A detailed view on pacemaker lead parameters remotely transmitted after magnetic resonance.

BACKGROUND: The purpose of this study was to analyze potential influences of magnetic resonance (MR) on the course of automatically device-based assessed lead parameters remotely transmitted in patients who were implanted with MR-conditional permanent pacemakers (PMs) and who had nondiagnostic brain and lumbar spine MR (1.5T) within the ProMRI single center pilot study. METHODS: The ProMRI study evaluated the feasibility of the Evia PMs with Safio S leads (Biotronik SE&Co KG, Berlin, Germany) in the MR environment. All patients were equipped with remote monitoring on the day of MR. Atrial (RA) und ventricular (RV) lead parameters (sensing, pacing capture threshold [PCT], pacing impedance) were automatically assessed and remotely transmitted on a daily or event-triggered basis for 3 months post MR. Remotely transmitted data were normalized for potential differences between at-daytime (in-office) and at-night-time (remotely) assessed parameters using the 1-month follow-up data for each patient. Confidence intervals of continuous data were calculated day-wise with one sample t-tests of post-MR/pre-MR differences, respectively. RESULTS: A total of 2,428 data sets (mean 80 ± 20 per patient) were transmitted. Mean values for the different lead parameters were (RA/RV) 3.3 ± 2.0/14.4 ± 6.9 mV for sensing, 0.65 ± 0.17/0.78 ± 0.23 V/0.4 ms for PCT, and 516 ± 60/607 ± 47 Ω for pacing impedance. No significant differences were found compared with pre-MR measurements. No atrial PCT increases ≥0.5 V compared with pre-MR were observed, and in only one patient the ventricular PCT increased by ≥0.5 V from day 76 post-MR, presumably based on new antiarrhythmic therapy with amiodarone. CONCLUSION: Our analyses of automatically assessed and remotely transmitted PM lead parameters after MR show that sensing amplitudes, PCTs, and pacing impedances are not affected in a clinically relevant way by MR.

Reel syndrome in an ICD with DF4 connector.

This is the first case report about a patient implanted with a DF4 lead suffering from reel syndrome. The reel syndrome may occur due to a ratchet mechanism where the device generator creates torque on a lead fixed at the fixation sleeve. Theoretically, this is less likely to occur in DF4 connectors due to their higher stiffness.

Safe performance of magnetic resonance of the heart in patients with magnetic resonance conditional pacemaker systems: the safety issue of the ESTIMATE study.

BACKGROUND: No published data exist about the safety of diagnostic magnetic resonance (MR) of the heart performed in a larger series of patients implanted with MR conditional pacemakers (PM). The purpose of our study is to analyse safety and potential alterations of electrical lead parameters in patients implanted with the EnRhythm/Advisa MRI SureScan PM with 5086MRI leads (Medtronic Inc.) during and after MR of the heart at 1.5 Tesla. METHODS: Patients enrolled in this single center pilot study who underwent non-clinically indicated diagnostic MR of the heart were included in this analysis. Heart MR was performed for analyses of potential changes in right and left ventricular functional parameters under right ventricular pacing at 80 and 110 bpm. Atrial/ventricular sensing, atrial/ventricular pacing capture threshold [PCT], and pacing impedances were assessed immediately before, during, and immediately after MR, as well at 3 and 15 months post MR. RESULTS: Thirty-six patients (mean age 69 ± 13 years; high degree AV block 18 [50%]) underwent MR of the heart. No MR related adverse events occurred during MR or thereafter. Ventricular sensing differed significantly between the FU immediately after MR (10.3 ± 5.3 mV) and the baseline FU (9.8 ± 5.3 mV; p < 0.05). Despite PCT [V/0.4ms] was not significantly different between the FUs (baseline: 0.84 ± 0.27; in-between MR scans: 0.82 ± 0.27; immediately after MR: 0.84 ± 0.24; 3-month: 0.85 ± 0.23; 15-month: 0.90 ± 0.67; p = ns), 7 patients (19%) showed PCT increases by 100% (max. PCT measured: 1.0 V) at the 3-month FU compared to baseline. RV pacing impedance [Ω/5V] differed significantly at the FU in-between MR scans (516 ± 47), and at the 15-month FU (482 ± 58) compared to baseline (508 ± 75). CONCLUSION: The results of our study suggest MR of the heart to be safe in patients with the MR conditional EnRhythm/Advisa system, albeit although noticeable but clinically irrelevant ventricular PCT changes were observed.

