Validation of a New Scoring Method to Assess the Efficacy of Rapid Initiation and Titration of Combination Pharmacotherapy for Patients Hospitalized with Acute Decompensated Heart Failure with Reduced and Mildly Reduced Ejection Fraction.

Background: Despite the encouragement of early initiation and titration of guideline-directed medical therapy (GDMT) for the treatment of heart failure (HF), most patients do not receive an adequate type and dose of pharmacotherapy in the real world. Objectives: This study aimed to determine the efficacy of titrating composite GDMT in patients with HF with reduced and mildly reduced ejection fraction and to identify patient conditions that may benefit from titration of GDMT. Methods: This was a two-center, retrospective study of consecutive patients hospitalized with acute decompensated heart failure (ADHF). Patients were classified into two groups according to a scoring scale determined by combination and doses of four types of HF agents (ACEis/ARBs/ARNis, BBs, MRAs, and SGLT2is) at discharge. A score of 5 or greater was defined as titrated GDMT, and a score of 4 or less was regarded as sub-optimal medical therapy (MT). Results: A total of 979 ADHF patients were screened. After 553 patients were excluded based on exclusion criteria, 426 patients (90 patients in the titrated GDMT group and 336 patients in the sub-optimal MT group) were enrolled for the analysis. The median follow-up period was 612 (453-798) days. Following statistical adjustment using the propensity score weighting method, the 2-year composite endpoint (composite of cardiac death and HF rehospitalization) rate was significantly lower in the titrated GDMT group, at 19%, compared with the sub-optimal MT group: 31% (score 3-4 points) and 43% (score 0-2 points). Subgroup analysis indicated a marked benefit of titrated GDMT in particular patient subgroups: age < 80 years, BMI 19.0-24.9, eGFR > 20 mL/min/1.73 m2, and serum potassium level ≤ 5.5 mmol/L. Conclusions: Prompt initiation and dose adjustment of multiple HF medications, with careful monitoring of the patient's physiologic and laboratory values, is a prerequisite for improving the prognosis of patients with heart failure.

Clinical Efficacy of Pre-Hospital Electrocardiogram Transmission in Patients Undergoing Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction.

Rapid reperfusion by primary percutaneous coronary intervention (pPCI) is an established strategy for the treatment of patients with ST-segment elevation myocardial infarction (STEMI). Pre-hospital electrocardiogram (PH-ECG) transmission by the emergency medical services (EMS) facilitates timely reperfusion in these patients. However, evidence regarding the clinical benefits of PH-ECG in individual hospitals is limited.This retrospective, observational study investigated the clinical efficacy of PH-ECG in STEMI patients who underwent pPCI. Of a total of 382 consecutive STEMI patients, 237 were enrolled in the study and divided into 2 groups: a PH-ECG group (n = 77) and non-PH-ECG group (n = 160). Door-to-balloon time (D2BT) was significantly shorter in the PH-ECG group (66 [52-80] min), compared to the non-PH-ECG group (70 [57-88] minutes, P = 0.01). The 30-day all-cause mortality rate was 6% in the PH-ECG group, which was significantly lower than that in the non-PH-ECG group (16%) (P = 0.037, hazard ratio [HR]: 0.38, 95% CI: 0.15-0.98). This trend was particularly evident in severely ill patients when stratified by GRACE score.The use of PH-ECG improved the survival rate of STEMI patients undergoing pPCI due to the improved pre-arrival preparation based on the EMS information. Coordination between EMS and PCI-capable institutes is essential for the management of PH-ECG.

Safety and efficacy of uninterrupted treatment with edoxaban or warfarin during the peri-procedural period of catheter ablation for atrial fibrillation.

