Medtronic Sprint Fidelis Research Articles

Abstract 17989: Generator Exchange is Associated with an Increased Rate of Sprint Fidelis Lead Failure

Background: The Medtronic Sprint Fidelis defibrillator lead is at an increased risk for failure and was recalled in October 2007. Approximately 268,000 leads were implanted and more than 100,000 patients still have active Sprint Fidelis leads. A number of studies have examined the rate and clinical predictors of lead failure, but none have addressed the effect of ICD generator exchange on subsequent lead failure. Although the manufacture claims that “Sprint Fidelis performance after device change-out is similar to lead performance without device change-out,” published data is lacking. Objective: The purpose of this study is to assess the effect of ICD generator exchange on the rate of Sprint Fidelis lead failure. Methods: A retrospective chart review was conducted in all patients who underwent implantation of a Sprint Fidelis lead at one academic medical center. All patients who had a normally functioning Sprint Fidelis lead at the time of generator exchange and elected to retain the lead were compared to controls with leads implanted for a comparable amount of time who did not undergo ICD replacement. Results: 668 patients received a Sprint Fidelis lead prior to the recall. 42 patients with a functioning lead underwent generator exchange without lead replacement. Following generator replacement, 4 leads failed within 3 months and an additional 4 within 1 year (19%). In comparison, 41 of 626 control leads malfunctioned during the study period, a total of 6.5%. Generator exchange significantly increased the rate of lead failure (19% vs. 6.5%, p < 0.05). Conclusions: Generator exchange is associated with a higher than expected rate of Fidelis lead failure, often within 3 months. These data suggest that the benefit-risk ratio of Fidelis lead replacement at the time of ICD generator exchange may be greater than previously appreciated and that increased frequency of monitoring may be appropriate when the lead is retained.

Disproportionality analysis for signal detection of implantable cardioverter–defibrillator‐related adverse events in the Food and Drug Administration Medical Device Reporting System

The Food and Drug Administration (FDA) became aware of lead fracture and inappropriate shock events related to Sprint Fidelis leads in January 2007. The manufacturer announced a voluntary market withdrawal in October 2007. Our aim was to retrospectively evaluate this safety signal using disproportionality analysis to estimate whether disproportionality analysis could have detected this particular safety signal earlier than actually occurred. The Manufacturer and User Facility Device Experience (MAUDE) database contains reports on device-related adverse events, of which, FDA receives several hundred thousand every year. For each manufacturer, a list of the top lead brand names was ranked by frequency of reports. We used the Multi-item Gamma Poisson Shrinker (MGPS) method for analysis. We isolated 11 top-reported implantable cardioverter defibrillator (ICD) lead brand names. Using MGPS methodology, we calculated the one-sided 95% lower confidence bound EB05 on the empirical Bayes geometric mean of the reporting ratio. We performed individual MGPS analysis for each of the top reported adverse events in 2006 for ICD leads. Fidelis had the highest EB05 scores for lead fractures and inappropriate shock. Through disproportionality analysis of the MAUDE database, we were able to identify known safety signals associated with the Medtronic Sprint Fidelis lead. If utilized at the time, this disproportionality analysis would have identified signals earlier for lead fractures, oversensing, high impedance, and inappropriate shock.

150 Implantable cardioverter-defibrillator lead complications and clinical effectiveness in patients with inherited cardiac conditions

