Exome sequencing of a family with lone, autosomal dominant atrial flutter identifies a rare variation in ABCB4 significantly enriched in cases.

BACKGROUND: Lone atrial flutter (AFL) and atrial fibrillation (AF) are common and sometimes consequential cardiac conduction disorders with a strong heritability, as underlined by recent genome-wide association studies that identified genetic modifiers. Follow-up family-based genetic analysis also identified Mendelian transmission of disease alleles. Three affected members were exome-sequenced for the identification of potential causative mutations, which were subsequently validated by direct sequencing in the other 3 affected members. Taqman assay was then used to confirm the role of any mutation in an independent population of sporadic lone AFL/AF cases. RESULTS: The family cluster analysis provided evidence of genetic inheritance of AFL in the family via autosomal dominant transmission. The exome-sequencing of 3 family members identified 7 potential mutations: of these, rs58238559, a rare missense genetic variant in the ATP-binding cassette sub-family B, member 4 (ABCB4) gene was carried by all affected members. Further analysis of 82 subjects with sporadic lone AF, 63 subjects with sporadic lone AFL, and 673 controls revealed that the allele frequency for this variation was significantly higher in cases than in the controls (0.05 vs. 0.01; OR = 3.73; 95% CI = 1.16-11.49; P = 0.013). CONCLUSIONS: rs58238559 in ABCB4 is a rare missense variant with a significant effect on the development of AFL/AF.

Acute superior vena cava syndrome after insertion of implantable cardioverter defibrillator.

We describe a rare case of superior vena cava syndrome that occurred a few hours after insertion of an implantable cardioverter defibrillator through the right subclavian vein in a patient with previous dual chamber DDD pacemaker. The patient was successfully treated with anticoagulant therapy showing a fast clinical and instrumental improvement.

Pulmonary vein isolation as index procedure for persistent atrial fibrillation: One-year clinical outcome after ablation using the second-generation cryoballoon.

BACKGROUND: No data are available about the clinical outcome of pulmonary vein isolation (PVI) as an index procedure for persistent atrial fibrillation (PersAF) ablation using the second-generation cryoballoon (CB-Adv). OBJECTIVE: The purpose of this study was to assess the 1-year efficacy of PVI as an index procedure for PersAF ablation using the novel CB-Adv. METHODS: Sixty-three consecutive patients (45 male [71.4%], mean age 62.7 ± 9.7 years) with drug-refractory PersAF undergoing PVI using the novel CB-Adv were enrolled. Follow-up was based on outpatient clinic visits including Holter ECGs. Recurrence of atrial tachyarrhythmias (ATas) was defined as a symptomatic or documented episode >30 seconds. RESULTS: A total of 247 PVs were identified and successfully isolated with a mean of 1.7 ± 0.4 freezes. Mean procedural and fluoroscopy times were 87.1 ± 38.2 minutes and 14.9 ± 6.1 minutes, respectively. Among 26 of 63 patients (41.3%) presenting with AF at the beginning of the procedure, 7 of 26 (26.9%) converted to sinus rhythm during ablation. Phrenic nerve palsy occurred in 4 of 63 patients (6.3%). At 1-year follow-up, after a 3-month blanking period (BP), 38 of 63 patients (60.3%) were in sinus rhythm. Because of ATa recurrences, 9 patients underwent a second procedure with radiofrequency ablation showing a pulmonary vein reconnection in 4 right-sided PVs (44.4%) and 3 left-sided PVs (33.3%). Multivariate analysis demonstrated that PersAF duration (P = .01) and relapses during BP (P = .04) were independent predictors of AT recurrences. CONCLUSION: At 1-year follow-up, freedom from ATas following PersAF ablation with the novel CB-Adv is 60%. Phrenic nerve palsy is the most common complication. PersAF duration and relapses during the BP appear to be significant predictors of arrhythmic recurrences.

The linear ablation of atrial fibrillation in the right atrium: can the isthmus ablation improve its efficacy?

