New-onset atrial fibrillation as first clinical manifestation of latent Brugada syndrome: prevalence and clinical significance

AIMS

To evaluate the prevalence, clinical significance, and prognosis of latent Brugada syndrome (BrS) in patients with new-onset atrial fibrillation (AF) unmasked by class 1C antiarrhythmic drugs.

METHODS AND RESULTS

Between January 2000 and June 2008, all consecutive patients with new-onset AF, who after flecainide exhibited typical Brugada ECG pattern, underwent electrophysiologic, pharmacologic, and genetic testing. Among 346 patients [median age 53 years; interquartile range (IQR), 15], 11 (3.2%; median age 51 years; IQR, 19) diagnosed as lone AF exhibited typical Brugada ECG pattern. Genetic testing was negative. Ventricular tachycardia/ventricular fibrillation (VT/VF) was induced by electrophysiologic testing (five patients) or during flecainide infusion (one patient). Six patients with type 1 ECG pattern and inducible VT/VF underwent ICD implantation. During a median follow-up of 31.5 months (range: 10-85) after ICD implantation, three patients developed BrS and one of them experienced VF. Patients without ICD (five patients) remained asymptomatic during a median follow-up of 74 months. Persistent type 1 pattern occurred only in the three patients who developed BrS.

CONCLUSION

This study, for the first time, reveals the prevalence of latent BrS in patients with new-onset lone AF, which may precede VT/VF. Persistence of type 1 and ventricular tachyarrhythmias inducibility represents a marker of electrical instability leading to sudden death.

Cardiac electrophysiology in diabetes

Patients with diabetes mellitus are at higher risk of cardiac arrhythmias and sudden death. Although there are several animal and human studies on this topic, the pathophysiology of the increased electrical vulnerability in diabetes is complex and remain undefined. It is conceivable that an interplay of several concomitant factors may facilitate the occurrence of arrhythmias. Atherosclerosis as well as microvascular disease, which are increased in diabetic patients, may facilitate myocardial ischemia that predisposes to cardiac arrhythmias and sudden death. In addition, autonomic neuropathy and/or cardiac repolarization abnormalities such as prolonged QT interval and altered T-waves of the diabetic heart also increases electrical instability. Therefore, all these factors may simultaneously contribute to create an electrical instability leading to cardiac arrhythmias and sudden cardiac death. Recently, we have demonstrated that diabetes is the strongest predictor of atrial fibrillation (AF) progression and that diabetic patients frequently have asymptomatic episodes of AF with silent arrhythmia progression. Another recent study has reported that patients with type 2 diabetes and AF are at substantially higher risk of death of any cause compared with those without AF. These seminal studies emphasize that AF in diabetic patients should be regarded as a prognostic marker of adverse outcome and then a prompt aggressive management of all risk factors is required. In conclusion, diabetes mellitus significantly alters the cardiac electrophysiology throughout several complex mechanisms greatly contributing to create an electrical instability of the heart, which may lead to potentially life-threatening arrhythmias and sudden cardiac death.

Clinical Experience with a Novel, Irrigated, Flexible Tip Ablation Catheter to Optimise Therapy Delivery

Innovative technologies are being developed to make current ablation procedures safer and easier. Sometimes conventional ablation catheters cannot easily adapt to anatomical targets, making radiofrequency applications challenging, time consuming or even ineffective. The Cool Flex is a novel, flexible and fully-irrigated tip catheter with an innovative design and various angular orientations to better adapt the ablation tip to the surrounding tissue. Here, peliminary experience with this new ablation catheter is reported in the treatment of different tachyarrhythmias, including slow and accessory pathway ablation, cavotricuspid isthmus-dependent atrial flutter and atrial fibrillation. One or two radiofreqency applications may be sufficient to eliminate the arrhythmogenic substrate in most patients without complications.

Asymptomatic Ventricular Preexcitation

Background— Sudden cardiac death can be the first clinical presentation of asymptomatic ventricular preexcitation.

