Coronary artery disease severity and risk stratification of patients with non ST-elevation acute coronary syndrome using CHA2DS2-VASc-HSF score.

BACKGROUND: Risk stratification assessment of patients with non-ST elevation acute coronary syndrome (NSTE ACS) plays an important role in optimal management and defines the patient's prognosis. This study aimed to evaluate the ability of CHA2DS2-VASc-HSF score (comprising of the components of the CHA2DS2-VASc score with a male instead of female sex category, hyperlipidemia, smoking, and family history of coronary artery disease respectively) to predict the severity and complexity of CAD and its efficacy in stratification for major adverse cardiovascular events (MACE) in patients with NSTE ACS without known atrial fibrillation. METHODS: This study included 200 patients (males 72.5%, mean age 55.8 ± 10.1 years) who were admitted with NSTE ACS. CHA2DS2-VASC-HSF score was calculated on admission. Patients were classified into three groups according to their CHA2DS2-VASC-HSF score: low score group (< 2; 29 patients), intermediate score group (2-4; 83 patients), and high score group (≥ 5; 88 patients). Coronary angiography was conducted and the Syntax score (SS) was calculated. Clinical follow-up at 6 months of admission for the development of MACE was recorded. RESULTS: SS was significantly high in the high CHA2DS2-VASc-HSF score group compared with low and intermediate score groups. CHA2DS2-VASc-HSF score had a significant positive strong correlation with syntax score (r = 0.64, P < 0.001). Smoking, vascular disease, hyperlipidemia, and CHA2DS2-VASc-HSF score were independent predictors of high SS. For the prediction of severe and complex CAD, CHA2DS2-VASc-HSF score had a good predictive power at a cut-off value ≥ 5 with a sensitivity of 86% and specificity of 65%. Hypertension, vascular disease, high SS, and CHA2DS2-VASc-HSF score were independent predictors of MACE. CHA2DS2-VASC-HSF score ≥ 4 was identified as an effective cut-off point for the development of MACE with 94% sensitivity and 70% specificity. CONCLUSIONS: CHA2DS2-VASC-HSF score is proposed to be a simple bedside score that could be used for the prediction of the severity and complexity of CAD as well as a risk stratification tool for the development of MACE in NSTE ACS patients.

An Aspirin-Free Strategy for Immediate Treatment Following Complex Percutaneous Coronary Intervention.

BACKGROUND: There was no study evaluating the effects of an aspirin-free strategy in patients undergoing complex percutaneous coronary intervention (PCI). OBJECTIVES: The authors aimed to evaluate the efficacy and safety of an aspirin-free strategy in patients undergoing complex PCI. METHODS: We conducted the prespecified subgroup analysis based on complex PCI in the STOPDAPT-3 (ShorT and OPtimal duration of Dual AntiPlatelet Therapy after everolimus-eluting cobalt-chromium stent-3), which randomly compared low-dose prasugrel (3.75 mg/d) monotherapy to dual antiplatelet therapy (DAPT) with low-dose prasugrel and aspirin in patients with acute coronary syndrome or high bleeding risk. Complex PCI was defined as any of the following 6 criteria: 3 vessels treated, ≥3 stents implanted, ≥3 lesions treated, bifurcation with 2 stents implanted, total stent length >60 mm, or a target of chronic total occlusion. The coprimary endpoints were major bleeding events (Bleeding Academic Research Consortium 3 or 5) and cardiovascular events (a composite of cardiovascular death, myocardial infarction, definite stent thrombosis, or ischemic stroke) at 1 month. RESULTS: Of the 5,966 study patients, there were 1,230 patients (20.6%) with complex PCI. Regardless of complex PCI, the effects of no aspirin relative to DAPT were not significant for the coprimary bleeding (complex PCI: 5.30% vs 3.70%; HR: 1.44; 95% CI: 0.84-2.47; P = 0.18 and noncomplex PCI: 4.26% vs 4.97%; HR: 0.85; 95% CI: 0.65-1.11; P = 0.24; P for interaction = 0.08) and cardiovascular (complex PCI: 5.78% vs 5.93%; HR: 0.98; 95% CI: 0.62-1.55; P = 0.92 and noncomplex PCI: 3.70% vs 3.10%; HR: 1.20; 95% CI: 0.88-1.63; P = 0.25; P for interaction = 0.48) endpoints without significant interactions. CONCLUSIONS: The effects of the aspirin-free strategy relative to standard DAPT for the cardiovascular and major bleeding events were not different regardless of complex PCI. (ShorT and OPtimal duration of Dual AntiPlatelet Therapy after everolimus-eluting cobalt-chromium stent-3 [STOPDAPT-3]; NCT04609111).

