## 2 Related Works
### TAVR and Complications  
The aortic valve is located between the left ventricle of the heart and the aorta, ensuring that blood flows in the correct direction from the heart into the aorta while preventing  
\begin{table}
\begin{tabular}{l c c c c c c} \hline \hline  & **TFF** & **LEAF** & **FATE** & **FedScale** & **FedML** & **FedOps** \\ \hline _Simulation_ & V & V & V & V & V & V \\ \hline _Scalability_ & - & - & - & O & - & V \\ \hline _Heterogeneous systems_ & O & - & V & V & V & V \\ \hline _Heterogeneous data_ & O & - & V & V & V & V \\ \hline _Communication overhead_ & - & - & O & O & - & V \\ \hline _Cloud-native platform_ & - & - & O & - & - & V \\ \hline _FL lifecycle management_ & - & - & - & - & - & V \\ \hline O: planned or partially implemented. & & & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: FedOps and other FL libraries comparison. Reprinted/adapted with permission from Ref. [19]. Published by [PERSON], 2024.  
backflow into the heart. Aortic valve stenosis occurs when the aortic valve becomes calcified owing to congenital reasons or other determinants, impairing its functionality. This leads to decreased cardiac performance and causes symptoms, such as thoracic discomfort, lethurgy, dyspnea, and syncope [26]. If neglected, the morbidity attributable to this condition escalates significantly [27].  
TAVR is a minimally invasive procedure that replaces the calcified aortic valve with an artificial valve via a catheter inserted through blood vessels such as the femoral artery. In contrast to traditional open-heart surgery, TAVR provides abbreviated recuperation periods and is particularly appropriate for high-risk patients who cannot undergo open-heart surgery, making it the standard treatment for managing aortic valve stenosis [28]. Over the preceding two decades, TAVR has transformed the management of aortic stenosis and has been demonstrated to be safer than open-heart surgery, for high-risk patients and individuals with lower surgical risks [29]. Moreover, advances in artificial valves, patient selection, and enhancements in TAVR methodologies have augmented safety and reduced procedure-related complications [29].  
Despite the widespread adoption of TAVR for managing aortic stenosis, the risk of postoperative complications persists. Common complications following TAVR include conduction abnormalities, paravalvular leaks, stroke, acute kidney injury, and bleeding complications, which can have severe consequences for the patient [9]. To address these concerns, extensive research has been conducted into the utilization of AI methodologies to forecast and manage post-TAVR complications at an early stage [9; 30; 31].  
Since its first implementation in 2002, TAVR has been performed in numerous hospitals and institutions, resulting in a substantial accumulation of procedural data. Leveraging this data can facilitate the development of highly efficacious AI models to anticipate post-TAVR complications, which could be crucial in reducing these complications. However, despite the existence of extensive TAVR data, security and privacy concerns restrict data sharing and utilization. This constrains research initiatives aimed at predicting complications using data from multiple institutions, underscoring the necessity for a solution that can enable AI models to be trained on data from various institutions while addressing privacy concerns.