Intracardiac blood flow dynamics depicted using 4D flow magnetic resonance imaging is increasingly used for analysis of cardiac health. Lagrangian Coherent Structures (LCS) is a powerful blood flow analysis tool, with applications in diastolic dysfunction and separating flowing blood with different behavior. However, use of LCS has been limited by long computation times. Therefore, a cloud-based computation engine for LCS analysis was developed, incorporating acceleration with graphical processing units (GPU:s). A speedup factor of up to 23 times is realized, enabling sub-second LCS computation times. Furthermore, the cloud platform makes rapid LCS analysis possible without investing in expensive GPU hardware.