Achieving radiation dose reduction without compromising efficacy and safety is a permanent goal in cardiac catheterization procedures, as they pose a health hazard to both the patients and physicians and support staff. An important component of radiation energy delivered during invasive procedures is the pulse rate at which fluoroscopic and cine-acquisition (CINE) images are generated. (1)
Previous research has shown that ultralow-dose protocols are feasible in a cardiac catheterization setting and result in a significant decrease in radiation exposure. Modern fluoroscopy devices deliver X-ray energy in a pulse range from 1 to 30 frames per second (FPS); the default setting is mostly in the range from 7.5-10.0 FPS. The evolution of catheterization-related radiation delivery has one of decreasing energy values: in the early years X-ray energy was delivered continuously; the first pulsed fluoroscopy regimes were performed at 30 FPS and later reduced to 15 FPS. In the recent decade, the agreed-upon standard has been 7.5 FPS, a value shown to significantly reduce adjusted total X-ray energy and radiation exposure in the staff and patients. (2,3)
Since late 2019, we have introduced and routinely use an “ultralow dose radiation protocol” at the Cardiac Catheterization Laboratory at Čakovec County Hospital, with a fluoroscopy pulse rate of 3.75 FPS and cine-acquisition at 7.5 FPS. All percutaneous coronary interventions (PCI) for acute coronary syndrome, including complex PCI like bifurcations and chronic total occlusion (CTO), are performed under fluoroscopy at 3.75 FPS. We did not notice a reduction in image quality, and the whole team quickly adopted to the lower frame rate without deleterious effects on efficacy/safety: i.e. procedure time, contrast usage, or less-than-optimal visualization. In comparison with the previously used 7.5 FPS protocol, the radiation exposure on part of the patient has been significantly reduced using the novel 3.75 FPS protocol. To scrutinize the proposed protocol scientifically, we have joined an outside center in conducting a randomized study aimed at investigating the radiation exposure reduction from the 3.75 FPS vs. the 7.5 FPS protocol.
While awaiting the results of said trial, we urge the community of interventional cardiologists to consider the new protocol even in the most complex cases, such as CTO procedures, to minimize radiation exposure for the patients and staff, since our experience shows that the new protocol does not compromise the procedure in any way.