Laurence D. Sterns

Radiofrequency ablation vs antiarrhythmic drugs as first-line treatment of paroxysmal atrial fibrillation (RAAFT-2): a randomized trial.

IMPORTANCE Atrial fibrillation (AF) is the most common rhythm disorder seen in clinical practice. Antiarrhythmic drugs are effective for reduction of recurrence in patients with symptomatic paroxysmal AF. Radiofrequency ablation is an accepted therapy in patients for whom antiarrhythmic drugs have failed; however, its role as a first-line therapy needs further investigation. OBJECTIVE To compare radiofrequency ablation with antiarrhythmic drugs (standard therapy) in treating patients with paroxysmal AF as a first-line therapy. DESIGN, SETTING, AND PATIENTS A randomized clinical trial involving 127 treatment-naive patients with paroxysmal AF were randomized at 16 centers in Europe and North America to received either antiarrhythmic therapy or ablation. The first patient was enrolled July 27, 2006; the last patient, January 29, 2010. The last follow-up was February 16, 2012. INTERVENTIONS Sixty-one patients in the antiarrhythmic drug group and 66 in the radiofrequency ablation group were followed up for 24 months. MAIN OUTCOMES AND MEASURES The time to the first documented atrial tachyarrhythmia of more than 30 seconds (symptomatic or asymptomatic AF, atrial flutter, or atrial tachycardia), detected by either scheduled or unscheduled electrocardiogram, Holter, transtelephonic monitor, or rhythm strip, was the primary outcome. Secondary outcomes included symptomatic recurrences of atrial tachyarrhythmias and quality of life measures assessed by the EQ-5D tool. RESULTS Forty-four patients (72.1%) in the antiarrhythmic group and in 36 patients (54.5%) in the ablation group experienced the primary efficacy outcome (hazard ratio [HR], 0.56 [95% CI, 0.35-0.90]; P = .02). For the secondary outcomes, 59% in the drug group and 47% in the ablation group experienced the first recurrence of symptomatic AF, atrial flutter, atrial tachycardia (HR, 0.56 [95% CI, 0.33-0.95]; P = .03). No deaths or strokes were reported in either group; 4 cases of cardiac tamponade were reported in the ablation group. In the standard treatment group, 26 patients (43%) underwent ablation after 1-year. Quality of life was moderately impaired at baseline in both groups and improved at the 1 year follow-up. However, improvement was not significantly different among groups. CONCLUSIONS AND RELEVANCE Among patients with paroxysmal AF without previous antiarrhythmic drug treatment, radiofrequency ablation compared with antiarrhythmic drugs resulted in a lower rate of recurrent atrial tachyarrhythmias at 2 years. However, recurrence was frequent in both groups. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00392054.

Ventricular Tachycardia Ablation versus Escalation of Antiarrhythmic Drugs

BACKGROUND Recurrent ventricular tachycardia among survivors of myocardial infarction with an implantable cardioverter-defibrillator (ICD) is frequent despite antiarrhythmic drug therapy. The most effective approach to management of this problem is uncertain. METHODS We conducted a multicenter, randomized, controlled trial involving patients with ischemic cardiomyopathy and an ICD who had ventricular tachycardia despite the use of antiarrhythmic drugs. Patients were randomly assigned to receive either catheter ablation (ablation group) with continuation of baseline antiarrhythmic medications or escalated antiarrhythmic drug therapy (escalated-therapy group). In the escalated-therapy group, amiodarone was initiated if another agent had been used previously. The dose of amiodarone was increased if it had been less than 300 mg per day or mexiletine was added if the dose was already at least 300 mg per day. The primary outcome was a composite of death, three or more documented episodes of ventricular tachycardia within 24 hours (ventricular tachycardia storm), or appropriate ICD shock. RESULTS Of the 259 patients who were enrolled, 132 were assigned to the ablation group and 127 to the escalated-therapy group. During a mean (±SD) of 27.9±17.1 months of follow-up, the primary outcome occurred in 59.1% of patients in the ablation group and 68.5% of those in the escalated-therapy group (hazard ratio in the ablation group, 0.72; 95% confidence interval, 0.53 to 0.98; P=0.04). There was no significant between-group difference in mortality. There were two cardiac perforations and three cases of major bleeding in the ablation group and two deaths from pulmonary toxic effects and one from hepatic dysfunction in the escalated-therapy group. CONCLUSIONS In patients with ischemic cardiomyopathy and an ICD who had ventricular tachycardia despite antiarrhythmic drug therapy, there was a significantly lower rate of the composite primary outcome of death, ventricular tachycardia storm, or appropriate ICD shock among patients undergoing catheter ablation than among those receiving an escalation in antiarrhythmic drug therapy. (Funded by the Canadian Institutes of Health Research and others; VANISH ClinicalTrials.gov number, NCT00905853.).

