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Danon disease is a rare X-linked lysosomal disease causing severe hypertrophic cardiomyopathy (LAMP2 cardiomyopathy) and an extremely poor prognosis in males, with several reported cases of sudden cardiac death despite the use of transvenous implantable cardioverter defibrillators (TV-ICD). We describe a case in which a TV-ICD was unable to defibrillate induced ventricular fibrillation (VF), but a wholly subcutaneous system (S-ICD) was successful in terminating induced VF and spontaneous ventricular tachycardia. These findings have relevance to the selection of device therapy in the management of these individuals and a wider group of young patients with severe hypertrophic cardiomyopathy., (© 2013 Wiley Periodicals, Inc.)

Cardioversion remains an important therapy in the management of atrial fibrillation. Here, we report a case where direct current cardioversion resulted in a sudden dramatic change of heart rate that was associated with multiple ventricular fibrillation arrests in a manner akin to that previously observed post-atrioventricular node ablation., (©2011, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.)

Introduction: The clinical value of cardioversion (CV) of persistent atrial fibrillation (AF) is limited by the high rate of early AF recurrence, which may be related to the persistence of atrial electrical remodeling. We examined the hypothesis that the likelihood of maintaining sinus rhythm after CV of persistent AF is significantly enhanced by a policy of early repeated CV., Methods and Results: Fifty-nine patients with persistent AF underwent internal CV (CV 1). Those patients cardioverted were monitored with daily transtelephonic ECG. In the event of AF recurrence, these patients were admitted rapidly for repeat CV (CV 2) and, if further recurrence occurred, a third CV (CV 3) was performed. Daily ECG monitoring was continued until 1 month of sinus rhythm was maintained or a total of three CVs were performed. Of the 59 patients undergoing CV 1, 43 were discharged in sinus rhythm and 29 subsequently had AF recurrence during monitoring. Twenty-three of these underwent CV 2 and 11 of these underwent CV 3. Of those having repeated CVs, only 4 patients maintained sinus rhythm for 1 month (3 after CV 2 and 1 after CV 3). The remaining patients had repeated AF recurrence during the monitoring period. Mean time from AF recurrence to CV 2 was 20+/-13 hours and from AF recurrence to CV 3 was 13+/-7.2 hours. Atrial effective refractory periods increased from 189+/-16 msec at CV 1 to 215+/-18 msec at CV 3 (P < 0.05), indicating reversal of atrial electrical remodeling during this period., Conclusion: A policy of early repeated CVs for AF recurrence has very limited clinical value despite evidence of reversal of atrial electrical remodeling. The time between AF recurrence and repeat CV may need to be reduced further if such a policy is to succeed.

Amiodarone and AF. Introduction: Amiodarone is effective in preventing the recurrence of atrial fibrillation (AF) after cardioversion (CV). Dispersion of atrial refractoriness may be relevant to the generation of AF. We designed a study to determine the electrophysiologic effects of amiodarone in patients with previous early recurrence of AF after CV. Methods and Results: Fifteen patients with previous AF recurrence (without antiarrhythmic drugs) after CV (CV1) were selected for amiodarone therapy and repeat CV (CV[sub amio]). Prior to CV1, mean AF cycle length (AFCL) had been recorded at four atrial sites (right atrial appendage [RAA], distal coronary sinus [DCS], right atrial lateral wall [LAT], and interatrial septum [IAS]) and dispersion of AFCL had been calculated. These patients were treated with amiodarone and, prior to CV[sub amio], AFCL was recorded at the four atrial sites as for CV1. Between CV1 and CV[sub amio], AFCL increased at all atrial sites: 153 ± 13 msec to 179 ± 14 msec at RAA, 144 ± 12 msec to 174 ± 18 msec at DCS, 158 ± 13 msec to 182 ± 16 msec at LAT, and 161 ± 18 msec to 181 ± 17 msec at IAS. Dispersion of AFCL decreased from 24 ± 10 msec at CV1 to 15 ± 11 msec at CV[sub amio] (P = 0.01) . The median time in sinus rhythm increased from 3.12 hours post CV1 to 28 days post CV[sub amio] (P < 0.02) . Conclusion: Amiodarone causes a reduction in the dispersion of AFCL. This action may be relevant to the beneficial effects of amiodarone in patients with AF.(J Cardiovasc Electrophysiol, Vol. 14, pp. 485-491, May 2003). [ABSTRACT FROM AUTHOR]

Introduction: Recent reports have highlighted the importance of focal atrial arrhythmias as a curable cause for a group of patients with frequently recurrent paroxysmal atrial fibrillation (AF). The importance of this arrhythmia mechanism in the general population of patients with persistent AF is unknown. Methods and Results: After successful internal cardioversion of 50 consecutive patients with persistent AF (mean age 60 years, mean duration of AF 26 months), endocardial activity in the immediate postcardioversion period was analyzed for the presence of focal atrial activity. Postcardioversion atrial arrhythmias were considered to be local if there was evidence of a localized source of repetitive early atrial activation, either in the form of (1) self-terminating monomorphic atrial tachycardia (at least five beats) or (2) recurrences of AF with an initial atrial activation sequence (first five beats) that was both monomorphic and reproducible with repeated recurrences. Evidence for a focal atrial arrhythmia was present in 20 of the total group of 50 patients (40%). Multivariate analysis of clinical characteristics revealed the diagnosis of lone AF as the only independent predictor of a focal source of AF (P = 0.028). Thirty-nine patients were discharged from hospital in sinus rhythm. At 1-month follow-up, 25 (64%) of these 39 patients had suffered AF recurrence. The only significant predictor of AF recurrence was evidence of a focal source of atrial arrhythmia immediately after cardioversion, with a relative risk of 1.73 (range 1.1 to 2.7; P = 0.015). Conclusion: Focal atrial arrhythmias are common in patients presenting with "idiopathic" persistent AF, suggesting a possible causative role in the generation of this common arrhythmia. [ABSTRACT FROM AUTHOR]