OBJECTIVES: The aims of this study were to compare the efficacy of a 2- versus a 3 RF lesions ablation procedure in the RA in patients with paroxysmal AF, and to map right atrial activation during AF. BACKGROUND: RF catheter-mediated ablation lines mimicking the Maze operation have been proposed as a novel curative approach for AF. The relationship between this type of ablation and right atrial mapping has not been extensively studied. METHODS: Twenty-four patients with recurrent, drug-refractory, paroxysmal AF underwent an extensive mapping of the RA before attempting linear lesion RF ablation. Patients were divided into two groups: 15 patients received two linear lesions (Group 1), 9 patients three linear lesions (Group 2). RESULTS: One-month success rate AF did not recur in 40% of Group 1 patients (6/15) and in 66% (6/9) of Group 2 patients. 27% of patients in Group 1 and 11% of patients in Group 2 had recurrences controlled by drugs. No benefit in 33% of Group 1 patients and 22% of Group 2. Long-term follow-up In the absence of any drug treatment, no AF recurrences were observed in 26% of Group 1 patients (FU: 23 to 47 months) and 55% of Group 2 (FU: 14 to 23 months). No complications were reported. CONCLUSIONS: Right atrial linear ablation is safe and may be proposed for AF treatment in selected patients.

Coronary vasospasm and aborted sudden death treated with an implantable defibrillator and stenting.

In selected patients suffering from variant angina, an implantable cardioverter-defibrillator (ICD) and coronary stenting can be helpful to prevent sudden death and treat coronary artery spasm. We report a case of a 47-year-old woman suffering from variant angina, who experienced an episode of ventricular fibrillation promptly cardioverted. After coronary angiography documentation of a mild atherosclerosis, an ICD was implanted and oral nitrates and calcium antagonists were prescribed. The recurrence of chest pain and palpitations prompted us to perform a second coronary angiography that documented a focal coronary artery spasm successfully treated with stent implantation. No other episodes of angina or ventricular arrhythmia were documented during the following 6 months of follow-up.

Myocardial ischemia due to a coronary-pulmonary fistula treated with coil embolization.

We describe one case of myocardial ischemia due to a coronary-pulmonary fistula, successfully treated with coils. Coronary fistulae are a rare cause of angina in adults with normal coronary arteries. Percutaneous treatment represents an alternative to surgery and may be offered as a relatively low risk procedure. The choice between surgical and percutaneous treatment must take into account clinical and anatomical considerations.

Fatty acid percentage in erythrocyte membranes of atrial flutter/fibrillation patients and controls.

PURPOSE: Several epidemiological published data support the protective role of omega-3 consumption in coronary artery disease, sudden cardiac death and ventricular arrhythmias, but interestingly, this is not the case for atrial arrhythmias. The purpose of this study is to evaluate different fatty acid profile between AF/AFL subjects and healthy controls. METHODS: Gas chromatography was employed to determine fatty acid percentage of erythrocyte membranes from 40 idiopathic AFL/AF patients and 53 healthy control subjects. RESULTS: AFL/AF erythrocyte membranes had significantly lower percentage of saturated fatty acid (43.1 +/- SD2.2 versus 47.8 +/- SD9.6, p < 0.001), monounsaturated fatty acid (18.2 +/- SD2.5 versus 22.6 +/- SD5.2, p < 0.001) and total trans fatty acid (0.2 +/- SD0.1 vs 1.3 +/- SD1.1, p < 0.001) than controls. Furthermore, fatty acid (FA) profiles of arrhythmic individuals showed an increased percent of total polyunsaturated fatty acid (PUFA) (36.7 +/- SD2.4 versus 26.4 +/- SD10.4, p < 0.001), PUFA n-3 (5.3 +/- SD1.1 versus 2.8 +/- SD1.8, p < 0.001) and n-6 (31.4 +/- SD2.2 versus 23.5 +/- SD9.9, p < 0.001). CONCLUSION: This study shows that the erythrocyte membranes FA composition of AF/AFL subjects differs from that of healthy controls.

Efficacy of automatic mode switching in DDDR mode pacemakers: the most 2 study.

BACKGROUND: Effective automatic mode switching (AMS) algorithms capable of detecting a range of supraventricular tachyarrhythmias is important given evidence of atrial fibrillation (AF), atrial flutter (AFL), and atrial tachycardia (AT) post-implantation of pacemakers. OBJECTIVES: The aim of the study was to assess the efficacy, defined as ability to detect a specific atrial rate and activate AMS, of five different AMS mechanisms during simulation of AF, AFL, and AT. MATERIALS AND METHODS: A total of 48 subjects (35 men, 13 women; mean age: 69 +/- 8 years) implanted with DDDR pacemakers utilizing five different AMS mechanisms (mean atrial rate, rate cut-off, complex 'fallback' algorithm, retriggerable atrial refractory period, and physiological band 'beat-to-beat') were tested using an external electronic device that simulated the occurrence of supraventricular tachyarrhythmias. AF, AFL, and AT were simulated by delivering low voltage pulse trains at 350, 250 and 160 beats/min, respectively. RESULTS: Mean efficacy for all AMS mechanisms was 81% [range: 57% to 100%] at 350 beats/min, 81% [range: 57-100%] at 250 beats/min, and 79% [range: 57-100%] at 160 beats/min. The AMS mechanisms that yielded 100% efficacy were the rate cut-off and physiological band 'beat-to-beat.' CONCLUSION: Not all AMS algorithms are equally efficacious at detecting atrial arrhythmias and subsequently activating AMS. Our results suggest that the most efficacious AMS algorithms are those that use rate cut-off and physiological band 'beat-to-beat' to detect supraventricular tachyarrhythmias.

