Biatrial Electrical and Structural Atrial Changes in Heart Failure: Electroanatomic Mapping in Persistent Atrial Fibrillation in Humans.

OBJECTIVES: This study sought to characterize the biatrial substrate in heart failure (HF) and persistent atrial fibrillation (PeAF). BACKGROUND: Atrial fibrillation (AF) and HF frequently coexist; however, the contribution of HF to the biatrial substrate in PeAF is unclear. METHODS: Consecutive patients with PeAF and normal left ventricular (NLV) systolic function (left ventricular ejection fraction [LVEF] >55%) or idiopathic cardiomyopathy (LVEF ≤45%) undergoing AF ablation were enrolled. In AF, pulmonary vein (PV) cycle length (PVCL) was recorded via a multipolar catheter in each PV and in the left atrial appendage for 100 consecutive cycles. After electrical cardioversion, biatrial electroanatomic mapping was performed. Complex electrograms, voltage, scarring, and conduction velocity were assessed. RESULTS: Forty patients, 20 patients with HF (mean age: 62 ± 8.9 years; AF duration: 15 ± 11 months; LVEF: 33 ± 8.4%) and 20 with NLV (mean age: 59 ± 6.7 years; AF duration: 14 ± 9.1 months; p = 0.69; mean LVEF: 61 ± 3.6%; p < 0.001), were enrolled. HF reduced biatrial tissue voltage (p < 0.001) with greater voltage heterogeneity (p < 0.001). HF was associated with significantly more biatrial fractionation (left atrium [LA]: 30% vs. 9%; p < 0.001; right atrium [RA]: 28% vs. 11%; p < 0.001), low voltage (<0.5 mV) (LA: 23% vs. 6%; p = 0.002; RA: 20% vs 11%; p = 0.006), and scarring (<0.05 mV) in the LA (p = 0.005). HF was associated with a slower average PVCL (185 vs. 164 ms; p = 0.016), which correlated significantly with PV antral bipolar voltage (R = -0.62; p < 0.001) and fractionation (R = 0.46; p = 0.001). CONCLUSIONS: HF is associated with significantly reduced biatrial tissue voltage, fractionation, and prolongation of PVCL. Advanced biatrial remodeling may have implications for invasive and noninvasive rhythm control strategies in patients with AF and HF.

A comparison of the electrophysiologic and electroanatomic characteristics between the right and left atrium in persistent atrial fibrillation: Is the right atrium a window into the left?

INTRODUCTION: The right atrium (RA) is readily accessible; however, it is unclear whether changes in the RA are representative of the LA. We performed detailed biatrial electroanatomic mapping to determine the electrophysiological relationship between the atria. METHODS AND RESULTS: Consecutive patients with persistent AF underwent biatrial electroanatomical mapping with a contact force catheter acquiring points with a CF >10 g prior to ablation. Points were analyzed for tissue voltage, complex electrograms, low voltage (<0.5 mV), scar (<0.05 mV), and conduction velocity (CV). Forty patients (mean age 59 ± 9.2 years, AF duration 12.9 ± 9.2 months, LA area: 28 ± 5.2, RA area: 25 ± 6.4 mm2 , LVEF: 44 ± 15%) underwent mapping during CS pacing. Bipolar voltage (R = 0.57, P <0.001), unipolar voltage (R = 0.68, P <0.001), low voltage (<0.5 nV) (R = 0.48, P = 0.002), fractionation (R = 0.73, P <0.001), and CV (R = 0.49, P = 0.001) correlated well between atria. There was no difference in global bipolar voltage (LA 1.89 ± 0.77 vs. RA 1.77 ± 0.57 mV, P = 0.57); complex electrograms (LA 20% vs. RA 20%, P = 0.99) or low voltage (LA 15% vs. RA 16%, P = 0.84). Global unipolar voltage was significantly higher in the LA compared to the RA (2.95 ± 1.14 vs. 2.28 ± 0.65 mV, P = 0.002) and CV was significantly slower in the RA compared to the LA (0.93 ± 0.15 m/s vs. 1.01 ± 0.19 m/s, P = 0.001). CONCLUSION: AF is associated with remodeling processes affecting both atria. The more accessible RA provides an insight into the biatrial process associated with AF in various disease states without trans-septal access.

Isolation of the posterior left atrium for patients with persistent atrial fibrillation: routine adenosine challenge for dormant posterior left atrial conduction improves long-term outcome.

