Vagal responses induced by endocardial left atrial autonomic ganglion stimulation before and after pulmonary vein antrum isolation for atrial fibrillation.

BACKGROUND: Elimination of vagal inputs into the left atrium (LA) may be necessary for successful catheter ablation of atrial fibrillation (AF). These vagal inputs are clustered in autonomic ganglia (AG) that are close to the pulmonary vein antrum (PVA) borders, but whether standard intracardiac echocardiography (ICE)-guided PVA isolation (PVAI) affects these inputs is unknown. OBJECTIVE: The purpose of this study was to assess whether standard ICE-guided PVAI affects vagal responses induced by endocardial AG stimulation in the LA. METHODS: Twenty consecutive patients undergoing first-time PVAI (group 1) and 20 consecutive patients undergoing repeat PVAI for AF recurrence (group 2) were enrolled in the study. Before ablation, electrical stimulation (20 Hz, pulse duration 10 ms, voltage range 12-20 V) was performed through an 8-mm-tip ablation catheter. Based on prior data, regions around all four PVA borders were carefully mapped and stimulated to localize AG inputs. A positive stimulated vagal response was defined as atrioventricular (AV) block, asystole, or increase in mean RR interval by >50%. Locations of positive vagal responses were recorded wth biplane fluoroscopy and CARTO. All patients then underwent standard ICE-guided PVAI by an operator blinded to the locations of vagal responses. Stimulation of the AG locations was then repeated postablation. RESULTS: Patients (age 54 +/- 11 years, 30% female, ejection fraction 54% +/- 7%) had a history of paroxysmal (75%) and persistent (25%) AF. In group 1, vagal responses were induced in all 20 patients around a mean of 3.8 +/- 0.4 PVAs per patient. The most common response was asystole (53%), mean RR slowing >50% (28%), and AV block (20%). Postablation, vagal responses could no longer be induced in all 20 patients. A diminished response was induced (RR slowing <50%) in 2/20 patients around one PVA each. In group 2, vagal responses were not induced in any of the 20 repeat patients. Stimulation capture postablation was confirmed because transient, nonsustained (<30 seconds) AF or atrial flutter was induced in all 40 patients with stimulation, whether vagal responses were induced or not. CONCLUSIONS: Standard ICE-guided PVAI eliminates vagal responses induced by AG stimulation. Responses are not seen in patients presenting for repeat PVAI, despite clinical recurrence of AF.

Incidence of atrial arrhythmias detected by permanent pacemakers (PPM) post-pulmonary vein antrum isolation (PVAI) for atrial fibrillation (AF): correlation with symptomatic recurrence.

BACKGROUND: Studies examining AF recurrences post-PVAI base recurrence on patient reporting of symptoms. However, whether asymptomatic recurrences are common is not well known. OBJECTIVE: To assess the incidence of atrial tachycardia/fibrillation post-PVAI as detected by a PPM and whether these recurrences correlate to symptomatic recurrence. METHODS: Eighty-six consecutive patients with symptomatic AF and PPMs with programmable mode-switch capability underwent PVAI. Mode switching was programmed post-PVAI to occur at an atrial-sensed rate of >170 bpm. Patients were followed with clinic visits, ECG, and PPM interrogation at 1, 3, 6, and 9 months post-PVAI. The number and duration of mode-switching episodes (MSEs) were recorded at each visit and is presented as median (interquartile range). RESULTS: The patients (age 57 +/- 8 years, EF 54 +/- 10%) had paroxysmal (65%) and persistent (35%) AF pre-PVAI. Sensing, pacing, and lead function were normal for all PPMs at follow-up. Of the 86 patients, 20 (23%) had AF recurrence based on symptoms. All 20 of these patients had appropriate MSEs detected. Of the 66 patients without symptomatic recurrence, 21 (32%) had MSEs detected. In 19 of these patients, MSEs were few in number, compared with patients with symptomatic recurrence (16 [4-256] vs 401 [151-2,470], P < 0.01). The durations were all <60 seconds. All of these nonsustained MSEs occurred within the first 3 months post-PVAI, gradually decreasing over time. The other 2 of 21 remaining patients had numerous (1,343 [857-1,390]) and sustained (18 +/- 12 minutes) MSEs that also persisted beyond 3 months (1 beyond 6 months). Therefore, the incidence of numerous, sustained MSEs in asymptomatic patients post-PVAI was 2 of 66 (3%). CONCLUSIONS: Detection of atrial tachyarrhythmias by a PPM occurred in 30% of patients without symptomatic AF recurrence. Most of these episodes were <60 seconds and waned within 3 months. Sustained, asymptomatic episodes were uncommon.

