Comparison of Radiation Dose and Contrast Use in CT vs. Diagnostic Invasive Angiography in Coronary Artery Bypass Graft Patients

Schwarz, Konstantin; Sultan, Abdullah; Poole, Harry; Jones, Hefin; Duckett, Simon; Nolan, Jim

Abstract

Modern CT coronary angiography (CT) technology and acquisition technique demonstrate excellent specificity and sensitivity (both 96–99%) for assessment of coronary graft stenoses (>50%) and graft occlusions when compared to invasive angiography (IA) [1,2]. Due to the inherently more complex nature of invasive angiography there is a shift to utilize CT coronary angiography as first line diagnostic investigation in haemodynamically stable graft (CABG) patients. It is less known how the two tests compare in regard to radiation dose, contrast use and impact on renal function in real life.

Assuming the virtual diagnostic equivalence we investigated the average radiation dose and contrast received by both diagnostic modalities. This was a single centre retrospective pilot study. Observed frequency distributions were reported and continuous data expressed as mean ± SD. Unpaired t-test was used for statistical analysis of continuous variables. Categorical data were compared using Fisher's exact test. If data were not normally distributed then non-parametric tests were used. Statistical significance was assumed if p < .05. Data were analysed using GraphPad Prism version 5 software (San Diego, USA).

We collected data from patients with history of CABG who were investigated with CT (n = 455) or diagnostic IA (n = 250). All invasive coronary angiography (IA) procedures, where the patient underwent percutaneous intervention in the same setting were excluded from analysis. Our standard IA acquisition setting to minimize radiation exposure involves 7.5 frames/s for both fluoroscopy and cine acquisition. It is possible that minority of IA cases had this setting altered to obtain better images (reflecting real life practice), however this information was not collected.

Patient demographics were similar for CT vs IA group with mean (±SD) age 69.5 (9.9) vs 71.0 (8.4) years (p = .128), male 78% vs 82% (p = .242) and diabetes 22.9% vs 26.8 (p = .564). The indication for the diagnostic test comparing CT vs invasive angiography were also fairly similar with stable angina in 52.0% vs 52.8%, Acute coronary syndromes 37.0% vs 47.2%, other (Heart failure, VT…) 10.5% vs 0%.

The radiation dose was calculated by conversion to estimated effective radiation dose (mSv) from dose-length-product (mGycm) obtained by CT and from dose-area-product (μGym2) measured by invasive angiography as previously reported [3] [4]. The calculated effective radiation dose was slightly higher in the CT vs invasive angiography group, 4.7 (4.0–5.3) mSv vs 4.0 (2.6–6.4) mSv; median (IQR), p = .005, Fig. 1A. Contrast use was significantly lower in the CT group when compared to invasive angiography 99.9 (±1.4) mls vs 150.3 (±56.9) mls, p < .001; Fig. 1B. Contrast induced nephropathy (CIN) was investigated for patients with blood results available before and within 7 days of their tests (serum Cr >25% from baseline or rise by >0.49 mg/dl [5]). CIN was significantly lower in the CT group, 3.2% (5/147) compared to 10.2% (12/117) in the IA group, p = .023; Fig. 1C.

Citation

Schwarz, K., Sultan, A., Poole, H., Jones, H., Duckett, S., & Nolan, J. (2020). Comparison of Radiation Dose and Contrast Use in CT vs. Diagnostic Invasive Angiography in Coronary Artery Bypass Graft Patients. Cardiovascular Revascularization Medicine, 21(7), 927-928. https://doi.org/10.1016/j.carrev.2020.03.016

• Journal Article Type: Article
• Acceptance Date: Mar 9, 2020
• Online Publication Date: Mar 13, 2020
• Publication Date: 2020-07
• Deposit Date: Jun 21, 2023
• Journal: Cardiovascular Revascularization Medicine
• Print ISSN: 1553-8389
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 21
• Issue: 7
• Pages: 927-928
• DOI: https://doi.org/10.1016/j.carrev.2020.03.016
• Keywords: Cardiology and Cardiovascular Medicine; General Medicine; Coronary artery bypass; CT angiography; Contrast; Radiation; Coronary angiography
• Additional Information: This article is maintained by: Elsevier; Article Title: Comparison of Radiation Dose and Contrast Use in CT vs. Diagnostic Invasive Angiography in Coronary Artery Bypass Graft Patients; Journal Title: Cardiovascular Revascularization Medicine; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.carrev.2020.03.016; Content Type: simple-article; Copyright: © 2020 Elsevier Inc. All rights reserved.