BACKGROUND: The real-world safety and efficacy of uninterrupted anticoagulation treatment with edoxaban (EDX) or warfarin (WFR) during the peri-procedural period of catheter ablation (CA) for atrial fibrillation (AF) are yet to be investigated. METHODS: We conducted a two-center experience, observational study to retrospectively investigate consecutive patients who underwent CA for AF and received EDX or WFR. We examined the incidence of thromboembolic and bleeding complications during the peri-procedural period. RESULTS: The EDX and WFR groups included 153 and 103 patients, respectively (total: 256 patients). Demise or thromboembolic events did not occur in either of the groups. The incidence of major bleeding in the EDX and WFR groups was 0.7% and 2.9%, respectively. The total incidence of major/minor bleeding in the EDX and WFR groups was 7.8% and 8.7%, respectively. Of note, the incidence of bleeding complications in the uninterrupted WFR strategy group was markedly high in patients with an estimated glomerular filtration rate (eGFR) <30 (75%) or a HAS-BLED score ≥3 (60%). Patients with eGFR ≥30 and a HAS-BLED score ≤2 had a lower incidence of bleeding (<10%), regardless of the administered anticoagulation drug (EDX or WFR). CONCLUSIONS: This study confirmed the safety and efficacy of uninterrupted anticoagulation therapy using EDX or WFR in real-world patients undergoing CA for AF. Patients with severely impaired renal function and/or a higher bleeding risk during uninterrupted therapy with WFR were at a prominent risk of bleeding. Therefore, particular attention should be paid in the treatment of these patients.

Antithrombotic therapy after femoropopliteal artery stenting: 12-month results from Japan Postmarketing Surveillance.

OBJECTIVE: To investigate the effects of antithrombotic therapy on target lesion revascularisation (TLR) and major adverse cardiovascular and cerebrovascular events (MACCEs) at 12 months after femoropopliteal intervention with second-generation bare metal nitinol stents. METHODS: A total of 277 lesions in 258 limbs of 248 patients with de novo atherosclerosis in the above-the-knee femoropopliteal segment were analysed from the Japan multicentre postmarketing surveillance. RESULTS: At discharge, dual antiplatelet therapy (DAPT) was prescribed in 68.5% and cilostazol in 30.2% of patients. At 12 months of follow-up, prescriptions of DAPT significantly (p=0.0001) decreased to 51.2% and prescription of cilostazol remained unchanged (p=0.592) at 28.0%. Prescription of warfarin also remained unchanged (14.5% at discharge, 13.3% at 12 months, p=0.70). At 12 months, freedoms from TLR and MACCE were 89.4% and 89.7%, respectively. In a multivariate Cox proportional hazards model, neither DAPT nor cilostazol at discharge was associated with both TLR and MACCE at 12 months. However, warfarin at discharge was only independently associated with TLR at 12 months. Kaplan-Meier estimates demonstrated that warfarin at discharge yielded a significantly (p=0.013) lower freedom from TLR at 12 months than no warfarin at discharge. Freedom from TLR at 12 months by the Kaplan-Meier estimates was 77.8% (95% CI 59.0% to 88.8%) in patients with warfarin at discharge and 91.2% (95% CI 86.3% to 94.3%) in those without warfarin at discharge. CONCLUSIONS: Clinical benefits of DAPT or cilostazol might be small in terms of TLR and MACCE at 12 months. Anticoagulation with warfarin at discharge might increase TLR at 12 months.

Recurrent Early Coronary Stent Thrombosis under Chronic Disseminated Intravascular Coagulation.

A 62-year-old Japanese man presented with chest pain indicating that acute myocardial infarction had occurred. Eleven years earlier, he underwent a splenectomy due to idiopathic portal hypertension. Coronary angiography revealed diffuse stenosis, with calcification in the left anterior descending coronary artery (LAD). We performed a primary percutaneous coronary intervention (PCI). We deployed two drug-eluting stents with sufficient minimal cross-sectional stent area by intravascular ultrasound and thrombolysis in myocardial infarction (TIMI) 3 flow. The initial laboratory examination revealed chronic disseminated intravascular coagulation (DIC). On the 8th hospital day, he developed chest pain indicating early coronary stent thrombosis, although he had been prescribed dual antiplatelet therapy. We performed an emergent second PCI, and the TIMI flow grade improved from 0 to 3. Clopidogrel was replaced with prasugrel. On the 18th hospital day, we detected a repeated coronary stent thrombosis again. We performed a third PCI and the TIMI flow grade improved from 0 to 3. After anticoagulation therapy with warfarin, the DIC was improved and his condition ran a benign course without the recurrence of stent thrombosis for 1 month. Contrast-enhanced CT showed portal vein thrombosis. This patient's case reveals the possibility that the condition of chronic DIC can lead to recurrent stent thrombosis. Stent thrombosis is infrequent, but remains a serious complication in terms of morbidity and mortality. Although stent thrombosis is multifactorial, the present case suggests that DIC is a factor in stent thrombosis. To prevent stent thrombosis after PCI under DIC, anticoagulation might be a treatment option in addition to antiplatelet therapy.