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.

Failure rate of the Riata lead under advisory: A report from the CHRS Device Committee

BACKGROUND A unique form of lead failure has been described in the Riata (8-F) and Riata ST (7-F) silicone defibrillation lead degradation of the outer insulation, resulting in the externalization of conductor cables. OBJECTIVE To assess rates of lead revision due to lead failure in Riata leads affected by the Riata advisory. METHODS Nineteen implantable cardioverter-defibrillator implant and follow-up centers were surveyed. RESULTS As of March 1, 2012, there were 5043 known affected leads implanted in Canada. Data on 4358 (86.4%) leads were obtained; 65.3% of these were Riata (8-F) and 32.4% were Riata ST (7-F) leads. The median time from implant to last follow-up was 5 years. Electrical abnormalities were reported in 4.6% of the affected leads; 8.0% of these were found to have concomitant radiographic evidence of externalization. The rate of electrical failure was higher in the 8-F (5.2%) vs 7-F (3.3%) leads (P = .007). Oversensing with or without inappropriate shocks was reported in 39.8% of the leads with confirmed failure. Abnormally high or low impedance values (29.9%) and elevated pacing capture thresholds (43.8%) were frequently reported. One death (0.5%) attributed to lead failure was reported. Among the leads that were replaced, 21% were extracted. Two major complications (1.0%) were attributed to extraction of these leads. CONCLUSIONS The overall rate of lead failure in the Riata (8-F) and Riata ST (7-F) leads is higher than previously reported by using passive surveillance data. The impact of recent advisories related to these leads is not yet apparent.

Cardiac injury after percutaneous catheter ablation for atrial fibrillation

AIMS Small elevations in troponin T levels have been shown with limited radiofrequency (RF) ablation procedures for supraventricular tachycardia, usually to levels below the threshold for ischaemia or infarction. Left atrial catheter ablation for atrial fibrillation (AF) requires far more RF energy, therefore could be expected to have greater elevation in troponin T. We determined troponin T levels before and after ablation in these patients to evaluate the amount of rise with this ablation. METHODS All patients undergoing pulmonary vein isolation (PVI) from May 2004 to October 2004 had troponin T levels measured 4 h following completion of the procedure. The first 30 patients also had a troponin T level measured 1 h prior to PVI to establish a baseline reference. RESULTS Sixty patients were studied, with 81.7% males and a mean age of 54.6 +/- 9.9 years. No patient had underlying structural heart disease. The baseline troponin T level was normal (<0.01 microg/L) in all 30 patients. Post-procedure troponin T levels were elevated in all 60 patients compared with baseline (P < 0.05), with a mean level of 0.85 microg/L and a range of 0.26-1.57 microg/L after an average RF ablation time of 56 +/- 15 min. All levels were above the reference range for diagnosis of acute myocardial infarction (>0.15 microg/L). Troponin T level was not related to the number of RF lesions, RF time, procedure time, or associated external cardioversion. CONCLUSIONS Troponin T elevations occurred in all patients undergoing PVI, to levels at least 20 times the normal concentration, into the range for diagnosis of acute myocardial infarction. Therefore, troponin T would not be specific for ischaemia in the setting of chest pain post-catheter ablation for AF.

Safety, efficacy, and performance of new discrimination algorithms to reduce inappropriate and unnecessary shocks: the PainFree SST clinical study design

INTRODUCTION Implantable cardioverter defibrillator (ICD) shock therapy improves survival of patients at risk for sudden cardiac death. The high sensitivity of ICDs to detect tachycardia events is accompanied by reduced specificity resulting in inappropriate and unnecessary shocks. Up to 30% of ICD patients may experience inappropriate shocks, which are most commonly caused by lead noise, oversensing of T-waves, and supraventricular tachycardias. The new Protecta ICD and cardiac resynchronization therapy devices have been designed to minimize inappropriate and unnecessary shocks through novel SmartShock(TM) technology algorithms targeting these causes. METHODS The PainFree SST study is a prospective, multicentre clinical trial, which will be conducted in two consecutive phases. Phase I will assess safety and any delay that may arise in ventricular fibrillation (VF) arrhythmia detection time using new algorithms. Phase II will evaluate reduction of inappropriate and unnecessary shocks at 1 year of follow-up. Additional objectives will include Quality of Life, healthcare utilization, safety of extending the ventricular tachyarrhythmia/VF interval detection duration (18 out of 24 vs. 30 out of 40 intervals), and reasons for inappropriate shock. Up to 2000 subjects in 150 centres worldwide will be enrolled with a follow-up of at least 1 year. Subjects enrolled in Phase I will continue in Phase II of the study and data from all enrolled subjects will contribute to the analysis of Phase II objectives. CONCLUSION Inappropriate and unnecessary shock delivery remains a significant clinical issue for patients receiving device therapies, which has considerable consequences for patients and the healthcare system. The PainFree SST study will investigate the ability of new algorithms to reduce inappropriate shocks. Results from this study are expected in mid-2013.