Implantable defibrillators with enhanced detection algorithms: detection performance and safety results from the PainFree SST study.

BACKGROUND: Implantable defibrillators (ICD) are highly effective in reducing arrhythmia-related mortality. ICD shock therapy has been shown to increase psychological distress, health care utilization, and is associated with increased mortality. The Protecta ICDs (Medtronic Inc., Minneapolis, MN, USA) have algorithms designed to reduce unnecessary and inappropriate shock therapy. METHODS AND RESULTS: The PainFree SmartShock™ Technology (PainFree SST) study is a prospective, multicenter, clinical trial with two consecutive phases, a premarket phase safety study and a postmarket phase effectiveness study. We report the results of the PainFree SST safety study. The premarket phase aimed to investigate safety in the first year postimplant, and to determine if the novel algorithms (T-wave discrimination, right ventricular lead noise discrimination and confirmation+) affect appropriate ventricular fibrillation (VF) detection. Patients (total: n = 246 [male 78%, mean age 63 year, primary prevention indication in 76%]) were implanted either with a Protecta XT dual-chamber ICD (n = 114 [46%]) or a defibrillator with cardiac resynchronization therapy (n = 132 [54%]). Appropriate VF detection was measured during VF induction at implantation when the novel algorithms were programmed ON. A two-second delay in VF detection was classified as clinically significant. No delay in VF detection was observed with all algorithms programmed ON. No unanticipated serious adverse device effects occurred during first year postimplant. CONCLUSION: The results of the premarket phase of the PainFree SST trial demonstrate the safety of the Protecta XT defibrillators. Detection of induced VF was not delayed with SmartShock™ algorithms ON.

Benefit of immediate beta-blocker therapy on mortality in patients with ST-segment elevation myocardial infarction.

OBJECTIVES: Despite the recommendations to initiate ß-blockade to all patients with an ST-segment elevation myocardial infarction, data concerning the timing of the administration of ß-blockers are controversially discussed. In view of these controversies, we analyzed the effect of immediate vs. delayed ß-blockade on all-cause mortality of patients with ST-segment elevation myocardial infarction in the Lower Austrian Myocardial Infarction Network. DESIGN: Nonrandomized, prospective observational cohort study. SETTING: Myocardial infarction network including the out-of-hospital emergency services, five primary-care hospitals and a percutaneous coronary intervention-capable hospital in the western part of Lower Austria. PATIENTS: The data of all patients with ST-segment elevation myocardial infarction defined according to the American Heart Association criteria and treated according to the treatment protocol of the network were consecutively collected. For the purpose of survival analyses, the baseline survival time was set to 48 hours after the first electrocardiogram, and in all patients with recurrent MI within the observational period, only the first MI was regarded. INTERVENTIONS: The treatment protocol recommended either the immediate oral administration of 2.5 mg bisoprolol (within 30 min after the first electrocardiogram) or 24 hours after acute myocardial infarction (delayed ß-blockade). MEASUREMENTS AND MAIN RESULTS: In total, out of the 664 patients with ST-segment elevation myocardial infarction, 343 (n = 52%) received immediate ß-blockade and 321 (48%) received delayed ß-blockade. The probability of any death (baseline survival time: 48 hours after first electrocardiogram; 640 patients) was 19.2% in the delayed treatment group and 10.7% in the immediate treatment group (p = 0.0022). Also the probability of cardiovascular mortality was significantly lower in the immediate ß-blocker treatment group (immediate treatment group: 9 (5.2%); delayed treatment group: 30 (13.4%); p = 0.0002). Multivariable Cox regression analysis identified immediate ß-blocker therapy to be independently protective against death of any cause (odds ratio: 0.55, p = 0.033). CONCLUSION: Immediate ß-blocker administration in the emergency setting is associated with a reduction of all-cause and cardiovascular mortality in patients with ST-segment elevation myocardial infarction and seems to be superior to a delayed ß-blockade in our patient cohort.

