Extended detection time to reduce shocks is safe in secondary prevention patients: The secondary prevention substudy of PainFree SST.

BACKGROUND: Prolonged ventricular fibrillation (VF) detection has been shown to reduce implantable cardioverter-defibrillator (ICD) therapies and improve prognosis in primary prevention ICD patients. Data in secondary prevention patients are limited. OBJECTIVE: The PainFree SST secondary prevention study is the largest trial of secondary prevention patients randomized between standard and prolonged detection to assess the safety of this strategy in these patients. METHODS: A total of 705 secondary prevention patients implanted with an ICD in the PainFree SST trial were enrolled in this substudy; 353 patients were randomized to VF detection of 18/24 intervals and 352 patients to 30/40. All other VF parameters were standardized by protocol. RESULTS: The 1-year arrhythmic syncope-free rates in the standard and prolonged groups were 97.7% vs 96.9%, respectively, (P = .0034 for noninferiority). Freedom from all-cause syncope was 96% in both arms (P = .0013 for noninferiority). There was no difference in the time to first appropriate or inappropriate VF therapy. However, the rates of treated VF episodes were lower in the prolonged arm (1.48 per patient per year vs 0.44 per patient per year, P = .0001). A trend toward lower mortality in the prolonged group was not statistically different (5.6% 1 year, 12% 2 years vs 3.8% 1 year, 7.7% 2 years, adjusted hazard ratio = 0.60, P = .061). CONCLUSION: This large prospective randomized study shows that prolonged detection can safely be programmed in secondary prevention ICD patients with new or existing devices. This programming strategy decreases the rate of treated events and is not associated with an increased risk of syncope or mortality.

Low inappropriate shock rates in patients with single- and dual/triple-chamber implantable cardioverter-defibrillators using a novel suite of detection algorithms: PainFree SST trial primary results.

BACKGROUND: The benefits of implantable cardioverter-defibrillators (ICDs) have been well demonstrated in many clinical trials, and ICD shocks for ventricular tachyarrhythmias save lives. However, inappropriate and unnecessary shock delivery remains a significant clinical issue with considerable consequences for patients and the healthcare system. OBJECTIVE: The purpose of the PainFree SmartShock Technology (SST) study was to investigate new-generation ICDs to reduce inappropriate and unnecessary shocks through novel discrimination algorithms with modern programming strategies. METHODS: This prospective, multicenter clinical trial enrolled 2790 patients with approved indication for ICD implantation (79% male, mean age 65 years; 69% primary prevention indication, 27% single-chamber ICD, 33% replacement or upgrade). Patients were followed for a minimum of 12 months, and mean follow-up was 22 months. The primary end-point of the study was the percentage of patients remaining free of inappropriate shocks at 1 year postimplant, analyzed separately for dual/triple-chamber ICDs (N = 2019) and single-chamber ICDs (N = 751). RESULTS: The inappropriate shock rate at 1 year was 1.5% for patients with dual/triple-chamber ICDs and 2.5% for patients with single-chamber devices. Two years postimplant, the inappropriate shock rate was 2.8% for patients with dual-/triple chamber ICDs and 3.7% for those with single-chamber ICDs. The most common cause of an inappropriate shock in both groups was atrial fibrillation or flutter. CONCLUSION: In a large patient cohort receiving ICDs for primary or secondary prevention, the adoption of novel enhanced detection algorithms in conjunction with routine implementation of modern programming strategies led to a very low inappropriate shock rate.

Continuation of warfarin during pacemaker or implantable cardioverter-defibrillator implantation: a randomized clinical trial.

