A Dual-Chamber Leadless Pacemaker.

BACKGROUND: Single-chamber ventricular leadless pacemakers do not support atrial pacing or consistent atrioventricular synchrony. A dual-chamber leadless pacemaker system consisting of two devices implanted percutaneously, one in the right atrium and one in the right ventricle, would make leadless pacemaker therapy a treatment option for a wider range of indications. METHODS: We conducted a prospective, multicenter, single-group study to evaluate the safety and performance of a dual-chamber leadless pacemaker system. Patients with a conventional indication for dual-chamber pacing were eligible for participation. The primary safety end point was freedom from complications (i.e., device- or procedure-related serious adverse events) at 90 days. The first primary performance end point was a combination of adequate atrial capture threshold and sensing amplitude at 3 months. The second primary performance end point was at least 70% atrioventricular synchrony at 3 months while the patient was sitting. RESULTS: Among the 300 patients enrolled, 190 (63.3%) had sinus-node dysfunction and 100 (33.3%) had atrioventricular block as the primary pacing indication. The implantation procedure was successful (i.e., two functioning leadless pacemakers were implanted and had established implant-to-implant communication) in 295 patients (98.3%). A total of 35 device- or procedure-related serious adverse events occurred in 29 patients. The primary safety end point was met in 271 patients (90.3%; 95% confidence interval [CI], 87.0 to 93.7), which exceeded the performance goal of 78% (P<0.001). The first primary performance end point was met in 90.2% of the patients (95% CI, 86.8 to 93.6), which exceeded the performance goal of 82.5% (P<0.001). The mean (±SD) atrial capture threshold was 0.82±0.70 V, and the mean P-wave amplitude was 3.58±1.88 mV. Of the 21 patients (7%) with a P-wave amplitude of less than 1.0 mV, none required device revision for inadequate sensing. At least 70% atrioventricular synchrony was achieved in 97.3% of the patients (95% CI, 95.4 to 99.3), which exceeded the performance goal of 83% (P<0.001). CONCLUSIONS: The dual-chamber leadless pacemaker system met the primary safety end point and provided atrial pacing and reliable atrioventricular synchrony for 3 months after implantation. (Funded by Abbott Medical; Aveir DR i2i ClinicalTrials.gov number, NCT05252702.).

Safety and feasibility of same-day discharge following uncomplicated transvenous lead extraction.

INTRODUCTION: Transvenous lead extraction (TLE), while mostly a safe procedure, has risk of serious periprocedural complications. As such, overnight hospitalization remains a routine practice. In our center, we routinely discharge patients on the same day following an uncomplicated TLE. METHODS: This is a retrospective study of 265 consecutive patients who underwent uncomplicated TLE in our center between 2019 and 2021. Same-day discharge (SDD) patients are compared with those who stayed at least overnight for observation after the TLE procedure (non-SDD group). To assess the safety of an SDD strategy after uncomplicated TLE, the main study endpoint was to compare the rate of major procedure-related complications at 1-, 7-, and 30-days. To identify the factors influencing the operator's decision to discharge the patient on the same day, the secondary endpoint was to analyze clinical and procedural predictors of SDD. RESULTS: A total of 153 patients were discharged the same day after uncomplicated TLE (SDD), while 112 stayed at least overnight after the procedure (non-SDD). There was no significant difference in major procedure-related complications at 1-day (SDD 0% vs. non-SDD 1.8%, p value = ns), while patients in the SDD group had a lower rate of 7- and 30-day complications when compared with those in the non-SDD group (2.1% vs. 8.2%, p value = .0308; and 3.5% vs. 16%, p value = .0049, respectively). Noninfectious indication for TLE (OR 16.1, 95% confidence interval [CI] 4.29-77.6) and procedure end time before 12:00 (OR 2.82, 95% CI 1.11-7.27) were the only independent predictors of SDD. CONCLUSION: SDD discharge following uncomplicated TLE in selected patients (i.e., those without device infection and when the TLE procedure is completed in the morning) is feasible and safe.

Laser-assisted lead extraction of a retained lead remnant in the femoral and iliac veins.