Monocenter feasibility study of the MRI compatibility of the Evia pacemaker in combination with Safio S pacemaker lead.

BACKGROUND: The purpose of this study was to evaluate the feasibility of the magnetic resonance (MR) conditional pacemaker (PM) system (Evia SR-T and DR-T with Safio S leads) under MR conditions. METHODS: Patients with standard PM indications and Evia PM were eligible for enrollment in this single center prospective non-randomized pilot study. Patients underwent MR of the brain and lower lumbar spine at 1.5 Tesla. Atrial (RA) und ventricular (RV) lead parameters (sensing, pacing threshold [PTH], pacing impedance) were assessed immediately before (baseline follow-up [FU]) and immediately after MRI (1st FU), after 1 month (2nd FU) and 3 months (3rd FU). The effect of MR on serious adverse device effect (SADE) free-rate, on atrial and ventricular sensing (AS/VS; mV) and atrial (RA) and ventricular (RV) pacing thresholds (PTH; V/0.4 ms) were investigated between baseline and 2nd FU. Continuous variables are expressed as mean ± SD and were compared using paired Student's t-test. A p < 0.05 was considered significant. RESULTS: Thirty-one patients were enrolled. One patient had to be excluded because of an enrollment violation. Therefore, data of 30 patients (female 12 [40%], age 73 ± 12 years, dual chamber PM 15 [50%]) were included in this analysis. No MR related SADE occurred. Lead measurements were not statistically different between the baseline FU and the 2nd FU (AS/VS at baseline 3.2 ± 2.1/15.0 ± 6.0, at 2nd FU 3.2 ± 2.1/14.9 ± 6.5; p = ns. RA-PTH/RV-PTH at baseline 0.68 ± 0.18/0.78 ± 0.22, at 2nd FU 0.71 ± 0.24/0.78 ± 0.22; p = ns). The presence of the permanent pacemakers led to MR imaging artifacts on diffusion weighted sequences of the brain, but did not affect other sequences (e.g. FLAIR and T2 weighted spin-echo images). CONCLUSION: The use of the MR conditional Evia PM in a MR environment under predefined conditions is feasible. No MR related SADEs nor clinically relevant changes in device functions occurred.

Explantation of implantable defibrillator leads using open heart surgery or percutaneous techniques.

BACKGROUND: To remove failing or infected implantable cardioverter defibrillator leads, percutaneous techniques and open heart surgery are two common approaches. However, well-defined indications for either technique are not available. We summarize our experience with implantable cardioverter defibrillator system explantation using open heart surgery and percutaneous lead removal. METHODS: A total of 1,391 transvenously introduced implantable cardioverter defibrillator systems were implanted during the analyzed time interval from January 1995 to June 2005 in our institution. In 21 patients (1.5%), open heart surgery for implantable cardioverter defibrillator lead and generator explantation was applied (group A), and in 53 patients (3.8%), a percutaneous lead removal was possible (group B). The log-rank test was used to calculate differences in survival between both patient groups, and the Student's t test was applied for differences in nonlethal complications. RESULTS: The 30-day, 6-month, 12-month, and 5-year survival rates were 91%, 91%, 81%, and 71%, respectively, for group A patients, and 100%, 100%, 94%, and 78%, respectively, for group B patients, which was not statistically different (p = 0.11). After open heart surgery, survival was comparable for cases with lead removal because of lead infection and those with lead malfunction (p = 0.28); however, patients with open heart surgery had a longer hospital stay (p = 0.03). Student's t test revealed no statistical difference in nonlethal complications between both patient groups (p = 0.37). CONCLUSIONS: As open heart surgery yielded similar results with regard to survival and complications, implantable cardioverter defibrillator lead removal using extracorporeal circulation may be well justified as a last therapeutic option, eg, in case of large bacterial vegetations.

