Formation of low-voltage zones on the anterior left atrial wall due to mechanical compression by the ascending aorta.

BACKGROUND: Although low-voltage zones (LVZs) in the left atrium (LA) are considered arrhythmogenic substrates in some patients with atrial fibrillation (AF), the pathophysiologic factors responsible for LVZ formations remain unclear. OBJECTIVE: To elucidate the anatomical relationship between the LA and ascending aorta responsible for anterior LA wall remodeling. METHODS: We assessed the relationship between existence of LVZs on the anterior LA wall and the three-dimensional computed tomography image measurements in 102 patients who underwent AF ablation. RESULTS: Twenty-nine patients (28%) had LVZs grearer than 1.0 cm2 on the LA wall in the LA-ascending aorta contact area (LVZ group); no LVZs were seen in the other 73 patients (no-LVZ group). The LVZ group (vs. no-LVZ group) had a smaller aorta-LA angle (21.0 ± 7.7° vs. 24.9 ± 7.1°, p = .015), greater aorta-left-ventricle (LV) angle (131.3 ± 8.8° vs. 126.0 ± 7.9°; p = .005), greater diameter of the noncoronary cusp (NCC; 20.4 ± 2.2 vs. 19.3 ± 2.5 mm; p = .036), thinner LA wall-thickness adjacent to the NCC (2.3 ± 0.7 vs. 2.8 ± 0.8 mm; p = .006), and greater cardiothoracic ratio (percentage of the area in the thoracic area, 40.1 ± 7.1% vs. 35.4 ± 5.7%, p < .001). The aorta-LA angle correlated positively with the patients' body mass index (BMI), and the aorta-LV angle correlated negatively with the body weight and BMI. CONCLUSION: Deviation of the ascending aorta's course and distention of the NCC appear to be related to the development of LA anterior wall LVZs in the LA-ascending aorta contact area. Mechanical pressure exerted by extracardiac structures on the LA along with the limited thoracic space may contribute to the development of LVZs associated with AF.

Electrophysiologic and anatomic factors predictive of a need for touch-up radiofrequency application for complete pulmonary vein isolation: Comparison between hot balloon- and cryoballoon-based ablation.

INTRODUCTION: Although electrophysiologic and anatomic factors associated with the need for touch-up radiofrequency (RF) applications after cryoballoon ablation (CBA) for atrial fibrillation (AF) have been well described, those associated with the need for such touch-up after hot balloon ablation (HBA) have not. We aimed to identify factors predictive of the need for touch-up applications following HBA. METHODS: Anatomic and electrophysiologic factors predictive of the need for touch-up RF ablation were compared between 46 propensity score-matched pairs of patients who underwent HBA or CBA for AF. RESULTS: Touch-up RF ablation was more frequently required after HBA than after CBA (57% vs 30%, respectively; P = .01), and mostly at the anterior aspect of the left superior pulmonary vein (LSPV) carina after HBA (35%) but at the inferior aspect of the right inferior PV (RIPV) after CBA (71%). Post HBA touch-up was associated with male gender, a CHA 2 DS 2 -VASc score ≤ 2, PV-left atrial bipolar voltage ≥ 1.35 mV, and PV trunk length ≥ 24.0 mm; post CBA touch-up associated with a history of heart failure. CONCLUSION: Following balloon ablation for AF, there may be a need for touch-up applications, especially at the LSPV ridge after HBA but at the RIPV after CBA. It may behoove operators to expect a need for touch-up following HBA when patients are male, have a CHA2 DS 2 -VASc score ≤ 2 points, when PV-LA bipolar voltage is ≥ 1.35 mV, or when the PV trunk is ≥ 24.0 mm or following CBA when there is a history of heart failure.