Leadless pacemaker perforations: Clinical consequences and related device and user problems.

BACKGROUND: Cardiac perforation during leadless pacemaker implantation is more likely to require intervention than perforation by a transvenous lead. This study reports the consequences of Micra pacemaker perforations and related device and operator use problems based on information the manufacturer has submitted to the Food and Drug Administration (FDA). METHODS: FDA's Manufacturer and User Facility Device Experience (MAUDE) database was searched for Micra perforations. Data extracted included deaths, major adverse clinical events (MACEs), and device and/or operator use problems. RESULTS: Between 2016 and July 2021, 563 perforations were reported within 30 days of implant and resulted in 150 deaths (27%), 499 cardiac tamponades (89%), 64 pericardial effusions (11%), and 146 patients (26%) required emergency surgery. Half of perforations were associated with 139 (25%) device problems, 78 (14%) operator use problems, and 62 (11%) combined device and operator use problems. Inadequate electrical measurements or difficult positioning were the most frequent device problems (n = 129); non-septal implants and perforation of other structures were the most frequent operator use problems (n = 69); a combined operator use and device problem resulted in 62 delivery system perforations. No device or operator use problem was identified for 282 perforations (50%), but they were associated with 78 deaths, 245 tamponades, and 57 emergency surgeries. CONCLUSION: The Micra perforations reported in MAUDE are often associated with death and major complications requiring emergency intervention. Device and use problems account for at least half of perforations. Studies are needed to identify who is at risk for a perforation and how MACE can be avoided or mitigated.

Ripple Frequency Determined via a Novel Algorithm Is Associated With Atrial Fibrillation Termination and Freedom From Atrial Fibrillation.

Background: Persistent atrial fibrillation (AF) is a complex arrhythmia, and attaining freedom from AF with ablation has been challenging. Objectives: This study evaluated a novel CARTO software algorithm based on the CARTO Ripple map for AF termination and 18-month freedom from AF. Methods: Consecutive patients who underwent first-time ablation for persistent AF were included. A high-density Ripple map was created using a Pentaray catheter. Following PVI, ablation was performed at locations with rapid Ripple activations, a protocol previously described by us. Patients were followed for 18 months to assess rhythm outcomes. A retrospective analysis was performed using the CARTO Ripple frequency software algorithm. The Ripple frequency algorithm quantifies amplitude changes in the bipolar electrogram. Results: A total of 115 AF maps were analyzed from 84 patients (mean age 65.9 years, 63.1% men). The top quartile of Ripple frequency corresponded to a visual reference with 96.7% sensitivity and 91.1% specificity. AF terminated during ablation in 88.1% of patients: pulmonary vein antrum alone (14.9%) or pulmonary vein plus nonantral sites (85.1%). The top quartile of Ripple frequency was present in nonantral areas associated with AF termination with 90.2% sensitivity and 86.5% specificity. After 14.0 ± 6.5 months and 1.2 ± 0.4 ablations, 78 (92.9%) of 84 patients were free of AF, and 79.8% were free of any atrial arrhythmia. Conclusion: A novel algorithm for automated analysis of CARTO Ripple frequency demonstrated good sensitivity and specificity for detecting atrial regions in persistent AF in which ablation is associated with frequent AF termination and freedom from AF during follow-up.

Major adverse clinical events associated with implantation of a leadless intracardiac pacemaker.