Efficacy of adjuvant anterior left atrial ablation during intracardiac echocardiography-guided pulmonary vein antrum isolation for atrial fibrillation.

BACKGROUND: Recent data have shown that the septum and anterior left atrial (LA) wall may contain "rotor" sites required for AF maintenance. However, whether adding ablation of such sites to standard ICE-guided PVAI improves outcome is not well known. OBJECTIVE: To determine if adjuvant anterior LA ablation during PVAI improves the cure rate of paroxysmal and permanent AF. METHODS: One hundred AF patients (60 paroxysmal, 40 persistent/permanent) undergoing first-time PVAI were enrolled over three months to receive adjuvant anterior LA ablation (Group I). These patients were compared with 100 randomly selected, matched first-time PVAI controls from the preceding three months who did not receive adjuvant ablation (Group II). All 200 patients underwent ICE-guided PVAI during which all four PV antra and SVC were isolated. In group I, a decapolar lasso catheter was used to map the septum and anterior LA wall during AF (induced or spontaneous) for continuous high-frequency, fractionated electrograms (CFAE). Sites where CFAE were identified were ablated until the local EGM was eliminated. A complete anterior line of block was not a requisite endpoint. Patients were followed up for 12 months. Recurrence was assessed post-PVAI by symptoms, clinic visits, and Holter at 3, 6, and 12 months. Patients also wore rhythm transmitters for the first 3 months. Recurrence was any AF/AFL >1 min occurring >2 months post-PVAI. RESULTS: Patients (age 56 +/- 11 years, 37% female, EF 53%+/- 11%) did not differ in baseline characteristics between group I and II by design. Group I patients had longer procedure time (188 +/- 45 min vs 162 +/- 37 min) and RF duration (57 +/- 12 min vs 44 +/- 20 min) than group II (P < 0.05 for both). Overall recurrence occurred in 15/100 (15%) in group I and 20/100 (20%) in group II (P = 0.054). Success rates did not differ for paroxysmal patients between group I and II (87% vs 85%, respectively). However, for persistent/permanent patients, group I had a higher success rate compared with group II (82% vs 72%, P = 0.047). CONCLUSIONS: Adjuvant anterior LA ablation does not appear to impact procedural outcome in patients with paroxysmal AF but may offer benefit to patients with persistent/permanent AF.

Incidence of atrial fibrillation in heart transplant patients: long-term follow-up.

BACKGROUND: The incidence of atrial fibrillation (AF) in heart transplant patients has not been well documented. METHODS: To determine the incidence of AF in a cohort of patients undergoing cardiac transplantation, clinical data were obtained from a prospectively collected database for all consecutive orthotopic heart transplantation (OHT) patients and for all consecutive coronary artery bypass graft (CABG) surgery patients between January 1984 and March 2004 at our institution. A cohort of 1,714 OHT patients and low-risk CABG (normal ejection fraction [EF] and no left ventricular hypertrophy [LVH]) patients were age- and sex-matched. RESULTS: The average age in the two groups was 56 +/- 7 years with 87% male and 81% white race and body mass index (BMI) of 26 +/- 4. There were 3 cases of AF (0.3%) in the OHT group and 757 cases of AF (21%) in the low-risk CABG group. The strongest independent predictor of freedom from postoperative AF was having had a transplant (odds ratio [OR] 96, 95% confidence interval [CI] 13-720). The incidence of AF, atrial flutter (AFL), and supraventricular tachycardia (SVT) in OHT was 0.33, 2.8%, and 1.3%, respectively. Given that incidence of AF, AFL, and SVT in historical post-CABG population is 25%, 17%, and 4.3%, transplanted patients appear to have lower incidence of AF, AFL, and SVT than the reference population. Consistent with this, transplanted patients underwent few ablation procedures for atrial arrhythmias. Additionally, the three patients with AF had bicaval anastomoses suggesting the possibility of PACs originating in the donor superior vena cava (SVC) or IVC (inferior vena cava) initiating AF in these patients. CONCLUSIONS: In a cohort study of transplant and low-risk CABG patients, the strongest independent predictor of freedom from AF is having undergone transplant surgery. One potential explanation for the markedly lower incidence of AF may be effective isolation of thoracic veins with documented cases retaining the native SVC.