Thursday, September 2, 2010

Use of Ivabradine in Postural Orthostatic Tachycardia Syndrome

Citation : Jamil-Copley S, Nagarajan DV, Baig MK.Use of Ivabradine in Postural Orthostatic Tachycardia Syndrome .JAFIB.2010 May;Volume 2 Issue(1): 745-746.

Postural orthostatic tachycardia syndrome (POTS) is characterized by inappropriate increase in heart rate on assuming upright position from a supine position without a necessary drop in blood pressure. Etiology of this condition is complex and multifactorial. Autonomic dysfunction, hypovolemia, hyper responsiveness of beta adrenergic receptors with associated elevations of plasma norepinephrine levels have been implicated as underlying pathophysiologic mechanisms. Beta blockers have previously been used to treat this condition. Ivabradine which selectively inhibits If ion current in the sino atrial node, has been reported to be useful in patients with POTS. We present one further such case of POTS successfully treated by Ivabradine.

Supraventricular Ectopic Activity: When Excessive it is not all Benign!

Citation : Tuan Le Nguyen, Liza Thomas.Supraventricular Ectopic Activity: When Excessive it is not all Benign! .JAFIB.2010 May;Volume 2 Issue(1): 742-744.

Stroke is a significant cause of mortality and disabling morbidity. The major subtypes of stroke are divided into thrombo-embolic, haemorrhagic and cryptogenic, with each having different predisposing risk factors and management strategies. Atrial fibrillation (AF) is the commonest arrhythmia predisposing to thrombo-embolic stroke. The incidence of AF increases with age, affecting up to 5% in the elderly population. Electrophysiology studies have implicated that spontaneous atrial ectopic beats that originate in or near pulmonary veins adjacent to the left atrium, may initiate paroxysms of AF.

Commentary on : New-Onset Atrial Fibrillation Predicts Long-Term Mortality After Coronary Artery Bypass Graft by El-chami

Citation : Giovanni Filardo.Commentary on : New-Onset Atrial Fibrillation Predicts Long-Term Mortality After Coronary Artery Bypass Graft by El-chami .JAFIB.2010 May;Volume 2 Issue(1): 740-741.
El-Chami and colleagues report that new-onset post-operative atrial fibrillation (AF) is associated with a significant reduction in long-term survival (adjusted hazard ratio: 1.21; 95% confidence interval: 1.12 to 1.32; follow-up: mean 6 years, range: 0 to 12.5 years) for patients undergoing isolated coronary artery bypass grafting (CABG). Moreover, the authors suggest that patients with new-onset post-CABG AF discharged on warfarin experienced reduced mortality during follow-up (adjusted HR: 0.78, 95% CI: 0.66 to 0.92) when compared to those who were not discharged on warfarin.

Is AF Ablation Cost Effective?

Citation :
William Martin-Doyle, Matthew R. Reynolds.Is AF Ablation Cost Effective? .JAFIB.2010 May;Volume 2 Issue(1): 727-739.
The use of catheter ablation to treat AF is increasing rapidly, but there is presently an incomplete understanding of its cost-effectiveness. AF ablation procedures involve significant up-front expenditures, but multiple randomized trials have demonstrated that ablation is more effective than antiarrhythmic drugs at maintaining sinus rhythm in a second-line and possibly first-line rhythm control setting. Although truly long-term data are limited, ablation, as compared with antiarrrhythmic drugs, also appears associated with improved symptoms and quality of life and a reduction in downstream hospitalization and other health care resource utilization. Several groups have developed cost effectiveness models comparing AF ablation primarily to antiarrhythmic drugs and the model results suggest that ablation likely falls within the range generally accepted as cost-effective in developed nations. This paper will review available information on the cost-effectiveness of catheter ablation for the treatment of atrial fibrillation, and discuss continued areas of uncertainty where further research is required.

Invasive Management of Atrial Fibrillation and the Elderly

Citation : Sandeep M. Patel, Samuel J. Asirvatham.Invasive Management of Atrial Fibrillation and the Elderly .JAFIB.2010 May;Volume 2 Issue(1): 715-726
Atrial fibrillation (AF) is the most common arrhythmia encountered by caregivers for the elderly. A plethora of new, mostly invasive techniques have evolved to treat patients who remain symptomatic from this arrhythmia despite attempts at pharmacological therapy. The most widely-used of these new techniques is radiofrequency ablation, but in select patients, special types of pacemaker, cryoablation, and surgical maze therapy may be of benefit.