Feasibility and safety of outpatient radiofrequency catheter ablation procedures for atrial fibrillation

Introduction Percutaneous catheter ablation for atrial fibrillation (AF) is a procedure performed typically in an inpatient setting. The feasibility and safety of catheter ablation in patients with paroxysmal and persistent AF were evaluated on an outpatient basis. Methods 230 AF ablation procedures were performed in 206 patients (74% male; mean age 56±9 years). Patients were admitted to the hospital outpatient facility in the morning for the AF ablation procedure on the same day. The ablation strategy consisted of wide area circumferential lines around both ipsilateral pulmonary veins. After monitoring in the outpatient service, patients were discharged on the same day, if they were clinically stable. Results Mean procedure time was 201±31 min. Major complications occurred in seven patients (3%). One patient (0.4%) suffered a minor stroke and six patients had pericardial tamponade requiring percutaneous drainage. Patients could be discharged on the same day following 205 (89%) procedures. Among the 148 patients whose clinical outcome was assessed at 6 months, 127 (86%) had a reduction of the total symptomatic AF episodes, compared to pre-ablation, with a complete lack of symptoms in 101 patients (68%). Conclusion Catheter ablation of AF on the day of admission is feasible and safe with a low risk of complications. The vast majority of the patients can be discharged on the same day.

Acute Efficacy and Chronic Follow‐Up of Patients with Non‐Thoracotomy Third Generation Implantahle Defibrillators

Non‐thoracotomy implantation of implantable cardioverter defibrillators (ICDs) has simplified the process of device inserfion, promising to decrease associated procedural coniplications while providing sudden death protection at least equal to epicardial systems. This study presents the acute and chronic results of 110 patients who underwent attempted non‐thoracotomy ICD impiuntation wiih the Medtronic Transvene lead system and PCD model 7217 or 7219. Of the 110 patients attempted, 100 (91%) had the system successfully implanted without the need for an epicar‐dial patch. One patient died 1 week postoperatively of septic shock related to the implantation (0.9% perioperative mortality). During folloiv‐up of 16 ± 11 months, 45% of the patients had an event detected as ventricular tachycardia; 26% of these detections were felt clinically to be due to supraventricular rhythms. Of the remainder, 87% were successfully treated with the first VT therapy, and 98% were terminated by the final therapy; 66% of the patients had at least one episode of ventricular fibrillation, of which 5% were felt to be inappropriate detections; 65% of the appropriate episodes were successfully treated with the first VF therapy, and all were converted by the final therapy. Total mortality at 6, 12, and 24 months was 3%, 11%, and 19% respectively. Only one patient had sudden cardiac death, occurring at 13 months postimplant. Overall, the non‐thoracotomy lead system for this ICD displayed infrequent implant complications and proved to be reliable ai terminating arrhythmias and maintaining a low rate of sudden cardiac death in this high risk popuiation.

Transesophageal echocardiography for the prevention of embolic complications after catheter ablation for atrial fibrillation.

Background: Thromboembolic complications during left‐sided ablations range between 1.5 and 5.4%. Preprocedural TEE has been used to exclude the presence of left atrial thrombi in order to minimize risk. The use of TEE is empiric and it has not been evaluated in contemporary practice.

A trial design for evaluation of empiric programming of implantable cardioverter defibrillators to improve patient management

The delivery of implantable cardioverter defibrillator (ICD) therapy is sophisticated and requires the programming of over 100 settings. Physicians tailor these settings with the intention of optimizing ICD therapeutic efficacy, but the usefulness of this approach has not been studied and is unknown. Empiric programming of settings such as anti-tachycardia pacing (ATP) has been demonstrated to be effective, but an empiric approach to programming all VT/VF detection and therapy settings has not been studied. A single standardized empiric programming regimen was developed based on key strategies with the intention of restricting shock delivery to circumstances when it is the only effective and appropriate therapy. The EMPIRIC trial is a worldwide, multi-center, prospective, one-to-one randomized comparison of empiric to physician tailored programming for VT/VF detection and therapy in a broad group of about 900 dual chamber ICD patients. The trial will provide a better understanding of how particular programming strategies impact the quantity of shocks delivered and facilitate optimization of complex ICD programming.