BACKGROUND: Leadless intracardiac pacemakers were developed to avoid the complications of transvenous pacing systems. The Medtronic Micra™ transcatheter pacemaker is one such system. We found an unexpected number of major adverse clinical events (MACE) in the Food and Drug Administration's Manufacturers and User Facility Device Experience (MAUDE) database associated with Micra implantation. OBJECTIVE: The purpose of this study was to describe these MACE and compare them to implant procedure MACE in MAUDE for Medtronic CapSureFix™ active-fixation transvenous pacing leads. METHODS: During January 2021, we queried the MAUDE database for reports of MACE for Micra pacemakers and CapSureFix leads using the simple search terms "death," "tamponade," and "perforation." Reports from 2016-2020 were included. RESULTS: The search identified 363 MACE for Micra and 960 MACE for CapSureFix leads, including 96 Micra deaths (26.4%) vs 23 CapSureFix deaths (2.4%) (P <.001); 287 Micra tamponades (79.1%) vs 225 tamponades for CapSureFix (23.4%) (P <.001); and 99 rescue thoracotomies for Micra (27.3%) vs 50 rescue thoracotomies for CapSureFix (5.2%) (P <.001). More Micra patients required cardiopulmonary resuscitation (21.8% vs 1.1%) and suffered hypotension or shock (22.0% vs 5.8%) than CapSureFix recipients (P <.001). Micra patients were more likely to survive a myocardial perforation or tear if they had surgical repair (P = .014). CONCLUSION: Micra leadless pacemaker implantation may be complicated by myocardial and vascular perforations and tears that result in cardiac tamponade and death. We estimate the incidence is low (<1%). Rescue surgery to repair perforations may be lifesaving. MACE are significantly less for implantation of CapSureFix transvenous ventricular pacing leads.

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.

Outcomes after pacemaker implantation in patients with new-onset left bundle-branch block after transcatheter aortic valve replacement.

New-onset left bundle branch block (N-LBBB) after transcatheter aortic valve replacement (TAVR) is a challenging clinical dilemma. In our single-center study, 60 out of 172 patients who underwent permanent pacemaker implantation (PPM) after TAVR had N-LBBB (34.9%). At a median follow-up duration of 357 days (IQR, 178; 560 days), two patients (3.5%) were completely pacemaker-dependent, and four others (7%) were partially dependent. Twelve patients (24%) recovered conduction in their left bundle at a median follow-up duration of 5 weeks (IQR, 4; 14 weeks). Due to the lack of clinical predictors of pacemaker dependency, active surveillance is warranted and may be an alternative to permanent pacemaker implantation.

Detection of Atrial Fibrillation and Atrial Flutter by Pacemaker Device Interrogation After Transcatheter Aortic Valve Replacement (TAVR): Implications for Management.

BACKGROUND: Atrial fibrillation (AF) and atrial flutter (AFL) are associated with increased risk of stroke and mortality after transcatheter aortic valve replacement (TAVR). Many episodes of new-onset AF/AFL (NOAF) occur after hospital discharge and may not be clinically apparent. Pacemakers can detect subclinical episodes of rapid atrial rate, which correlate with electrocardiographically documented AF. METHODS: From 2012 to 2017, patients who underwent pacemaker implantation after TAVR were reviewed, and pacemaker data from device checks were analyzed for detection of NOAF. Patients with prior AF/AFL were excluded. Secondary outcomes were mortality and ischemic stroke. RESULTS: A total of 172 patients underwent TAVR and pacemaker implantation, and 95 were without pre-existent AF/AFL. Over a median follow-up of 15 months, a total of 24 patients had NOAF (25%), of which 10 patients (10.5%) had manifest NOAF detected on electrocardiography, and 14 patients (14.7%) had subclinical NOAF first identified on device interrogation. The cumulative incidence of mortality was 16.7% for NOAF and 15.5% for normal sinus rhythm (P=.83). The cumulative incidence of stroke was 12.5% for NOAF and 1.4% for normal sinus rhythm (P=.04). Subclinical NOAF patients were less likely to be started on anticoagulation compared with manifest NOAF patients (70% vs 15.3%, respectively; P=.02). CONCLUSION: Subclinical NOAF is common after TAVR, usually occurs months after hospital discharge, and is associated with lack of anticoagulation therapy and increased risk of stroke. Prolonged surveillance of subclinical NOAF may be warranted after TAVR.

Leadless Pacemaker Implantation in Hemodialysis Patients: Experience With the Micra Transcatheter Pacemaker.

