S. Ahmed Athar, MD, FSCAI; HuuTam Truong, MD, FSCAI; Faisal Latif, MD, FSCAI

Introduction

Minimizing iodinated contrast volume during cath lab procedures is associated with reduction in contrast-induced acute kidney injury, length of stay, and health care system costs.¹ As such, cath lab operators can improve patient outcomes by making consistent efforts to use lower contrast volumes without sacrificing procedural success rates. While zero-contrast and ultra-low-contrast complex coronary interventions have been demonstrated,² in this SCAI Tip of the Month, we focus on simple, practical, and sustainable techniques to effectively reduce contrast volumes for diagnostic angiography and percutaneous coronary intervention (PCI).

Prior to the Procedure

1. Carefully review the patient’s prior angiograms, especially for patients with complex anatomy or a prior coronary artery bypass graft (CABG). This helps to limit angiograms to the projections that best show significant lesions. For example, a priori knowledge of a dilated ascending aorta or an anterior origin of the right coronary artery (RCA) that requires modification from standard diagnostic catheters can save time and contrast.
2. Review prior chest computed tomography (CT) imaging. This can offer significant information regarding the aortic locations and patency of coronaries and grafts as well as the presence and location of coronary calcification.
3. Incorporate the patient’s creatinine, estimated glomerular filtration rate (GFR), and safe-contrast limits in their procedural timeouts.³
4. Obtain an echocardiogram prior to cardiac catheterization, if feasible. This obviates the need for a routine left ventriculogram.

During the Procedure

1. Reduce the volume and frequency of “puffs.” Use of fluoroscopic markers such as calcium and graft clips or markers, along with watching for the subtle motion of the catheter when it engages a coronary, can reduce repeated “puffs” of contrast.
2. Use the fewest number of injections to obtain a diagnostic study. Not every patient requires a full injection of contrast for each coronary or graft in the “standard” six views. For example, known coronary/graft occlusions need not be routinely redemonstrated; a small, nondominant RCA might need one view and only 1–2 mL of contrast.
3. Use biplane angiography, if available, especially in patients with chronic kidney disease (CKD). Biplane imaging can significantly reduce contrast usage by acquiring two images for each injection.
4. Perform smart angiography. Operators should assess in real time the vessel size and opacification to understand when to stop injecting. Prolonged injections after vessel opacification lead to continued reflux of contrast into the aorta and do not add value or quality to the image. Female patients with smaller coronaries or post-CABG patients with native vessels supplying less territory typically need less volume per image. It is also important to obtain optimal vessel engagement to increase image quality and reduce the need for repeated injections.
5. Consider using automated injectors. Automated injectors and contrast-saving devices can significantly reduce the volume of contrast delivered to the patient.⁴
6. Use smaller catheters for diagnostic angiography. 4F or 5F catheters can produce good-quality diagnostic angiograms with a lower volume of contrast, especially when used with a power injector.
7. Remove contrast prior to catheter removal or intracoronary medication delivery. Diagnostic catheters can hold 1–2 mL of contrast in their lumens, and 6F guide catheters hold nearly 3 mL. For example, a post-CABG case that uses four different diagnostic catheters and one guide catheter and delivers intracoronary medications can save up to 15 mL of contrast with this method.
8. Use coronary physiology and intracoronary imaging. The Fractional Flow Versus Angiography for Multivessel Evaluation (FAME) trial demonstrated that the use of fractional flow reserve (FFR) in multivessel disease led to a decrease in the number of stents used, and the volume of contrast delivered in the FFR arm was decreased by 10 percent relative to the angiography arm.⁵ Intravascular ultrasound-guided PCI can reduce contrast usage in addition to optimizing stent results by aiding lesion preparation strategy, accurate stent sizing, and post-stent deployment assessment.⁶

Quality Improvement Processes

1. Accurate documentation of contrast volume should be maintained.
2. Cath lab directors must understand their facility’s average contrast use compared to the national average and should identify and work with operators who use higher contrast amounts relative to their peers.
3. A low-contrast protocol for patients with CKD should be used. Our average diagnostic coronary angiography contrast volume for CKD patients is less than 25 mL, and we have achieved volumes as low as 13 mL (using biplane imaging).

Conclusion

Consistent use of these methods has helped our cath lab achieve very low contrast volumes. Our mean diagnostic contrast volume is 42 mL/case (Veterans Affairs [VA] national median 70 mL/case), and despite high clinical and anatomic complexity compared to our peer facilities’ average, the mean contrast volume for PCI at our center is 76 mL (VA national median >140 mL/PCI). We currently utilize intracoronary imaging (intravascular ultrasound [IVUS] and optical coherence tomography [OCT]) in 67 percent of our PCIs.

Reduction of contrast volume is an important component of improving outcomes in patients undergoing coronary angiography and PCI and decreases health care costs. Being mindful of some of the above-mentioned practices to lower contrast use and tracking individual- and facility-level data allows operators to improve patient safety without compromising quality.

References

1. Morabito S, Pistolesi V, Benedetti G, et al. Incidence of contrast-induced acute kidney injury associated with diagnostic or interventional coronary angiography. J Nephrol. 2012 Nov–Dec;25(6):1098–107. 
2. Galougahi KK, Mintz GS, Karmpaliotis D, et al. Zero-contrast percutaneous coronary intervention on calcified lesions facilitated by rotational atherectomy. Catheter Cardiovasc Interv. 2017 Oct 1;90(4):E85–E89.
3. Gurm HS, Dixon SR, Smith DE, et al. Renal function-based contrast dosing to define safe limits of radiographic contrast media in patients undergoing percutaneous coronary interventions. J Am Coll Cardiol. 2011 Aug 23;58(9):907–14.
4. Minsinger KD, Kassis HM, Block CA, et al. Meta-analysis of the effect of automated contrast injection devices versus manual injection and contrast volume on risk of Contrast induced nephropathy. Am J Cardiol. 2014 Jan 1;113(1):49–53.
5. Tonino PAL, De Bruyne B, Pijls NH, et al. Fractional flow reserve versus angiography for guiding percutaneous coronary intervention. N Engl J Med 2009 Jan 15;360(3):213–224.
6. Mariani J Jr, Guedes C, Soares P, et al. Intravascular ultrasound guidance to minimize the use of iodine contrast in percutaneous coronary intervention: the MOZART (Minimizing cOntrast utiliZation With IVUS Guidance in coRonary angioplasTy) randomized controlled trial. JACC Cardiovasc Interv. 2014 Nov;7(11):1287–1293.