γ-Glutamyl Transferase and Long-Term Survival in the SYNTAXES Trial: Is It Just the Liver?

BACKGROUND: Recently, machine learning algorithms have identified preprocedural γ-glutamyl transferase (GGT) as a significant predictor of long-term mortality after coronary revascularization in the SYNTAX (Synergy Between PCI [Percutaneous Coronary Intervention] With Taxus and Cardiac Surgery) trial. The aim of the present study is to investigate the impact of preprocedural GGT on 10-year all-cause mortality in patients with complex coronary artery disease after revascularization. METHODS AND RESULTS: The SYNTAX trial was a randomized trial comparing PCI with coronary artery bypass grafting in 1800 patients with complex coronary artery disease. The present report is a post hoc subanalysis of the SYNTAXES (Synergy Between PCI With Taxus and Cardiac Surgery Extended Survival) trial, an investigator-driven extended 10-year follow-up of the SYNTAX trial. The association between preprocedural GGT and 10-year all-cause mortality was investigated. The mean values of GGT for men and women were 43.5 (SD, 48.5) and 36.4 (SD, 46.1) U/L, respectively. In multivariable Cox regression models adjusted by traditional risk factors, GGT was an independent predictor for all-cause death at 10-year follow-up, and each SD increase in log-GGT was associated with a 1.24-fold risk of all cause death at 10-year follow-up (95% CI, 1.10-1.40). According to previously reported sex-related GGT thresholds, patients with higher GGT level had a 1.74-fold risk of all-cause death at 10-year follow-up (95% CI, 1.32-2.29) compared with patients with lower GGT level. CONCLUSIONS: Preprocedural GGT is an independent predictor of 10-year mortality after coronary revascularization in patients with complex coronary artery disease. In patients with elevated GGT, strong secondary prevention may be required after revascularization and must be studied prospectively. REGISTRATION: URL: https://clinicaltrials.gov/study/NCT03417050.

Coronary bypass surgery guided by computed tomography in a low-risk population.

BACKGROUND AND AIMS: In patients with three-vessel disease and/or left main disease, selecting revascularization strategy based on coronary computed tomography angiography (CCTA) has a high level of virtual agreement with treatment decisions based on invasive coronary angiography (ICA). METHODS: In this study, coronary artery bypass grafting (CABG) procedures were planned based on CCTA without knowledge of ICA. The CABG strategy was recommended by a central core laboratory assessing the anatomy and functionality of the coronary circulation. The primary feasibility endpoint was the percentage of operations performed without access to the ICA. The primary safety endpoint was graft patency on 30-day follow-up CCTA. Secondary endpoints included topographical adequacy of grafting, major adverse cardiac and cerebrovascular (MACCE), and major bleeding events at 30 days. The study was considered positive if the lower boundary of confidence intervals (CI) for feasibility was ≥75% (NCT04142021). RESULTS: The study enrolled 114 patients with a mean (standard deviation) anatomical SYNTAX score and Society of Thoracic Surgery score of 43.6 (15.3) and 0.81 (0.63), respectively. Unblinding ICA was required in one case yielding a feasibility of 99.1% (95% CI 95.2%-100%). The concordance and agreement in revascularization planning between the ICA- and CCTA-Heart Teams was 82.9% with a moderate kappa of 0.58 (95% CI 0.50-0.66) and between the CCTA-Heart Team and actual treatment was 83.7% with a substantial kappa of 0.61 (95% CI 0.53-0.68). The 30-day follow-up CCTA in 102 patients (91.9%) showed an anastomosis patency rate of 92.6%, whilst MACCE was 7.2% and major bleeding 2.7%. CONCLUSIONS: CABG guided by CCTA is feasible and has an acceptable safety profile in a selected population of complex coronary artery disease.

Impact of left ventricular ejection fraction on 10-year mortality in the SYNTAX trial.

BACKGROUNDS: The impact of reduced left ventricular ejection fraction (LVEF) on very long-term prognosis following percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) has been debated. The aim of this study was to investigate the impact of LVEF at baseline on 10-year mortality in the SYNTAX trial. METHODS: Patients (n = 1800) were categorized into three sub-groups: reduced (rEF ≤ 40 %), mildly reduced (mrEF 41-49 %), and preserved LVEF (pEF ≥ 50 %). The SYNTAX score 2020 (SS-2020) was applied in patients with LVEF<50 % and ≥ 50 %. RESULTS: Ten-year mortalities were 44.0 %, 31.8 %, and 22.6 % (P < 0.001) in patients with rEF (n = 168), mrEF (n = 179), and pEF (n = 1453). Although no significant differences were observed, the mortality with PCI was higher than with CABG in patients with rEF (52.9 % vs 39.6 %, P = 0.054) and mrEF (36.0 % vs. 28.6 %, P = 0.273), and comparable in pEF (23.9 % vs. 22.2 %, P = 0.275). Calibration and discrimination of the SS-2020 in patients with LVEF<50 % were poor, whilst they were reasonable in those with LVEF≥50 %. The proportion of patients eligible for PCI who had a predicted equipoise in mortality with CABG was estimated to be 57.5 % in patients with LVEF≥50 %. CABG was safer than PCI in 62.2 % of patients with LVEF<50 %. CONCLUSIONS: Reduced LVEF was associated with an increased risk of 10-year mortality in patients revascularized either surgically or percutaneously. Compared to PCI, CABG was safe revascularization in patients with LVEF≤40 %. In patients with LVEF≥50 % individualized 10-year all-cause mortality predicted by SS-2020 was helpful in decision-making whilst the predictivity in patients with LVEF<50 % was poor.