<h3>Background</h3> Implantable cardioverter-defibrillator (ICD) therapy can reduce sudden death due to ventricular arrhythmia (VT/VF) but is not without complication, particularly in young patients who live for many years with a device in situ. We aimed to determine the ICD complication rate in our inherited cardiac condition (ICC) population compared with international reports. Particular importance was given to inappropriate shock therapy due to lead failure as there are new ICD technologies available. <h3>Methods</h3> Patients with ICCs who had ICD implantation or box change between January 2006 and September 2009 were included. Data on clinical characteristics, complications and ICD therapies were obtained from pacing and hospital records. We compared our data with several ICD studies of patients with specific ICCs (Abstract 150 table 1). <h3>Results</h3> 101 patients (mean age 44.1±14.8 years; 59 male) were included (idiopathic VF 15%; DCM 17%; ARVC 22%; HCM 21%; long QT syndrome 17%; Brugada syndrome 6%; others 2%). During a mean follow-up of 74.0±53.2 months 2 patients died (1 inappropriate shocks; 1 stroke). Indications were secondary prevention in 71.3% of patients. ICD types were 56.4% single chamber; 39.6% dual chamber; 4.0% biventricular. Appropriate therapy successfully terminated VT/VF in 27 (26.7%) patients 34.7% of secondary and 6.9% of primary prevention patients received appropriate therapy. Inappropriate therapy occurred in 18 (17.8%) patients and lead failure (noise/wear/fracture) in 22 (20.8%) patients (Abstract 150 table 2). 12 out of 18 inappropriate shocks were due to lead failure, 5 sensing errors (1 T-wave oversensing; 4 AF), 1 generator fault. 10/22 leads that failed were Medtronic Sprint Fidelis and these were responsible for 8/12 patients receiving inappropriate shocks including one death due to lead fracture. Comparison with other studies indicates a high lead failure rate due to the long follow-up period, similar to the LQT Study which reports 25% lead failure over 87 months (Abstract 150 table 1). With lead failure excluded the complication rate is comparable to shorter follow-up studies. Inappropriate and appropriate therapy rates are similar among all studies. <h3>Conclusions</h3> There is a significant rate of ICD lead failure in patients with ICCs, which may be expected given the high frequency of Sprint Fidelis leads implanted during this period and the long follow-up. Our results compare favourably to other similar studies. The high rate of appropriate therapy highlights the clinical effectiveness of ICD intervention in secondary prevention. Lead complications may be lower with the use of new ICD technology in selected patients.

Risk of Sprint Fidelis defibrillator lead failure is highly dependent on age

In 2007, Medtronic Sprint Fidelis defibrillator leads were taken off the market due to a high rate of lead failure. Current data do not allow for risk stratification of patients with regard to lead failure. We sought to determine predictors of Sprint Fidelis lead failure. Between 2004 and 2007, 269 Sprint Fidelis leads were implanted in 258 patients in our centre. Variables associated with lead failure were assessed by the Kaplan-Meier method and a Cox survival model. During a median follow-up of 2.80 years (maximum 5.32), we observed 33 (12.3%) Sprint Fidelis lead failures (5-year survival, 65.6% ± 7.5%). In univariate analysis, age was the only predictor of lead failure (hazard ratio [HR] for 1-year increase 0.97; 95% confidence interval [CI] 0.95-0.99; p=0.009). Patients aged<62.5 years (median) had a significantly increased risk of lead failure compared with patients aged>62.5 years (HR 2.80; CI 1.30-6.02; p=0.009). Survival without Sprint Fidelis lead failure was 55.6% ± 10.4%) in patients aged<62.5 years (24/134 leads) vs 78.6% ± 8.8% in patients aged>62.5 years (9/135 leads). The annual incidence of lead failure in patients aged<62.5 years was 11.6% ± 4.9% during the fourth year after implantation and 22.9% ± 13.2% during the fifth year. Overall, we found a higher rate of Sprint Fidelis lead dysfunction than previously described. Lead failure was much more frequent in younger patients. Our results emphasize the need for close follow-up of younger patients with Sprint Fidelis leads and suggest that, in these patients, the implantation of a new implantable cardioverter defibrillator lead at the time of generator replacement might be reasonable.