OBJECTIVES: This study sought to report periprocedural outcomes and intermediate-term follow-up of hemodialysis patients undergoing Micra implantation. BACKGROUND: Leadless pacemakers may be preferred in patients with limited vascular access and high-infection risk, such as patients on hemodialysis. METHODS: Patients on hemodialysis at the time of Micra implantation attempt (n = 201 of 2,819; 7%) from the Micra Transcatheter Pacing Study investigational device exemption trial, Micra Transcatheter Pacing System Continued Access Study Protocol, and Micra Transcatheter Pacing System Post-Approval Registry were included in the analysis. Baseline characteristics, periprocedural outcomes, and intermediate-term follow-up were summarized. RESULTS: Patients on hemodialysis at the time of Micra implantation attempt were on average 70.5 ± 13.5 years of age and 59.2% were male. The dialysis patients commonly had hypertension (80%), diabetes (61%), coronary artery disease (39%), and congestive heart failure (27%), and 72% had a condition that the implanting physician felt precluded the use of a transvenous pacemaker. Micra was successfully implanted in 197 patients (98.0%). Reasons for unsuccessful implantation included inadequate thresholds (n = 2) and pericardial effusion (n = 2). The median implantation time was 27 min (interquartile range: 20 to 39 min). There were 3 procedure-related deaths: 1 due to metabolic acidosis following a prolonged procedure duration in a patient undergoing concomitant atrioventricular nodal ablation and 2 deaths occurred in patients who needed surgical repair after perforation. Average follow-up was 6.2 months (range 0 to 26.7 months). No patients had a device-related infection or required device removal because of bacteremia. CONCLUSIONS: Leadless pacemakers represent an effective pacing option in this challenging patient population on chronic hemodialysis. The risk of infection appears low with an acceptable safety profile. (Micra Transcatheter Pacing Study; NCT02004873; Micra Transcatheter Pacing System Continued Access Study Protocol; NCT02488681; Micra Transcatheter Pacing System Post-Approval Registry; NCT02536118).

Leadless pacemaker implantation and concurrent atrioventricular junction ablation in patients with atrial fibrillation.

BACKGROUND: Atrioventricular junctional (AVJ) ablation and pacemaker implantation are indicated when pharmacotherapy fails to achieve adequate rate control in atrial fibrillation (AF). The purpose of our study is to assess the feasibility and safety of concurrent Micra leadless transcatheter pacemaker implantation and AVJ ablation. METHODS: We retrospectively assessed patients who underwent Micra implantation and concurrent AVJ ablation at three institutions between August 2014 and March 2016. All patients and devices were followed at baseline and at 1, 3, 6, and 12 months postimplantion. RESULTS: Twenty-one patients with permanent AF (median age 77 [range: 62-88], female 15 [71.4%]) underwent successful Micra implantation followed by concurrent AVJ ablation. There was no device dislodgement or malfunction during the 12-month follow-up. Complete 12-month electrical performance data were available in 14 patients (67%). Among patients with the complete data set, median pacing thresholds at implant and at 1, 3, 6, and 12 months were 0.5 V (range: 0.25-0.88), 0.44 V (range: 0.25-2.0), 0.5 V (range: 0.25-1.63), 0.5 V (range: 0.25-1.13), and 0.5 V (range: 0.25-1.13) at a pulse width of 0.24 msec, respectively. Two patients died due to noncardiac causes during follow-up. There were no patients with major device-related complications. CONCLUSIONS: Concurrent Micra implantation and AVJ ablation is feasible and appears safe. There was no device dislodgement, malfunction, or significant pacing threshold rise requiring device reimplantation during the 12-month follow-up. This combined approach can be considered for patients with AF with suboptimal rate control who have failed AF catheter ablation and/or pharmacotherapy.

A Leadless Intracardiac Transcatheter Pacing System.