Successful hybrid treatment with endovascular aorto-iliac revascularization and coronary bypass surgery in a patient with an advanced complex polyvascular disease.

A 72-year-old Japanese man was admitted to our hospital for effort chest pain and bilateral claudication. He was diagnosed as having severe ischemic heart disease and chronic bilateral aorto-iliac occlusions (Leriche syndrome) by a diagnostic angiography. Manifest collaterals via bilateral internal thoracic arteries (ITA) supplied sufficient blood flow for his lower limbs. We planned a two-stage operation for both the severe coronary artery disease and peripheral artery occlusive disease. He first underwent endovascular therapy (EVT) for bilateral aorto-iliac occlusion. One month later he underwent coronary artery bypass grafting (CABG) that was carried out for three coronary arteries with bilateral ITAs, also known as the internal thoracic artery, and the gastroepiploic artery. His chest symptoms and claudication were completely relieved and he was discharged uneventfully. We hereby suggest that EVT can be a safe, effective, and minimally invasive treatment to enable the patient to undergo CABG with all arterial grafts. .

Transcatheter closure of atrial septal defect protects from pulmonary edema: septal occluder device gradually reduces LR shunt.

A 56-year-old woman was diagnosed as atrial septal defect (ASD) with pulmonary hypertension; pulmonary blood flow/systemic blood flow (Qp/Qs) of 2.3, pulmonary artery pressure (PAP) of 71/23(39) mmHg and diastolic dysfunction of left ventricle. PAP was improved after medical therapy; therefore, transcatheter ASD closure was performed. Seven days later, left-sided heart failure occurred, however, the improvement of Qp/Qs (1.7) and PAP of 51/21(32) was confirmed. Diuretic therapy was introduced which led to further decrease of PAP 40/12(25) and Qp/Qs (1.1). Because of gradual decrease of Qp/Qs, this patient appeared to be protected from acute pulmonary edema.

Intra-Plaque Hematoma and Minor Intimal Disruption Detected by Optical Frequency Domain Imaging in a Case of Acute Coronary Syndrome.

A 39-year-old man exhibiting unstable angina was admitted to our hospital, and urgent coronary angiography revealed stenosis of the proximal left anterior descending coronary artery (LAD). A drug eluting stent was implanted at this site, and the patient was discharged uneventfully on the 3rd hospital day. Optical frequency-domain imaging (OFDI) was successful in detecting an intra-plaque hematoma, minor intimal disruption, and thrombus at the culprit lesion in this patient. These observations suggest that this hematoma might be the result of subsequent blood filling into the ruptured plaque through this minor intimal disruption.

Final 3-Year Outcome of a Randomized Trial Comparing Second-Generation Drug-Eluting Stents Using Either Biodegradable Polymer or Durable Polymer: NOBORI Biolimus-Eluting Versus XIENCE/PROMUS Everolimus-Eluting Stent Trial.

BACKGROUND: There is a paucity of data reporting the clinical outcomes of biodegradable polymer biolimus-eluting stent (BP-BES) compared with durable polymer everolimus-eluting stent (DP-EES) beyond 1 year after stent implantation when the polymer is fully degraded. METHODS AND RESULTS: The NOBORI Biolimus-Eluting Versus XIENCE/PROMUS Everolimus-Eluting Stent Trial (NEXT) is a prospective, multicenter, randomized, open-label, noninferiority trial comparing BP-BES with DP-EES in patients scheduled for percutaneous coronary intervention using drug-eluting stent (DES) without any exclusion criteria among 98 participating centers in Japan. The trial was designed to evaluate noninferiority of BP-BES relative to DP-EES in terms of any target-lesion revascularization at 1 year and death or myocardial infarction at 3 years. Between May and October 2011, 3235 patients were randomly assigned to receive either BP-BES (1617 patients) or DP-EES (1618 patients). Complete 3-year follow-up was achieved in 97.6% of patients. At 3 years, the primary safety end point of death or myocardial infarction occurred in 159 patients (9.9%) in the BP-BES group and in 166 patients (10.3%) in the DP-EES group, demonstrating noninferiority of BP-BES relative to DP-EES (P noninferiority<0.0001 and P superiority=0.7). Cumulative incidence of target-lesion revascularization was not significantly different between the 2 groups (7.4% versus 7.1%; P=0.8). By a landmark analysis at 1 year, the cumulative incidences of death or myocardial infarction and target-lesion revascularization were also not significantly different between the 2 groups (4.6% versus 5.2%; P=0.46 and 3.3% versus 2.7%; P=0.39, respectively). CONCLUSIONS: Safety and efficacy outcomes of BP-BES were non inferior to those of DP-EES 3 years after stent implantation. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01303640.

