Year in Review: 2005

As the field of electrophysiology (EP) continues to explode, serving as probably the fastest-growing part of cardiology, we look back at the year at some of the major publications in EP. Due to space limitations, we cannot obviously mention every worthy publication, so we will highlight the more important ones. Interest remains quite high in the area of radiofrequency ablation for atrial fibrillation (pulmonary vein or PV ablation). Although considered a rare complication, there are concerns about esophageal perforation during PV ablation, which can be devastating. An interesting article from Spain examined the esophageal course in 15 cadavers.¹ The authors found that the esophagus takes a variable course along the posterior part of the left atrium. They commented this anatomic feature must be considered during a PV ablation. Other authors also evaluated the proximity of the esophagus to the left atrium during PV ablation and noted the importance of defining it during the procedure.^2,3 There is still no consensus as to which radiofrequency ablation approach is safer or more effective for PV ablation. Karch et al. attempted to address this question in a well-done study of 100 patients undergoing PV ablation randomly assigned to either circumferential or segmental PV ablation.⁴ At six-month follow-up, there was no significant difference between the two patient groups for safety, although slightly more patients in the segmental PV ablation approach were arrhythmia-free on a seven-day Holter monitor. The area of sudden death continues to be a fertile avenue of EP research. Burke et al. published an interesting paper in Circulation linking the Y1102 polymorphism in the SCN5A gene (cardiac sodium channel) to an increased risk of sudden cardiac death in blacks with this polymorphism.⁵ Such findings are provocative and may shed light onto why certain ethnic groups (such as African-Americans) may suffer from higher sudden death rates than the general population. Indications for which Brugada syndrome patients should receive an ICD continue to evolve as we learn more about the natural history of the disease. Eckardt et al. studied 212 patients with the Brugada syndrome pattern on ECG. During a mean follow-up time of 40 months, a substantial proportion of symptomatic patients had aborted cardiac arrest, whereas few of the asymptomatic patients had an event.⁶ The authors conclude that asymptomatic Brugada syndrome patients have a very low event rate (at least during the course of their study), and that there is little role for the electrophysiology study to try and risk stratify these patients. It remains a difficult management issue: should patients routinely receive a dual-chamber pacemaker (versus a single-chamber) if they have high-grade AV block? It might seem intuitively obvious that dual-chamber pacing would provide a benefit. Toff et al. studied this question in a large, multicenter study involving 2,021 patients randomized to receive either pacemaker type.⁷ Interestingly, at 4.6 years median follow-up there was no difference in the two groups with regard to death rates, rates of atrial fibrillation, or heart failure. Such findings might suggest that not all patients with high-grade heart block need to receive dual-chamber pacemakers. Indications for who should receive a biventricular device for CRT (cardiac resynchronization therapy) continue to evolve. Cleland et al. published their results of the CARE-HF study (Cardiac Resynchronization on Morbidity and Mortality in Heart Failure) in 2005.⁸ They looked at 813 patients with severe heart failure who received a CRT device or medical therapy. They found a marked improvement in ejection fraction, improvement in heart failure symptoms, and other echo findings in the CRT group. Along those lines, probably the biggest EP news of 2005 was the publication of the long-awaited SCD-HeFT trial, looking at the usefulness of ICD therapy for patients with nonischemic cardiomyopathy.⁹ It has been widely accepted that ICD therapy reduces mortality in patients with an ischemic cardiomyopathy, but treatment for nonischemic patients has been unclear. The authors assigned roughly 2,500 patients with Class II or III heart failure and ejection fraction of 35% or less to conventional therapy, conventional therapy plus amiodarone, or conventional therapy plus ICD. ICD therapy was associated with a 23% decreased risk of death in these patients. The Center for Medical and Medicaid Services (CMS) expanded coverage for ICDs in this patient group.