Herein, we present a case of laser-assisted extraction of a retained lead remnant following incomplete removal of an implantable cardiac defibrillator system implanted via a left femoral approach.

Dizziness during atrial antitachycardia pacing: What is the cause.

A 74-year-old with a history of sinus node dysfunction and intermittent AV block s/p permanent pacemaker implant 6 years prior, complains of one episode of dizziness.

Performance of a novel active fixation quadripolar left ventricular lead for cardiac resynchronization therapy: Attain Stability Quad Clinical Study results.

INTRODUCTION: The Medtronic Attain Stability Quad lead is a quadripolar left ventricular (LV) lead with an active fixation helix assembly designed to fixate the lead within the coronary sinus and pace nonapical regions of the LV. The primary objective of this study was to determine the safety and effectiveness of this novel active fixation quadripolar LV lead. METHODS: Patients with standard indications for cardiac resynchronization therapy (CRT) were enrolled. All patients were followed at 3 and 6 months post-implant and every 6 months thereafter until study closure. Pacing capture thresholds (PCTs) were measured at implant and each follow-up and adverse events (AEs) were recorded upon occurrence. RESULTS: Of the 440 patients who underwent implant procedures, placement of the Attain Stability Quad lead was successful in 426 (96.8%). LV lead-related complications occurred in 10 patients (2.3%), including LV lead dislodgement in three patients (0.7%). The percentage of patients with at least one LV pacing vector with a PCT ≤2.5 V at a 6-month follow-up was 96.3%. The LV lead was successfully fixated to the prespecified pacing location in 97.4% of cases. CONCLUSIONS: This large, multinational study of the Attain Stability Quad lead demonstrated a high rate of implant success with a low complication rate. The active fixation mechanism allowed precise placement of the pacing electrodes at the desired target region with good PCTs and a very low dislodgement rate.

Association of Antitachycardia Pacing or Shocks With Survival in 69,000 Patients With an Implantable Defibrillator.

AIMS: Antitachycardia pacing (ATP) is an effective treatment for ventricular tachycardia (VT) and can reduce the frequency of shocks in patients with an implantable cardioverter defibrillator (ICD). The association between survival and ATP, as compared to a shock, has not been confirmed in a large patient population. This study aims to determine if patients with an ICD receiving ATP have lower mortality, as compared to those receiving shock. METHODS: Sixty-nine thousand three hundred and sixty-eight patients underwent ICD implantation between October 2008 and May 2013 and were enrolled in the remote monitoring network Merlin.net™ (St. Jude Medical, St. Paul, MN, USA). Patients were categorized into three groups based on the type of ICD therapy received during follow-up: no therapy (N = 47,927), ATP (N = 8,049), and shock (N = 13,392) groups. Survival was determined by linking implant records to the Social Security Death Index. RESULTS: The no therapy (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.56-0.64, P < 0.001) and ATP (HR 0.70, 95% CI 0.64-0.77, P < 0.001) groups were associated with a lower mortality risk than the shock group. These results were unaffected by age, gender, device type, atrial fibrillation (AF) burden, or ventricular rate. ATP was effective in 85% of episodes and ATP effectiveness was dependent on the ventricular rate. CONCLUSIONS: Mortality rates were higher in ICD patients who received only ATP compared to no therapy, but ICD patients who received a shock had higher mortality compared to both groups. Furthermore, the data suggest that age, gender, device type, AF burden, and rate of arrhythmia do not change the trend of higher mortality in patients receiving ICD shock compared to ATP alone.

Six-month electrical performance of the first dual-chamber leadless pacemaker.

