Intravascular Ultrasound Guidance to Minimize the use of Iodine Contrast in Percutaneous Coronary Intervention: The MOZART Randomized Controlled Trial

Abstract

Objective

To evaluate the impact of IVUS guidance on the final volume of contrast agent utilized in patients undergoing PCI.

Background

To date, few approaches have been described to reduce the final dose of contrast agent in percutaneous coronary interventions (PCI). We hypothesized that intravascular ultrasound (IVUS) might serve as an alternative imaging tool to angiography in many steps during PCI, thereby reducing the use of iodine contrast.

Methods

A total of 83 patients were randomized to I) angiography-guided PCI or II) IVUS-guided PCI, both groups treated according to a pre-defined meticulous procedural strategy. The primary endpoint was the total volume contrast agent used during PCI. Patients were followed clinically for an average of 4 months.

Results

The median total volume of contrast was 64.5 ml (interquartile range [IQR] 42.8 – 97.0 ml; minimum 19 ml; maximum 170 ml) in angiography-guided group vs. 20.0 ml (IQR 12.5 – 30.0 ml; minimum 3 ml; maximum 54 ml) in IVUS-guided group (p<0.001). Similarly, the median volume of contrast / creatinine clearance ratio was significantly lower among patients treated with IVUS-guided PCI (1.0 [IQR 0.6 – 1.9] vs. 0.4 [IQR 0.2 – 0.6] respectively; p<0.001). In-hospital and 4-month outcomes were not different between patients randomized to angiography-guided and IVUS-guided PCI.

Conclusions

Thoughtful and extensive utilization of IVUS as the primary imaging tool to guide PCI is safe, and markedly reduces the volume of iodine contrast, compared to angiography-alone guidance. The use of IVUS should be considered for patients at high risk for contrast-induced acute kidney injury or volume overload undergoing coronary angioplasty.

Introduction

Contrast-induced acute kidney injury (CI-AKI) is a potential complication of diagnostic and therapeutic angiographic procedures. Almost unanimously, previous studies have shown that CI-AKI is associated with worse clinical outcomes.(1) It remains debatable, however, whether CI-AKI is solely a marker for future morbi-mortality or, conversely, it is also causally implicated in the occurrence of adverse events.(1,2)

A number of strategies have been tested to reduce the incidence of CI-AKI. Vigorous fluid administration before and after the procedure is considered the most important prophylactic scheme for patients at risk of CI-AKI.(3,4) Multiple other preventive measures have been evaluated in clinical studies, but none has been widely adopted and, in practice, CI-AKI persists as a major clinical problem for patients undergoing angiographic procedures.(4-13)

Even though the incidence of CI-AKI is modulated by several clinical characteristics, the volume of iodine contrast seems to be a major factor leading to CI-AKI, independently of the baseline risk profile.(14-18) Curiously, thus far, few approaches have been described to reduce the primary cause of CI-AKI after PCI, namely the contrast agent dose.(19-22) It is of note that, in addition to be of potential benefit for patients at risk of CI-AKI, strategies to decrease the use of contrast may be valuable also for other subgroups of patients, such as those at risk of volume overload.

Intravascular ultrasound (IVUS) is largely used to guide percutaneous coronary interventions (PCI).(23) Due to its ability to accurately measure lumen, plaque, and vessel dimensions, it is possible that IVUS might serve as an alternative tool to angiography in many steps during PCI. We, therefore, hypothesized that IVUS imaging during coronary angioplasty may lead to a reduced use of contrast media. The present report describes the primary endpoint analysis of the Minimizing cOntrast utiliZAtion with IVUS guidance in coRonary angioplasTy - MOZART randomized controlled trial study, which evaluated the impact of thorough IVUS guidance on the final dose of contrast agent utilized in patients undergoing PCI.

Methods

Patient Population

Patients aged 18 or older scheduled for PCI were considered for enrollment in the MOZART trial. Included patients were at high risk for CI-AKI or volume overload, according to the presence of one or more of the following criteria: a) age > 75 years; b) diabetes; c) acute ischemic syndrome needing urgent or emergent PCI; d) creatinine clearance < 60 ml/min/1.73 m² or single remaining kidney or previous renal transplantation; e) congestive heart failure or pulmonary congestion or severe left ventricular dysfunction (ejection fraction < 45%) or cardiogenic shock or intra-aortic balloon pumping. Angiographic eligibility required that all target vessels needed to be amenable to IVUS imaging at baseline (i.e. before any balloon dilatation), as judged by an experienced interventionalist. Exclusion criteria included use of iodinated contrast agents < 72 hours or other nephrotoxic agents < 7 days; known allergy to contrast agents; unstable or unknown renal function prior to PCI. The study was approved by the institutional review board and signed written informed consent was obtained from every patient.