Is there a link between atrial fibrillation and certain bacterial infections?

The pathogenesis of atrial fibrillation (AF), the most common cardiac dysrhythmia, remains unknown. However, many recent studies point to an association between AF and inflammation because of a demonstrable significant correlation between the dysrhythmia and various biomarkers of inflammation. For example, C-reactive protein (CRP), a sensitive biomarker of systemic inflammation, has been reported to be significantly higher in patients with AF compared with a control group with no history of atrial dysrhythmias. Histological anomalies in the atria of patients with AF have also been observed. These anomalies may have an inflammatory basis, although it is not known if the structural changes within the atria of patients with AF are a cause or consequence of the dysrhythmia. Given the suggested involvement of inflammation with this dysrhythmia, an initiating factor for inflammation has been sought. Chronic bacterial infection is the most likely event to initiate and maintain an inflammatory process. Recently, bacteria infections have been hypothesized to be involved in the pathogenesis of AF, and Helicobacter pylori and Chlamydia pneumoniae are two bacteria that have aroused interest. Here, we give a brief overview of AF and then specifically explore the recent evidence that suggests that AF may be caused by bacterial infection(s) in certain patients.

Is Helicobacter pylori a cause of atrial fibrillation?

Inflammation has been implicated in the pathogenesis of cardiovascular diseases. C-reactive protein, a sensitive marker of systemic inflammation, has recently been reported to be significantly higher in patients with atrial fibrillation (AF) compared with a control group with no history of atrial arrhythmia. Elevated C-reactive protein levels in patients with AF reflects an underlying inflammatory process. Histological anomalies in the atria of patients with AF have also been observed. These anomalies may have an inflammatory basis, although it is not known if any structural changes within the atria are a cause or a consequence of the arrhythmia. Ongoing chronic infection(s) has been suggested as a possible cause of the inflammatory process demonstrated in patients with AF. Helicobacter pylori, a Gram-negative bacterium more commonly known for infecting the gastric mucosa and causing peptic ulcers, is a noncardiac factor that has been controversially reported to be associated with cardiovascular diseases. This article gives a brief overview of AF and specifically explores the recent evidence that suggests that Helicobacter pylori infection causes AF.

Early EPS/ICD strategy in survivors of acute myocardial infarction with severe left ventricular dysfunction on optimal beta-blocker treatment. The BEta-blocker STrategy plus ICD trial.

AIMS: This multicentre prospective randomised trial was undertaken to evaluate the usefulness of an electrophysiological study (EPS)-guided/implantable cardioverter defibrillator (ICD) strategy in patients at high risk of sudden death (SD) early after myocardial infarction (MI). Previous studies have shown the benefits of such a strategy only in high-risk patients late after MI. METHODS AND RESULTS: We enrolled 143 survivors of acute MI (<1 month) with left ventricular ejection fraction < or = 35% and either frequent (> or =10/h) premature ventricular complexes (PVCs), or depressed heart rate variability (SDNN < 70 ms) or abnormal signal-averaged ECG, who were able to tolerate optimised beta-blocker therapy (68 +/- 40 mg/day of metoprolol). Of these, 138 were randomised, in a 2:3 ratio, to two therapeutic strategies: conventional (CONV) strategy (n = 59) or EPS-guided/ICD strategy (n = 79). The latter resulted in ICD implantation in 24 inducible patients and in CONV therapy in the remaining 55. During a mean follow-up of 540 +/- 378 days, 26 patients (19%) died: nine (6.5%) SD, nine (6.5%) non-SD, and four (3%) non-cardiac death; in four patients (3%) the cause of death was unknown. The actuarial overall mortality for the CONV and EPS-guided/ICD arms was 18% vs 14% after 1 year and 29.5% vs 20% after 2 years, respectively (P = 0.3 and 0.2). CONCLUSIONS: Despite optimal therapy, mortality remains significant in high-risk patients following MI. Although there is a trend in favour of EPS-guided/ICD, our data are insufficient to demonstrate a survival benefit of this strategy early after MI.