Methods and Results— From 1995 to 2005, we prospectively collected clinical and electrophysiological data among 293 adults with asymptomatic ventricular preexcitation (61.4% males; median age, 36 years; interquartile range [IQR], 28 to 47.5). After electrophysiological testing, patients were prospectively followed, taking no drugs. The primary end point of the study was the occurrence of a first arrhythmic event. Predictors of arrhythmic events were analyzed by univariate and multivariate Cox models. Over a median follow-up of 67 months (minimum to maximum, 8 to 90), after electrophysiological testing, 262 patients (median age, 37 years; IQR, 30 to 48) did not experience arrhythmic events, remaining totally asymptomatic, whereas 31 patients (median age, 25 years; IQR, 22 to 29; median follow-up, 27 months; minimum to maximum, 8 to 55) had a first arrhythmic event, which was potentially life-threatening in 17 of them (median age, 24 years; IQR, 20 to 28.5; median follow-up, 25 months; minimum to maximum, 9 to 55). Potentially life-threatening tachyarrhythmias resulted in resuscitated cardiac arrest (1 patient), presyncope (7 patients) syncope (4 patients), or dizziness (5 patients). In multivariate analysis age ( P =0.004), inducibility ( P =0.001) and anterograde effective refractory period of the accessory pathway ≤250 ms ( P =0.001) predicted potentially life-threatening arrhythmias.

Conclusions— These results indicate that prognosis of adults who present with asymptomatic ventricular preexcitation is good, and the risk of a significant event is small. Short anterograde effective refractory period of the accessory pathway and inducibility at baseline are independent predictors of potentially life-threatening arrhythmic events, and the risk decreases with increasing age.

Mapping and ablation: a worldwide perspective

Currently, many ablative techniques have reported excellent long-term results in restoring and maintaining sinus rhythm among patients with paroxysmal and persistent AF. Catheter ablation of AF should not be performed too late over time when recurrent paroxysmal AF progresses to the persistent or to the permanent form. Among patients with permanent AF, the stepwise approach requires very extensive lesions in both the left and right atrium to obtain the same success rate as reported by CPVA as performed in Milan many years ago. Long-term prospective multicenter randomized studies comparing the impact of medical therapy with catheter ablation strategy on "hard" outcomes such as morbidity and mortality are required to better define the patient population that may mostly benefit from ablation at the lowest risk and acceptable cost.

A Randomized Trial of Circumferential Pulmonary Vein Ablation Versus Antiarrhythmic Drug Therapy in Paroxysmal Atrial Fibrillation

OBJECTIVES

We compared ablation strategy with antiarrhythmic drug therapy (ADT) in patients with paroxysmal atrial fibrillation (PAF).

BACKGROUND

Atrial fibrillation (AF) ablation strategy is superior to ADT in patients with an initial history of PAF, but its role in patients with a long history of AF as compared with ADT remains a challenge.

METHODS

One hundred ninety-eight patients (age, 56 +/- 10 years) with PAF of 6 +/- 5 years' duration (mean AF episodes 3.4/month) who had failed ADT were randomized to AF ablation by circumferential pulmonary vein ablation (CPVA) or to the maximum tolerable doses of another ADT, which included flecainide, sotalol, and amiodarone. Crossover to CPVA was allowed after 3 months of ADT.

RESULTS

By Kaplan-Meier analysis, 86% of patients in the CPVA group and 22% of those in the ADT group who did not require a second ADT were free from recurrent atrial tachyarrhythmias (AT) (p < 0.001); a repeat ablation was performed in 9% of patients in the CPVA group for recurrent AF (6%) or atrial tachycardia (3%). At 1 year, 93% and 35% of the CPVA and ADT groups, respectively, were AT-free. Ejection fraction, hypertension, and age independently predicted AF recurrences in the ADT group. Circumferential pulmonary vein ablation was associated with fewer cardiovascular hospitalizations (p < 0.01). One transient ischemic attack and 1 pericardial effusion occurred in the CPVA group; side effects of ADT were observed in 23 patients.

CONCLUSIONS

Circumferential pulmonary vein ablation is more successful than ADT for prevention of PAF with few complications. Atrial fibrillation ablation warrants consideration in selected patients in whom ADT had already failed and maintenance of sinus rhythm is desired. (A Controlled Randomized Trial of CPVA Versus Antiarrhythmic Drug Therapy in for Paroxysmal AF: APAF/01; http://clinicaltrials.gov/ct/show; NCT00340314).

Ablation of atrial fibrillation

Fueled by dissatisfaction with pharmacologic strategies to treat atrial fibrillation (AF), the results of basic and clinical investigation into the understanding of AF initiation and maintenance mechanisms, and the explosive development in catheter-based technologies, AF ablation has matured from a purely investigational technique to a preferred, safe, and effective approach for curing AF, particularly with the circumferential approach. Future insights and developments will help us refine our treatment strategies in patients with permanent AF, making chronic AF ablation safer, faster, and more effective. As the prevalence of AF in the general population continues to increase, the purpose of optimizing our strategy becomes evermore important and more pressing.