[Stress-Echocardiography in Low-risk Acute Coronary Syndrome Without Persistent ST-segment Elevation Diagnostic Algorithm].

This review addresses the capabilities of stress EchoCG as a simple, non-invasive, non-radiation method for diagnosing occult disorders of coronary blood flow in patients with non-ST-elevation acute coronary syndrome on a low-risk electrocardiogram. The capabilities of the enhanced stress EchoCG protocol are based on supplementing the standard detection of transient disturbances of local contractility, generally associated with coronary artery obstruction, with an assessment of the heart rate reserve, coronary reserve and other parameters. This approach is considered promising for a more complete characterization of heart function during exercise and an accurate prognosis of the clinical case, which allows determining the tactics for patient management not limited to selection for myocardial revascularization.

Angiographic patterns in spontaneous coronary artery dissection: novel diagnostic insights.

INTRODUCTION: Spontaneous coronary artery dissection (SCAD) is a rare but well-recognized cause of acute coronary syndrome, especially important in women. Invasive coronary angiography (ICA) is the fundamental diagnostic technique for the confirmation of SCAD. Knowing the angiographic patterns suggestive of SCAD is essential for the correct identification of patients with this entity. AREAS COVERED: In this narrative review, the main angiographic characteristics of SCAD lesions as detected by ICA are presented and discussed. EXPERT OPINION: In addition to the specific angiographic classification of SCAD, several authors have described complementary angiographic patterns suggestive of SCAD. Knowledge and correct identification of these angiographic patterns is essential for the correct diagnosis of patients with clinical suspicion of SCAD.

Intravascular ultrasound-guided versus angiography-guided percutaneous coronary intervention in acute coronary syndromes (IVUS-ACS): a two-stage, multicentre, randomised trial.

BACKGROUND: Intravascular ultrasound-guided percutaneous coronary intervention has been shown to result in superior clinical outcomes compared with angiography-guided percutaneous coronary intervention. However, insufficient data are available concerning the advantages of intravascular ultrasound guidance for patients with an acute coronary syndrome. This trial aimed to investigate whether the use of intravascular ultrasound guidance, as compared with angiography guidance, improves the outcomes of percutaneous coronary intervention with contemporary drug-eluting stents in patients presenting with an acute coronary syndrome. METHODS: In this two-stage, multicentre, randomised trial, patients aged 18 years or older and presenting with an acute coronary syndrome at 58 centres in China, Italy, Pakistan, and the UK were randomly assigned to intravascular ultrasound-guided percutaneous coronary intervention or angiography-guided percutaneous coronary intervention. Patients, follow-up health-care providers, and assessors were masked to random assignment; however, staff in the catheterisation laboratory were not. The primary endpoint was target vessel failure, a composite of cardiac death, target vessel myocardial infarction, or clinically driven target vessel revascularisation at 1 year after randomisation. This trial is registered at ClinicalTrials.gov, NCT03971500, and is completed. FINDINGS: Between Aug 20, 2019 and Oct 27, 2022, 3505 patients with an acute coronary syndrome were randomly assigned to intravascular ultrasound-guided percutaneous coronary intervention (n=1753) or angiography-guided percutaneous coronary intervention (n=1752). 1-year follow-up was completed in 3504 (>99·9%) patients. The primary endpoint occurred in 70 patients in the intravascular ultrasound group and 128 patients in the angiography group (Kaplan-Meier rate 4·0% vs 7·3%; hazard ratio 0·55 [95% CI 0·41-0·74]; p=0·0001), driven by reductions in target vessel myocardial infarction or target vessel revascularisation. There were no significant differences in all-cause death or stent thrombosis between groups. Safety endpoints were also similar in the two groups. INTERPRETATION: In patients with an acute coronary syndrome, intravascular ultrasound-guided implantation of contemporary drug-eluting stents resulted in a lower 1-year rate of the composite outcome of cardiac death, target vessel myocardial infarction, or clinically driven revascularisation compared with angiography guidance alone. FUNDING: The Chinese Society of Cardiology, the National Natural Scientific Foundation of China, and Jiangsu Provincial & Nanjing Municipal Clinical Trial Project. TRANSLATION: For the Mandarin translation of the abstract see Supplementary Materials section.

Can prolonged P-R interval predict clinical outcomes in non-ST elevation acute coronary syndrome patients?