Study Design, Treatment Protocol and Follow-up

All patients at high risk for CI-AKI received intravenous hydration during 12 hours pre- and 12 hours post-PCI. The interventional plan was left to the discretion of the operator, but regardless of the allocated arm, operators were strongly recommended to follow strict strategies to reduce the total volume of contrast for all patients, as summarized in Table 1. Saline (NaCl 0.9%) infusion was recommended at a dose of 1 ml / kg body weight per hour, (24) and reduced to 0.5 ml/kg/h for those at high risk of volume overload (e.g. reduced left ventricular function or overt heart failure).(15) The use of N-acetylcysteine or sodium bicarbonate was left to operator discretion. All percutaneous procedures were performed using non-ionic, low-osmolar or iso-osmolar, iodine-based contrast media (iopromide [Ultravist^®; Bayer Pharma AG, Berlin, Germany] or iodixanol [Visipaque™; GE Healthcare Ireland, Cork, Ireland]).

Table 1. Guidelines to reduce the volume of contrast during percutaneous coronary angioplasty (to be applied in both study arms).

Awareness of the baseline creatinine clearance in order to target the contrast use not to exceed a volume-to-creatinine clearance ratio of 2. All measures should be employed to never exceed a ratio of 3, whenever possible. Detailed analysis of the diagnostic coronary angiography in order to plan the interventional procedure (e.g. choice for best projections, selection of treatment strategies) and anticipate potential complications. If the diagnostic coronary angiography is recent and of good quality, consider avoiding any baseline angiography during PCI. In this case, the diagnostic angiography, displayed in an auxiliary video monitor, should be used as baseline reference. Extensive use of auxiliary video monitors with reference images of the target vessel anatomy during the procedure. Extensive use of online X-ray (non-contrast) stent enhancement post-processing techniques Small-diameter guiding catheters (5 or 6 French), with no side holes. Small volume syringes for contrast injection (3 or 5 ml) Extensive use of diluted contrast during the procedure (at least 1:1) All contrast injections must be done during acquisition (not fluoroscopy), for better visualization of target segments and to allow for repeat video loops. Avoid unnecessary “puff testing” of contrast. Liberal use of high acquisition rates. Increased acquisition rates (i.e. > 15 frames per second) may be used during the procedure to improve angiographic image quality, particularly in patients with high heart rate or for fast moving target segments (e.g. mid right coronary artery or mid left circumflex artery). Before insertion of any new interventional material into the guiding catheter (e.g. balloons, stents), caution must be taken to clean the lumen of the catheter free of contrast.

Patients were randomized unblindedly in blocks via an electronic system in a 1:1 ratio to I) angiography-guided PCI or II) IVUS-guided PCI.

For those allocated to the IVUS-guided group, intravascular ultrasound was performed with the Atlantis™ SR Pro Imaging Catheter 40 MHz connected to an iLab™ Ultrasound Imaging System (both by Boston Scientific Corporation, Natick, MA, USA). Vessels were imaged during automated pullback at 0.5 mm/s, but additional manual runs were strongly stimulated to allow for detailed analysis of specific issues. Operators were stimulated to utilize IVUS to the limit of its potentialities, aiming to ultimately replace angiographic imaging. Table 2 provides a detailed description of the contrast-avoiding IVUS strategy. A final IVUS pullback was required to document the results at the end of the procedure, targeting to achieve complete stent apposition, without residual plaque burden at the stent edges (ideally <50% plaque burden) or major edge dissections, and to maximize stent expansion (ideally the intra-stent minimal luminal area should be >90% of the smallest reference lumen area).

Table 2.

Technical description of IVUS guidance to minimize contrast utilization.