AIMS: Catheter ablation to achieve posterior left atrial wall (PW) isolation may be performed as an adjunct to pulmonary vein isolation (PVI) in patients with persistent atrial fibrillation (AF). We aimed to determine whether routine adenosine challenge for dormant posterior wall conduction improved long-term outcome. METHODS AND RESULTS: A total of 161 patients with persistent AF (mean age 59 ± 9 years, AF duration 6 ± 5 years) underwent catheter ablation involving circumferential PVI followed by PW isolation. Posterior left atrial wall isolation was performed with a roof and inferior wall line with the endpoint of bidirectional block. In 54 patients, adenosine 15 mg was sequentially administered to assess reconnection of the pulmonary veins and PW. Sites of transient reconnection were ablated and adenosine was repeated until no further reconnection was present. Holter monitoring was performed at 6 and 12 months to assess for arrhythmia recurrence. Posterior left atrial wall isolation was successfully achieved in 91% of 161 patients (procedure duration 191 ± 49 min, mean RF time 40 ± 19 min). Adenosine-induced reconnection of the PW was demonstrated in 17%. The single procedure freedom from recurrent atrial arrhythmia was superior in the adenosine challenge group (65%) vs. no adenosine challenge (40%, P < 0.01) at a mean follow-up of 19 ± 8 months. After multiple procedures, there was significantly improved freedom from AF between patients with vs. without adenosine PW challenge (85 vs. 65%, P = 0.01). CONCLUSION: Posterior left atrial wall isolation in addition to PVI is a readily achievable ablation strategy in patients with persistent AF. Routine adenosine challenge for dormant posterior wall conduction was associated with an improvement in the success of catheter ablation for persistent AF.

Determining the Optimal Dose of Adenosine for Unmasking Dormant Pulmonary Vein Conduction Following Atrial Fibrillation Ablation: Electrophysiological and Hemodynamic Assessment. DORMANT-AF Study.

INTRODUCTION: ELECTROPHYSIOLOGICAL AND HEMODYNAMIC ASSESSMENT. DORMANT-AF STUDY: The significance of adenosine induced dormant pulmonary vein (PV) conduction in atrial fibrillation (AF) ablation remains controversial. The optimal dose of adenosine to determine dormant PV conduction is yet to be systematically explored. METHODS AND RESULTS: ELECTROPHYSIOLOGICAL AND HEMODYNAMIC ASSESSMENT. DORMANT-AF STUDY: Consecutive patients undergoing index AF ablation received 3 adenosine doses (12, 18, and 24 mg) in a randomized blinded order, immediately after pulmonary vein isolation (PVI). Electrophysiological (PR prolongation, AV block (AVB) and PV reconnection) and hemodynamic (BP) parameters were measured. A total, 339 doses (113/dose) assessed 191 PVs in 50 patients (66% male, 72% PAF, 52% hypertensive). Dormant PV conduction occurred in 28% of patients (16.5% [32] of PVs). All cases were associated with AVB (AVB: PV reconnection vs. no PV reconnection 100% vs. 83%, P = 0.007). AVB occurred more frequently at 24 mg versus 12 mg (92% vs. 82%, P = 0.019) but not versus 18 mg (91%, P = 0.62). AVB duration progressed between 12 mg (12.0 ± 8.9 seconds), 18 mg (16.1 ± 9.1 seconds, P = 0.001), and 24 mg (19.0 ± 9.3 seconds, P < 0.001) doses. MBP fell further at 24 mg (ΔMBP: 27 ± 12 mmHg) and 18 mg (26 ± 13 mmHg) doses compared to 12 mg (22 ± 10 mmHg vs., P < 0.001). A significant reduction in AVB in patients >110 kg (65% vs. 91% in 70-110 kg group, P < 0.001) in response to adenosine was seen. CONCLUSION: ELECTROPHYSIOLOGICAL AND HEMODYNAMIC ASSESSMENT. DORMANT-AF STUDY: An adenosine dose producing AVB is required to unmask dormant PV conduction. AVB is significantly reduced in patients >110 kg. Weight and dosing variability may in part explain the conflicting results of studies evaluating the clinical utility of adenosine in PVI.

Deglutition-Induced Atrial Tachycardia Localised with Contact Force-Guided Activation Mapping.