Should industry share a greater burden for the cost of device recalls?

w a n u Burke et al, in this issue of the Journal, estimated that he cost to Medicare related to the Medtronic Sprint Fidelis ead failures is in the range of $167,000,000 to 806,000,000. Although critics may dispute the methods sed in these calculations, the assumptions are reasonable, nd whatever the true cost may be, it is substantial. In a arger context, the cost to Medicare related to treatment of atients with medical devices that fail or cause less catatrophic problems is a huge number. A recent analysis of edical device recalls identified 113 recalls from 2005 hrough 2009 that could cause serious health problems or eath, and cardiovascular devices comprised the largest ecall category. In 2005, approximately 24,000 patients underwent procedures related to other problems with Medtronic or Guidant devices. Although the companies rovided replacements and compensated patients for up to 2,500 in out-of-pocket expenses, the remaining cost to edicare and private insurers was not shared by industry. y one estimate, the cost to Medicare related to those eplacement procedures was about $120 million. Should industry have a greater responsibility to share in the overall costs related to recalls of their devices? If industry had more liability for these costs, how would it affect their resources for research and development, support of medical education, and other services to patients, hospitals, or physicians? Would they be more cautious about introducing new technologies, and would the risk of device failures decline if industry shared a greater burden for the cost of device failures? Could this burden be counterproductive by stifling innovation at the cost of delaying the introduction of life-saving new technologies? These questions are fraught with the potential for unintended consequences. It is tempting to compare recalls of medical devices to safety recalls by the automotive industry, which can be

Management of the Patient With Implantable Cardioverter-Defibrillator Lead Failure

52-year-old man was brought to the emergency department because of multiple implantable cardioverter-defibrillator (ICD) shocks. His existing dual-chamber pacemaker was upgraded from a biventricular ICD 4 years ago. The ECG in the emergency department showed sinus tachycardia with left bundle-branch block at a rate of 135 bpm. In the emergency department, the patient received 5 additional shocks without a change in rhythm. A donut magnet was placed over the ICD. Interrogation revealed evidence of a lead fracture, and tachycardia therapies were disabled. The high-voltage lead was a Medtronic Sprint Fidelis ICD lead. Admission to the hospital was recommended for definitive correction of his problem. This case illustrates the most common presentation of an ICD lead failure and the resulting management challenges. Lead failure is typically thought of as an intrinsic design or construction defect leading to an adverse clinical event. However, any adverse clinical event mediated through malfunction of an ICD lead represents lead failure. An ICD lead failure can occur in any patient, even with leads that have a proven record of reliability. The overall incidence of ICD lead failure is difficult to assess because of its underreporting and the absence of strict reporting requirements. Random component failures in individual patients are especially difficult to quantify, but some studies suggest a failure rate of ≈0.58%/y among modern ICD leads.1 Leads that have undergone manufacturer advisory or Food and Drug Administration alerts have a much higher incidence of failure. Examples of ICD leads with high failure rates include the Guidant Endotak DSP (model 0125) and the Medtronic Transvene (model 6936). The 6936 lead had a 90% survival rate at 4 to 5 years and a nearly 60% survival rate at 8 to 9 years. Therefore, lead failure rates are not linear over time. The recent recall of the Medtronic …

Psychological Effects of Implantable Cardioverter-Defibrillator Leads under Advisory

Automatic implantable cardioverter-defibrillators (ICDs) are standard therapy for patients at high risk of sudden cardiac death. Device implantation is a stressful event that has been associated with patient and anticipatory anxiety. While the psychological effects of normally functioning ICDs are known, only a dearth of literature evaluates how a warning about the potential for malfunction of an ICD lead, related to a device advisory, influences the degree of psychological distress. These effects are evaluated in a patient population with the Medtronic Sprint Fidelis defibrillation lead 6949 (Medtronic, Minneapolis, MN, USA). A sample of 413 patients were studied. Groups included 158 with an advisory Medtronic 6949 and 255 with an ICD that had no current advisories. Patients were administered a validated disease-specific metric assessing concerns over ICDs, as well as a demographics questionnaire. The primary outcome was the total score on the ICD concerns (ICDC). Analysis was with one-way Analysis of Variance with preplanned orthogonal contrasts and multivariate regression. The advisory group tended to have higher numbers of high school and college graduates. The average length of device implant in the nonadvisory group was higher at 4.29 years versus 3.99 years in the advisory group (t = 0.901, P ≤ 0.5). A higher percentage of those with an advisory experienced more shocks (39% vs 32%; z =-1.51, P ≤ 0.5). Average ICDC scores in the advisory group with previous shock were significantly higher than in the nonadvisory group with prior shock ([27.7 standard deviation (SD) ± 14.5] vs [18.5 SD ± 12.5], P = 0.0001) . Average ICDC score in the advisory group without shock was also significantly elevated compared to the nonadvisory group (18.5 SD ± 14.5 vs 10.8, SD ± 12.5, P = 0.0001). There was a significant effect of having an advisory on total ICDC scores (F = 21.32, P ≤ 0.0001). History of shock also significantly increased total ICDC scores (F = 20.07, P ≤ 0.0001). In multivariate regression, presence of Fidelis lead and history of shock were predictors for increased ICDC scores (R(2) = 0.158, F = 38.88, P = 0.0001). When controlling for shock history, presence of Fidelis lead remained an independent predictor of elevated ICDC scores (R(2) = 0.125, F = 59.30, P ≤ 0.0001). Our study attempts to address some of the psychological differences between participants with advisory and nonadvisory leads. Higher scores on the ICDC were found in our advisory group. While statistically significant, it is entirely unclear if these scale elevations are clinically significant or if directed counseling at this stage may reduce these elevations. This raises the suspicion that directed counseling be undertaken for patients with future advisories.