General rule: IVUS guidance aims to minimize contrast utilization. However, non-contrast X-ray imaging is not precluded. Fluoroscopy and cine runs without contrast might be used (and are encouraged), for instance, to visualize the stent limits and borders, identify the position of IVUS probe inside the vessel, and register balloon expansion. Aim for a single angiographic acquisition at baseline. Extra baseline views are almost always unnecessary when using IVUS. Use IVUS, not angiography, as the main source of information to plan PCI strategy. Baseline as well as interim IVUS runs should be liberally utilized to evaluate intervening results and help plan the next steps. Use baseline IVUS to choose between direct stenting or not. For short, non-calcified, not severely obstructive lesions consider direct stenting. Conversely, long fibro-calcified diffusely diseased segments should undergo lesion preparation, with balloon dilatation or rotablation. Use IVUS, not angiography, to check the results of pre-dilatation. Need for additional dilatation and the occurrence of dissections are readily assessable by IVUS For stent sizing, aim to use IVUS only, not angiography. Identification of the proximal and distal reference segments is central for IVUS selection of stent diameter and length. Liberal use of manual IVUS imaging to precisely identify the two proximal and distal reference spots. Selection of stent diameter: Stent diameter is primarily based on the size of reference segments. IVUS guidance to select stent diameter is particularly informative in lesions with a large disproportion between the reference segment sizes, in diffusely diseased arteries, or lesions with extreme remodeling patterns (either positive or negative) Selection of stent length: Stent length should aim to cover “from normal to normal” segments, ideally. Stent length should be selected based on the longitudinal measurements of an IVUS run acquired with automatic pullback at known speed (preferably 0.5 mm/s). Also, manual IVUS imaging can be used as an auxiliary practical way of assessing/confirming stent length. With the IVUS probe turned on in continuous imaging, the proximal and distal reference points are iteractively selected. The distance between the chosen landing zones can be easily measured, manually, using the length measurement registered in the electronic display of the pullback device. Minimize contrast using IVUS for stent positioning. Get an X-ray acquisition (without contrast) with the IVUS probe at the proximal and distal references spots: Store these images and display them in an auxiliary monitor during stent placement to guide positioning, minimizing contrast “puffing”. Use IVUS, not angiography, to verify the results of stent implantation. Most often, stent underexpansion is better managed with higher pressure post-dilation with an appropriately sized non-compliant balloon Incomplete apposition should be treated with post-dilatation using appropriately sized semi-compliant balloons Use IVUS to judge the need of additional stenting, and to select the size of the extra stent, to treat residual plaque or edge dissection. Final results should be primary assessed by IVUS, not angiography. Restrict final angiography to one projection. There is no need for extra angiography if good quality IVUS imaging shows satisfactory results. Consider not acquiring a final angiography whatsoever, in cases with a high confidence of optimal final results.

IVUS = intravascular ultrasound; PCI = percutaneous coronary ultrasound

After the index procedure, patients were followed for 30 days with the main objective of detecting safety clinical events, namely death, myocardial infarction, or unplanned re-interventions.

Endpoint Definitions and Statistical Considerations

The primary endpoint of the MOZART trial was the total volume of contrast agent used during PCI. The present report also analyzes the in-hospital and post-discharge incidence of adverse clinical events, a pre-defined safety endpoint. All deaths were considered for analysis. Myocardial infarctions were classified into a) spontaneous, b) secondary to ischaemic imbalance, c) leading to death with biomarkers unavailable, d) post-PCI, e) post-coronary bypass surgery, or f) related to stent thrombosis.(25) Stent thrombosis were further classified according to the degree of certainty as definite, probable, or possible.(26) Unplanned coronary re-interventions were computed if motivated by a stenosis located in any segment of the epicardial vessel treated at the index procedure.

Cumulative air kerma (measured in Grays), cumulative dose-area product (measured in Gray square centimeter) and the number of cine runs were prospectively collected as metrics for radiation dose. The duration of the intervention was estimated by the cumulative fluoroscopic time (in minutes) and by the procedure time (in minutes), defined as the time from the first injection to the time the guiding catheter was removed.

The creatinine clearance was calculated based on the serum creatinine, using the equation proposed by Cockcroft and Gault.(27) For all patients, sequential serum creatinine measurements were obtained in a daily basis during the index hospitalization. Post-PCI CI-AKI was defined as any increase in baseline serum creatinine values > 0.5 mg/dl.(28) A series of 25 consecutive patients with low creatinine clearance (<60 ml/min/1.73 m2) undergoing angiography-guided PCI in our institution (unpublished data) was used as a basis for the sample size calculation. In that cohort, the average volume of contrast was 147.6 ml ± 66.8 ml. A sample size of 80 patients was found to be sufficient to show a significant reduction of the volume of contrast by 33% in the IVUS-guided group, assuming a similar standard deviation for both study groups, with an alpha value of 0.05 and a beta value of 0.1. All analyses were carried out according to the intention to treat principle. Categorical variables and adverse events were presented as percentages and compared using the Fisher's exact test or the Chi square test. Continuous variables were presented as median and interquartile range and compared using Mann-Whitney Test. The incidences of post-discharge adverse events were estimated according to the Kaplan-Meier method and were compared between the groups using the log-rank test. All p values were 2-tailed and were considered significant if < 0.05.

