Surgical Ablation of Atrial Fibrillation with Cryo and Radiofrequency Concomitant to Mitral Valve Surgery : Clinical, Biochemical and Echocardiography Outcomes

Sammanfattning: Atrial fibrillation (AF) is the most common arrhythmia seen in clinical practice. In cardiac surgery, the negative influence of AF on short- and long-term outcomes has made concomitant ablation procedures more common. The indications, clinical aspects, results, risks, and benefits of the additional surgical ablation are still valuable topics for discussion. This compilation thesis consists of four papers aiming to investigate some of the clinical, biochemical, and echocardiographic aspects of surgical ablation for AF (Cox-Maze IV) when performed concomitant to mitral valve surgery (MVS).Through a retrospective, case-control, single-center study, we described the impact of the Cox-Maze IV procedure added to MVS with focus on postoperative heart failure (paper I).Cryoenergy (cryo) and radiofrequency (RF) are the two different energy sources mainly used in Cox-Maze IV for AF ablation. To achieve linear scars in the atrial wall, the RF procedure uses heat damage, whereas the cryo method freezes down to -150°C. Through a prospective, randomized, longitudinal, controlled study, we compared the biochemical responses of the two ablative methods in concomitant MVS and the release of enzymes expressing myocardial injury, as well as inflammatory, cell stress, and apoptosis-specific proteins. We could show that cryo results in a larger release of markers for myocardial damage but has no impact on the early inflammatory response (paper II).Extended scar lesions resulting after maze may influence atrial function. As the left atrium plays a key role in the altered cardiac hemodynamics in AF, an echocardiographic analysis of the effects of the Cox-Maze IV procedure concomitant to MVS on the left atrium was carried out. The impacts of the two energy sources (cryo and RF) on left atrial remodeling and function had not been compared previously. Their direct effect on left atrial remodeling and mechanical function were assessed 1 year after surgery in patients with restored sinus rhythm. Sinus rhythm restoration after MVS concomitant to Cox-Maze IV results in a reduced left atrium size regardless of the energy source used. Three-dimensional echocardiography showed that, compared to RF, the extension of the ablation area produced by cryo implies major left atrium structural remodeling affecting systolic function. The negative effect on left atrium remodeling seems to be linear with the duration of the AF (paper III).An overview of the pacemaker implantation rate after the Cox-Maze IV procedure concomitant to MVS was obtained in a multicenter study using national qualitative registers (SWEDHEART, Carath, Svenska ICD- och Pacemakerregistret) (paper IV, sumbitted).Our results contribute to optimizing surgical indications and patient selection, providing a deeper understanding of the biochemical and echocardiographic changes during and after surgical ablation.