Rationale and design of a randomised controlled clinical trial on supplemental intake of n-3 fatty acids and incidence of cardiac arrhythmia: SOFA.

BACKGROUND: Evidence from earlier studies indicates that intake of very long-chain n-3 polyunsaturated fatty acids (n-3 PUFA, also named omega-3 fatty acids) as present in fish oil reduces the risk of sudden death. Sudden death forms a major part of mortality from cardiovascular disease and is in most cases a direct consequence of cardiac arrhythmia. n-3 PUFA may exert their protective effect through reducing the susceptibility for cardiac arrhythmia. OBJECTIVE: To investigate the effect of n-3 PUFA on the incidence of recurrent ventricular arrhythmia. This paper presents the rationale, design and methods of the Study on Omega-3 Fatty acids and ventricular Arrhythmia (SOFA) and discusses problems encountered in conducting a multicentre clinical trial on food. DESIGN: A randomised, parallel, placebo-controlled, double blind intervention study, which obeys the guidelines for Good Clinical Practice. SETTING: Multiple cardiology centres in Europe. SUBJECTS: A total of 500 patients with an implantable cardioverter defibrillator (ICD). An ICD detects, treats and stores cardiac arrhythmic events in its memory chip. INTERVENTIONS: Patients receive either 2 g/day of fish oil, containing approximately 450 mg eicosapentaenoic acid and 350 mg docosahexaenoic acid, or placebo for 12 months. PRIMARY OUTCOME: Spontaneous ventricular tachyarrhythmias as recorded by the ICD or all-cause mortality. CONCLUSION: SOFA is designed to answer the question whether intake of n-3 PUFA from fish-a regular food ingredient-can reduce the incidence of life-threatening cardiac arrhythmia. If this proves to be true, increasing the intake of n-3 PUFA could be an easy, effective and safe measure to prevent fatal arrhythmia in the general population.

Fast and slow narrow complex tachycardia in one patient: two of a kind?

A 35-year-old female was referred to our hospital. For more than ten years, she had had complaints of two types of paroxysmal palpitations, both with a sudden onset. The first type was rapid and often accompanied by light-headedness; the second she described as much less rapid, better tolerated, and often terminated by the Valsalva manoeuvre. The incidence and duration of both types of paroxysms were increasing. In the emergency room of the referring hospital, the tachycardia was terminated with intravenous verapamil. The electrophysiological study revealed normal conduction parameters. Premature atrial beats (due to catheter manipulation) or delivered atrial extra stimuli over a wide range easily induced two types of tachycardia. AV node modification by radiofrequency ablation using the posterior approach was performed. With this approach, RF ablation of the caudal extension of the AV node is performed, which modifies the slow pathway, so that the reentrant circuit is interrupted. After this intervention, no tachycardia whatsoever could be induced and during followup (8 months), no recurrent arrhythmia of any kind occurred.

Technique of pulmonary vein isolation by catheter ablation.

In selected patients with atrial fibrillation, the fibrillation episodes may be initiated by single or short bursts of ectopy often originating from one or more pulmonary veins (PVs). Therefore, electrical isolation of these veins by catheter ablation is currently being explored as a treatment modality for patients with paroxysmal and even more permanent types of atrial fibrillation. At present, two different techniques are used: 1) selective ablation of electrical connections between left atrium and myocardial sleeves inside the PVs; and 2) contiguous encircling lesions around and outside the PV ostia. With both techniques, moderate to high success rates have been reported with a limited follow-up duration. Both types of procedure are very complex and require a highly skilful team. With the variable anatomy of the PVs, non-invasively acquired angiographic images may serve as a roadmap for catheter manipulation. Modern three-dimensional catheter navigation techniques can be applied to facilitate accurate catheter positioning with limited fluoroscopic exposure. Experimental and clinical research is needed to define patient selection criteria.

Ten year follow-up after radiofrequency catheter ablation for atrioventricular nodal reentrant tachycardia in the early days forever cured, or a source for new arrhythmias?

BACKGROUND: Radiofrequency (RF) catheter ablation is highly effective with a low complication rate. However, lesions created by RF energy are irreversible, inhomogeneous, and therefore potentially proarrhythmic. OBJECTIVES: The aim of this study was to examine the magnitude and importance of long-term proarrhythmic effects of RF energy. METHODS AND RESULTS: Between 1991 and 1995, 120 patients underwent RF ablation for atrioventricular nodal reentrant tachycardia (AVNRT). Patient data were collected by contacting patients and/or filling out a questionnaire, and medical files were screened for recurrent, documented arrhythmias, pharmacological treatment, and repeated EP study. Referring cardiologists were asked about recurrences of tachyarrhythmias. Fourteen patients (11%) were lost to follow-up. During a mean follow-up of 10 years, six patients died. Recurrences of AVNRT were not any more observed after 3 years after ablation. A total of 29 patients (24%) suffered from new arrhythmias, 6 from type 1 atrial flutter, 6 from atrial tachycardia, 9 from atrial fibrillation, and finally 16 from symptomatic premature atrial contractions (PACs), needing medical treatment or a combination of these arrhythmias. Nine patients underwent pacemaker implantation, 4 after developing procedural atrioventricular (AV) conduction disturbances, 2 after His ablation for permanent atrial fibrillation, 1 patient for sick sinus syndrome, and another 2 patients after developing late AV block, respectively, 7 and 9 years after ablation. CONCLUSION: During long-term follow-up after RF ablation for AVNRT, no AVNRT recurrences were observed, but 29 patients (24%) suffered from new arrhythmias or late AV block. This potential proarrhythmic effect of RF energy promotes the application of alternative energy sources for ablative therapies for cardiac arrhythmias.