Ranolazine for Atrial Fibrillation: Too Good to be True?

Citation : Joseph J. Gard, Samuel J. Asirvatham. Ranolazine for Atrial Fibrillation: Too Good to be True? .JAFIB.2010 May;Volume 2 Issue(1): 711-714.
Several management options for patients with symptomatic atrial fibrillation (AF) available today were not even in the realm of discussion two decades ago. These advances, however, have primarily involved invasive management options for patients with drug refractory arrhythmia. After the recognition that electrical isolation of the thoracic veins benefits patients with paroxysmal AF, a slew of more involved ablative techniques evolved. Major breakthroughs in antiarrhythmic therapy, however, have not paralleled this meteoric development of invasive techniques. The drive for invasive procedures has, in fact, been widely based on the lack of availability of simple, effective, and safe pharmacological options for AF. The introduction of dronedarone into clinical practice represented a recent addition to antiarrhythmic therapy options for use in the management of patients with AF. This agent is an analogue of amiodarone but devoid of the iodine moiety which allows its use without the well-recognized and dreaded organ toxicity associated with long-term use. Nevertheless, a significant need exists for a drug with limited side effects that can be used for symptomatic intermittent AF without the need for daily chronic use, fear of organ toxicity, and concern regarding proarrhythmia in patients with structural heart disease.

The Conversion of Paroxysmal or Initial Onset Atrial Fibrillation with Oral Ranolazine: Implications for a New "Pill-In-Pocket" Approach in Structural

Citation : David K. Murdock, James A Reiffel, Jeff Kaliebe, German Larrain.The Conversion of Paroxysmal or Initial Onset Atrial Fibrillation with Oral Ranolazine: Implications for a New "Pill-In-Pocket" Approach in Structural Heart Disease .JAFIB.2010 May;Volume 2 Issue(1): 705-710.
Background: The "Pill-in-Pocket" (PIP) is an approach to atrial fibrillation (AF) where oral anti-arrhythmics at 75% to 100% of the normal daily dose, given as a single dose, is used to convert recent-onset AF. Pro-arrhythmic risk has limited this approach to patients without structural heart disease (SHD). Ranolazine is an anti-anginal agent, which inhibits the abnormal late Na+ channel current resulting in decreased Na+/Ca++ overload. This inhibits after-depolarizations and reduces pulmonary vein firing, which have been implicated in the initiation and propagation of AF. Ranolazine increases atrial refractoriness and has no known pro-arrhythmic affects. Ranolazine is routinely given to patients with SHD. The ability of Ranolazine to terminate AF in man has not been described but if useful could be a safer PIP agent with application in the presence or absence of SHD. We describe our experience using oral Ranolazine to convert new or recurrent AF.
Method: 2000 mg of ranolazine was administered to 35 patients with new (16 patients) or recurrent (19 patients) AF of at least 3 but not greater than 48 hours duration. Clinical features, echocardiographic data, and SHD were noted. Success was defined as restoring sinus rhythm within 6 hours of Ranolazine.
Results: All but 4 patients had some form of SHD. Twenty-five patients were in the hospital, 5 were in the office, and 5 were at home at the time Ranolazine was administered. Twenty-five of 35 patients converted to sinus rhythm. No pro-arrhythmic effects, hemodynamic instability, adverse rate effects, or perceived intolerance were noted. The 71% conversion rate was comparable to other reported PIP protocols and much higher than reported placebo conversion rates.
Conclusion: High dose oral Ranolazine shows utility as a possible safe agent to convert new or recurrent AF. Larger placebo-controlled studies would appear to be warranted.

AF Termination: the Holy Grail of Persistent AF Ablation?

