Cardiac catheterization procedures are routinely guided by X-ray fluoroscopy but suffer from poor soft-tissue contrast and a lack of depth information. These procedures often employ pre-operative magnetic resonance or computed tomography imaging for treatment planning due to their excellent soft-tissue contrast and 3D imaging capabilities. We developed a 2D-3D image registration method to consolidate the advantages of both modalities by overlaying the 3D images onto the X-ray. Our method uses electrophysiology catheters that are typically placed in vessels of the heart where they remain throughout the procedure. Vessels were segmented from the 3D anatomical scans, and the 3D catheter positions were reconstructed from sequential biplane X-ray image pairs. To achieve registration, an automatic global-fit algorithm was developed which minimized the RMS distance error of the catheter to the medial line of its respective vessel. Data were processed for two clinical cases and an accurate registration was validated by visual inspection.