BACKGROUND: The first dual-chamber leadless pacemaker (DC-LP) system consists of 2 separate atrial and ventricular devices that communicate to maintain synchronous atrioventricular pacing and sensing. The initial safety and efficacy were previously reported. OBJECTIVE: The purpose of this study was to evaluate the chronic electrical performance of the DC-LP system. METHODS: Patients meeting standard dual-chamber pacing indications were enrolled and implanted with the DC-LP system (Aveir DR, Abbott), including right atrial and ventricular helix-fixation LPs (atrial leadless pacemaker [ALP], ventricular leadless pacemaker [VLP]). Pacing capture threshold, sensed amplitude, and pacing impedance were collected using the device programmer at prespecified timepoints from 0-6 months postimplant. RESULTS: De novo devices were successfully implanted in 381 patients with complete 6-month data (62% male; age 69 ± 14 years; weight 82 ± 20 kg; 65% sinus nodal dysfunction, 30% atrioventricular block). ALPs were implanted predominantly in the right atrial appendage anterior base and VLPs primarily at the mid-to-apical right ventricular septum. From implant to 1 month, pacing capture thresholds (0.4-ms pulse width) improved in both ALPs (2.4 ± 1.5 V to 0.8 ± 0.8 V; P <.001) and VLPs (0.8 ± 0.6 V to 0.6 ± 0.4 V; P <.001). Sensed amplitudes improved in both ALPs (1.8 ± 1.3 mV to 3.4 ± 1.9 mV; P <.001) and VLPs (8.8 ± 4.0 mV to 11.7 ± 4.2 mV; P <.001). Impedances were stable in ALPs (334 ± 68 Ω to 329 ± 52 Ω; P = .17) and reduced in VLPs (789 ± 351 Ω to 646 ± 190 Ω; P <.001). Electrical measurements remained relatively stable from 1-6 months postimplant. No differences in electrical metrics were observed among ALP or VLP implant locations. CONCLUSION: This first in-human evaluation of the new dual-chamber leadless pacemaker system demonstrated reliable electrical performance throughout the initial 6-month evaluation period.

Safety and effectiveness of transvenous lead extraction in octogenarians.

INTRODUCTION: As the population ages, the number of elderly patients with implantable cardiac devices referred for transvenous lead extraction will dramatically increase in Western countries. The safety and effectiveness of lead extraction in elderly patients has not been well evaluated. We report the safety and effectiveness of transvenous lead extraction in octogenarians. METHODS AND RESULTS: From January 2005 to January 2011, we reviewed data from consecutive patients ≥ 80 years referred to our institutions for transvenous lead extraction because of cardiac device infection or lead malfunction. Clinical characteristics, procedural features, and periprocedural major and minor complications were compared between octogenarians and younger patients. Out of 849 patients undergoing lead extraction in the participating institutions during the study period, 150 (18%) patients were octogenarians (mean age 84 years; range 80-96; 64% males). A significantly higher percentage of octogenarians presented with chronic renal failure (55% vs 26%; P < 0.001), history of malignancy (22% vs 6%; P < 0.001), and chronic obstructive pulmonary disease (46% vs 19%; P < 0.001). Complete lead extraction rates were similar in the 2 age groups (97% in octogenarians vs 96% in patients <80 years; P = 0.39). Periprocedural death occurred in 2 (1.3%) patients ≥80 years and in 5 (0.72%) patients <80 years (P = 0.45 for comparison). No differences in terms of other periprocedural major and minor complications were found between the 2 age groups. CONCLUSION: Despite presenting with a significantly higher rate of comorbidities, transvenous lead extraction can be performed safely and successfully in octogenarians.

Closed loop stimulation is effective in improving heart rate and blood pressure response to mental stress: report of a single-chamber pacemaker study in patients with chronotropic incompetent atrial fibrillation.

