Effects of focal impulse and rotor modulation-guided ablation on atrial arrhythmia termination and inducibility: Impact on outcomes after treatment of persistent atrial fibrillation.

INTRODUCTION: The role of focal impulse and rotor modulation (FIRM)-guided ablation for the treatment of atrial fibrillation (AF) remains unclear. Previous studies on the FIRM-guided ablation outcomes have been limited by a focus on AF termination as an endpoint and by patient population heterogeneity. We sought to determine differences in rates of AF termination, inducibility, and recurrence in patients with persistent AF undergoing first-time ablation with a FIRM-guided approach compared with patients undergoing conventional ablation. METHODS AND RESULTS: Eight-five consecutive patients (38 FIRM, 47 conventional) with persistent AF undergoing first-time ablation were retrospectively analyzed. There were no significant differences in the rates of AF termination in the FIRM group compared to the conventional group (26% vs 15%; P = .15). Rates of inducible AF after ablation were 37% in the FIRM group and 30% in the conventional group (P = .32). Over a median follow-up of 2.4 years, the rates of freedom from AF were similar between the FIRM and conventional groups (1-year freedom from AF 65% vs 50%, respectively; P = .18). Procedural termination of AF with either FIRM ablation or conventional ablation was not associated with any significant reduction in AF recurrence. CONCLUSION: A FIRM-guided approach was not associated with a significant difference in freedom from AF when compared to conventional ablation. Termination of AF with ablation was not associated with increased freedom from AF. While AF termination using substrate-based ablation may have mechanistic implications for understanding AF rotor physiology, its impact on clinical outcomes remains unclear.

Recovery of atrioventricular conduction in patients with heart block after transcatheter aortic valve replacement.

INTRODUCTION: Recovery of conduction has been demonstrated in >50% of patients who receive pacemakers (PPMs) for high-degree atrioventricular block (HD-AVB) after transcatheter aortic valve replacement (TAVR). Little information is available about the time course of conduction recovery in these patients and if any features predict early recovery of conduction. METHODS: A retrospective review was performed of patients who underwent TAVR with balloon and self-expanding valves who required PPMs for HD-AVB. Serial PPM interrogations were analyzed to detect recovery of AV conduction. Analysis was performed to identify predictors and timing of conduction recovery. RESULTS: Of a total population of 578 patients, 54 (9%) received PPMs for HD-AVB. In multivariate analysis, predictors of HD-AVB requiring a PPM included age (P = 0.014), right bundle branch block (OR 7.33 [3.64-14.8], P < 0.0001), atrial fibrillation (OR 2.16 [1.16-4.05], P = 0.016), and self-expanding valves (OR 4.19 [2.20-7.97], P < 0.0001). Of the 54 patients who received PPMs, 38 had follow-up sufficient to evaluate AV conduction recovery. Of these, 23 (61%) showed recovery of AV nodal conduction; 20 had already recovered by their first interrogation, a median of 22 days (IQR 14-31) post-PPM placement. There were no statistically significant predictors of AV nodal conduction recovery, including type of valve implanted. CONCLUSIONS: A majority of patients who receive PPMs for HD-AVB after TAVR recover AV conduction during follow-up, and in most patients conduction recovery occurs within weeks. These findings imply that programming to minimize ventricular pacing may be beneficial in a majority of these patients.

Radiation dose and excess risk of cancer in children undergoing neuroangiography.

OBJECTIVE: The primary goal of this study was to determine the radiation dose received during diagnostic and interventional neuroangiographic procedures in a group of pediatric patients. A second goal was to approximate the total average radiation dose from all angiographic and CT studies that pediatric patients underwent during the study period and to estimate the increased risk of cancer incidence in this patient group. MATERIALS AND METHODS: The study subjects were pediatric patients who had undergone one or more neuroangiographic procedures at Harborview Medical Center between December 1, 2004, and April 30, 2008. Recorded radiation doses were converted to entrance skin dose (ESD) and effective dose (ED) to indicate deterministic and stochastic damage, respectively. The Biologic Effects of Ionizing Radiation (BEIR) VII, phase 2, report was used to estimate the expected increased risk of cancer in the study population. RESULTS: For diagnostic and therapeutic procedures, a mean ED of 10.4 and 34.0 mSv per procedure was calculated, respectively. The ESD values proved too low to cause deterministic harm. The estimated number of excess cases of malignancy projected from the total average radiation exposure was 890.6 per 100,000 exposed male children and 1,222.5 per 100,000 exposed females, an overall increase of approximately 1% to the lifetime attributable risk of cancer. CONCLUSION: Although both angiography and CT have revolutionized the practice of medicine and confer benefits to patients, it is important that we continue to investigate the possible adverse effects of these technologies. Protocols that minimize radiation dose without compromising a study should be implemented.