Medtronic Sprint Fidelis lead recall: Determining the initial 5-year management cost to Medicare

The Medtronic Sprint Fidelis defibrillator lead has a high failure rate and was recalled in October 2007. The purpose of this study was to determine the incremental cost of the management of this lead to Medicare. Real hospital cost data in U.S. dollars were collected on 32 patients with a Medtronic Sprint Fidelis lead who underwent lead revision. Of these patients, 15 were excluded because they had insurance coverage other than that provided by the Centers for Medicare & Medicaid Services. Seventeen patients with Medicare or Medicaid coverage underwent lead revision either electively (n = 6) or after being hospitalized for multiple shocks caused by a lead fracture (n = 11). Eighty-eight percent of the patients underwent extraction of the Fidelis lead at the time of lead revision. A decision model was made that outlines the potential management of the lead recall over time. The existing literature and Medtronic data were reviewed for parameters included in the decision model. The model assumed that 175,000 patients were alive with an implanted Fidelis lead at the time of the recall and that the annual failure rate will be 1.8% over the first 5 years. It was also assumed that 1% of patients without a lead fracture would also undergo elective lead revision each year and that the proportion of patients who would have the Fidelis lead extracted rather than abandoned would be 20:80. Estimates with ranges were used for parameters for which no data are available. The industry standard rate of lead failure was estimated based on the Sprint Quattro model 6947 lead, and this was subtracted from the estimated rates for the Sprint Fidelis lead such that the incremental cost of the lead failure could be estimated. The cost of lead revision trended higher when the Fidelis lead was extracted rather than abandoned ($45,077 ± $11,693 vs $33,802 ± $33, P = .20). In 5 years, the estimated cost impact of the Medtronic Sprint Fidelis lead recall to Medicare will be $287,000,000 (range $176,000,000-$1,186,000,000, October 2007 USD). The cost impact of managing a defibrillator lead with a high failure rate to Medicare will be substantial.

Delayed ICD Lead Cardiac Perforation: Comparison of Small versus Standard‐Diameter Leads Implanted in a Single Center

An increased risk of delayed cardiac perforation (DCP) with active-fixation small-diameter ICD leads has recently been reported, especially with regard to the St. Jude Riata lead (St. Jude Medical, Sylmar, CA, USA). Few data on the risk of DCP in small versus standard-diameter leads implanted in a single high-volume center are available. Moreover, no data on the performances of St. Jude's new small-diameter Durata lead are as yet available. The aim of this study was to assess the incidence of DCP in small versus standard-diameter leads implanted in our center. Between January 2003 and October 2009, 437 small-diameter leads (190 Medtronic Sprint Fidelis [Medtronic Inc., Minneapolis, MN, USA], 196 Riata, 51 Durata) and 421 standard-diameter (>8 Fr) leads were implanted. After a median follow-up of 421 days seven of 858 (0.8%) patients experienced DCP. The incidence of DCP was higher in patients with small-diameter leads than in those with standard-diameter leads (1.6% vs 0%, P = 0.01). No cases of DCP occurred among 371 passive-fixation leads versus 1.4% of events among active-fixation leads (P = 0.02). The incidence of DCP was 2.5% in Riata, 1% in Sprint Fidelis, 0% in Durata, and 0% in standard-diameter leads (P < 0.01 for Riata vs standard-diameter leads). Small-diameter active-fixation ICD leads are at increased risk of DCP, a finding mostly due to the higher incidence of events in the Riata family. By contrast, passive-fixation small-diameter leads and standard-diameter leads appear to be safe enough regarding the risk of DCP. Our preliminary data suggest that the new Durata lead is not associated with an increased risk of DCP.