INTRODUCTION: Closed-loop stimulation (CLS) is a form of rate-adaptive pacing capable of providing an effective pacing rate profile not only during physical exercise but also during mental stress. To test its effectiveness, CLS and accelerometer sensor (AS) rate response were compared intraindividually during a mental stress test (MST). METHODS: Thirty-six patients (mean age 78.9 ± 6.4 years) implanted with a pacemaker with the CLS algorithm (Cylos, Biotronik, Berlin, Germany) underwent MSTs in different pacing configurations: nonrate-adaptive mode (VVI), AS mode (VVIR), and CLS mode, respectively. A modified Stroop test was used in order to induce mental stress. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure, and pacing percentage burden were collected for 5 minutes before, during, and 5 minutes after the test. RESULTS: Mean peak-HR during MST was significantly higher in CLS configuration than in VVIR and VVI modes (92.8 ± 12.6 vs 78.9 ± 6.5 vs 77.8 ± 7.5; P ≤ 0.001). The average HR increase during MST was also higher in CLS configuration than in VVIR and VVI modes (22.7 ± 16.7 vs 8.2 ± 8.6 vs 6.6 ± 6.3; P ≤ 0.001). The percentage of pacing beats during MST was higher in CLS configuration than with the other two algorithms (48.4 ± 17.9 vs 27.4 ± 17.5 vs 25.8 ± 17.6; P ≤ 0.001). The average peak-SBP was significantly higher during MST in CLS mode than in VVIR and VVI configurations (172.6 ± 15.5 vs 156.7 ± 12.2 vs 145.5 ± 13.7; P ≤ 0.001). The mean SBP increase showed a similar behavior (51.8 ± 24.7 vs 18.4 ± 13.7 vs 16.4 ± 10.3; P ≤ 0.001). CONCLUSION: CLS algorithm in a single-chamber device is more effective than AS in detecting an hemodynamic demand due to an emotional stress and supplying a proper HR increase. These results are even more surprising compared to previous data in dual-chamber pacemakers, because they imply that CLS algorithm can provide an appropriate rate-modulation in patients with AF and chronotropic incompetence.

Positioning of left ventricular pacing lead guided by intracardiac echocardiography with vector velocity imaging during cardiac resynchronization therapy procedure.

INTRODUCTION: Intraoperative modality for "real-time" left ventricular (LV) dyssynchrony quantification and optimal resynchronization is not established. This study determined the feasibility, safety, and efficacy of intracardiac echocardiography (ICE), coupled with vector velocity imaging (VVI), to evaluate LV dyssynchrony and to guide LV lead placement at the time of cardiac resynchronization therapy (CRT) implant. METHODS: One hundred and four consecutive heart failure patients undergoing ICE-guided (Group 1, N = 50) or conventional (Group 2, N = 54) CRT implant were included in the study. For Group 1 patients, LV dyssynchrony and resynchronization were evaluated by VVI including visual algorithms and the maximum differences in time-to-peak (MD-TTP) radial strain. Based on the findings, the final LV lead site was determined and optimal resynchronization was achieved. CRT responders were defined using standard criteria 6 months after implantation. RESULTS: Both groups underwent CRT implant with no complications. In Group 1, intraprocedural optimal resynchronization by VVI including visual algorithms and MD-TTP was a predictor discriminating CRT response with a sensitivity of 95% and specificity of 89%. Use of ICE/VVI increased number of and predicted CRT responders (82% in Group 1 vs 63% in Group 2; OR = 2.68, 95% CI 1.08-6.65, P = 0.03). CONCLUSION: ICE can be safely performed during CRT implantation. "Real-time" VVI appears to be helpful in determining the final LV lead position and pacing mode that allow better intraprocedural resynchronization. VVI-optimized acute resynchronization predicts CRT response and this approach is associated with higher number of CRT responders.

Impact of cardiac resynchronization therapy on the severity of mitral regurgitation.

AIMS: Functional mitral regurgitation (MR) could be managed by both cardiac resynchronization therapy (CRT) and mitral-valve surgery. Clinical decision making regarding the appropriateness of mitral-valve surgery vs. CRT is a challenging task. This study assessed the prevalence and prognosis of various degrees of functional MR in CRT candidates. Additionally, we sought to identify functional MR patients who either can be adequately managed by CRT only or will need surgery. METHODS AND RESULTS: Cardiac resynchronization therapy recipients (n= 794) were followed-up for 26 ± 18 months. Mitral regurgitation severity was quantified on scale 0-4. Cardiac resynchronization therapy responders were identified based on improvement in the New York Heart Association class and left-ventricular ejection fraction. Severity of MR and LV reverse remodelling were assessed at 3 and 12 months. Predictors of long-term MR change and CRT response were explored with multivariable models. Mitral regurgitation was present in 86%, with 35% prevalence of advanced MR (grade 3-4). Improvement of MR ≥ 1° after 12 months occurred in 46% of patients. It was relatively more frequent in patients with advanced MR at baseline (63%, P< 0.01). Baseline MR severity and change in MR at 3-month follow-up predicted response to CRT. Patients with ≥ 1° MR improvement at 12 months had more reverse remodelling compared with those with no change or worsening of MR. CONCLUSIONS: Mitral regurgitation improvement at 3 months predicts CRT response and MR improvement at 12-month follow-up. This finding could have implications for subsequent MR surgical therapies.