The Efficacy and Feasibility of Chronic Total Occlusion by Transradial Intervention: A Japanese Single-Center Retrospective Study.

OBJECTIVES: To evaluate transradial intervention (TRI) for chronic total occlusion (CTO). BACKGROUND: Although TRI has been applied to more complex lesions in percutaneous coronary intervention, efficacy and feasibility of TRI versus transfemoral intervention (TFI) for CTO have not yet been determined. METHODS: We retrospectively analyzed 207 CTO lesions in 195 patients in a single center between January 2008 and December 2011. Patients were divided into four groups according to procedures: TRI (135 lesions in 124 patients); TFI (40 lesions in 39 patients); TRI/TFI (20 lesions in 20 patients); and TFI/TFI (12 lesions in 12 patients). Antegrade approach was used in TRI and TFI, but antegrade plus retrograde approach was used in TRI/TFI and TFI/TFI. RESULTS: Although there were no differences in patient characteristics, complex CTO lesions such as blunt-type entry and retry lesions were frequently observed in the TFI/TFI group. Average sheath size was 5.7 Fr for TRI and 6.6 Fr for TFI. Fluoroscopy time was significantly longer for the antegrade plus retrograde approach. Procedure success rates were not statistically different: 82.2% in TRI, 72.5% in TFI, 75.0% in TRI/TFI, and 75.0% in TFI/TFI groups. There was no death, myocardial infarction, or stroke at 30 days in any groups. Two femoral cases and no radial cases had access-site complications. Access-site crossover from radial to femoral was conducted in 4 cases. CONCLUSION: More than one-half of CTO lesions can be treated with high success and low complication rates by TRI if the lesions are carefully selected.

Coronary angiographic characteristics that influence fractional flow reserve.

BACKGROUND: Percutaneous coronary intervention (PCI) guided with fractional flow reserve (FFR) has been shown to improve clinical outcome. Although coronary angiography is the standard method for PCI guidance, the visual severity of stenosis is not always correlated with functional severity, suggesting that there are additional angiographic factors that affect functional ischemia. METHODS AND RESULTS: To evaluate angiographic predictors of positive FFR in stenotic lesions, angiographic characteristics of 260 consecutive patients (362 lesions) who underwent FFR testing from April 2009 to September 2012 were analyzed. A scoring system (STABLED score) using these predictors was developed and compared with quantitative coronary angiography (QCA). %Diameter stenosis >50% (OR, 8.43; P<0.0001), tandem lesion (OR, 4.00; P<0.0001), true bifurcation (OR, 2.42; P=0.028), lesion length >20 mm (OR, 5.40; P=0.0002), and distance from ostium <20 mm (OR, 1.94; P=0.028) were determined as independent predictors of positive FFR. Area under the ROC curve for probability of positive FFR using the STABLED score (Stenosis 2 points, TAndem lesion 1 point, Bifurcation 1 point, LEsion length 1 point, Distance from ostium 1 point) was 0.85, higher than that for QCA stenosis alone (0.76). STABLED score ≥3 had 72.3% sensitivity and 83.6% specificity for predicting positive FFR, and PPV was 76.7%. CONCLUSIONS: Specific angiographic features are applicable for predicting functional ischemia. STABLED score correlates well with FFR.

Impact of transient or persistent slow flow and adjunctive distal protection on mortality in ST-segment elevation myocardial infarction.

