Atrioesophageal Fistula Rates Before and After Adoption of Active Esophageal Cooling During Atrial Fibrillation Ablation.

BACKGROUND: Active esophageal cooling reduces the incidence of endoscopically identified severe esophageal lesions during radiofrequency (RF) catheter ablation of the left atrium for the treatment of atrial fibrillation. A formal analysis of the atrioesophageal fistula (AEF) rate with active esophageal cooling has not previously been performed. OBJECTIVES: The authors aimed to compare AEF rates before and after the adoption of active esophageal cooling. METHODS: This institutional review board (IRB)-approved study was a prospective analysis of retrospective data, designed before collecting and analyzing the real-world data. The number of AEFs occurring in equivalent time frames before and after adoption of cooling using a dedicated esophageal cooling device (ensoETM, Attune Medical) were quantified across 25 prespecified hospital systems. AEF rates were then compared using generalized estimating equations robust to cluster correlation. RESULTS: A total of 14,224 patients received active esophageal cooling during RF ablation across the 25 hospital systems, which included a total of 30 separate hospitals. In the time frames before adoption of active cooling, a total of 10,962 patients received primarily luminal esophageal temperature (LET) monitoring during their RF ablations. In the preadoption cohort, a total of 16 AEFs occurred, for an AEF rate of 0.146%, in line with other published estimates for procedures using LET monitoring. In the postadoption cohort, no AEFs were found in the prespecified sites, yielding an AEF rate of 0% (P < 0.0001). CONCLUSIONS: Adoption of active esophageal cooling during RF ablation of the left atrium for the treatment of atrial fibrillation was associated with a significant reduction in AEF rate.

Cholinergic atrial fibrillation: I(K,ACh) gradients determine unequal left/right atrial frequencies and rotor dynamics.

OBJECTIVE: We tested the hypothesis that left atrial (LA) myocytes are more sensitive to acetylcholine (ACh) than right atrial (RA) myocytes, which results in a greater dose-dependent increase in LA than RA rotor frequency, increased LA-to-RA frequency gradient and increased incidence of wavelet formation during atrial fibrillation (AF). METHODS AND RESULTS: AF was induced in seven Langendorff-perfused sheep hearts in the presence of ACh (0.1-4.0 microM) and studied using optical mapping and bipolar recordings. Dominant frequencies (DFs) were determined in optical and electrical signals and phase movies were used to identify rotors and quantify their dynamics. DFs in both atria increased monotonically with ACh concentration until saturation, but the LA frequency predominated at all concentrations. Rotors were also seen more often in the LA, and although their life span decreased, their frequency and number of rotations increased. Patch-clamp studies demonstrated that ACh-activated potassium current (I(K,ACh)) density was greater in LA than RA sheep myocytes. Additionally, ribonuclease protection assay demonstrated that Kir3.4 and Kir3.1 mRNAs were more abundant in LA than in RA. CONCLUSIONS: A greater abundance of Kir3.x channels and higher I(K,ACh) density in LA than RA myocytes result in greater ACh-induced speeding-up of rotors in the LA than in the RA, which explains the ACh dose-dependent changes in overall AF frequency and wavelet formation.

Wavebreak formation during ventricular fibrillation in the isolated, regionally ischemic pig heart.

Both fixed and dynamic heterogeneities were implicated in the mechanism of wavebreak (WB) generation during ventricular fibrillation (VF). However, their relative roles remain unclear. We hypothesized that during ischemic VF, the WBs are produced primarily because of a fixed heterogeneity; namely, the gradient of refractoriness across the ischemic border zone (BZ). Ischemia was induced in 15 isolated blood-perfused hearts by occluding the left anterior descending coronary artery. Simultaneous video imaging (approximately 32x32 mm2) of Di-4-ANEPPS fluorescence in the ischemic zone (IZ), the BZ, and the nonischemic zone (NIZ) was performed. Dominant-frequency maps were constructed to assess gradients of refractoriness during VF. We used singularity points analysis to quantify the incidence of WBs per square centimeter per second. During preischemic VF, the distribution of WBs was relatively uniform. Ischemia caused an increase of WBs in the BZ (from 6.2+/-2.8 to 10.8+/-4.0) and a decrease of WBs in the IZ (from 5.8+/-2.8 to 2.8+/-1.4), without a significant change in NIZ (from 6.4+/-2.3 to 4.1+/-1.7). This finding is fully consistent with the dominant-frequency distribution during ischemic VF: the average dominant frequency was significantly slower in IZ than in NIZ (7.8+/-0.7 versus 10.1+/-1.0 Hz), suggesting a large gradient in refractory periods across the BZ. We concluded that acute regional ischemia plays a dual role in the maintenance of VF, decreasing the incidence of WB in the IZ while increasing it in the BZ. This suggests a predominant role of fixed heterogeneities in the formation of WB during VF in acute regional ischemia.