BACKGROUND: The present study aimed to respond to clinical question, can prolonged P-R interval predict clinical outcomes in non-ST elevation acute coronary syndrome patients? METHODS: This descriptive-analytical study was conducted on cardiac patients. All of the non-ST elevation acute coronary syndrome (NSTEACS) including non-ST elevation myocardial infarction (NSTEMI) and unstable angina patients included in the study. Then they divided into two groups: prolonged P-R interval and normal P-R interval. The patients who had a history of digoxin and calcium channel blocker use, using antiarrhythmic drugs, known valvular or congenital heart disease and connective tissue, unreadable P-R interval and cardiac block were excluded. Data were collected using the questionnaire consisted demographic data and clinical outcomes and a follow-up part was completed by one of the researchers. RESULTS: Finally, 248 patients completed the study. The results showed both of the two groups had significant differences in terms of the history of myocardial infarction (MI) (p = 0.018), the level of high-density lipoprotein (HDL) (p = 0.004), heart rate (p = 0.042), inverted T wave (p = 0.017), anterior ST- segment depression (p = 0.008), normal report of coronary angiography (CAG) (p = 0.003), three vessels disease (p = 0.043), left main lesion (p = 0.045) and SYNTAX score (p = 0.032) based on the CAG report. The results of six-month follow-up showed although, the frequency of ischemic stroke, coronary artery disease (CAD) and cardiovascular death were higher in prolonged P-R interval groups. The chi-square test showed this difference was statistically non-significant (p > 0.05). The multivariate logistic regression model revealed non-significant relationships between prolonged P-R interval and SYNTAX score, significant CAD, three-vessel disease, inverted T wave, anterior ST depression, heart rate and HDL. CONCLUSIONS: Based on the results of our study the six-month follow-up showed non-significant outcomes. Further studies are recommended to assess the long-term outcomes.

Predictive value of the serum uric acid to high-density lipoprotein cholesterol ratio for culprit plaques in patients with acute coronary syndrome.

BACKGROUND: Hyperuricemia and low level of high-density lipoprotein cholesterol (HDL-C) are both risk factors for coronary artery disease (CAD). The uric acid to HDL-C ratio (UHR) has recently been identified as a new inflammatory and metabolic biomarker. However, the relationship between the UHR and coronary culprit plaques has not been fully investigated in patients with acute coronary syndrome (ACS). METHODS: A total of 346 patients with ACS were enrolled in this study. Culprit lesion characteristics were assessed by optical coherence tomography (OCT). Logistic regression and linear correlation analyses were performed to assess the association between the UHR and culprit plaques. The predictive value of the UHR was investigated by receiver operating characteristic (ROC) curve analysis. RESULTS: The percentages of typical culprit plaques, including ruptures, erosions and thrombi, were greater in the high-UHR subgroup than those in the low-UHR subgroup. A positive relationship was also found between the UHR and diameter stenosis (r = 0.160, P = 0.003) and between the UHR and area stenosis (r = 0.145, P = 0.007). The UHR was found to be independently associated with plaque rupture, erosion and thrombus. Furthermore, ROC analysis suggested that the UHR had a better predictive value than low-density lipoprotein cholesterol. CONCLUSIONS: An elevated UHR level was independently related to the occurrence rate of culprit plaques. The UHR is a simple and easily acquired parameter for detecting culprit plaques in patients with ACS.

Mixed plaque on coronary CT angiography predicts atherosclerotic events in asymptomatic intermediate-risk individuals.

OBJECTIVE: Coronary CT angiography (CCTA) permits both qualitative and quantitative analysis of atherosclerotic plaque and may be a suitable risk modifier in assessing patients at intermediate risk of atherosclerotic cardiovascular disease. We sought to determine the association of plaque components with long-term major adverse cardiovascular events (MACEs) in asymptomatic intermediate-risk patients, compared with conventional coronary artery calcium (CAC) score. METHODS: 100 intermediate-risk patients underwent double-blinded CCTA. Follow-up was conducted at 10 years and data were cross-referenced with the National Death Index. The primary outcome was MACE, which was a composite of death, acute coronary syndrome (ACS), revascularisation and stroke. RESULTS: The median time from CCTA to follow-up was 9.5 years. 83 patients completed follow-up interview and mortality data were available on all 100 patients. MACE occurred in 17 (20.5%) patients, which included 2 (2%) deaths, 8 (10%) ACS, 3 (4%) strokes and 5 (6%) revascularisation procedures. 47 (57%) patients had mixed plaque, which was predictive of MACE (OR 4.68 (95% CI 1.19 to 18.5) p=0.028). The burden of non-calcified and mixed plaque, defined by non-calcified plaque segment stenosis score, was also a predictor of long-term MACE (OR 1.59 (95% CI 1.18 to 2.13) p=0.002). Neither calcified plaque (OR 3.92 (95% CI 0.80 to 19.3)) nor CAC score (OR 1.01 (95% CI 0.999 to 1.02)) was associated with long-term MACE. CONCLUSION: The presence and burden of mixed plaque on CCTA is associated with an increased risk of long-term MACE among asymptomatic intermediate-risk patients and is a superior predictor to CAC score.