Routine use of distal protection for ST-segment elevation myocardial infarction (STEMI) is not recommended. The purpose of this study was to analyze the impact of slow flow on mortality after STEMI, and the efficacy of adjunctive distal protection following primary thrombus aspiration. We retrospectively analyzed 414 STEMI patients who underwent primary PCI. Distal protection was used following primary thrombus aspiration only when the operator judged the patient to be at high risk of slow flow. Patients were divided into 3 groups: those receiving no thrombus aspiration (A- Group), thrombus aspiration without distal protection (A+/D- Group) or a combination of aspiration with distal protection (A+/D+ Group). Slow flow/no reflow was characterized as transient or persistent. The A-, A+/D-, and A+/D+ Groups consisted of 28.5 % (n = 118), 44.4 % (n = 184), and 27.1 % (n = 112) of patients, respectively. All-cause mortality at 180 days was 6.8 % without slow flow, 14.1 % with transient and 44.4 % with persistent slow flow (P < 0.0001), but was similar whether or not distal protection was used among these groups complicated without slow flow (A-, 8.7 %; A+/D-, 6.3 %; A+/D+, 4.3 %; P = 0.5854). However, in cases complicated with transient or persistent slow flow, distal protection reduced all-cause mortality to 38.5 % (A-), 23.3 % (A+/D-), and 10.8 % (A+/D+) at 180 days (P = 0.0114). Our data confirm that routine distal protection is not to be recommended. However, it is suggested that it could reduce mortality of patients with slow flow. Predicting slow flow accurately before PCI, however, remains a challenge.

Plaque protrusion detected by intravascular ultrasound during carotid artery stenting.

BACKGROUND: Stroke is a major complication of carotid artery stenting (CAS) that can occur during the procedure and for up to 30 days after the procedure in the late phase. Although the cause of late stroke after CAS is unknown, plaque protrusion may be one of the potential causes. This study aims to assess the rate of plaque protrusion during CAS by intravascular ultrasound (IVUS). METHODS: We performed 77 consecutive CAS procedures using IVUS between May 2008 and December 2012. The rate of plaque protrusion was assessed at the end of the procedure using IVUS and angiography. RESULTS: Mean age of patients was 72.5 ± 7.5 years. Sixty-eight patients were male and 42 had diabetes mellitus. In all, 65 PRECISE stents and 12 Carotid Wall stents were used. All cases were distally protected with filter devices. Six plaque protrusions (7.8%) through the stent struts were detected by IVUS but only 2 (2.6%) by angiography. A predictor of plaque protrusion was preprocedural severe stenosis with flow delay. Additional postdilations (n = 6) and stent-in-stent implantations (n = 4) were performed to correct the plaque protrusions. No remaining plaque protrusion was observed in the final IVUS. Overall stroke rate was 2.6% (major 0%, minor 2.6%), and these occurred in the catheterization laboratory, but no late stroke was observed at 30 days after procedure. CONCLUSIONS: IVUS can detect plaque protrusion better than angiography. Because adequate management of plaque protrusion may reduce stroke complications, IVUS usage is worth considering.

Diagnostic accuracy of Global Registry of Acute Coronary Events (GRACE) risk score in ST-elevation myocardial infarction for in-hospital and 360-day mortality in Japanese patients.

BACKGROUND: The purpose of the present study was to confirm the diagnostic accuracy of Global Registry of Acute Coronary Events (GRACE) risk score 1.0 (GRACE 1.0) and updated GRACE 1.0 (GRACE 2.0) for in-hospital and 360-day mortality in ST-elevation myocardial infarction (STEMI) in Japanese patients. GRACE 1.0 and GRACE 2.0 are the established predictive models in acute coronary syndrome, but their application to Japanese patients has not been fully verified. METHODS AND RESULTS: The present study retrospectively analyzed 412 consecutive STEMI patients who had undergone primary percutaneous coronary intervention from January 2006 to September 2011. All causes of death during hospitalization were examined to confirm the diagnostic accuracy of GRACE 1.0 on receiver operating characteristic (ROC) analysis. Similarly, all causes of death during the 360 days after hospitalization were analyzed to confirm the diagnostic accuracy of GRACE 2.0. The average GRACE 1.0 score was 175.8±50.9. In-hospital and 360-day mortality were 13.1% and 15.5%, respectively. Area under the ROC curve, which describes the diagnostic accuracy of the GRACE 1.0 predicted in-hospital mortality and the GRACE 2.0 predicted 360-day mortality, was as high as 0.95 and 0.92, respectively. CONCLUSIONS: Both GRACE 1.0 and GRACE 2.0 had a high diagnostic accuracy for prediction of in-hospital and 360-day mortality in Japanese STEMI patients.

Comparison of in vivo longitudinal strength and conformability following stent implantation in rabbit iliac artery.