Citation : Dennis H. Lau, Anthony G. Brooks, Prashanthan Sanders.AF Termination: the Holy Grail of Persistent AF Ablation? .JAFIB.2010 May;Volume 1 Issue(12): 702-704.
The optimal catheter ablation approach for long-standing persistent atrial fibrillation (AF) remains elusive despite significant advances made in our understanding of this arrhythmia. A recent systematic review highlighted the significant variation in procedural success rate both within and between techniques, necessitating repeat ablation procedures and anti-arrhythmic drugs to achieve improved outcomes in those with long-standing persistent AF. Indeed, current expert consensus statement recommended ablation beyond ostial pulmonary vein isolation for these patients.

Atrial Fibrillation Susceptibility Alleles on Chromosome 4q25 Modulate Response to Catheter Ablation

Citation : Dawood Darbar.Atrial Fibrillation Susceptibility Alleles on Chromosome 4q25 Modulate Response to Catheter Ablation .JAFIB.2010 May;Volume 1 Issue(12): 699-701
In the last five years, increasing evidence has emerged for a genetic predisposition to atrial fibrillation (AF). Framingham Heart Study investigators observed that the odds of developing AF were three times higher for individuals with at least one parent in whom AF was diagnosed before the age of 75 than in those without a parental history of AF. Similarly, in a large group of Icelanders, the risk of developing AF was increased nearly five-fold if one parent was affected before the age of 60. Furthermore, single rare genetic variants thought to be responsible for familial AF have been identified.

Is Isolation of Arrhythmogenic Pulmonary Veins Sufficient for the Long-term Efficacy of Atrial Fibrillation Ablation?

Citation :Sanjay Dixit. Is Isolation of Arrhythmogenic Pulmonary Veins Sufficient for the Long-term Efficacy of Atrial Fibrillation Ablation? .JAFIB.2010 May;Volume 1 Issue(12): 685-698.
Atrial fibrillation (AF) is the commonest cardiac rhythm disorder, affecting about 5% of elderly patients. Despite the wide spread prevalence of AF, treatment options for the condition up until recently, were limited. Antiarrhythmic drug therapy which for a long time had been and to some extent still is the cornerstone for treating these patients, has shown a disappointing (£ 40%) efficacy for long-term maintenance of sinus rhythm. The seminal observations by Haissaguerre and colleagues demonstrating AF initiation from electrical depolarizations in the pulmonary veins (PV) and cure of AF in these patients by radiofrequency ablation (RFA) of the PV focus, has led to the emergence of percutaneous catheter based AF ablation. Since its original description in 1998, the AF ablation procedure has evolved considerably.

Lone AF – Etiologic Factors and Genetic Insights into Pathophysiolgy

Citation : Babar Parvez, Dawood Darbar. Lone AF – Etiologic Factors and Genetic Insights into Pathophysiolgy .JAFIB.2010 May;Volume 1 Issue(12): 675-684.
Ever since atrial fibrillation (AF) was first recognized in young people (so called “lone” AF) over 4 decades ago, there has been increasing focus on determining the underlying pathophysiology of condition. Although lone AF is presumed to be a highly heterogeneous disease, recent studies have identified novel risk factors such as inflammation, oxidative stress, endurance sports and genetics, for the arrhythmia. This monograph aims to highlight some of the recent advances in our understanding of the molecular pathophysiology of lone AF especially insight provided by contemporary genetic studies. These insights may provide novel therapeutic targets for treatment of this challenging arrhythmia in young patients.

The Utility of Ambulatory Electrocardiographic Monitoring for Detecting Silent Arrhythmias and Clarifying Symptom Mechanism in an Elderly Urban Popula

Citation : Kathleen T. Hickey, James Reiffel, Robert R. Sciacca, William Whang, Angelo Biviano, Maurita Baumeister, Carmen Castillo, Jyothi Talathothi, Hasan Garan.The Utility of Ambulatory Electrocardiographic Monitoring for Detecting Silent Arrhythmias and Clarifying Symptom Mechanism in an Elderly Urban Population with Heart Failure and Hypertension: Clinical Implications .JAFIB.2010 May;Volume 1 Issue(12): 663-674.