Giant coronary sinus aneurysm: an incidental discovery in a case of acute coronary syndrome.

Coronary sinus (CS) anomalies, although infrequent, are increasingly diagnosed with advances in interventional procedures and imaging techniques. Most cases are asymptomatic and incidentally diagnosed. We present a case of an elderly male without comorbidities who presented with acute angina. Coronary catheterisation revealed a double-vessel disease, but incidentally, sequential angiograms captured contrast filling in the levophase of CS, revealing a giant CS. Primary percutaneous angioplasty of the right coronary artery was performed successfully. Echocardiography confirmed the aneurysm, and a CT scan showed an aneurysmally dilated CS and other coronary veins alongside a normal-sized persistent left superior vena cava draining to the right atrium through CS. CS aneurysms may lead to complications such as thrombosis, embolic events, arrhythmias and heart failure, stressing the importance of vigilant monitoring and timely intervention. This case underscores the significance of recognising CS anomalies in cardiac procedures, even when asymptomatic, for proper management.

Timing of Complete Multivessel Revascularization in Patients Presenting With Non-ST-Segment Elevation Acute Coronary Syndrome.

BACKGROUND: Complete revascularization of the culprit and all significant nonculprit lesions in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) and multivessel disease (MVD) reduces major adverse cardiac events, but optimal timing of revascularization remains unclear. OBJECTIVES: This study aims to compare immediate complete revascularization (ICR) and staged complete revascularization (SCR) in patients presenting with NSTE-ACS and MVD. METHODS: This prespecified substudy of the BIOVASC (Percutaneous Complete Revascularization Strategies Using Sirolimus Eluting Biodegradable Polymer Coated Stents in Patients Presenting With Acute Coronary Syndrome and Multivessel Disease) trial included patients with NSTE-ACS and MVD. Risk differences of the primary composite outcome of all-cause mortality, myocardial infarction (MI), unplanned ischemia-driven revascularization (UIDR), or cerebrovascular events and its individual components were compared between ICR and SCR at 1 year. RESULTS: The BIOVASC trial enrolled 1,525 patients; 917 patients presented with NSTE-ACS, of whom 459 were allocated to ICR and 458 to SCR. Incidences of the primary composite outcome were similar in the 2 groups (7.9% vs 10.1%; risk difference 2.2%; 95% CI: -1.5 to 6.0; P = 0.15). ICR was associated with a significant reduction of MIs (2.0% vs 5.3%; risk difference 3.3%; 95% CI: 0.9 to 5.7; P = 0.006), which was maintained after exclusion of procedure-related MIs occurring during the index or staged procedure (2.0% vs 4.4%; risk difference 2.4%; 95% CI: 0.1 to 4.7; P = 0.032). UIDRs were also reduced in the ICR group (4.2% vs 7.8%; risk difference 3.5%; 95% CI: 0.4 to 6.6; P = 0.018). CONCLUSIONS: ICR is safe in patients with NSTE-ACS and MVD and was associated with a reduction in MIs and UIDRs at 1 year.

Thin-cap fibroatheroma in acute coronary syndrome: Implication for intravascular imaging assessment.

Acute coronary syndrome (ACS), a significant cardiovascular disease threat, has garnered increased focus concerning its etiological mechanisms. Thin-cap fibroatheroma (TCFA) are central to ACS pathogenesis, characterized by lipid-rich plaques, profuse foam cells, cholesterol crystals, and fragile fibrous caps predisposed to rupture. While TCFAs may be latent and asymptomatic, their pivotal role in ACS risk is undeniable. High-resolution imaging techniques like Optical coherence tomography (OCT) and Intravascular ultrasound (IVUS) are instrumental for effective TCFA detection. Therapeutic strategies encompass pharmacological and interventional measures, including antiplatelet agents, statins, and Percutaneous Coronary Intervention (PCI), aiding in plaque stabilization, inflammation reduction, and rupture risk mitigation. Despite the strong correlation between TCFAs and adverse prognoses in ACS patients, early detection and rigorous treatment significantly enhance patient prognosis and diminish cardiovascular events. This review aims to encapsulate recent advancements in TCFA research within ACS, covering formation mechanisms, clinical manifestations, and prognostic implications.