Results

Between November 2012 and September 2013, a total of 83 patients were randomly allocated to angiography-guided PCI (n=42 patients) or IVUS-guided PCI (n=41 patients). Patients' characteristics at baseline were similar between the study groups (Table 3). Overall, the vast majority of the patients had diabetes mellitus (77.1%) and most had stable coronary disease (73.5%). The median serum creatinine of the study population was 1.13 mg/dl (interquartile range [IQR] 0.9 – 1.4 md/dl) and 44.6% had a calculated creatinine clearance < 66.0 ml/min/1.73 m². A median of 2.0 stents (IQR 1.0 – 2.0 stents) were used and most patients had complex target lesions (at least one type C lesion in 63.9% of patients).

Table 3. Baseline and procedural characteristics.

	Angiography-guided (n=42 pts)	IVUS-guided (n=41 pts)	p-value
Age, years	62.1 (57.3 – 76.5)	67.1 (58.3 – 76.1)	0.3
Male sex	57.1	61.0	0.8
Hypertension	100	97.6	0.5
Smoking status			0.9
Never	59.5	58.5
Past	33.3	36.6
Current	7.1	4.9
Diabetes mellitus	81.0	73.2	0.4
PAD	4.8	4.9	>0.9
Previous stroke	4.8	12.2	0.3
Previous CABG	16.7	14.6	>0.9
Previous PCI	11.9	26.8	0.1
Clinical presentation			>0.9
Silent ischemia or stable angina	71.4	75.6
Acute coronary syndrome	16.7	14.6
Ischemic equivalent*	11.9	9.8
Serum creatinine, mg/dl	1.1 (0.9 – 1.3)	1.2 (0.9 – 1.5)	0.4
Creatinine clearance, ml/min/1.73 m2	72.4 (47.2 – 89.9)	60.5 (43.9 – 73.1)	0.2
Creatinine clearance < 60 ml/min/1.73 m2	40.5	48.8	0.5
Treated vessel
LMC	7.1	4.9	>0.9
LAD	52.4	34.1	0.1
LCx	28.6	46.3	0.1
RCA	35.7	22.0	0.2
Graft	2.4	9.8	0.2
Lesion type
A	9.5	2.4	0.4
B1	16.7	22.0	0.6
B2	35.7	24.4	0.3
C	64.3	63.4	>0.9
Bifurcation lesion†	26.2	24.4	0.5
Moderate or severe calcification	33.3	51.2	0.1
Pre-dilatation	57.1	68.3	0.4
Number of stents	2.0 (1.0 – 2.3)	2.0 (1.0 – 2.0)	0.8
Overlapping stents	38.1	43.9	0.7
Stent diameter, mm	3.0 (3.0 – 3.5)	3.0 (2.8 – 3.5)	0.7
Stent diameter ≤ 2.5 mm	40.5	29.3	0.4
Total sum of stent length, mm	33.0 (22.3 – 54.5)	32.0 (20.0 – 46.0)	0.5
Stent length ≥ 20 mm	66.7	73.2	0.6
Post-dilatation	78.6	95.1	0.048

Numbers are percentage or median (interquatile range)

CABG=coronary artery bypass graft surgery; LAD=left anterior descending artery; LCx = left circumflex artery; LMC=left main coronary; NSTEAMI= Non-ST segment elevation acute myocardial infarction; PAD=peripheral artery disease; PCI=percutaneous coronary intervention; RCA = right coronary artery

^*Heart failure or arrhythmias documented related to myocardial ischemia

^†Defined as a bifurcated target segment involving a side branch > 2.0 mm in diameter

Iodine Contrast Utilization and Procedural Characteristics

The total volume of contrast (study's primary endpoint) was 64.5 ml (IQR 42.8 – 97.0 ml) (ranging from 19 to 170 ml) in the angiography-guided group vs. 20.0 ml (IQR 12.5 – 30.0 ml) (ranging from 3 ml to 54 ml) in the IVUS-guided group (p<0.001) (Table 4). Similarly, the volume of contrast / creatinine clearance ratio was significantly different between the study groups (1.0 [IQR 0.6 – 1.9] vs. 0.4 [IQR 0.2 – 0.6] respectively; p<0.001). Low-osmolar contrast media was used in all patients, except by one case in the angiography-guided group who was treated with iso-osmolar agent (p>0.9). Slight differences in indices of renal function favored neither group and were statistically indistinguishable.

