P867Postoperative atrial velocity and deformation - the impact of radiofrequency ablation detected by intraoperative transesophageal doppler myocardial imaging

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Background: Sinus rhythm (SR) restitution often occurs in patients (pts) with permanent atrial fibrillation (AF) early following various cardiac surgical procedures, but it is unclear whether adequate atrial mechanical activity occurs as well. We aim to detect restoration of atrial function by intraoperative tissue velocity (TVI) and deformation (Strain rate (SRI)) analysis before and immediately after surgery associated with conversion to SR.Methods: 24 pts (11F/13M, 67±9 yrs) with permanent AF undergoing various cardiac surgical procedures were divided in two groups: 12 pts additionally undergoing radiofrequency ablation (RFA) and the non-RFA group of 12 sex-, age-matched pts briefly in SR intraoperatively, not undergoing AF surgery. An intraoperative TEE study including Doppler myocardial imaging was acquired pre- and post-surgical intervention. TVI and SRI data were acquired at the mid segment of the left atrial lateral wall.Results: Intraoperative baseline ECG demonstrated AF in all pts, while electrical atrial activation was present in all pts at postprocedural data acquisition. No significant difference was found for the preprocedural TVI or SRI values between the two groups. Following restoration of atrial activation, atrial contraction was restored in both groups. Within the RFA group, postprocedural TVI values were significantly lower during ventricular systole and early diastole compared to preprocedural values (-2.1±2.2 vs -4.1±2.3, P=0.03 and 3.1±1.3 vs 4.8±2.9, P=0.04, respectively). Such changes were not noted in the non-RFA group. Conversely, the late diastolic postprocedural SRI was significantly higher in the RFA group than in the non-RFA group (-1.4±1.2 vs -0.6±0.6, P=0.04). These TVI and SRI values were much lower in both groups compared to reported normal values.Conclusion: Restoration of atrial activation with subsequent induction of atrial contraction occurs in the early postoperative period. Although higher in the RFA group, this late diastolic contraction occurs with low deformation values both in pts with and without RFA. Thus, atrial electrical activation does not implicate restoration of atrial mechanics in the early postoperative phase, potentially due to atrial stunning or irreversible atrial structural remodeling. Our findings also demonstrate impairment in atrial reservoir function post-RFA likely due to ablation induced changes in tissue compliance. The results suggest individualization of anticoagulation therapy cessation in pts after successful AF surgery, since the ECG appearance of SR does not necessarily translate into complete restoration of atrial transport.

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