Quantitative Coronary Angiography vs Intravascular Ultrasonography to Guide Drug-Eluting Stent Implantation: A Randomized Clinical Trial.

Importance: Although intravascular ultrasonography (IVUS) guidance promotes favorable outcomes after percutaneous coronary intervention (PCI), many catheterization laboratories worldwide lack access. Objective: To investigate whether systematic implementation of quantitative coronary angiography (QCA) to assist angiography-guided PCI could be an alternative strategy to IVUS guidance during stent implantation. Design, Setting, and Participants: This randomized, open-label, noninferiority clinical trial enrolled adults (aged ≥18 years) with chronic or acute coronary syndrome and angiographically confirmed native coronary artery stenosis requiring PCI. Patients were enrolled in 6 cardiac centers in Korea from February 23, 2017, to August 23, 2021, and follow-up occurred through August 25, 2022. All principal analyses were performed according to the intention-to-treat principle. Interventions: After successful guidewire crossing of the first target lesion, patients were randomized in a 1:1 ratio to receive either QCA- or IVUS-guided PCI. Main Outcomes and Measures: The primary outcome was target lesion failure at 12 months, defined as a composite of cardiac death, target vessel myocardial infarction, or ischemia-driven target lesion revascularization. The trial was designed assuming an event rate of 8%, with the upper limit of the 1-sided 97.5% CI of the absolute difference in 12-month target lesion failure (QCA-guided PCI minus IVUS-guided PCI) to be less than 3.5 percentage points for noninferiority. Results: The trial included 1528 patients who underwent PCI with QCA guidance (763; mean [SD] age, 64.1 [9.9] years; 574 males [75.2%]) or IVUS guidance (765; mean [SD] age, 64.6 [9.5] years; 622 males [81.3%]). The post-PCI mean (SD) minimum lumen diameter was similar between the QCA- and IVUS-guided PCI groups (2.57 [0.55] vs 2.60 [0.58] mm, P = .26). Target lesion failure at 12 months occurred in 29 of 763 patients (3.81%) in the QCA-guided PCI group and 29 of 765 patients (3.80%) in the IVUS-guided PCI group (absolute risk difference, 0.01 percentage points [95% CI, -1.91 to 1.93 percentage points]; hazard ratio, 1.00 [95% CI, 0.60-1.68]; P = .99). There was no difference in the rates of stent edge dissection (1.2% vs 0.7%, P = .25), coronary perforation (0.2% vs 0.4%, P = .41), or stent thrombosis (0.53% vs 0.66%, P = .74) between the QCA- and IVUS-guided PCI groups. The risk of the primary end point was consistent regardless of subgroup, with no significant interaction. Conclusions and Relevance: Findings of this randomized clinical trial indicate that QCA and IVUS guidance during PCI showed similar rates of target lesion failure at 12 months. However, due to the lower-than-expected rates of target lesion failure in this trial, the findings should be interpreted with caution. Trial Registration: ClinicalTrials.gov Identifier: NCT02978456.

The accuracy of detailed analysis of optical coherence tomography in detection of plaque lipid content: dual-imaging study with optical coherence tomography and near-infrared spectroscopy.

BACKGROUND: Lipid-rich plaque covered by a thin fibrous cap (FC) has been identified as a frequent morphological substrate for the development of acute coronary syndrome. Optical coherence tomography (OCT) permits the identification and measurement of the FC. Near-infrared spectroscopy (NIRS) has been approved for detection of coronary lipids. AIMS: We aimed to assess the ability of detailed OCT analysis to identify coronary lipids, using NIRS as the reference method. METHODS: In total, 40 patients with acute coronary syndrome underwent imaging of a non-culprit lesion by both NIRS and OCT. For each segment, the NIRS-derived 4 mm segment with maximal lipid core burden index (maxLCBI4mm) was assessed. OCT analysis was performed using a semi-automated method including measurement of the fibrous cap thickness (FCT) of all detected fibroatheromas. Subsequent quantitative volumetric evaluation furnished FCT, FC surface area (FC SA), lipid arc, and FC (fibrous cap) volume data. OCT features of lipid plaques were compared with maxLCBI4mm. Predictors of maxLCBI4mm >400 was assessed by using univariable and multivariable analysis. RESULTS: OCT features (mean FCT, total FC SA, FC volume, maximal, mean, and total lipid arcs) strongly correlated with the maxLCBI4mm (p = 0.012 for the mean FCT, respectively p < 0.001 for all other aforementioned features). The strongest predictors of maxLCBI4mm >400 were the maximal (p = 0.002) and mean (p = 0.002) lipid arc, and total FC SA (p = 0.012). CONCLUSIONS: We found a strong correlation between the OCT-derived features and NIRS findings. Detailed OCT analysis may be reliably used for detection of the presence of coronary lipids.