Table 4. Iodine contrast utilization and procedural characteristics.

	Angiography-guided (n=42 pts)	IVUS-guided (n=41 pts)	p-value
Total contrast volume, ml*	64.5 (42.8 – 97.0)	20.0 (12.5 – 30.0)	<0.001
Volume of contrast per stent implanted, ml	40.5 (25.7 – 48.3)	13.0 (7.1 – 20.0)	<0.001
Contrast volume/creat. clearance ratio	1.0 (0.6 – 1.9)	0.4 (0.2 – 0.6)	<0.001
Contrast volume/creat. clearance ratio >2	19.0	4.9	0.09
Procedure time, min	34.0 (18.5 – 54.5)	48.0 (34.0 – 61.0)	0.006
Fluoroscopic time, min	12.2 (6.8 – 24.1)	12.2 (8.4 – 20.8)	0.5
Number of cine runs	22.5 (16.0 – 36.3)	25.0 (19.0 – 32.5)	0.5
Cumulative DAP, Gy × cm2	82.1 (54.5 – 132.0)	73.7 (44.8 – 118.3)	0.4
Cumulative air Kerma, Gy	1.4 (1.0 – 2.7)	1.4 (1.0 – 2.0)	0.3

^*Primary endpoint

Numbers are percentage or median (interquartile range)

Creat. = creatinine; DAP=dose-area product

The procedure time of IVUS-guided PCI was significantly longer than angiography-guided interventions (median difference 14.0 minutes; p=0.006) (Table 4). However, the groups did not differ in relation to fluoroscopic time, number of cine runs, cumulative dose-area product, or cumulative air Kerma (p ≥ 0.3 for all) (Table 4).

In-Hospital and Post-Discharge Outcomes

In-hospital outcomes during the index hospitalization were not different between patients randomized to angiography-guided or IVUS-guided PCI (Table 5). The peak serum creatinine in the angiography-guided PCI was 1.2 mg/dl (IQR 1.0 – 1.5 mg/dl) versus 1.3 mg/dl (IQR 1.0 – 1.6 mg/dl) in the IVUS-guided group (p=0.4) (Table 5). Contrast-induced acute kidney injury (i.e. increase in serum creatinine > 0.5 mg/dl) was diagnosed in 19.0% of patients treated with angiography-guided PCI and 7.3% of those randomized to IVUS-guided PCI (p=0.2) (Table 5).

Table 5. In-hospital and 4-monthoutcomes^*.

	Angiography-guided (n=42 pts)	IVUS-guided (n=41 pts)	p-value
In hospital
Death	0	0	-
Acute myocardial infarction†	4.8	4.9	>0.9
Unplanned revascularization	0	0	-
Stent thrombosis	0	0	-
CK-MB rise > 5X ULN	11.9	14.6	0.8
CK-MB peak, ng/ml	2.4 (1.3 – 3.7)	2.5 (1.1 – 9.4)	0.5
Peak serum creatinine, mg/dl	1.2 (1.0 – 1.5)	1.3 (1.0 – 1.6)	0.4
Lowest creatinine clearance, ml/min/1.73 m2	61.9 (43.8 – 79.1)	51.4 (40.5 – 72.9)	0.3
Peak rise in creatinine > 0.5 mg/dl	19.0	7.3	0.2
4-month post-discharge
Death	0	4.2	0.3
Acute myocardial infarction‡	3.3	4.2	>0.9
Unplanned revascularization	11.7	4.2	0.3
Stent thrombosis	0	0	-
Any event	11.7	4.2	0.3

Numbers are percentage or medianinterquartile interval)

CKMB = creatine kinase-MB; URL = upper reference limit

^*Kaplan-Meier estimates

^†All post-PCI

^‡All spontaneous

The median follow-up was 117 days [interquartile range 45 – 177 days], there were no patients lost and all patients had at least one month of post-discharge follow-up. The incidence of death, myocardial infarction, unplanned revascularization, or stent thrombosis was not significantly different between the study groups (Table 5).

