Cost comparison of radiofrequency modification and ablation of the atrioventricular junction in patients with chronic atrial fibrillation

Ablate and Pace: Is There Still a Role?

Despite the development of newer drugs and procedures to improve rhythm control, there is still a place for ablation of the atrioventricular junction (AVJ) in the management of selected patients with AF who are refractory to medical therapy, to improve quality of life, prevent ventricular dysfunction, and to optimize cardiac resynchronization therapy. We review all aspects of the "ablate and pace" strategy, from its history to patient selection, technique, outcomes and applications, and identify the need for randomized clinical trials to address some of the remaining questions regarding its application in some groups of patients.

Ectopic and reentrant activation patterns in the posterior left atrium during stretch-related atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in humans and is predicted to dramatically increase its prevalence in the future. There is experimental evidence that increasing stretch increases the dominance of the pulmonary veins (PVs) during AF in isolated hearts and ectopic activity in the isolated PVs, but the ionic mechanisms underlying such effects are not clear and the ability of the PVs to favorably host functional reentry during stretch cannot be excluded. We used a combination of endocardial-epicardial optical mapping with phase and spectral analysis to study stretch-related AF (SRAF) in normal isolated sheep hearts. We have found rapid AF sources in the posterior left atrium (PLA) and PV region and their activation frequency and level of organization correlated with intra-atrial pressure. Analysis of the surfaces' optical mapping data in the phase domain reveals that activation of the PLA consisted of alternating patterns of breakthroughs, reentries and relatively simple waves swiping across the mapped field. The patterns on the endocardial and epicardial PLA surface at any given moment of time of the SRAF could be either identical or not identical, and the activity in the thickness of the PLA wall is hypothesized to conform to either ectopic discharge or scroll waves, but a definite evidence for the presence of such mechanisms is currently lacking. Thus the understanding of the manner by which the mechano-electric feedback effects in the PLA, including the PVs, become important in the initiation and maintenance of AF requires further detailed investigation.

Assessing the direct costs of treating nonvalvular atrial fibrillation in the United States

OBJECTIVE

To determine the health-care resource use and costs attributable to treating atrial fibrillation (AF) in the United States.

METHODS

Retrospective analyses of three federally funded US databases (2001 data): 1) hospital inpatient stays (the Healthcare Cost and Utilization Project [HCUP]); 2) physician office visits (the National Ambulatory Medical Care Survey [NAMCS]); and 3) emergency department (ED) and hospital outpatient department visits (OPD) (the National Hospital Ambulatory Medical Care Survey [NHAMCS]). Identification of AF medical encounters was based on occurrence of AF-specific International Classification of Diseases (9th Edition)--Clinical Modification (ICD-9-CM) diagnosis code 427.31 (principal discharge diagnosis for inpatient setting; any diagnosis field for other settings). For the 10 most common principal discharge diagnoses in the inpatient setting, case-control comparison analyses were performed to estimate annual incremental costs of AF as a comorbid discharge diagnosis for hospital stays. Regression models were used to assess the impact of AF on hospitalization costs. Costs were estimated in year 2005 US dollars.

RESULTS

Approximately 350,000 hospitalizations, 5.0 million office visits, 276,000 ED visits, and 234,000 OPD were attributable to AF annually within the United States. Total annual costs for treatment of AF were estimated at $6.65 billion, including $2.93 billion (44%) for hospitalizations with a principal discharge diagnosis of AF, $1.95 billion (29%) for the incremental inpatient cost of AF as a comorbid diagnosis, $1.53 billion (23%) for outpatient treatment of AF, and $235 million (4%) for prescription drugs. In all regressions, AF was a significant contributor to hospital cost.

CONCLUSIONS

Treatment of AF represents a significant health-care burden with the costs of treating AF in the inpatient setting outweighing the costs of treating AF in the office, emergency room or hospital outpatient settings. Further research is needed to fully capture the costs of treating AF.

Gene Therapy for Cardiac Arrhythmias

Myocardial gene transfer has become a routine tool to investigate the pathophysiology of cardiac diseases, although translation of gene transfer techniques into therapeutics has not come as quickly as many had hoped. In the field of cardiac arrhythmias, there is a great need for new therapeutic options. The current work reviews the use of gene transfer to evaluate cellular electrophysiology, the application of in vivo gene transfer to treat common arrhythmias, and the current problems in the field of cardiac gene therapy. Arrhythmia gene therapy is a field in its infancy, and future human applications are dependent on solutions to the problems discussed in this review.