No-Reflow Prediction in Acute Coronary Syndrome During Percutaneous Coronary Intervention: The NORPACS Risk Score.

BACKGROUND: Suboptimal coronary reperfusion (no reflow) is common in acute coronary syndrome percutaneous coronary intervention (PCI) and is associated with poor outcomes. We aimed to develop and externally validate a clinical risk score for angiographic no reflow for use following angiography and before PCI. METHODS: We developed and externally validated a logistic regression model for prediction of no reflow among adult patients undergoing PCI for acute coronary syndrome using data from the Melbourne Interventional Group PCI registry (2005-2020; development cohort) and the British Cardiovascular Interventional Society PCI registry (2006-2020; external validation cohort). RESULTS: A total of 30 561 patients (mean age, 64.1 years; 24% women) were included in the Melbourne Interventional Group development cohort and 440 256 patients (mean age, 64.9 years; 27% women) in the British Cardiovascular Interventional Society external validation cohort. The primary outcome (no reflow) occurred in 4.1% (1249 patients) and 9.4% (41 222 patients) of the development and validation cohorts, respectively. From 33 candidate predictor variables, 6 final variables were selected by an adaptive least absolute shrinkage and selection operator regression model for inclusion (cardiogenic shock, ST-segment-elevation myocardial infarction with symptom onset >195 minutes pre-PCI, estimated stent length ≥20 mm, vessel diameter <2.5 mm, pre-PCI Thrombolysis in Myocardial Infarction flow <3, and lesion location). Model discrimination was very good (development C statistic, 0.808; validation C statistic, 0.741) with excellent calibration. Patients with a score of ≥8 points had a 22% and 27% risk of no reflow in the development and validation cohorts, respectively. CONCLUSIONS: The no-reflow prediction in acute coronary syndrome risk score is a simple count-based scoring system based on 6 parameters available before PCI to predict the risk of no reflow. This score could be useful in guiding preventative treatment and future trials.

Kidney Injury After Minimal Radiographic Contrast Administration in Patients With Acute Coronary Syndromes.

BACKGROUND: Acute kidney injury (AKI) is common in patients with acute coronary syndromes (ACS) treated by percutaneous coronary intervention. OBJECTIVES: Contrast media (CM) volume minimization has been advocated for prevention of AKI. The DyeVert CM diversion system (Osprey Medical, Inc) is designed to reduce CM volume during coronary procedures. METHODS: In this randomized, single-blind, investigator-driven clinical trial conducted in 4 Italian centers from February 4, 2020 to September 13, 2022, 550 participants with ACS were randomly assigned in a 1:1 ratio to the following: 1) the contrast volume reduction (CVR) group (n = 276), in which CM injection was handled by the CM diversion system; and 2) the control group (n = 274), in which a conventional manual or automatic injection syringe was used. The primary endpoint was the rate of AKI, defined as a serum creatinine (sCr) increase ≥0.3 mg/dL within 48 hours after CM exposure. RESULTS: There were 412 of 550 (74.5%) participants with ST-segment elevation myocardial infarction (211 of 276 [76.4%] in the CVR group and 201 of 274 [73.3%] in the control group). The CM volume was lower in the CVR group (95 ± 30 mL vs 160 ± 23 mL; P < 0.001). Seven participants (1 in the CVR group and 6 in the control group) did not have postprocedural sCr values. AKI occurred in 44 of 275 (16%) participants in the CVR group and in 65 of 268 (24.3%) participants in the control group (relative risk: 0.66; 95% CI: 0.47-0.93; P = 0.018). CONCLUSIONS: CM volume reduction obtained using the CM diversion system is effective for prevention of AKI in patients with ACS undergoing invasive procedures. (REnal Insufficiency Following Contrast MEDIA Administration TriaL IV [REMEDIALIV]: NCT04714736).