[ICD lead defects: diagnosis and therapeutical options]. / Diagnostik und Therapie von ICD-Elektrodendefekten.

The number of cardioverter/defibrillator (ICD) implantations has been steadily increasing; thus, ICD lead-associated complications are an important issue. No clear recommendations for the diagnosis and management are available. This article gives an overview of how to diagnose and manage an ICD lead defect. Possible therapeutic options are discussed by reviewing the literature.

Two different therapeutic strategies in ICD lead defects: additional combined lead versus replacement of the lead.

OBJECTIVES: Implantation of an additional HV-P/S lead versus extraction of the defective HV-P/S lead and implantation of a new one is one possible therapeutic approach in cases of a defective high-voltage pace/sense lead (HV-P/S). No information is available on potential differences in clinical outcome in these different approaches. METHODS: Between January 2000 and February 2006, 86 patients with HV-P/S lead defect received either an additional transvenous HV-P/S lead (n = 33, group 1) or the HV-P/S lead was replaced (n = 53, group 2). The duration of the initially implanted leads was significantly different in the two groups (7.4 +/- 2.9; group 1 and 4.1 +/- 3.4 years; group 2). The outcome of these two groups of patients was retrospectively analyzed. RESULTS: Seventy-three patients [85%] survived until the end of follow-up of 29 +/- 15 (group 1) and 33 +/- 21 (group 2) months (P = ns), respectively. Thirteen patients died: six in group 1 and seven in group 2 (P = ns). Fourteen patients experienced perioperative complications (group 1: six; group 2: eight; P = ns). ICD system-related complications occurred in 22 patients (group 1: seven; group two: 15; P = ns). The event-free cumulative survival of patients with additional and replaced HV-P/S lead for postoperative events (including death) after 1, 2, and 3 years was 82%, 70%, 70%, and 86%, 81%, 66%, respectively (P = 0.93). CONCLUSIONS: Implantation of an additional HV-P/S lead or replacement of the HV-P/S lead in case of HV-P/S lead failure is statistically not different concerning mortality and morbidity. There are no predictors for further lead defects. Implantation of an additional HV-P/S lead should not be recommended in young patients or patients with greater likelihood of living many years. Predictors for death were an age over 70 years and renal insufficiency.

Reduction of ventricular tachyarrhythmia by treatment of atrial fibrillation in ICD patients with dual-chamber implantable cardioverter/defibrillators capable of atrial therapy delivery: the REVERT-AF Study.

AIMS: The purpose of this prospective, randomized, multicentre study was to investigate whether the incidence of ventricular tachyarrhythmia can be reduced in standard implantable cardioverter/defibrillator (ICD) patients by implanting a dual-chamber ICD capable of atrial therapy delivery. METHODS AND RESULTS: A Jewel AF or GEM III AT ICD (Medtronic Inc., Minneapolis, MN, USA) was implanted in 122 patients (62.3 +/- 10.5 years; 84.4% male; coronary artery disease 71.3%; left ventricular ejection fraction 39.7 +/- 13.6%; secondary ICD indication 91%). Overall, 31.2% of the patients had paroxysmal atrial fibrillation (AF)/atrial tachycardia (AT) before ICD implantation (n = 38). Implantable cardioverter/defibrillator therapies for AT/AF were activated and de-activated every 3 months in a cross-over study design. The mean follow-up was 18.5 +/- 7.7 months (6.29 +/- 2.2 cross-over/patient). Overall, there were 684 episodes of ventricular tachyarrhythmias in 48.4% of patients (n = 59). In 33.6% of patients (n = 41), 532 supraventricular tachyarrhythmias occurred. Activation of ICD therapies for AT/AF did not result in a reduction of ventricular tachyarrhythmias (P = 0.92). Patients with monomorphic ventricular tachycardias (mVTs) as index arrhythmia for ICD implantation or inducible mVTs in the electrophysiological study had the highest probability of recurrences of ventricular tachyarrhythmias. CONCLUSION: For patients with standard indications for ICD therapy and no indication for cardiac pacing, a dual-chamber ICD capable of atrial tachyarrhythmia treatment offers no benefit concerning a reduction of ventricular tachyarrhythmias.