Lead integrity alert algorithm decreases inappropriate shocks in patients who have Sprint Fidelis pace-sense conductor fractures

The Medtronic Sprint Fidelis high-voltage implantable cardioverter-defibrillator (ICD) lead is prone to fracture. The majority of fractures involve the pace-sense (P/S) conductors and may result in multiple inappropriate shocks. The Medtronic lead integrity alert (LIA) algorithm was designed to improve early detection of transient P/S conductor fractures and to decrease the incidence and number of inappropriate shocks. The purpose of this prospective single-center study was to assess the effectiveness of the LIA algorithm for warning patients of an impending Sprint Fidelis P/S conductor fracture and for decreasing the incidence and number of inappropriate shocks. The study population included all patients who had Sprint Fidelis leads and Medtronic ICD pulse generators that were implanted and followed at the Minneapolis Heart Institute. Patients were evaluated in the clinic every 3 to 4 months or by remote monitoring using the Medtronic CareLink system. When the LIA algorithm was released in August 2008, the RAMware was downloaded to the pulse generator of all patients with the Sprint Fidelis lead. Patients and family members received educational materials and were given a demonstration of the audible alerts. Between October 2004 and January 2010, 52 (11.3%) of 461 Sprint Fidelis leads failed in the study population. Inappropriate shocks were the first sign of lead failure in 18 (69%) of the 26 patients who did not have the LIA compared to 4 (17%) of 23 patients who had the LIA (P = .0004). Patients who experienced inappropriate shocks without the LIA received an average of 13.2 +/- 13.6 inappropriate shocks (range 2-54) versus 3.0 +/- 2.0 inappropriate shocks (range 2-6) in patients who had the LIA (P = .017). The audible alert was effective in 70% (16/23) and 35% (6/17) of patients with and without the LIA, respectively, whose alerts were programmed ON (P = .053). Overall, 8 (32%) of 25 patients whose audible alerts were triggered did not immediately hear or recognize the tone. The LIA appears to be an effective method for detecting most Sprint Fidelis lead fractures and for decreasing the incidence and number of inappropriate shocks. However, a better method for alerting patients and caregivers is needed.

Risk Factors for Implantable Defibrillator Lead Fracture in a Recalled and a Nonrecalled Lead

The Medtronic Sprint Fidelis implantable cardioverter defibrillator (ICD) lead was "recalled" in October 2007 after 268,000 implants worldwide due to increased failure risk. Manufacturer suggested monitoring has not been shown effective at preventing adverse events. Only limited data exist regarding clinical predictors of Fidelis lead fracture. We sought to identify risk factors for Fidelis fracture to guide clinical monitoring and compare its performance with a control lead. Fractured lead cases were retrospectively reviewed for demographic data, implant technique, radiographic appearance and clinical presentation was analyzed. Lead survival was compared using Kaplan-Meir curves. Study patients (n = 1314) experienced 18 Fidelis and 6 Quattro lead fractures. Patients with failed Fidelis leads were younger than those with surviving leads (49.5 vs 64.6 years, P = 0.0066). Fidelis lead fractures often occurred around the time of physical activity. No other measured demographic or technique related factors were associated with lead fracture. Fidelis leads had significantly decreased survival compared with Quattro leads (89.3 vs 98.9% at 30 months). Patients less than 50 years old had significantly decreased lead survival compared with those older than 50 in both Fidelis (79.6% vs 96.5% at 24 months) and Quattro (93.4 vs 99.8%, P < 0.001 at 24 months) leads. Patients under age 50, with either Fidelis or Quattro ICD leads, are at increased risk of lead fracture compared with patients over 50, particularly around the time of intense physical activity. Aggressive monitoring and advisory programming appears warranted in patients with Fidelis leads as well as especially in younger patients.