Angioplasty and stents in coronary artery disease: a systematic review and meta-analysis

OBJECTIVES

To undertake a systematic review of the clinical effectiveness of routine percutaneous transluminal coronary angioplasty (PTCA) plus stenting vs PTCA alone.

DATA SOURCES

MEDLINE; EMBASE; Science Citation Index; The Cochrane Library; cardiovascular journals and conference proceedings; Internet resources (including industry supported web pages); and reference lists of included studies and relevant reviews.

REVIEW METHODS

Study selection included published and unpublished randomized controlled trials (RCTs) comparing the use of coronary stents to PTCA. Outcome measures assessed included death, acute myocardial infarction (AMI), event rate (such as major cardiac adverse events (MACE) or other composite measures), and binary restenosis (BR). Data extraction and quality assessment were conducted according to internationally recognized methods. Data synthesis included meta-analysis of assessed outcomes, reported as odds ratios (ORs).

RESULTS

Fifty RCTs involving 16,500 patients met the inclusion criteria (39 full articles, 11 abstracts). Of these, 23 studies compared stenting with PTCA in patients with non-specific coronary artery disease (CAD), 11 compared stents with PTCA following AMI, 8 included patients with small coronary arteries and 8 included patients whose vessels had chronic total occlusion. There were no differences in rates of death or AMI. There were reductions in the rates of MACE (death, AMI or revascularization) with stents compared to PTCA (at 6 months, for non-specific group OR: 1.64, 95% CI 1.44-1.87; for AMI group OR: 2.36, 95% CI 1.92-2.89; for small vessel group OR: 1.38, 95% CI 1.10-1.74; at 12 months, for non-specific group OR: 1.31, 95% CI 1.11-1.55; for AMI OR: 2.26, 95% CI 1.47-3.46). Reporting of combined major adverse cardiac events was inconsistent across studies. Most events were revascularizations that may have been partly driven by protocol-required angiograms. Stents reduced BR rates at angiogram at 6 months compared to PTCA in all groups.

CONCLUSION

We found no differences in mortality or AMI, but the studies were not powered to identify changes in these endpoints. Coronary stenting is associated with reduced restenosis and combined adverse cardiac events, primarily revascularizations. However, the frequency of revascularization may have been distorted by protocol-dictated angiography.

Gene Therapy for Cardiac Arrhythmias

Myocardial gene transfer has shown tremendous potential to investigate pathophysiology and potential therapies for cardiac diseases. In the field of cardiac arrhythmias, there is a tremendous need for new therapeutic options. The current work reviews the need for new therapies for cardiac arrhythmias, the use of gene transfer to evaluate cellular electrophysiology, the application of in vivo gene transfer to treatment of common arrhythmias, and the current problems in the field of cardiac gene therapy. Arrhythmia gene therapy is a field in its infancy, and future human applications are dependent on solutions to the problems discussed here.

Gene transfer techniques for cardiac arrhythmias

Therapy for cardiac arrhythmias is inadequate, based on current options. Gene therapy has shown tremendous potential to investigate pathophysiology and potential therapies for cardiac diseases. The current work reviews the possibilities for application of in vivo gene transfer to treatment of common arrhythmias, including vector selection, delivery technique, and data on in vivo gene transfer for rate control in atrial fibrillation and for pacemaking activity. Arrhythmia gene therapy is a field in its infancy, and future human applications are dependent on solutions to the problems discussed in this review.

Atrial fibrillation in patients with congestive heart failure

CHF and AF are common problems that are frequently encountered together. These two disease states interact in a way that can result in a viscous cycle. This brief review will attempt to address the interaction between AF and CHF, atrial pathology and abnormal electrophysiology, clinical consequences, prognostic importance, and therapy.