Creating a safe workplace by universal testing of SARS-CoV-2 infection in asymptomatic patients and healthcare workers in the electrophysiology units: a multi-center experience.

BACKGROUND: As the coronavirus cases continue to surge, the urgent need for universal testing to identify positive cases for effective containment of this highly contagious pandemic has become the center of attention worldwide. However, in spite of extensive discussions, very few places have even attempted to implement it. We evaluated the efficacy of widespread testing in creating a safe workplace in our electrophysiology (EP) community. Furthermore, we assessed the new infection rate in patients undergoing EP procedure, to see if identification and exclusion of positive cases facilitated establishment of a risk-free operating environment. METHODS: Viral-RNA and serology tests were conducted in 1670 asymptomatic subjects including patients and their caregivers and staff in our EP units along with the Emergency Medical Service (EMS) staff. RESULTS: Of 1670, 758 (45.4%) were patients and the remaining 912 were caregivers, EMS staff, and staff from EP clinic and lab. Viral-RNA test revealed 64 (3.8%) positives in the population. A significant increase in positivity rate was observed from April to June 2020 (p = 0.02). Procedures of positive cases (n = 31) were postponed until they tested negative at retesting. Staff testing positive (n = 33) were retested before going back to work after 2 weeks. Because of suspected exposure, 67 staff were retested and source was traced. No new infections were reported in patients during or within 2 weeks after the hospital-stay. CONCLUSIONS: Universal testing to identify positive cases was helpful in creating and maintaining a safe working environment without exposing patients and staff to new infections in the EP units. TRIAL REGISTRATION: Trial Registration Number: clinicaltrials.gov : NCT04352764.

The Subtle Journey of a Right Atrial Lead: Hemopneumothorax Due to Subacute Pacemaker Lead Perforation.

We report an unusual case of subacute right atrial perforation by a screw-in pacemaker lead that migrated into the right lung causing hemopneumothorax 2 weeks after the procedure. After transvenous simple manual traction and minithoracotomy repair of the right atrial wall, the lead was repositioned without any complications. (Level of Difficulty: Beginner.).

Ablation of atrial fibrillation utilizing robotic catheter navigation in comparison to manual navigation and ablation: single-center experience.

BACKGROUND: Robotic catheter navigation and ablation either with magnetic catheter driving or with electromechanical guidance have emerged in the recent years for the treatment of atrial fibrillation. OBJECTIVE: The aim of this study was to compare our center's experience of atrial fibrillation ablation using the Hansen Robotic Medical System with our current manual ablation technique in terms of acute and chronic success, as well as procedure time and radiation exposure to both the patient and the operator. METHODS: A total of 390 consecutive patients with symptomatic and drug-resistant atrial fibrillation (289 males, 62 +/- 11 years) were prospectively enrolled in the study. All patients underwent the procedure either with conventional manual ablation (group 1, n = 197) or with the robotic navigation system (RNS) (group 2, n = 193). RESULTS: The success rate for RNS was 85% (164 patients), while for manual ablation it was 81% (159 patients) (p = 0.264) at 14.1 +/- 1.3 months with AADs previously ineffective. Fluoroscopy time was significantly lower for RNS (48.9 +/- 24.6 minutes for RNS vs. 58.4 +/- 20.1 minutes for manual ablation, P < 0.001). Mean fluoroscopy time was statistically reduced after 50 procedures (61.8 +/- 23.2 minutes for first 50 cases vs. 44.5 +/- 23.6 minutes for subsequent procedures, P < 0.0001). CONCLUSION: Robotic navigation and ablation of atrial fibrillation is safe and effective. Fluoroscopy time decreases with experience.