Time-Dependent Risk of Fidelis Lead Failure

The Medtronic Sprint Fidelis leads (models 6930, 6931, 6948, 6949) are 6.6-F bipolar high-voltage implantable cardioverter-defibrillator electrodes that were first introduced in September 2004. In October 2007, Fidelis leads were removed from the market. We sought to determine the time-dependent hazard of the Fidelis failure rate to date. A retrospective chart review was conducted in all patients who underwent implantation of a Sprint Fidelis lead (426 leads) at our center. We primarily implanted models 6931 and 6949. With 1,056 years of combined follow-up (average 2.3 +/- 1), 38 of 426 (8.92%) Sprint Fidelis leads failed (3.6%/year). The hazard of fracture increased exponentially over time by a power of 2.13 (95% confidence interval [CI] 1.98 to 2.27, p <0.001) and the 3-year survival was 90.8% (95% CI 87.4 to 94.3). If a Fidelis lead was functioning normally at 1 year, the chance it would survive another year was 97.4% (95% CI 95.7 to 99.1); if functioning at 2 years, the chance of surviving another year was 94.7% (95% CI 91.8 to 97.7); and if functioning at 3 years, the chance of surviving 1 more year was 86.7% (95% CI 78.8 to 95.5). Other commonly used implantable cardioverter-defibrillator leads showed no evidence of increased failure rates. In conclusion, to date, the hazard of Fidelis lead fracture is increasing exponentially with time and, based on our data, occurring at a higher rate than the latest manufacturer's performance update. Further accumulative data are needed because it remains unknown if the fracture rate will level off or continue to increase.

Implementation of Lead Safety Recommendations

The Medtronic Sprint Fidelis (SF) implantable cardioverter defibrillator (ICD; Medtronic Inc., Minneapolis, MN, USA) lead has a higher than expected failure rate. Because of patient safety, Medtronic announced two advisories consisting of (1) adjustments in device settings (October 2007) and (2) installation of a lead integrity algorithm (May 2008). The objective of this study was to evaluate the effect of Medtronic's announcements on patient safety. To comply with the advisories, two clinical evaluations were conducted. The effect of the advisories was assessed by the lead failure rate and the occurrence of inappropriate shocks due to lead failure. Three periods were distinguished in the comparison of event rates: lead implantation to advisory 1 (period A), in-between both advisories (period B), and advisory 2 to follow-up (period C). Since 2004, 372 patients received a Medtronic ICD and SF lead and were followed from first implant (December 2004) to April 2009. Cumulative incidence rate of lead failure was 3.6%[95% confidence interval (CI) 1.6-5.6] at 21 months and increased to 11.0% (95% CI 6.1-15.9) at 42 months. After implementation of both advisories, the occurrence of inappropriate shocks due to lead failure decreased from 1.5 (95% CI 0.59, 3.00) per 100 lead-years in period A to 0.8 (95% CI 0.02, 4.25) per 100 lead-years in period C. The current study demonstrates that despite an increasing risk for SF lead failure, implementation of the advisories decreased the occurrence of inappropriate shocks due to lead failure. (PACE 2010; 431-436).

Alert Tones Are Frequently Inaudible among Patients with Implantable Cardioverter‐Defibrillators

