Damian P. Redfearn

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.).

Esophageal Temperature Monitoring During Radiofrequency Ablation of Atrial Fibrillation

Introduction: Ablative strategies for atrial fibrillation have centered on the left atrium, in particular the pulmonary veins. An emphasis on ablating outside the ostia of the pulmonary veins appears to have reduced the risk of pulmonary vein stenosis. Unfortunately, ablation in the posterior left atrium has been reported to result in fatal atrio‐esophageal fistula.

Recommendations for the use of genetic testing in the clinical evaluation of inherited cardiac arrhythmias associated with sudden cardiac death: Canadian Cardiovascular Society/Canadian Heart Rhythm Society joint position paper.

The era of gene discovery and molecular medicine has had a significant impact on clinical practice. Knowledge of specific genetic findings causative for or associated with human disease may enhance diagnostic accuracy and influence treatment decisions. In cardiovascular disease, gene discovery for inherited arrhythmia syndromes has advanced most rapidly. The arrhythmia specialist is often confronted with the challenge of diagnosing and managing genetic arrhythmia syndromes. There is now a clear need for guidelines on the appropriate use of genetic testing for the most common genetic conditions associated with a risk of sudden cardiac death. This document represents the first ever published recommendations outlining the role of genetic testing in various clinical scenarios, the specific genes to be considered for testing, and the utility of test results in the management of patients and their families.

Cardiac resynchronization therapy for the treatment of sleep apnoea: a meta-analysis

AIMS Sleep apnoea (SA) is a common problem among congestive heart failure (CHF) patients. Evidence has shown that cardiac resynchronization therapy (CRT) reduces morbidity and mortality associated with CHF. The aim of this paper was to review studies evaluating the reduction of the Apnoea-Hypopnoea Index (AHI) in patients with SA after treatment with CRT and to perform a meta-analysis to estimate the true effect of CRT on SA. METHODS AND RESULTS A systematic electronic literature search was conducted in Medline and Embase to identify studies reporting on the effects of CRT on SA. A hand search of five major cardiology societies was performed to identify any unpublished studies through structured abstracts submitted to conference proceedings. To be eligible for inclusion, studies had to include a comparison of CRT vs. no pacing and use AHI as an outcome. Non-English studies were excluded. Nine manuscripts and five abstracts were identified for review. Six manuscripts and three abstracts were included in meta-analysis, which included 170 patients. After treatment with CRT, a significant reduction in AHI was found in patients with central sleep apnoea (CSA) with a mean reduction of -13.05 (CI -16.74 to -9.36; P < 0.00001) but not in patients with obstructive sleep apnoea (13.32; CI -9.04 to 2.39; P = 0.25). CONCLUSION Cardiac resynchronization therapy reduces the severity of SA. Major effects are seen in patients with CSA. The presence of SA may be an additional consideration when deciding on which heart failure patients will receive CRT.

Cavotricuspid isthmus conduction is dependent on underlying anatomic bundle architecture : Observations using a maximum voltage-guided ablation technique

Objectives: We hypothesized an ablation strategy directly targeting muscle bundles might demonstrate functionally distinct “routes” of conduction, potentially shortening ablation times.

Electrocardiography Pitfalls and Artifacts: The 10 Commandments

Artifacts are common in patients who require ECG monitoring. Artifacts can simulate arrhythmias such as atrial flutter and ventricular tachycardia and lead to inappropriate treatment. Electrode and lead misplacements are another common pitfall and can lead to ECG changes that may be interpreted as ischemic in origin and can mimic serious arrhythmias. A simplified algorithm (REVERSE is the mnemonic) may help clinicians correctly identify both suspected electrode misplacements and artifacts.

New-onset atrial fibrillation after cavotricuspid isthmus ablation: identification of advanced interatrial block is key

AIMS A significant proportion of patients develop atrial fibrillation (AF) following cavotricuspid isthmus (CTI) ablation for typical atrial flutter (AFl). The objective of this study was to assess whether the presence of advanced interatrial block (aIAB) was associated with an elevated risk of AF after CTI ablation in patients with typical AFl and no prior history of AF. METHODS AND RESULTS This study included patients with typical AFl and no prior history of AF that were referred for CTI ablation. Patients were excluded when they had received repeat ablations or did not demonstrate a bidirectional block. In all patients, a post-ablation electrocardiogram (ECG) in sinus rhythm was evaluated for the presence of aIAB, defined as a P-wave duration ≥120 ms and biphasic morphology in the inferior leads. New-onset AF was identified from 12-lead ECGs, Holter monitoring, and device interrogations. The cohort comprised 187 patients (age 67 ± 10.7 years; ejection fraction 55.8 ± 11.2%). Advanced interatrial block was detected in 18.2% of patients, and left atrium was larger in patients with aIAB compared with those without aIAB (46.2 ± 5.9 vs. 43.1 ± 6.0 mm; P = 0.01). Over a median follow-up of 24.2 months, 67 patients (35.8%) developed new-onset AF. The incidence of new-onset AF was greater in patients with aIAB compared with those without aIAB (64.7 vs. 29.4%; P < 0.001). After a comprehensive multivariate analysis, aIAB emerged as the strongest predictor of new-onset AF [odds ratio (OR) 4.2, 95% confidence interval (CI): 1.9-9.3; P < 0.001]. CONCLUSION Advanced interatrial block is a key predictor for high risk of new-onset AF after a successful CTI ablation in patients with typical AFl.

Acquired Long QT Interval: A Case Series of Multifactorial QT Prolongation

Acquired long QT (LQT) interval is thought to be a consequence of drug therapy and electrolyte disturbances.

Electromagnetic Interference of Communication Devices on ECG Machines

Use of communication devices in the hospital environment remains controversial. Electromagnetic interference (EMI) can affect different medical devices. Potential sources for EMI on ECG machines were systematically tested.

It's time to wake up!: sleep apnea and cardiac arrhythmias

Obstructive sleep apnea (OSA) syndrome is a common breathing disorder, affecting ∼5% of North American adults, the prevalence in men being almost twice that of women.1 The diagnosis is suspected by history and often body habitus, but requires confirmation with a formal sleep study. Polysomnography is the gold-standard study for the diagnosis of OSA. It determines the severity of OSA by measuring the apnea-hypopnoea index (AHI), which is the number of apnoeic and hypopnoeic episodes that occur during 1 h. The condition is associated with increased cardiovascular morbidity and mortality, somnolence, neurocognitive dysfunction, mood disorders, and an increased risk of motor vehicle accidents; despite this, it is usually under-diagnosed (20–30% depending on clinical scenario).2–8 Researchers have demonstrated an increased incidence of cardiac arrhythmias among patients with OSA.9 Interestingly, however, there has been no systematic effort to identify the prevalence of OSA among patients with cardiac arrhythmias. Early reports described an increased association between OSA and bradyarrhythmias.10 This led to an intense focus on the role of pacemakers as …