Omega-3 polyunsaturated Fatty Acid supplementation reduced atrial fibrillation recurrence after pulmonary vein antrum isolation.

OBJECTIVE: To assess if patients treated with omega-3(n-3) polyunsaturated fatty acids (PUFAS) had lower procedural failure rates compared to an untreated population. METHODS AND RESULTS: From January 2004 to 2007, 1500 PVAI patients underwent catheter ablation. Two hundred and eighty five (19%) patients were treated with PUFAs. These patients were matched in a nested case controlled analysis. After matching, there were 129 patients in the PUFA group and 129 in the control group. Thirty-five (27.1%) patients in the study group had early recurrence vs. 57 (44.1%) in the control group p-value< 0.0001. Twenty-nine (23.2%) patients in the PUFA group vs. 41 (31.7%) in the non-PUFA group had procedural failure (p-value < 0.003). There were no significant differences in complications in the PUFA and non-PUFA groups. CONCLUSION: Patients treated with PUFAs had lower incidences of early recurrence and procedural failure compared to an untreated population.

Initial Clinical Experience With a New Automated Antitachycardia Pacing Algorithm: Feasibility and Safety in an Ambulatory Patient Cohort.

BACKGROUND: Antitachycardia pacing (ATP) in implantable cardioverter-defibrillators (ICD) decreases patient shock burden but has recognized limitations. A new automated ATP (AATP) based on electrophysiological first principles was designed. The study objective was to assess the feasibility and safety of AATP in ambulatory ICD patients. METHODS AND RESULTS: Enrolled patients had dual chamber or cardiac resynchronization therapy ICDs, history of ≥1 ICD-treated ventricular tachycardias (VT)/ventricular fibrillation episode, or a recorded, sustained monomorphic VT. Detection was set to ventricular fibrillation number of intervals to detect=24/32, VT number of intervals to detect≥16, and a fast VT zone of 240 to 320 ms. AATP prescribed the components and delivery of successive ATP sequences in real time, using the same settings for all patients. ICD datalogs were uploaded every ≈3 months, at unscheduled visits, exit, and death. Episodes and adverse events were adjudicated by separate committees. Results were adjusted (generalized estimating equations) for multiple episodes. AATP was downloaded into the ICDs of 144 patients (121 men), aged 67.4±11.9 years, left ventricular ejection fraction 33.1±13.6% (n=137), and treated 1626 episodes in 49 patients during 14.5±5.1 months of follow-up. Datalogs permitted adjudication of 702 episodes, including 669 sustained monomorphic VT, 20 polymorphic VT, 10 supraventricular tachycardia, and 3 malsensing episodes. AATP terminated 39 of 69 (59% adjusted) sustained monomorphic VT in the fast VT zone, 509 of 590 (85% adjusted) in the VT zone, and 6 of 10 in the ventricular fibrillation zone. No supraventricular tachycardias converted to VT or ventricular fibrillation. No anomalous AATP behavior was observed. CONCLUSIONS: The new AATP algorithm safely generated ATP sequences and controlled therapy progression in all zones without need for individualized programing.

Validation of a defibrillation lead ventricular volume measurement compared to three-dimensional echocardiography.

BACKGROUND: There is increasing evidence that using frequent invasive measures of pressure in patients with heart failure results in improved outcomes compared to traditional measures. Admittance, a measure of volume derived from preexisting defibrillation leads, is proposed as a new technique to monitor cardiac hemodynamics in patients with an implantable defibrillator. OBJECTIVE: The purpose of this study was to evaluate the accuracy of a new ventricular volume sensor (VVS, CardioVol) compared with 3-dimenssional echocardiography (echo) in patients with an implantable defibrillator. METHODS: Twenty-two patients referred for generator replacement had their defibrillation lead attached to VVS to determine the level of agreement to a volume measurement standard (echo). Two opposite hemodynamic challenges were sequentially applied to the heart (overdrive pacing and dobutamine administration) to determine whether real changes in hemodynamics could be reliably and repeatedly assessed with VVS. Equivalence of end-diastolic volume (EDV) and stroke volume (SV) determined by both methods was also assessed. RESULTS: EDV and SV were compared using VVS and echo. VVS tracked expected physiologic trends. EDV was modulated -10% by overdrive pacing (14 mL). SV was modulated -13.7% during overdrive pacing (-6 mL) and increased over baseline +14.6% (+8 mL) with dobutamine. VVS and echo mean EDVs were found statistically equivalent, with margin of equivalence 13.8 mL (P <.05). Likewise, mean SVs were found statistically equivalent with margin of equivalence 15.8 mL (P <.05). CONCLUSION: VVS provides an accurate method for ventricular volume assessment using chronically implanted defibrillator leads and is statistically equivalent to echo determination of mean EDV and SV.

