Correlation between pulmonary vein isolation efficacy and myocardial morphological changes

Aim. To investigate the correlation between the efficacy of pulmonary vein ostial isolation and morphological changes in the myocardium.

Methods. The study included 118 patients with paroxysmal or persistent atrial fibrillation (AF) and no significant structural heart disease. All patients underwent primary cryoballoon isolation of the pulmonary vein ostia with simultaneous implantation of a loop ECG recorder (Medtronic Reveal XT) and myocardial biopsy of the interatrial septum (IAS) and the interventricular septum (IVS). Tissue samples were obtained before cryoballoon ablation (CBA). Patients were followed for one year with regular visits at 3, 6, and 12 months. If AF recurred, patients underwent a repeat electrophysiological study to assess the durability of pulmonary vein isolation. In cases of recovered pulmonary vein conduction, reisolation was performed, followed by another year of followup using the same visit schedule. Consequently, two patient groups were formed: those without AF recurrence (after one or two procedures) and those with recurrence (after two catheter isolation attempts).

Results. Owing to an insufficient number of representative IAS biopsy samples (the biopsy material mainly consisted of the fibrous portion of the IAS), the analysis of the relationship between IAS morphological changes and nonpulmonaryveindependent AF recurrence could not be performed. In IVS biopsy samples, the most common morphological findings were myocardial hypertrophy, loss of myocardial crossstriation, endocardial thickening and lipomatosis, and cardiomyocyte dystrophy.

Conclusion. In all AF patients without severe organic heart disease, various morphological changes of the IVS myocardium were identified, including fibrosis, lipomatosis, and dystrophy. Histological changes in myocardial biopsies from AF patients, such as cardiomyocyte degeneration and endocardial thickening, are important components of atrial remodelling that contribute to arrhythmia initiation, maintenance, and progression - consistent with the concept of atrial cardiomyopathy (atrial myopathy) regardless of its origin. A deeper understanding of these cellular and molecular changes may inform the development of novel targeted strategies for AF prevention and treatment. No clear predictors of a specific electrophysiological type of AF recurrence (pulmonaryveindependent vs. nonpulmonaryveindependent) after radiofrequency ablation were identified, which may reflect common underlying mechanisms and warrants further investigation.

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