Introduction Minimisation of radiation exposure during cardiac procedures is required by statute (IRMER 2000). During coronary angioplasty 47% of radiation dose is related to screening at standard frame rate (15 frames per second). Digital fluoroscopic technology has improved imaging making the use of lower frame rates feasible. This study assessed whether low frame rate screening (7.5 frames per second) reduced radiation without affecting patient outcomes.
Method We prospectively collected data from consecutive coronary angioplasty procedures performed at reduced screening frame rate (7.5 frames per second). We included elective, urgent and emergency procedures. Audit data from procedures performed at standard frame rate with the same inclusion criteria were used as a control group. Phillips Allura flat plate XPER FD10 catheterisation equipment was used. The frame rate could be increased at the operator's request, and any safety concerns were reported immediately.
Data collection Patient data:
Screening DAP (mGycm2)
Total DAP (mGycm2)
Total Fluoroscopy time (mm:ss)
Number of acquisition runs
Need to increase screening frame rate
30 day incidence of major adverse cardiovascular event (MACE): death, non-fatal myocardial infarction or need for urgent revascularisation.
Results 55 consecutive studies were examined at low-frame rate and compared with the audit control group (n=105). Mean age was 67 in the low screening rate group and 65 in the control group. Weight was similar in both groups (83 kg vs 82 kg). The screening times and number of acquisition runs were similar in each group. In every case image quality was acceptable, with no requirement for increased screening frame rate. No safety concerns were reported. 30-day incidence of major adverse cardiovascular events (MACE) was similar in both groups. In the screening group there was 1 MACE event at 30 days (2%), with 2 MACE events (2%) in the control group. Screening and Total DAPs (mean mGycm2) were 33% and 16% lower respectively in the low frame rate group. Statistical comparison was made with the Man-Whitney U-test. This showed a significant reduction in the Screening DAP (p≤0.01) with low frame rate screening. See Abstract 28 table 1 and graph.
Conclusions Low frame rate screening is a practical way of reducing radiation exposure in line with the ALARA “As Low As Reasonably Acheivable” principle. Having shown that low frame rate screening for coronary angiography gives good imaging quality and is safe, we now demonstrate that low frame rate screening coronary angioplasty is also safe. Radiation exposure from screening is significantly reduced by 33% and total exposure is reduced by 16%. Low frame rate screening should be standard practice where modern facilities allow. We suggest that centres currently using 15 frames per second screening should undertake a similar assessment in order to minimise radiation.