Discussion

The main finding of the present study was that percutaneous coronary intervention performed primarily through IVUS imaging is safe and significantly reduces the dose of iodine contrast in comparison to an angiography-only approach. The mean contrast volume was three-fold lower in the IVUS compared to the angiography arm. Both study groups were mainly composed of diabetics, frequently with long, calcified, bifurcated, and complex lesions, who often needed multiple stent implantation. It is of note that patients randomized to the angiography group also received a relatively low contrast dose, particularly when considering such a high-risk population,(24) given rigid contrast-saving strategies universally applied for the whole patient cohort, as suggested by Nayak et al.(20) and expanded in the present study. It must be highlighted, therefore, that the effects of IVUS guidance appeared as an added gain in contrast avoidance, arising on top of an already reduced contrast usage.

IVUS was extensively employed in the MOZART trial, almost as a substitute for angiography during PCI. Such an approach was proven safe, with no excess in the use of additional stents or in the incidence of clinical adverse events. The IVUS-guided group had slightly but significantly longer procedures and higher use of stent post-dilatation, even though no differences were noticed in the number, length or diameter of stents, as well as in fluoroscopy time, the number of cine runs, or radiation dose. Most probably, the longer duration of IVUS-guided procedures resulted from IVUS acquisition and interpretation. This finding reinforce that specific IVUS training is needed to obtain the maximal results from the technology, as well as to imprint fluency to the procedure.

Over the last years, optical coherence tomography has been increasingly reported as an imaging tool to guide PCI. The relative advantages and disadvantages of optical coherence tomography over IVUS are yet to be established. The much higher spatial resolution of optical coherence tomography progressively established it as an important method for in vivo evaluation lumen and plaque, as well as stent expansion, apposition and tissue coverage. Current guidelines of utilization of frequency-domain optical coherence tomography recommend intracoronary administration of contrast for blood cleaning during image acquisition. It is therefore improbable the strategy and the results proposed in the present study could be directly extrapolated to contrast-based optical coherence tomography imaging. Intracoronary saline infusion could be explored as an alternative to contrast media, even though the safety and diagnostic accuracy of this approach is yet to be validated.

A number of randomized and observational studies have previously evaluated the impact of IVUS guidance on the outcomes after coronary stent implantation, with recent meta-analytic data showing a significant decrease in the risk of adverse events.(23) Our study was not designed or powered to detect differences in post-PCI renal function or clinical outcomes. Nevertheless, paralleling the decrease in contrast volume, patients treated with IVUS-guided PCI showed a numerically (non-significant) lower rate of post-PCI CI-AKI and adverse cardiac events after the index procedure. Trends in indices of renal function that favored extensive IVUS use might likely emerge in larger and adequately designed studies.

Patients were enrolled in the MOZART according to somewhat restricted criteria, which excluded cases with recent catheterization, in use of nephrotoxic agents, or with unstable or unknown renal function. Such a study population was selected mainly to reduce confounding factors in assessing the impact of contrast saving on post-procedure renal function and clinical outcomes. In fact, in “real world” practice, also those patients would potentially benefit from IVUS guidance. It is possible that the increased interventional time and the use of IVUS catheters would increase the costs of the procedure in the IVUS-guided PCI. On the other hand, the reduction in contrast usage and an eventual decrease in complications could potentially offset the increased costs. Further analysis in larger populations would be desirable to evaluate the cost-effectiveness profile of IVUS utilization in CI-AKI-prone patients undergoing PCI.

Conclusions

Thoughtful and extensive utilization of IVUS as the primary imaging tool to guide percutaneous coronary intervention is safe and markedly reduces the volume of iodine contrast, compared to angiography-alone guidance. IVUS imaging should be considered for patients at high risk for contrast-induced acute kidney injury or volume overload undergoing coronary angioplasty.

List of Abbreviations

CABG

Coronary artery bypass graft surgery

CI-AKI

Contrast-induced acute kidney injury

CKMB

creatine kinase-MB

DAP

Dose-area product

IVUS

Intravascular ultrasound

IQR

Interquartile range

LAD

Left anterior descending artery

LCx

Left circumflex artery

LMC

Left main coronary

MOZART

Minimizing cOntrast utiliZAtion with IVUS guidance in coRonary angioplasty trial

NSTEAMI

Non-ST segment elevation acute myocardial infarction

PAD

Peripheral artery disease

PCI

Percutaneous coronary intervention

RCA

Right coronary artery