Current management guidelines for patients with Medtronic Sprint Fidelis ICD leads (Medtronic Inc., Minneapolis, MN, USA) include prominent use of Patient Alert, a feature in which the ICD generator emits audible beeps at two programmable frequencies. Because hearing loss is highly prevalent beyond the sixth decade of life, the utility of this feature is unclear. Therefore, we conducted a survey of patients' ability to hear the Medtronic Patient Alert. During visits to an outpatient device clinic, patients with Medtronic ICDs were evaluated for their ability to hear ICD tones. The patient group consisted of 102 patients. Patients older than 70 years comprised 68% of the sample, with 16% between 60 and 70, and 17% younger than 60 years. Of the 102 patients, 59% (56% of males and 70% of females) were able to hear at least one tone. Ability to hear ICD tones decreased with advancing age. Among patients over 60 and 70 years, 52% and 43%, respectively (P < 0.001 vs. patients below 60 and 70 years), could hear at least one tone. The Patient Alert feature is not useful among a large proportion of ICD patients. Patients with Sprint Fidelis leads should be evaluated for their ability to hear audible ICD tones. For patients who cannot hear the Patient Alert feature, a wireless remote monitoring and/or daily application of a magnet by a caregiver should be considered. Device manufacturers should include nonauditory alert technologies such as wireless remote monitoring and vibratory stimulation in future devices.

Analysis of Pacing/Defibrillator Lead Failure Using Device Diagnostics and Pacing Maneuvers

Patients with Medtronic Sprint Fidelis (Medtronic Inc., Minneapolis, MN, USA) lead failures present with oversensing, resulting in pacing inhibition and inappropriate shocks. We present a case of lead noise from the right ventricular (RV) ring conductor, resulting in multiple inappropriate shocks with subsequent pacing inhibition and syncope. RV pacing lead impedance at no point exceeded 1,000 ohms. We found that increased noise and oversensing was more likely to be induced when pacing at higher pulse widths. RV pacing outputs at lower pulse widths may decrease susceptibility to noise generation and prove an effective temporizing measure in pacing-dependent patients.

Fatal Outcome in a Pacemaker‐Dependent Patient

The recent advisory of Medtronic Sprint Fidelis leads has resulted in significant controversy over proper management of patients. The current manufacture's guidelines recommend programming specific device alerts with close follow-up and implantable cardioverter-defibrillator lead replacement in patients with evidence of breach in lead integrity. Recently, several studies have identified significant limitations in this method of surveillance. We report the case of a pacemaker-dependent patient with an ischemic cardiomyopathy, who presented with cardiac arrest and evidence of fracture of the pace/sense portion of a Sprint Fidelis lead during postmortem interrogation. Likely mechanisms leading to his ultimate demise are discussed.

Increasing hazard of Sprint Fidelis implantable cardioverter-defibrillator lead failure

The Medtronic Sprint Fidelis defibrillator lead is prone to fracture and was recalled in 2007 after 665 failures and five reported deaths. Approximately 150,000 patients at risk for sudden death in the United States have Sprint Fidelis leads. The rate of Sprint Fidelis lead failure may be increasing, and physicians are confronted with the decision to replace the lead prophylactically. The purpose of this study was to determine if the hazard of Sprint Fidelis lead failure is changing and to compare its performance to other contemporary implantable cardioverter-defibrillator (ICD) leads. Transvenous ICD leads implanted and followed at our two tertiary-care referral centers between January 2004 and December 2008 were included in the study. Lead failure data were entered prospectively by both centers via the Multicenter Registry. Clinical data were collected prospectively by each center and merged for the purpose of this study. During 5,700 implant years of follow-up (average 1.9 +/- 1.3 years), 94 of 3,037 defibrillator leads failed (1.65%/year), including 72 (8.5%) of 848 Sprint Fidelis leads. The cumulative hazard of Sprint Fidelis failure was significantly greater compared to 2,189 other defibrillator leads (P <.0001), and the hazard of Sprint Fidelis failure accelerated after the first year and continued to increase during the study. In contrast to other defibrillator leads, the Sprint Fidelis failure rate was significantly higher (3.75%/year vs 0.58%/year) and the 3-year estimated survival was significantly lower (87.9% [95% CI 84.8, 90.9] vs 98.5% [95% CI 97.8, 99.3]; P <.0001). The chance that a Sprint Fidelis lead would survive another year decreased progressively during the study. Most Sprint Fidelis failures were caused by pace-sense conductor fracture (n = 63 [87.5%]), which caused inappropriate shocks in 36 of 72 patients. The hazard of Sprint Fidelis lead failure is increasing, whereas the failure rates of other defibrillator leads are low and stable. Physicians should consider these data when managing patients who have Sprint Fidelis leads.

