INFLUENCE OF EXTENT OF RADIOFREQUENCY ABLATION ON CONTRACTILE FUNCTION OF LEFT ATRIUM AND PULMONARY VEINS

To assess the dynamics of the left atrium (LA) contractility in relation to the extent of radiofrequency ablation (RFA) for treatment of atrial fibrillation (AF), 66 patients aged 56.2±7.3 years were examined. The ratio of the myocardial area subjected to radiofrequency exposure to the total LA area was assessed in all patients upon termination of antral pulmonary vein isolation (APVI); it made up 27.8±4.1%. In Group I (n=36) APVI was accompanied by RFA in LA, as opposed to Group II (n=30). Transesophageal and transthoracic echocardiography was performed in all subjects before and immediately after RFA. Worsening of contractility of the LA or pulmonary vein was revealed after RFA which included an altered transmitral flow velocity, the pulmonary vein flow, and an increased LA size and volume. The “pseudo-restriction” of the left ventricle filling and a decreased LA ejection fraction predominantly due to the passive phase were found. No statistically significant difference was found between the study groups for any index assessed during the study. “Expansion” of PVI area to a certain extent did not deteriorate intra-atrial hemodynamics, but further expansion led to alteration of the LA passive distensibility. This cut-off level was determined and made up 25% of the total LA area. Thus, depression of the LA contractility occurs in the early post-operation period after antral PVI due to its passive ejection. Expansion of areas of isolation on the inter-atrial septum and the LA lateral crest improves effectiveness of the procedure but worsens the LA contractility if the injury area exceeds 25% of the total LA area.

atrial fibrillation, radiofrequency ablation, antral isolation, pulmonary veins, left atrium, interatrial septum, contractility, echocardiography

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