Purpose To quantify periods of low motion and cross-sectional area changes of the coronary veins during the cardiac cycle for planning magnetic resonance coronary venograms (MRCV). Materials and Methods Images were acquired from nineteen patients with coronary artery disease (CAD) and thirteen patients scheduled for cardiac resynchronization therapy (CRT). The displacement and cross-sectional area of the coronary sinus was tracked and periods of low motion were defined as consecutive time points during which the position of the coronary sinus remained within a 0.67 mm diameter region. Patients were classified as systolic dominant or diastolic dominant based on the relative duration of their low motion periods. Results All CRT patients were classified as systolic dominant, and 32% of these had no separate diastolic rest period. All CAD patients with ejection fraction <35% were classified as systolic dominant, while all CAD patients with ejection fraction >35%were diastolic dominant. In 77% of all subjects, the cross-sectional area of the coronary sinus was larger in systole than in diastole. Conclusion The movement of the coronary sinus can be used to classify patients as either having a longer systolic or diastolic rest period. The classification of the CRT patients as systolic dominant suggests that MRCVs be acquired in systole for CRT planning; however, each patient’s low motion periods should be categorized to ensure the correct period is being utilized to minimize motion artifacts.