BACKGROUND: A leadless intracardiac transcatheter pacing system has been designed to avoid the need for a pacemaker pocket and transvenous lead. METHODS: In a prospective multicenter study without controls, a transcatheter pacemaker was implanted in patients who had guideline-based indications for ventricular pacing. The analysis of the primary end points began when 300 patients reached 6 months of follow-up. The primary safety end point was freedom from system-related or procedure-related major complications. The primary efficacy end point was the percentage of patients with low and stable pacing capture thresholds at 6 months (≤2.0 V at a pulse width of 0.24 msec and an increase of ≤1.5 V from the time of implantation). The safety and efficacy end points were evaluated against performance goals (based on historical data) of 83% and 80%, respectively. We also performed a post hoc analysis in which the rates of major complications were compared with those in a control cohort of 2667 patients with transvenous pacemakers from six previously published studies. RESULTS: The device was successfully implanted in 719 of 725 patients (99.2%). The Kaplan-Meier estimate of the rate of the primary safety end point was 96.0% (95% confidence interval [CI], 93.9 to 97.3; P<0.001 for the comparison with the safety performance goal of 83%); there were 28 major complications in 25 of 725 patients, and no dislodgements. The rate of the primary efficacy end point was 98.3% (95% CI, 96.1 to 99.5; P<0.001 for the comparison with the efficacy performance goal of 80%) among 292 of 297 patients with paired 6-month data. Although there were 28 major complications in 25 patients, patients with transcatheter pacemakers had significantly fewer major complications than did the control patients (hazard ratio, 0.49; 95% CI, 0.33 to 0.75; P=0.001). CONCLUSIONS: In this historical comparison study, the transcatheter pacemaker met the prespecified safety and efficacy goals; it had a safety profile similar to that of a transvenous system while providing low and stable pacing thresholds. (Funded by Medtronic; Micra Transcatheter Pacing Study ClinicalTrials.gov number, NCT02004873.).

Elevated T-wave alternans predicts nonsustained ventricular tachycardia in association with percutaneous coronary intervention in ST-segment elevation myocardial infarction (STEMI) patients.

INTRODUCTION: Successful reperfusion with primary percutaneous coronary intervention (PCI) can paradoxically elicit temporary vulnerability to ventricular arrhythmia. We examined whether T-wave alternans (TWA) level is correlated with nonsustained ventricular tachycardia (NSVT) incidence in association with PCI in patients with acute ST-segment elevation myocardial infarction (STEMI). METHODS AND RESULTS: We analyzed continuous 24-hour ambulatory electrocardiograms in 48 STEMI patients during and after successful primary PCI, achieving Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow. TWA was measured using modified moving average method. Maximum TWA was elevated in patients with (N = 22) compared to without (N = 26) NSVT (75.1 ± 6.3 vs 49.9 ± 3.6 µV, P < 0.005) during the 22-hour monitoring period. TWA ≥ 60µV predicted NSVT with sensitivity of 77%; specificity, 73%; positive predictive value, 71%; and negative predictive value, 79%. Area under receiver operator characteristic curve (AUC) was 0.87 for maximum TWA in predicting NSVT. By comparison, ST-segment levels did not differ in patients with versus without NSVT and were not predictive (AUC = 0.52). TWA was elevated prior to PCI and remained elevated at 30 minutes after balloon inflation despite restoration of TIMI grade 3 flow in all patients, declining by 22 hours (P < 0.05). Maximum ST-segment levels decreased from before PCI to 30 minutes after balloon inflation. TWA is regionally specific, with higher values prior to PCI in precordial lead V5 than in V1 for left coronary lesions. CONCLUSIONS: TWA may be useful in identifying individuals at heightened risk for arrhythmia in association with primary PCI and can potentially signal time-dependent changes in arrhythmia vulnerability.

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

BACKGROUND: 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. OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Deaths and cardiovascular injuries due to device-assisted implantable cardioverter-defibrillator and pacemaker lead extraction.

AIMS: An estimated 10,000-15,000 pacemaker and implantable cardioverter-defibrillator (ICD) leads are extracted annually worldwide using specialized tools that disrupt encapsulating fibrous tissue. Additional information is needed regarding the safety of the devices that have been approved for lead extraction. The aim of this study was to determine whether complications due to device-assisted lead extraction might be more hazardous than published data suggest, and whether procedural safety precautions are effective. METHODS AND RESULTS: We searched the US Food and Drug Administration's (FDA) Manufacturers and User Defined Experience (MAUDE) database from 1995 to 2008 using the search terms 'lead extraction and death' and 'lead extraction and injury'. Additional product specific searches were performed for the terms 'death' and 'injury'. Between 1995 and 2008, 57 deaths and 48 serious cardiovascular injuries associated with device-assisted lead extraction were reported to the FDA. Owing to underreporting, the FDA database does not contain all adverse events that occurred during this period. Of the 105 events, 27 deaths and 13 injuries occurred in 2007-2008. During these 2 years, 23 deaths were linked with excimer laser or mechanical dilator sheath extractions. The majority of deaths and injuries involved ICD leads, and most were caused by lacerations of the right atrium, superior vena cava, or innominate vein. Overall, 62 patients underwent emergency surgical repair of myocardial perforations and venous lacerations and 35 (56%) survived. CONCLUSION: These findings suggest that device-assisted lead extraction is a high-risk procedure and that serious complications including death may not be mitigated by emergency surgery. However, skilled standby cardiothoracic surgery is essential when performing pacemaker and ICD lead extractions. Although the incidence of these complications is unknown, the results of our study imply that device-assisted lead extractions should be performed by highly qualified physicians and their teams in specialized centres.