Atrial Fibrillation

The conversion of atrial fibrillation (AF) to normal sinus rhythm should be attempted in patients who present with this condition, as long as the cure is not worse than the disease itself. In young patients with normal hearts, AF has a small impact on morbidity and mortality. The primary indication for conversion in this population is often symptoms. In contrast, in patients with diseased hearts or who are older than 65 years, maintaining sinus rhythm may have a favorable impact on stroke risk, ventricular function, and symptoms. In the absence of normal sinus rhythm, these patients should receive anticoagulants. Rate control is the preferred first-line strategy for asymptomatic patients and patients presenting with a history of long-standing, persistent AF, making conversion and maintenance of sinus rhythm unlikely. Rate control may be used in patients who develop AF during an acute systemic illness, which will likely terminate with time or therapy. Conversion to sinus rhythm should be considered in patients with a first episode of AF, as unconverted AF tends to perpetuate itself. Conversion can be attempted if the duration of AF is less than 48 hours or if the patient has received anticoagulants when the duration is not known. Other indications for cardioversion are prolonged episodes in patients with otherwise infrequent episodes of paroxysmal AF, and in patients who refuse to take anticoagulants or in whom anticoagulation is contraindicated. After the patient is converted to sinus rhythm, the decision to initiate chronic drug therapy should be based on the presence of other cardiac and medical diseases that increase the risk of recurrence and serious symptoms in case of recurrence (such as hypertrophic cardiomyopathy or mitral stenosis). It is acceptable to manage patients with new-onset AF and normal cardiac function with cardioversion alone and not initiate chronic antiarrhythmic therapy afterwards. However, in patients with abnormal hearts (coronary artery disease, hypertensive or mitral valvular heart disease, and cardiomyopathy) AF is likely to recur, and such patients should be placed on antiarrhythmic medication.

Supraventricular Tachyarrhythmia

The main treatment modalities for supraventricular tachycardia are medications and catheter ablation. Ablation is appropriate therapy for paroxysmal supraventricular tachycardia in patients who have a preference for ablation over medications, symptoms that are refractory to medications, severe symptoms, Wolff-Parkinson-White syndrome, or incessant tachycardia. Ablation also is reasonable as first-line therapy in patients with recurrent typical atrial flutter.

Catheter-ablative techniques for the treatment of atrial fibrillation

Atrial fibrillation is the most commonly encountered arrhythmia in clinical practice and is associated with significant morbidity and mortality. Pharmacologic therapy, although useful for rate control, has proven much less effective in the long term maintenance of sinus rhythm. The utility of implantable atrial defibrillators or pacing to prevent atrial fibrillation remains largely untested. This article describes four catheter-based therapies for atrial fibrillation: His ablation, atrioventricular nodal modification, the Maze procedure, and the ablation of pulmonary vein foci which initiate the arrhythmia. Whereas the first two procedures are largely palliative and recommended for patients with symptomatic, drug-refractory atrial fibrillation, the latter two offer the potential for a curative intervention.

Radiofrequency ablation of atrioventricular junction and pacemaker implantation versus modulation of atrioventricular conduction in drug refractory atrial fibrillation

Modulation of atrioventricular (AV) node conduction and radiofrequency ablation of AV junction are alternative approaches to control ventricular rate in drug refractory atrial fibrillation (AF). In 2 centers, 120 patients were treated either with AV junction ablation (center 1, group 1, 60 patients [30 men, aged 64 +/- 11 years], paroxysmal AF in 24 patients) or with modulation (group 2, 60 patients [32 men, aged 58 +/- 12 years], paroxysmal AF in 43 patients). In group 1, complete AV block was achieved in all patients. In group 2, the procedure was performed in sinus rhythm (30 patients), prolonging the Wenckebach cycle length from 328 +/- 85 to 466 +/- 80 ms (p <0.01) or during AF (30 patients), decreasing ventricular rate from 178 +/- 35 to 96 +/- 35 beats/min (p <0.01), and to <100 beats/min in 17 patients (61%). Complete AV block was induced in 9 of 60 patients (15%). In groups 1 and 2, at a follow-up of 27 +/- 7 and 26 +/- 6 months, there were 2 deaths (1 cardiac, 1 sudden death) and 1 death for end-stage heart failure, respectively. Hospital readmissions decreased from 3.2 to 0.2 and from 4.2 to 0.2/year; late AF recurrences at of >120 beats/min were documented in 6% and 12%, respectively. Symptom score analysis including effort and rest dyspnea, exercise intolerance, weakness, and palpitation showed a significant improvement in both treatment groups, when acutely effective, in patients with paroxysmal and/or chronic AF. In conclusion, ablation of the AV junction shows a higher acute success rate compared with modulation of the AV node conduction in patients with drug refractory AF. Depending on the acute success, both approaches therefore were similarly effective in achieving long-term ventricular rate control and symptom score improvement.