Deglutition-induced atrial tachycardia is a rare arrhythmia with a poor response to medical therapy. Electrophysiological study is challenging due to the dependence of induction on swallowing. We present a novel approach to management of deglutition-induced atrial tachycardia arising from right superior pulmonary vein. Use of minimal conscious sedation and repeated swallow challenge inductions, together with contact force-guided mapping were key determinants of success. We review published cases, discussing potential mechanisms including oesophageal distension and neural reflexes.

Reverse cardiac remodeling after renal denervation: Atrial electrophysiologic and structural changes associated with blood pressure lowering.

BACKGROUND: Hypertension is the most common modifiable risk factor associated with atrial fibrillation. OBJECTIVE: The purpose of this study was to determine the effects of blood pressure (BP) lowering after renal denervation on atrial electrophysiologic and structural remodeling in humans. METHODS: Fourteen patients (mean age 64 ± 9 years, duration of hypertension 16 ± 11 years, on 5 ± 2 antihypertensive medications) with treatment-resistant hypertension underwent baseline 24-hour ambulatory BP monitoring, echocardiography, cardiac magnetic resonance imaging, and electrophysiologic study. Electrophysiologic study included measurements of P-wave duration, effective refractory periods, and conduction times. Electroanatomic mapping of the right atrium was completed using CARTO3 to determine local and regional conduction velocity and tissue voltage. Bilateral renal denervation was performed, and all measurements repeated after 6 months. RESULTS: After renal denervation, mean 24-hour BP reduced from 152/84 mm Hg to 141/80 mm Hg at 6-month follow-up (P < .01). Global conduction velocity increased significantly (0.98 ± 0.13 m/s to 1.2 ± 0.16 m/s at 6 months, P < .01), conduction time shortened (32 ± 5 ms to 27 ± 6 ms, P < .01), and complex fractionated activity was reduced (37% ± 14% to 19% ± 12%, P = .02). Changes in conduction velocity correlated positively with changes in 24-hour mean systolic BP (R(2) = 0.55, P = .01). There was a significant reduction in left ventricular mass (139 ± 37 g to 120 ± 29 g, P < .01) and diffuse ventricular fibrosis (T1 partition coefficient 0.39 ± 0.07 to 0.31 ± 0.09, P = .01) on cardiac magnetic resonance imaging. CONCLUSION: BP reduction after renal denervation is associated with improvements in regional and global atrial conduction and reductions in ventricular mass and fibrosis. Whether changes in electrical and structural remodeling are solely due to BP lowering or are due in part to intrinsic effects of renal denervation remains to be determined.

The transesophageal echo probe may contribute to esophageal injury after catheter ablation for paroxysmal atrial fibrillation under general anesthesia: a preliminary observation.

INTRODUCTION: The transesophageal echo probe (TEE) is commonly used before and during atrial fibrillation (AF) ablation under general anesthesia (GA). We sought to determine the potential contribution of the TEE probe to esophageal injury after pulmonary vein isolation (PVI) alone for paroxysmal AF. METHODS AND RESULTS: Seventy-six patients undergoing PVI with TEE, PVI/TEE, 16 undergoing PVI without TEE (PVI/No TEE), and 27 undergoing TEE without any left atrial ablation (TEE/No LA ablation) under GA were included. Posterior wall ablation was power (20-25 W) and time limited (electrogram attenuation or ≤30 s). Esophageal capsule endoscopy (n = 206) was performed pre- and post-procedure and at 2 weeks. Esophageal lesions were seen in 30% of PVI/TEE, 0% of patients in the PVI/No TEE (P = 0.009), and 22% of TEE/No LA ablation groups (P = 0.47 vs. PVI/TEE). There were no instances of esophageal bleeding, perforation, or need for gastrointestinal intervention. Self-resolving dysphagia was the only reported symptom (5%). All lesions healed within 2 weeks. There was no significant difference in the location or morphological appearance of esophageal lesions seen in the PVI/TEE versus TEE/No LA ablation groups. CONCLUSIONS: Esophageal lesions were seen in 30% of patients undergoing PVI alone under GA with use of TEE and in a similar proportion (22%) of patients undergoing TEE in the absence of left atrial ablation. This study makes the preliminary observation that one must be cognizant of the TEE probe as a potential contributor to esophageal injury after AF ablation. Larger studies are needed to confirm these findings.