BACKGROUND: Management of oral anticoagulation in patients undergoing pacemaker (PPM) or implantable cardioverter-defibrillator (ICD) implantation remains controversial. Prior studies demonstrate that continuation of warfarin may be safer when compared with strategies requiring interruption and/or heparin bridging. Limited data from randomized trials exist. OBJECTIVE: We conducted a randomized trial to determine whether warfarin continuation is superior to warfarin interruption during PPM or ICD implantation. METHODS: Patients on oral anticoagulation referred for PPM or ICD implantation were randomized to warfarin continuation versus interruption. Patients randomized to warfarin interruption were further stratified into two groups based on their risk for thromboembolic events in the absence of warfarin. Moderate-risk patients were randomized to warfarin continuation versus warfarin interruption. High-risk patients were randomized to warfarin continuation versus warfarin interruption with heparin bridging. The primary combined outcome included thromboembolic events, anticoagulant-related complications, or any significant bleeding necessitating additional intervention or discontinuation of anticoagulation. RESULTS: We studied 100 patients (average age 70.8 years, 21% female, mean body mass index 28.4) who underwent 64 ICD and 36 PPM implantations. Fifty patients were assigned to continue warfarin. The randomized groups were well matched. Among patients randomized to warfarin interruption, there were two pocket hematomas, one pericardial effusion, one transient ischemic attack, and one patient who developed heparin-induced thrombocytopenia. No events were noted among patients continuing warfarin (P = .056). CONCLUSIONS: While the results were not statistically significant, there was a trend toward reduced complications in patients randomized to warfarin continuation. This strategy should be considered in patients undergoing PPM or ICD implantation.

Dual antiplatelet therapy and heparin "bridging" significantly increase the risk of bleeding complications after pacemaker or implantable cardioverter-defibrillator device implantation.

OBJECTIVES: This study was designed to assess the risk of significant bleeding complications in patients receiving antiplatelet or anticoagulation medications at the time of implantable cardioverter-defibrillator (ICD) device implantation. BACKGROUND: Periprocedural management of antiplatelet or anticoagulation therapy at the time of device implantation remains controversial. METHODS: We performed a retrospective chart review of bleeding complications in all patients undergoing ICD or pacemaker implantation from August 2004 to August 2007. Aspirin or clopidogrel use was defined as taken within 5 days of the procedure. A significant bleeding complication was defined as need for pocket exploration or blood transfusion; hematoma requiring pressure dressing or change in anticoagulation therapy; or prolonged hospitalization. RESULTS: Of the 1,388 device implantations, 71 had bleeding complications (5.1%). Compared with controls not taking antiplatelet agents (n = 255), the combination of aspirin and clopidogrel (n = 139) significantly increased bleeding risk (7.2% vs. 1.6%; p = 0.004). In patients taking aspirin alone (n = 536), bleeding risk was marginally higher than it was for patients taking no antiplatelet agents (3.9% vs. 1.6%, p = 0.078). The use of periprocedural heparin (n = 154) markedly increased risk of bleeding when compared with holding warfarin until the international normalized ratio (INR) was normal (n = 258; 14.3% vs. 4.3%; p < 0.001) and compared with patients receiving no anticoagulation therapy (14.3% vs.1.6%; p < 0.0001). There was no statistical difference in bleeding risk between patients continued on warfarin with an INR > or =1.5 (n = 46) and patients who had warfarin withheld until the INR was normal (n = 258; 6.5% vs. 4.3%; p = 0.50). CONCLUSIONS: Dual antiplatelet therapy and periprocedural heparin significantly increase the risk of bleeding complications at the time of pacemaker or ICD implantation.

Computed tomography to assess possible cardiac lead perforation.

BACKGROUND: Chest radiography and echocardiography are standard techniques to evaluate possible extracardiac migration of pacemaker and defibrillator leads, but computed tomography (CT) scanning may be a helpful adjunct. METHODS: Chest CT using a 64-detector helical scanner was performed in three cases of lead perforation where standard techniques did not yield a definitive diagnosis. In two patients, a cardiac CT protocol was followed, the primary indication for which was to assess the lead tip location. On one patient, persistent chest pain several days after the implant led to a chest CT to rule out a pulmonary embolism, and the extracardiac lead was found fortuitously. RESULTS: In all cases, CT scan images resulted in a definitive diagnosis of extracardiac migration of pacemaker or defibrillator leads. One patient had an extracardiac atrial lead which was dysfunctional but not associated with symptoms. The risks of repositioning were felt to outweigh potential benefits in this patient with chronic obstructive pulmonary disease, and treatment was conservative. The other two patients had extracardiac ventricular leads and were symptomatic with pleuritic chest pain. These patients were treated by lead revision with no evidence of bleeding into the pericardial space. All patients did well and none have suffered any further complications. CONCLUSION: CT images aid in the diagnosis of lead perforation when other modalities are nondiagnostic. Recent advances in CT technology have been associated with increased use of this technique for evaluation of chest pain, analysis of which should now include location of intracardiac leads.