Post-transplant Left Atrial Function Depends on the Technique Used for Orthotopic Heart Transplantation

Abstract Background Even short episodes of post-transplant atrial fibrillation (AF) have been shown to increase the risk of adverse outcomes, including thromboembolic events, graft failure, and increased mortality. Of the two most commonly used heart transplantation techniques - bicaval and total orthotopic heart transplantation (OHTx), the former approach combines the donor and recipient atria, and may predispose to supraventricular arrhythmias, especially atrial fibrillation, as well as lead to a higher incidence of atrioventricular valve incompetence. Existing data relate mainly to the more non-physiological left atrial (LA) size and geometry after bicaval OHTx, while little is known about differences in LA function between patients treated with both techniques. Aim To compare LA functional and morphological characteristics between patients after bicaval and total OHTx. Methods The study group consisted of 28 patients who underwent OHTx between May 2021 and December 2022: 14 consecutive patients after total OHTx and 14 subjects after bicaval OHTx matched by age and time from heart transplant. Echocardiographic examination included standard measurements and left ventricle (LV) and LA longitudinal deformation assessment by speckle tracking technique. Results All enrollees were male. There were no differences between the groups after total and bicaval OHTx in anthropometric and laboratory parameters. Routine endomyocardial biopsies performed during follow-up after OHTx in all patients did not show severe graft rejection. No significant differences were found in LV dimensions, ejection fraction and stroke volume, Doppler velocities of mitral inflow and mitral annulus, as well as LV global longitudinal strain. In contrast to LV measures, significant between-group differences were demonstrated for LA parameters: LA volume index was significantly higher, and peak atrial longitudinal strain (PALS) corresponding to LA early diastole in the reservoir phase and peak atrial contraction strain (PACS) corresponding to LA systole were significantly higher in the total OHTx group than in the bicaval OHTx group (Table). Conclusions Total OHTx technique is associated with a more favorable LA morphology and function, which may explain the lower prevalence of atrial fibrillation reported in the literature in patients treated with this method. The clinical significance of reduced LA contribution to LV filling in patients subjected to bicaval OHTx needs further exploration.