Near fatal arrhythmia induction by an implantable cardioverter defibrillator.

Sudden death among implantable cardioverter defibrillator (ICD) recipients is well known. The underlying mechanism remains unclear in most cases. One possible mechanism is an accidentally induced arrhythmia by the ICD itself. This report describes for the first time a case of a life-threatening ventricular arrhythmia induced by a specific algorithm for ventricular arrhythmia reconfirmation before shock delivery in a fourth-generation ICD.

Incidence of complications in patients with implantable cardioverter/defibrillator who receive additional transvenous pace/sense leads.

BACKGROUND: Implantation of an additional pace/sense (P/S) lead is commonly used in patients with implantable cardioverter/defibrillators (ICDs) to overcome P/S defects of integrated defibrillation leads (HV-P/S leads). No information is available about the clinical outcome and the incidence of complications in these patients. METHODS: Retrospective analysis was performed in 151 patients (125 male, age 54.9 +/- 13.6 years, LVEF 48.1 +/- 17.8%, CAD in 86 [57%], DCM in 24 [16%], ARVCM in 11 [7%]) who received an additional P/S lead between 1990 and 2002 (54 patients with abdominal and 97 patients with pectoral ICD system). Statistical analysis was done using Kaplan-Meier survival curves. RESULTS: The average follow-up (FU) after implantation of the additional P/S lead was 43 +/- 27 months. In total 117 patients [77.5%] remain implanted; 22 patients died due to cardiac-related reasons. After a FU of 23 +/- 23 months, 43 patients [28.5%] experienced lead-related problems after implantation of the additional P/S lead: oversensing in 23 [53.5%], insulation defect in 3 [7.0%], fracture in 1 [2.3%], system infection in 4 [9.3%], and defect of the HV-P/S lead in 6 [14.0%] patients. The event-free cumulative survival of the additional P/S lead after 1, 2, and 5 years was 87.0%, 79.8%, and 59.4%, respectively (for pectoral leads: 89.6%, 82.0%, and 60.0%, respectively). CONCLUSIONS: Implantation of an additional P/S lead in case of failure of an HV-P/S lead is safe. However, it is associated with a substantial rate of complications during FU. Therefore, extraction of damaged defibrillation leads instead of implantation of P/S leads should be favored.

Comparison of induced and spontaneous atrial tachyarrhythmias in patients with a history of spontaneous atrial tachyarrhythmias.

INTRODUCTION: This retrospective study investigated whether induced episodes could be used to predict the morphology of future spontaneous atrial episodes. METHODS: Eighty-two patients (64 +/- 12 years; 77% male; CAD in 60%; left ventricular ejection fraction 45 +/- 16%) with a history of atrial tachycardia or atrial fibrillation (AT/AF) were implanted with a dual-chamber implantable cardioverter defibrillator (ICD) and followed for 6 months. A total of 224 episodes of induced and spontaneous AT/AF were classified into type I, II, and III according to the method of Israel et al. and then compared based on average cycle length (CL) and atrial amplitude. Episodes were also grouped as "pace-terminable" or "nonpace-terminable" based on the CL definition of Gillis et al. RESULTS: The analysis of 121 induced episodes (from 80 patients) and 103 spontaneous episodes (from 43 patients) showed that within each arrhythmia type, there were no significant differences in CL or mean amplitude between induced and spontaneous episodes. Additional analysis of patients that had both induced and spontaneous episodes (n = 41) showed 78% had at least one spontaneous episode that matched the induced episode. Fifty-seven percent of spontaneous episodes were considered to be pace-terminable based on CL. CONCLUSIONS: Our data suggest that there is no significant difference between induced and spontaneous episodes of AT/AF of the same type. The majority of patients had at least one spontaneous episode of the same type as the induced episode, showing that induced atrial arrhythmias may be useful in predicting the morphology of future spontaneous episodes and in identifying patients potentially benefiting from atrial antitachycardia pacing.