Background: Atrial and ventricular tachyarrhythmias, including atrial fibrillation (AF) as well as bradyarrhythmias have been well documented in elderly and generally symptomatic patients with heart failure (HF) and/or hypertension (HTN), most often using 24 hour continuous monitoring. However, the frequency of these arrhythmias, including silent as well as symptomatic, as assessed by more prolonged monitoring, the relationship between symptoms in patients with HF and/or HTN and an underlying arrhythmia, and the association of arrhythmias including those that are silent with subsequent cardiac events has not been well defined in patients 65 years or older with HF and other cardiovascular risk factors. Importantly in such patients, AF, even if symptomatic, would yield a CHADS2 score indicative of anticoagulation.

Objective: A pilot study to assess the potential value of 2 weeks of out-patient, transtelephonic cardiac auto-triggered loop-monitoring for detecting arrhythmias, assessing their relationship to symptoms, predicting the risk of subsequent cardiac events, and determining if they result in therapy in an elderly, urban population living with HF.

Methods: Fifty-four subjects with a history of systolic HF and/or HTN consented to wear an auto triggered cardiac loop monitor for 2 weeks. This device captures EKG data, including silent and symptomatic arrhythmias. Subjects were requested to transmit data once daily as well as to transmit if they were symptomatic to determine if an underlying dysrhythmia was present.

Results: Mean age was 73 ± 6 years with 59% were female, 74% Hispanic, 22% black, and 4% white/other. All subjects had HF and 94% had HTN; all were in sinus rhythm at the time of enrollment. From the cardiac monitoring, 72% demonstrated ectopic atrial and ventricular activity. In addition, 1 paroxysmal episode of AF was documented, 3 people had significant non-sustained ventricular tachycardia that contributed to the placement of an internal cardioverter defibrillator (ICD), and 4 individuals underwent subsequent placement of a pacemakers for severe bradycardia/heart block (per established guidelines). The relationship between arrhythmia and symptoms was weak. These events would have otherwise gone undetected and untreated. During follow-up, 15 subjects (28%) had significant cardiac events, including one patient with a non ST segment myocardial infarction (NSTEMI) infarct due to undetected and untreated AF and one patient with symptomatic 2:1 atrial flutter. The AF and flutter patients all had CHADS2 scores appropriate for initiation of anticoagulation.

Conclusion: A substantial proportion of subjects exhibited arrhythmias during monitoring, cardiac events during follow-up and consequent therapy. This approach to arrhythmia screening appears to have sufficient merit to warrant further study.

Electrophysiological Changes of the Atrium in Patients with Lone Paroxysmal Atrial Fibrillation

Citation : Osmar Antonio Centurion, Shojiro Isomoto, Akihiko Shimizu.Electrophysiological Changes of the Atrium in Patients with Lone Paroxysmal Atrial Fibrillation .JAFIB.2010 May;Volume 1 Issue(12): 656-662.

Introduction: Paroxysmal atrial fibrillation (PAF) is a common arrhythmia, and it is associated with various cardiac conditions. On the other hand, lone PAF has no identifiable underlying cause, and can occur any time for no apparent reason. The underlying causes may modify the electrophysiological properties of the atrium in different ways and extent. However this setting may be different in patients with lone PAF. We sought to investigate the atrial electrophysiological properties in lone PAF.
Material and Methods: This study included 62 control subjects (Control group) and 58 patients with lone PAF (LAF group). The following atrial vulnerability parameters induced by programmed atrial stimulation were assessed and quantitatively measured: 1) the atrial effective refractory period (ERP), 2) the atrial conduction delay (CD) zone, and 3) the maximum CD.
Results: The mean atrial ERP of the Control group was 215±29 ms, and that of LAF group was 208±28 ms, p<0.05. The mean atrial CD zone of the LAF group was (50±28 ms) significantly greater than that of controls (34±22 ms) (p<0.01). The mean maximum CD of the LAF group (62±29 ms) was also significantly greater than that of controls (43±20 ms) (p<0.01).
Conclusions: There is a greater conduction delay of the atrium and shorter refractoriness in patients with lone PAF. Patients without underlying causes for the development of PAF exhibit abnormalities in the electrophysiological properties of the atrium.
Key words: Atrial vulnerability. Atrial refractory period. Atrial conduction time. Atrial fibrillation. Atrial conduction delay.