A C-arm X-ray system includes synchronized ECG gating for enhanced cardiac soft-tissue imaging. The system includes an X-ray source disposed on a C-arm for rotation in a circular path about a patient and configured to release X-ray radiation synchronously with an ECG-gating signal, an X-ray image sensor disposed on the C-arm in a fixed opposing position to the X-ray source and configured to rotate with the source and receive the X-ray radiation and an ECG unit for acquiring ECG data from the patient. The system also includes a digital image acquisition processor arranged in communication with the X-ray source, X-ray image sensor and ECG unit for acquiring 2D projection images at predetermined C-arm angulations in the presence of the ECG-gating signal and an image processor arranged in communication with the digital image acquisition processor to receive and process the series of 2D projection images and reconstruct a continuous 3D volumetric image of the patient's cardiac soft tissue therefrom. A user interface to allow user control of the C-arm system and to display the continuous 3D volumetric image.