upgrades. In this issue, the retrospective data of upgrading procedures to CRT devices were compared with the complications in primary CRT implants during the same period [5]. These retrospective data originate from one tertiary centre with a high patient load. Only three experienced operators performed the majority of procedures or supervised them. A: Total number of individual implants of 165 (62 %), including 82 upgrade procedures. Thirty assists of which 16 assists in an upgrade procedure. B: Total number of individual implants of 30 (11 %), including 13 upgrade procedures. Six assists of which 4 assists in an upgrade procedure. C: Total number of individual implants of 18 (7 %), including 9 upgrade procedures. Three assists of which 0 assists in an upgrade procedure. Though these data are retrospective, the complication rate is considerably lower when compared with the literature [3]. The most determining factor in the difference of complication rate is most likely skill, which comes from experience and cooperation during these complicated procedures. It was not investigated whether the determining factor was cooperation or experience or its combination.

Detect Long-term Complications After ICD Replacement (DECODE): Rationale and Study Design of a Multicenter Italian Registry.

The replacement of implantable cardioverter-defibrillators (ICDs) may give rise to considerable clinical consequences, the importance of which is underrated by the medical community. Replacement-related adverse events are difficult to identify and require monitoring of both short-term complications and long-term patient outcome. The aim of this study is to perform a structured evaluation of both short- and long-term adverse events and a cost analysis of consecutive ICD replacement procedures. Detect Long-term Complications After ICD Replacement (DECODE) is a prospective, single-arm, multicenter cohort study designed to estimate long-term complication rates (at 12 months and 5 years) in patients undergoing ICD generator replacement. The study will also evaluate predictors of complications, patient management before and during the replacement procedure in clinical practice, and the costs related to use of health care resources. About 800 consecutive patients with standard indications for ICD generator replacement will be enrolled in this study. The decision to undertake generator replacement/upgrade will be made according to the investigators' own judgment (which will be recorded). Patients will be followed for 60 months through periodic in-hospital examinations or remote monitoring. Detailed data on complications related to ICD replacement in current clinical practice are still lacking. The analysis of adverse events will reveal the value of new preventive strategies, thereby yielding both clinical and economic benefits. Moreover, assessment of complication rates after ICD replacement in a real-life setting will help estimate the actual long-term cost of ICD therapy and assess the real impact of increasing ICD longevity on cost-effectiveness.

Benefit of implantable cardioverter-defibrillator therapy after generator replacement in patients with Brugada syndrome

BackgroundAn implantable cardioverter-defibrillator (ICD) is the only proven effective therapeutic strategy for patients with Brugada syndrome (BS). However, it is controversial whether the device should be replaced even in patients who had never experienced appropriate ICD therapy until the time of generator replacement. Methods and resultsThis was a nationwide, multicenter retrospective study that enrolled patients who were diagnosed with BS and had an ICD implantation between January 1998 and April 2014. Appropriate ICD therapies administered for ventricular tachyarrhythmia were evaluated during follow-up. A total of 117 patients (age 43±12years, male 115 [98.3%]) were enrolled, and the mean follow-up duration was 6.0±4.1years. Thirty-seven (31.6%) patients had experienced appropriate ICD therapy during follow-up. Of all patients, 46 underwent replacement of the device. After the first generator replacement, the incidence of appropriate ICD therapy remained as high as 65.2% in patients who previously experienced appropriate ICD therapy before generator replacement. In 30 patients who did not experience any cardiac events until the first generator change, two (8.7%) had an episode of appropriate ICD therapy afterwards. ConclusionsNo episode of ICD therapy before generator replacement could not guarantee a safe clinical course. ICD generator replacement should be considered even in patients without ICD therapy before.

Influence of renal function on mortality and ventricular arrhythmias in patients undergoing first implantable cardioverter-defibrillator generator replacement.

Impaired renal function is associated with increased mortality among patients with implantable cardioverter-defibrillators (ICDs). The relationship between renal function at time of ICD generator replacement and subsequent appropriate ICD therapies is not known. We identified 441 patients who underwent first ICD generator replacement between 2000 and 2011 and had serum creatinine measured within 30 days of their procedure. Patients were divided into tertiles based on estimated glomerular filtration rate (eGFR). Adjusted Cox proportional hazard and competing risk models were used to assess relationships between eGFR and subsequent mortality and appropriate ICD therapy. Median eGFR was 37.6, 59.3, and 84.8 mL/min/1.73 m(2) for tertiles 1-3, respectively. Five-year Kaplan-Meier survival probability was 34.8%, 61.4%, and 84.5% for tertiles 1-3, respectively (P < 0.001). After multivariable adjustment, compared to tertile 3, worse eGFR tertile was associated with increased mortality (HR 2.84, 95% CI [1.36-5.94] for tertile 2; HR 3.84, 95% CI [1.81-8.12] for tertile 1). At 5 years, 57.0%, 58.1%, and 60.2% of patients remained free of appropriate ICD therapy in tertiles 1-3, respectively (P = 0.82). After adjustment, eGFR tertile was not associated with future appropriate ICD therapy. Results were unchanged in an adjusted competing risk model accounting for death. At time of first ICD generator replacement, lower eGFR is associated with higher mortality, but not with appropriate ICD therapies. The poorer survival of ICD patients with reduced eGFR does not appear to be influenced by arrhythmia status, and there is no clear proarrhythmic effect of renal dysfunction, even after accounting for the competing risk of death.