Feasibility and safety of remote-controlled magnetic navigation for ablation of atrial fibrillation.

Radiofrequency ablation for atrial fibrillation (AF) involves complex catheter manipulation resulting in prolonged procedure time and fluoroscopy exposure. Remote magnetic navigation (RMN) represents a novel approach toward improving the ability to perform complex ablation. Forty patients underwent ablation for AF, 20 using RMN (NIOBE II, Stereotaxis, Inc) with a 4-mm-tip magnetic catheter (Celsius, Biosense Webster) and 20 using a conventional 8-mm-tip bidirectional ablation catheter (Blazer, Boston Scientific). All patients underwent a combined wide area circumferential ablation and segmental pulmonary vein (PV) isolation using a circular mapping catheter and cavotricuspid isthmus ablation for right atrial flutter. The procedural end point was PV entrance block. There was no difference in atrial size, left ventricular systolic function, or type of AF between groups. PV entrance block was achieved in all patients. Mean procedure time was 279 +/- 60 minutes in the conventional group versus 209 +/- 56 minutes in the RMN group (p <0.001). Mean fluoroscopy time in the conventional group was 58.6 +/- 21 minutes versus 19.5 +/- 9.8 in the RMN group (p <0.001). At 1 year there were 15 patients in the conventional group and 16 in the RMN group free from clinical AF and off antiarrhythmic drugs (p = NS). There were 2 additional ablations performed for atypical atrial flutter in the conventional group and 3 in the RMN group (p = ns). Ablation catheter char formation was not observed. There were no procedural complications. In conclusion, radiofrequency ablation of AF performed with RMN is safe and feasible. Compared with conventional hand-navigated ablation, RMN ablation results in similar clinical outcomes with decreased fluoroscopy and procedure times.

Failure of impedance monitoring to prevent adverse clinical events caused by fracture of a recalled high-voltage implantable cardioverter-defibrillator lead.

BACKGROUND: The Medtronic Sprint Fidelis implantable cardioverter-defibrillator high-voltage lead is prone to fracture. The October 2007 safety advisory recommended lead impedance monitoring to aid in identifying lead fractures. OBJECTIVE: The aim of this single-center study was to examine the effectiveness of impedance monitoring for detecting Sprint Fidelis lead failures before they caused adverse clinical events such as inappropriate shocks. METHODS: Impedance and sensing information were acquired during routine clinic and CareLink follow-up and at the time of lead failure using the Patient Alert, sensing integrity counter, nonsustained episode, and electrogram features in Medtronic pulse generators. RESULTS: Between September 2004 and February 2008, 17 of 514 Sprint Fidelis leads (3.3%) followed up at our center failed between 11 and 35 months after implantation (mean 23.0 +/- 8.0 months). Fifteen of these failures (88%) were caused by pace-sense conductor fractures, and 2 (12%) were caused by high-voltage conductor defects. Twelve of 15 patients (80%) with pace-sense conductor fractures received inappropriate shocks; of these, 4 had no significant increase in lead impedance before they were shocked, 2 were shocked <3 hours after their lead impedances exceeded the 1,000 Omega audible alert threshold, and 2 patients did not hear the alarm. All pace-sense conductor failures whose sensing function could be evaluated (13 of 15) had oversensing based on stored data, and oversensing usually (11 of 13) preceded impedances changes. CONCLUSION: Impedance monitoring did not prevent inappropriate shocks in two-thirds of our patients. Thus, pace-sense conductor impedance monitoring as currently implemented does not reliably forewarn patients of a lead malfunction. Consequently, patients who have Sprint Fidelis leads remain at risk for adverse clinical events associated with pace-sense conductor fracture.

