Red blood cell omega-3 fatty acids and the risk of ventricular arrhythmias in patients with heart failure.

BACKGROUND: Epidemiological studies support the protective effect of omega-3 fatty acids on sudden cardiac death. However, patients with structural heart disease and an implantable cardioverter defibrillator (ICD) showed no effect or even a proarrhythmic response to fish oil supplementation. Animal studies suggest different electrophysiologic effects of circulating and incorporated omega-3 fatty acids. METHODS: In 102 ICD patients in New York Health Association functional class II or III, the fatty acid composition of red blood cells was analyzed by gas chromatography. The omega-3 index was calculated from eicosapentaenoic acid and docosahexaenoic acid. Patients were followed for 1 year, and ventricular arrhythmias requiring antitachycardic therapy were analyzed. Twenty-five healthy subjects served as control. RESULTS: In ICD patients, the fatty acid profile was significantly altered and the baseline omega-3 index was significantly elevated, as compared to control subjects (5.12% +/- 0.87% vs 4.24% +/- 0.96%, P < .001). Kaplan-Meier estimates of probability of ventricular arrhythmias showed significant differences among quartiles of the omega-3 index. Twelve percent of patients in the lowest quartile had ventricular arrhythmias, as compared to 54% of patients in the highest quartile (P = .022). In a multivariate analysis, the omega-3 index was the only independent predictor for ventricular arrhythmias up to 9 months. At 12 months, a reduced ejection fraction was an additional risk predictor. CONCLUSIONS: In heart failure patients, the red blood cell fatty acid profile is altered. Omega-3 fatty acids are elevated and predict the risk of ventricular arrhythmias.

Atrial distribution of connexin 40 and 43 in patients with intermittent, persistent, and postoperative atrial fibrillation.

BACKGROUND: Sustained atrial fibrillation (AF) causes alterations in atrial electrical and structural properties. Conflicting data regarding the structural remodeling of the gap junction proteins connexin (Cx) 40 and 43 in human and animal studies exists. We investigated the amount and distribution of Cx40 and Cx43 in three subtypes of AF. METHODS: In 50 patients undergoing coronary artery bypass graft and/or mitral or aortic valve surgery, right atrial appendages were taken and examined with immunoconfocal microscopy. Retrospectively, four groups were built: (1) sinus rhythm pre- and postoperative (SR, n=20), (2) intermittent AF, but SR prior to surgery (intAF, n=6), (3) postoperative AF (popAF, n=12), and (4) persistent AF, at least 3 month prior to surgery (persAF, n=12). We analyzed the amount of Cx40 and Cx43 and the degree of fibrosis in three randomly selected areas of each sample. RESULTS: As compared with SR, the amount of Cx40 was significantly reduced by 53% in persAF. The distribution pattern of Cx40 was heterogeneous in patients with SR, intAF, and popAF, whereas patients with persAF showed similar densities of Cx40 in the three examined areas. We found no significant difference in the amount of Cx43 between the four groups. The distribution pattern of Cx43 was heterogeneous in all four groups. The Cx40/Cx43 ratio was significantly reduced in patients with popAF and persAF by 51% and 53%, respectively. No difference was seen in the degree of fibrosis between the four groups. CONCLUSIONS: In this study, sustained AF leads to a reduction in the amount of Cx40. Together with a specific Cx40/Cx43 ratio, this may contribute to localized conduction abnormalities, facilitating the self-perpetuation of re-entry pathways in AF. In the time course of structural atrial remodeling these changes seem to be earlier than a concomitantly developing fibrosis.

Is electrical stimulation during administration of catecholamines required for the evaluation of success after ablation of atrioventricular node re-entrant tachycardias?

OBJECTIVES: The purpose of this study was to answer the question of whether stimulation after administration of catecholamines is mandatory for identifying unsuccessful ablations of atrioventricular node re-entrant tachycardia (AVNRT). BACKGROUND: The success of radiofrequency (RF) catheter ablation in AVNRT is confirmed in many centers by noninducibility of tachycardias during stimulation after the administration of catecholamines. METHODS: A total of 131 patients (81 women and 50 men; mean age 53.6 +/- 13.7 years [range 20 to 77]) were studied. Electrical stimulation was performed without and with the beta-adrenergic amine Orciprenaline (metaproterenol) before and after RF catheter ablation. RESULTS: In 100 patients (76.3%; confidence interval [CI] 68.1% to 83.3%) an AVNRT was inducible without administration of Orciprenaline. Thirty minutes after the initially successful ablation in 95 patients, tachycardia was inducible in none of these patients, not even after Orciprenaline administration. In the 31 patients (23.7%; CI 16.7% to 31.9%) in whom there was no tachycardia inducible before ablation, Orciprenaline was given, and the stimulation protocol was repeated. In only five patients (3.8%; CI 1.3% to 8.7%) was there still no tachycardia inducible. After an initially successful ablation in the 26 patients who had inducible tachycardias with Orciprenaline before ablation, no tachycardia could be re-induced. After Orciprenaline, the tachycardia was inducible again in only one patient. CONCLUSIONS: Only patients who require catecholamines for tachycardia induction before ablation need catecholamines for control of the success of the ablation of AVNRT.