Prospective randomized multicenter trial of empirical antitachycardia pacing versus shocks for spontaneous rapid ventricular tachycardia in patients with implantable cardioverter-defibrillators: Pacing Fast Ventricular Tachycardia Reduces Shock Therapies (PainFREE Rx II) trial results.

BACKGROUND: Successful antitachycardia pacing (ATP) terminates ventricular tachycardia (VT) up to 250 bpm without the need for painful shocks in implantable cardioverter-defibrillator (ICD) patients. Fast VT (FVT) >200 bpm is often treated by shock because of safety concerns, however. This prospective, randomized, multicenter trial compares the safety and utility of empirical ATP with shocks for FVT in a broad ICD population. METHODS AND RESULTS: We randomized 634 ICD patients to 2 arms-standardized empirical ATP (n=313) or shock (n=321)-for initial therapy of spontaneous FVT. ICDs were programmed to detect FVT when 18 of 24 intervals were 188 to 250 bpm and 0 of the last 8 intervals were >250 bpm. Initial FVT therapy was ATP (8 pulses, 88% of FVT cycle length) or shock at 10 J above the defibrillation threshold. Syncope and arrhythmic symptoms were collected through patient diaries and interviews. In 11+/-3 months of follow-up, 431 episodes of FVT occurred in 98 patients, representing 32% of ventricular tachyarrhythmias and 76% of those that would be detected as ventricular fibrillation and shocked with traditional ICD programming. ATP was effective in 229 of 284 episodes in the ATP arm (81%, 72% adjusted). Acceleration, episode duration, syncope, and sudden death were similar between arms. Quality of life, measured with the SF-36, improved in patients with FVT in both arms but more so in the ATP arm. CONCLUSIONS: Compared with shocks, empirical ATP for FVT is highly effective, is equally safe, and improves quality of life. ATP may be the preferred FVT therapy in most ICD patients.

Worldwide evaluation of a defibrillation lead with a small geometric electrode surface for high-impedance pacing.

BACKGROUND: Pacing leads with a small electrode surface for high-impedance stimulation have been shown to prolong pacemaker longevity, but no sufficient data is available on the safety and feasibility of a defibrillation lead with this novel design. METHODS: We evaluated the clinical performance of a tined, steroid-eluting defibrillation lead with a small electrode surface area (model 6944) in a prospective multicenter study. A total of 542 patients with conventional indications for an implantable cardioverter defibrillator were randomized 1:1 to receive either the model 6944 or a tined, steroid-eluting defibrillation lead with a conventional sized electrode surface area (model 6942). Device performance and electrical parameters were evaluated at implant and 1, 3, 6, and 12 months thereafter (mean follow-up 11.3 +/- 5.6 months). RESULTS: Baseline characteristics, lead implant success rates, and defibrillation thresholds did not differ significantly between the 2 groups. While pacing thresholds did not differ significantly during follow-up, pacing impedance was approximately twice as high in the model 6944 as in the model 6942 lead (P <.0001). Mean R-wave amplitudes were smaller in patients with a 6944 (9.1 +/- 3.1 mV vs 9.8 +/- 3.6 mV for model 6942, P <.05), but remained stable within both groups throughout the observation period. The total number of ventricular lead-related adverse events and patient survival did not differ significantly between the 2 groups. CONCLUSIONS: The use of a defibrillation lead with a small electrode surface for high-efficiency pacing is safe and feasible and increases pacing impedance without significantly compromising clinical performance.