Early failure of a small-diameter high-voltage implantable cardioverter-defibrillator lead.

BACKGROUND: We have observed a higher than expected rate of Sprint Fidelis model 6949 lead failures in our practice. OBJECTIVE: The aim of this study was to assess the performance of small-diameter Sprint Fidelis high-voltage ICD leads. METHODS: The actuarial survival of Sprint Fidelis model 6949 leads implanted at our center was compared with that of the Sprint Quattro Secure model 6947. The United States Food and Drug Administration Manufacturers and User Facility Device Experience (MAUDE) database was searched for Sprint Fidelis models. RESULTS: The survival of 583 Sprint Fidelis 6949 leads implanted at our center between September 2004 and February 2007 was significantly less than 285 Sprint Quattro Secure model 6947 leads implanted by us between November 2001 and February 2007 (P = .005). Six patients presented with Sprint Fidelis lead failure 4-23 months after implant. Five of the six patients experienced multiple inappropriate shocks associated with pace-sense conductor and coil fractures; the sixth patient had a fixation mechanism failure. The MAUDE search rendered reports for 679 Sprint Fidelis leads. The most frequent complaints or observations were inappropriate shocks (33%), high impedance (33%), and fracture (35%). Of 125 leads analyzed by the manufacturer, 62 involved fracture of the pace-sense conductor or coil and the high-voltage (defibrillation) conductor. CONCLUSIONS: The Sprint Fidelis high-voltage lead appears to be prone to early failure. Its use should be limited until the failure mechanism is identified and corrected. Patients should be evaluated quarterly, and automatic lead test features should be enabled. While more data are needed, routine prophylactic replacement of intact, normally functioning Sprint Fidelis leads does not appear justified.

Use of ultrasound to determine ventricular capture in transcutaneous pacing.

Determining ventricular capture when using transcutaneous pacing (TCP) can be difficult. Our objective was to evaluate the use of ultrasound (US) to determine capture in patients undergoing TCP. We studied 15 patients in a convenience sample. Videotaped US views were obtained during TCP with concurrent electrocardiographic monitoring on the US screen. The treating physician made capture determinations first by using clinical indicators, followed by US images. Two reviewing physicians blinded to the treating physician's findings and to each other determined capture on videotape. Kappa levels of agreement were calculated. A value of kappa = 0.84 was found for agreement of the treating physician's findings through clinical measures and US. Agreement between the first reviewer and the treating physician had kappa =.47 and between the second reviewer and the treating physician was had kappa =.67. All P values were <.05. US and clinical impression of ventricular capture have good to excellent agreement. US may be useful for determining ventricular capture in patients undergoing TCP.

Comparison of plasma concentrations for two amiodarone products.

BACKGROUND: A generic formulation of amiodarone was recently approved by the Food and Drug Administration based on single-dose equivalence data. Because amiodarone has complex pharmacokinetic properties, a narrow therapeutic range, and a significant adverse effect profile, concern about equivalency persists. OBJECTIVE: To compare steady-state plasma concentrations of the brand-name reference product Cordarone with the AB-rated generic formulation, Pacerone, in patients exposed to both products. METHODS: A retrospective analysis was performed at the Minneapolis Veterans Affairs Medical Center on 138 patients who were taking a stable dose of amiodarone before and after an amiodarone generic product substitution. RESULTS: Seventy-seven patients had steady-state plasma concentrations documented for each product at the same dose. The mean steady-state plasma concentrations of amiodarone were not significantly different for Cordarone compared with Pacerone (1.07 +/- 0.48 vs. 1.19 +/- 0.66 micro g/mL, respectively); similarly, the concentrations of the active metabolite (desethylamiodarone) did not differ (0.95 +/- 0.30 vs. 0.96 +/- 0.49 micro g/mL, respectively). However, the variability in plasma drug concentrations between products was increased as compared to variability within each product. CONCLUSIONS: This study indicates that comparable steady-state concentrations can be achieved with a change in formulation from Cordarone to Pacerone. However, individual responses vary, suggesting that monitoring of plasma concentrations is prudent 1-3 months after any change from one product to another.