The Dx-AF study: a prospective, multicenter, randomized controlled trial comparing VDD-ICD to VVI-ICD in detecting sub-clinical atrial fibrillation in defibrillator patients.

PURPOSE: Atrial fibrillation (AF) is the most common cardiac dysrhythmia. Appropriate detection of AF and early initiation of oral anticoagulation therapy are critical to reduce the risk of stroke. Patients with implantable cardioverter defibrillators (ICD) are at high risk of developing AF. The purpose of the Dx-AF study is to demonstrate that a novel single-lead VDD-ICD system (Linox smart S DX) will facilitate adequate recognition of sub-clinical AF and ultimately stroke prevention with a comparable safety profile in comparison to VVI-ICD. METHODS AND RESULTS: Dx-AF is a prospective, randomized controlled, open-label trial. Patients who are indicated to receive a single-chamber ICD will be randomized to a VDD-ICD (experimental group) or single-chamber ICD (control group). We have used a sample size of 355, which after generous allowance for loss-to-follow-up, yields a sample size of 378 patients at up to 13 Canadian sites. The trial will enroll patients with ischemic or non-ischemic cardiomyopathy, age > 50 years, LVEF < 50%, scheduled for primary or secondary prevention single-chamber ICD, with no ECG-documented history of AF or flutter. The primary (efficacy) outcome of this study will be the time to the first detected and confirmed episode of AF or atrial flutter lasting at least 6 min. The secondary (safety) outcome will be a composite outcome of serious device-related complications. The proposed follow-up period in this trial will be 36 months after randomization. CONCLUSIONS: The Dx-AF Study should provide significant scientific evidence and guidance to an adequate ICD system choice and early AF detection/management hence improve clinical outcomes in a large patient population.

Snapshot of adult invasive cardiac electrophysiology in Canada: results of the web-based registry.

PURPOSE: Interventional cardiac electrophysiology (EP) has experienced a significant growth in Canada. Our aim is to establish a periodic registry as a nationwide initiative. METHODS: The registry is designed to collect information regarding EP laboratory infrastructure, human resources, and the spectrum and volumes of EP procedures. Respective administrative staff were contacted electronically. RESULTS: Out of 25 identified Canadian EP centers, 19 centers (76%) have participated in the registry. Responding centers have access on average to 5.3 lab days per week to perform EP studies/ablations; average lab time per full- and part-time (prorated to 0.5) EP physician is 0.8 day per week. Diagnostic EP studies and radio-frequency ablations are performed in all (19) centers; cryoablation is available in 83% of centers. Two centers have remote magnetic navigation systems. EnSite NavX is the most widely available 3D mapping system utilized in 15 (83%) centers, followed by CARTO and intracardiac echo which are each available in 14 (78%) centers; LocaLisa is actively used in one center. The number of full-time physicians ranges between 0 and 7, with a mean of 3.5 full-time physicians per center. The ratio of staff to trainees is 1.6:1. A total of 8,041 EP procedures are performed in the 19 centers per annum. On an annual average, 104 procedures per one operator and 159 procedures per trainee are performed. CONCLUSIONS: This registry provides contemporary information on invasive EP lab resources and procedures in Canada. It also demonstrates that Canadian EP procedural intensities of practice and training are comparable to international standards.

Predictors of short-term complications after implantable cardioverter-defibrillator replacement: results from the Ontario ICD Database.

BACKGROUND: Complications after implantable cardioverter-defibrillator (ICD) replacement are often clinically devastating, particularly when infection or reoperation occurs. Identifying factors contributing to complications may permit identification of high-risk individuals that warrant incremental monitoring and therapy to attenuate risk. In addition, replacement may be a discretionary decision in the context of an advisory or borderline device performance and patient, device, and implanter factors that predict adverse outcome may assist in clinical decision-making. METHODS AND RESULTS: In a prospective, multicenter, population-based registry of all ICD patients at 18 centers in Ontario, Canada, we examined 45-day complication and all-cause mortality rates from February 2007 to August 2009 in patients undergoing ICD generator replacement. Complications were determined longitudinally and were categorized as major or minor. ICD replacement was performed in 1081 of 5176 patients (20.8%) undergoing ICD implantation (age, 64.3±12.7 years; 78.5% men). In patients undergoing ICD replacement, 47 patients (4.3%) had a complication within 45 days, with 47 major complications in 28 patients (2.6%), most commonly infection (n=23), lead revision (n=35), electrical storm (n=14), and pulmonary edema (n=13). Minor complications occurred in 2.3% of patients, most commonly incisional infection (n=10) and pocket hematoma (n=10). On multivariable analysis, risk factors associated with major complications were Canadian Cardiovascular Society angina class (adjusted hazard ratio [HR], 3.70 for class 2 to 4 versus 0 to 1; P=0.027) and multiple previous procedures on the pocket (adjusted HR, 3.35 for >1 versus 1; P=0.058). Risk factors associated with any complication were the use of antiarrhythmic therapy (adjusted HR, 6.29; P=0.001), implanter volume (adjusted HR 10.4 for <60/y versus >120/y, P=0.026), and Canadian Cardiovascular Society angina class (adjusted HR, 3.00 for class 2 to 4 versus 0 to 1; P=0.031). In a Cox model with a time-dependent variable of major complication within 45 days after replacement, major complications after ICD replacement were associated with an increased risk of mortality at 45, 90, and 180 days (adjusted HR, 9.61, 12.69, and 6.41, respectively; P=0.002 to 0.039). CONCLUSIONS: Risk factors associated with complications after ICD replacement include the presence of angina, antiarrhythmic therapy, increased number of previous procedures, and low implanter volume. Major complications may be associated with increased risk of subsequent mortality.

Evaluation of early complications related to De Novo cardioverter defibrillator implantation insights from the Ontario ICD database.

OBJECTIVES: This study examined the predictors of early complications after defibrillator implantation. BACKGROUND: Although implantable cardioverter-defibrillators are widely used, predictors of procedural complications and the consequences of these events have not been determined. METHODS: In a prospective, multicenter, population-based clinical outcomes registry of all newly implanted defibrillator patients at 18 centers in Ontario, Canada, we examined 45-day complications and all-cause mortality from February 2007 to May 2009. Complications were determined longitudinally and were categorized as direct implant-related or indirect events. RESULTS: Among 3,340 patients (mean age 63.8 +/- 12.5 years, 78.5% men), major complications occurred in 4.1% of de novo procedures. Compared with those undergoing a single-chamber device, implantation of a cardiac resynchronization defibrillator (adjusted hazard ratio [HR]: 2.17, 95% confidence interval [CI]: 1.38 to 3.43, p < 0.001) or dual-chamber device (adjusted HR: 1.82, 95% CI: 1.19 to 2.79, p = 0.006) was associated with increased risk of major complications. Major complications were increased in women (adjusted HR: 1.49, 95% CI: 1.02 to 2.16, p = 0.037) and when left ventricular end-systolic dimension exceeded 45 mm (adjusted HR: 1.54, 95% CI: 1.08 to 2.20, p = 0.018). Major complications (excluding death) occurring early after defibrillator implantation were associated with increased adjusted risk of subsequent death up to 180 days after defibrillator implant (adjusted HR: 3.70, 95% CI: 1.64 to 8.33, p = 0.002). Direct implant-related complications were associated with increased risk of early death (adjusted HR: 24.89, p = 0.01), whereas indirect clinical complications conferred increased risk of near-term death (adjusted HR: 12.35, p < 0.001) after defibrillator implantation. CONCLUSIONS: Complications after de novo defibrillator implantation were strongly associated with device type. Major complications were associated with increased risk of mortality.