OBJECTIVES: The aim of this study was to determine the in vivo longitudinal strength and conformability of various stent platforms following stent implantation in rabbit iliac arteries. BACKGROUND: Recently, longitudinal coronary stent deformation has been highlighted and bench tests have demonstrated differences in longitudinal strength among various stent platforms. However, this has not been investigated in an in vivo setting. This is of interest because there may be a trade-off between longitudinal strength and conformability. METHODS: We evaluated 4 types of commercially available stents: Multi-Link 8 (Abbott Vascular); Omega (Boston Scientific); Integrity (Medtronic); and Nobori (Terumo Corporation). To investigate the longitudinal strength, constant axial force was applied to the stent edge by a guiding catheter after deployment in a rabbit iliac artery. The amount of longitudinal stent deformation was calculated by measuring stent length. In order to evaluate conformability, stents were deployed crossing over the iliac bifurcation and the bifurcation angles were measured before and after stent implantation. If the change in the angle was small, the stent was considered to be more conformable. RESULTS: The Omega stent demonstrated significantly greater longitudinal compression compared with other stents (Omega, 17.4 ± 9.3%; Multi-Link 8, 2.8 ± 2.3%; Integrity, 2.8 ± 1.4%; Nobori, 3.8 ± 3.2%; P=.01), but Omega showed better conformability, as evidenced by the smallest percent change in the bifurcation angle (Omega, 12.7 ± 0.8%; Multi-Link 8, 25.7 ± 2.4%; Integrity, 28.3 ± 1.1%; Nobori, 28.1 ± 6.8%; P=.03). CONCLUSION: In this rabbit model, the Omega stent, which has the platform of the Element stent, showed less longitudinal strength but greater conformability compared with the other stent platforms.

Impact of transport pathways on the time from symptom onset of ST-segment elevation myocardial infarction to door of coronary intervention facility.

BACKGROUND: Reducing total ischemic time is important in achieving better outcome in ST-segment elevation myocardial infarction (STEMI). Although the onset-to-door (OTD) time accounts for a large portion of the total ischemic time, factors affecting prolongation of the OTD time are not established. PURPOSE: The purpose of this study was to determine the impact of transport pathways on OTD time in patients with STEMI. METHODS AND SUBJECTS: We retrospectively studied 416 STEMI patients who were divided into 4 groups according to their transport pathways; Group 1 (n = 41): self-transportation to percutaneous coronary intervention (PCI) facility; Group 2 (n = 215): emergency medical service (EMS) transportation to PCI facility; Group 3 (n = 103): self-transportation to non-PCI facility; and Group 4 (n = 57): EMS transportation to non-PCI facility. OTD time was compared among the 4 groups. ESSENTIAL RESULTS: Median OTD time for all groups combined was 113 (63-228.8)min [Group 1, 145 (70-256.5); Group 2, 71 (49-108); Group 3, 260 (142-433); and Group 4, 184 (130-256)min]. OTD time for EMS users (Groups 2 and 4) was 138 min shorter than non-EMS users (Groups 1 and 3). Inter-hospital transportation (Groups 3 and 4) prolonged OTD by a median of 132 min compared with direct transportation to PCI facility (Groups 1 and 2). Older age, history of myocardial infarction, prior PCI, shock at onset, high Killip classification, and high GRACE Risk Score were significantly more frequent in EMS users. PRINCIPAL CONCLUSIONS: Self-transportation without EMS and inter-hospital transportation were significant factors causing prolongation of the OTD time. Approximately 35% of STEMI patients did not use EMS and 21% of patients were transported to non-PCI facilities even though they called EMS. Awareness in the community as well as among medical professionals to reduce total ischemic time of STEMI is necessary; this involves educating the general public and EMS crews.

Safety margin of minimized contrast volume during percutaneous coronary intervention in patients with chronic kidney disease.

Maximum allowable contrast dose (MACD) calculated as body weight × 5/serum creatinine has been a standard contrast dye volume (CV) used to decrease contrast-induced acute kidney injury. Recent advances in intravascular ultrasound-guided percutaneous coronary intervention (PCI) can dramatically minimize CV. The safe threshold when using an extremely low-dose CV is unknown. This study was designed as a multicenter, retrospective study of chronic kidney disease (CKD) patients with estimated glomerular filtration rate (eGFR) <30 ml/min/1.73 m(2) undergoing elective PCI. We divided the patients into three groups according to following criteria: (1) low dose, CV/eGFR ratio <1.0; (2) medium dose, CV/eGFR ratio ≥1 and