High sensing integrity counter in a patient with a Sprint Fidelis defibrillation lead: What is the cause?

The Medtronic Sprint Fidelis implantable cardioverter-defibrillator (ICD) lead has a higher than expected incidence of conductor fractures. Their identification is important to the prevention of inappropriate shocks.1,2 The sensing integrity counter, which stores the cumulative number of nonphysiologically short ventricular intervals ≤130 ms, is a diagnostic feature designed to enhance early identification of lead failures.3 Values greater than 300 are abnormal.

A Better Method for Preventing Adverse Clinical Events Caused by Implantable Cardioverter-Defibrillator Lead Fractures?

In October 2007, the Medtronic Sprint Fidelis implantable cardioverter-defibrillator (ICD) lead was voluntarily withdrawn from the market by the manufacturer because of a higher-than-expected fracture rate.1 Most Sprint Fidelis fractures involve the pace-sense component of the lead, which may cause oversensing of electrical artifacts, undersensing of ventricular depolarizations, and/or loss of ventricular capture. Approximately 10% to 20% of Sprint Fidelis fractures involve the high-voltage conductor, which may compromise defibrillation. The most common clinical consequence of pace-sense conductor fracture is inappropriate shocks, which often occur in painful clusters and without warning.2–4 Inappropriate shocks may be proarrhythmic and lethal,5,6 and patients who experience them may suffer psychological sequelae. ICD lead failures are more likely to result in oversensing than pacemakers because the ICD pulse generators use high-sensitivity amplifiers to effectively detect ventricular fibrillation (VF). In this issue of Circulation , Swerdlow et al7 describe a new algorithm that may avoid or reduce inappropriate shocks and other serious adverse events in patients with failed Sprint Fidelis and possibly other high-voltage leads. If this algorithm proves to be safe and effective, it will be an important advance in ICD therapy. Article p 2122 Fracture of a transvenous high-voltage ICD lead was first observed in the original CPI Endotak model in 1988.8 Patients who had this lead suffered multiple inappropriate shocks, and it was withdrawn from clinical trial. Since then, conductor fractures and insulation disruption have challenged engineers and physicians to develop improved designs and implant techniques. Progress has been made, but not without setbacks. The Medtronic Transvene lead, a coaxial polyurethane design introduced in 1993 and implanted in >24 000 patients, exhibited both insulation degradation and conductor fractures; these failures typically appeared ≥4 years after implant and most commonly presented as inappropriate shocks.9 A mismatch between the terminal …

Rates and severity of perforation from implantable cardioverter-defibrillator leads: A 4-year study

Although recent case reports and one small single-year observational study report a substantially increased rate of perforation with the St. Jude Riata series defibrillator lead, these results have not been externally validated. From 2004 to 2007, 593 implantable cardioverter-defibrillator (ICD) implants were performed by six faculty and 13 fellows at four University of California, San Francisco, CA, USA and affiliate hospitals. An electronic medical records system was systematically searched to identify clinically significant cases of ICD lead dislodgment or perforation. Of 307 (56%) St. Jude leads (all Riata series 6.3- and 7.3-French leads), 188 (29%) Medtronic leads (including 99 Sprint Fidelis 6.6 French leads), and 98 (15%) Guidant/Boston Scientific leads, there were three perforations in 593 cases (0.51%). One perforation occurred with a Medtronic Sprint Fidelis 6949 lead (0.53%), and two with a St. Jude Riata 1581 lead (0.65%). There were no statistically significant differences in perforation or dislodgement rates between manufacturers or lead models (p = NS for all). In both cases of perforation with the St. Jude Riata leads, the lead tip perforated through the pericardium into the pleural space. In our 4-year series of ICD implants, perforation and dislodgement rates were low, similar across all lead makes and models, and well below published and accepted complication rates. Our findings contradict previously-reported higher rates of perforation with the Riata lead. Registry and product performance reports should also classify complications by severity and outcome to provide a more complete assessment of product safety.