LAUSR

Percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) is associated with a longer fluoroscopy time and a higher radiation dose as compared to non‐CTO PCI. Absorbed radiation dose, in turn, is a relevant issue for both the patient and the cath lab staff, being associated with deterministic as well as stochastic effects. Therefore, the ALARA principle (as low as reasonably achievable) should represent a primary objective and an important quality metric in every catheterization laboratory. Recently, mobile lead equivalent radiation protective devices, used on top of personal lead‐equivalent aprons, have been shown to significantly reduce the radiation exposure to interventionists but not to the patient. Differently, a simple and effective way to reduce the dose for both the patient and the operator is represented by the reduction of the fluoroscopy frame rate. In this issue of Catheterization and Cardiovascular Interventions, Bacci et al. report the results of a retrospective registry enrolling 150 consecutive patients who underwent CTO PCI in a high volume center from January 2019 to August 2021. In the first 85 patients, a standard dose protocol (SDP, 7.5 frames per second for angiography and fluoroscopy) was used, whereas in the following 65 patients, an ultra‐low dose protocol (ULDP, 7.5 frames per second for angiography and 3.75 for fluoroscopy) was implemented. The procedures were further stratified according to technical complexity by means of the JCTO score. The main results of the study are the following: the dose area product was significantly lower in ULDP patients as compared to SDP patients in both simple and complex CTOs (6861.0 vs. 13236.0mGy× cm; p= 0.014 and (8865.0 vs. 16618.0mGy× cm; p< 0.001, respectively). Differently, Air‐Kerma was significantly lower in ULDP patients as compared to SDP patients only in complex CTOs (1499.0 vs. 2794.0 cGy; p<0.001). As far as procedural success is concerned, the authors report no statistically significant differences; this notwithstanding, a trend towards higher failure rate is actually detectable with the adoption of ULDP, especially in complex CTOs (p=0.058). Finally, there were no differences in procedural time, fluoroscopy time and contrast volume in simple CTOs between ULDP and SDP patients, whereas all these parameters were significantly reduced in complex CTOs when the ULDP protocol was used; of note, the authors attribute this contra‐intuitive findings to the fact that, in patients with complex CTOs, SDP group received more frequently PCI of non‐CTO lesions as compared to ULDP group, arguably leading to longer procedures. The findings of the manuscript, although interesting, need to be interpreted with caution. First, apart from the methodological limitations acknowledged by the authors (mainly single‐center, retrospective design and lack of measurement of operator radiation dose), there are several other issues that need to be elucidated, the first being represented by the quality of fluoroscopy when a ULDP is adopted. Unfortunately, the authors did not provide a formal evaluation of image quality (e.g., grading by experienced angiographers blinded to the protocol used); in fact, the only pertinent information is that a switch from ULDP to SDP was not needed in any procedure. Second, both Air Kerma and dose‐area product values should have been corrected for the fluoroscopy time given the observed differences in the complex CTO group. Finally, there was a large heterogeneity in the selection of vascular approaches for the procedures (radial vs. femoral) that was not considered in the analysis of data; this