Coronary computed tomography angiography-based SYNTAX score for comprehensive assessment of advanced coronary artery disease.

BACKGROUND: Since the initial attempt to adapt the anatomical SYNTAX score (aSS) to coronary computed tomography angiography (CCTA), CCTA imaging technology has evolved, and is currently used as a "decision-maker" for revascularization strategy in complex coronary artery disease (CAD) and has rendered necessary some updating of the aSS to the CCTA modality. OBJECTIVES: The aim is to provide updated definitions of the aSS derived from CCTA in patients with complex CAD undergoing CABG. METHODS: The modifications of CCTA-aSS are the following; (i) updated definition and detection criteria of total occlusion (TO) in CCTA based on length assessment, (ii) inclusion of scoring points for serial bifurcations located in one single coronary segment. (iii) inclusion of weighing score points for lesions located distal to a TO, not visualized on conventional coronary angiography, but visible in CCTA, (iv) removal of thrombus and bridging collateral items from the weighing score, considering the limited diagnostic capability of CCTA in detecting these specific lesion characteristics. RESULTS: the updated CCTA-aSS was tested in a first-in-man study using the sole guidance of CCTA for the planning and performance of bypass surgery in complex CAD (n â€‹= â€‹114). An interobserver analysis showed excellent reproducibility (ICC â€‹= â€‹0.96, 95 â€‹% confidence interval 0.94-0.97). CONCLUSION: The updated CCTA-aSS was implemented in a cohort of patients with complex CAD undergoing CABG with the sole guidance of CCTA and FFRCT and the Inter-reproducibility of the analysis of the updated score was found excellent. The prognostic value of the modified CCTA-aSS will be examined in future studies.

Can Machine Learning Aid the Selection of Percutaneous vs Surgical Revascularization?

BACKGROUND: In patients with 3-vessel coronary artery disease (CAD) and/or left main CAD, individual risk prediction plays a key role in deciding between percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). OBJECTIVES: The aim of this study was to assess whether these individualized revascularization decisions can be improved by applying machine learning (ML) algorithms and integrating clinical, biological, and anatomical factors. METHODS: In the SYNTAX (Synergy between PCI with Taxus and Cardiac Surgery) study, ML algorithms (Lasso regression, gradient boosting) were used to develop a prognostic index for 5-year death, which was combined, in the second stage, with assigned treatment (PCI or CABG) and prespecified effect-modifiers: disease type (3-vessel or left main CAD) and anatomical SYNTAX score. The model's discriminative ability to predict the risk of 5-year death and treatment benefit between PCI and CABG was cross-validated in the SYNTAX trial (n = 1,800) and externally validated in the CREDO-Kyoto (Coronary REvascularization Demonstrating Outcome Study in Kyoto) registry (n = 7,362), and then compared with the original SYNTAX score II 2020 (SSII-2020). RESULTS: The hybrid gradient boosting model performed best for predicting 5-year all-cause death with C-indexes of 0.78 (95% CI: 0.75-0.81) in cross-validation and 0.77 (95% CI: 0.76-0.79) in external validation. The ML models discriminated 5-year mortality better than the SSII-2020 in the external validation cohort and identified heterogeneity in the treatment benefit of CABG vs PCI. CONCLUSIONS: An ML-based approach for identifying individuals who benefit from CABG or PCI is feasible and effective. Implementation of this model in health care systems-trained to collect large numbers of parameters-may harmonize decision making globally. (Synergy Between PCI With TAXUS and Cardiac Surgery: SYNTAX Extended Survival [SYNTAXES]; NCT03417050; SYNTAX Study: TAXUS Drug-Eluting Stent Versus Coronary Artery Bypass Surgery for the Treatment of Narrowed Arteries; NCT00114972).

CCTA-based CABG SYNTAX Score: a tool to evaluate completeness of coronary segment revascularization after bypass surgery.

To describe the updated coronary computed tomographic angiography (CCTA)-based coronary artery bypass graft (CABG) anatomic SYNTAX Score (aSS) and assess its utility and reproducibility for assessing the completeness of revascularization after CABG. The CCTA-CABG aSS is a visual assessment using CCTA post-CABG which quantifies the failure in effectively grafting stenotic coronary segments, and therefore assesses the completeness of surgical revascularization. It is calculated by subtracting the aSS of successfully anastomosed coronary segments from the aSS of the native coronary tree. The inter-observer reproducibility of the CCTA-CABG aSS was evaluated in 45 consecutive patients with three-vessel disease with or without left main disease who underwent a CCTA 30 days (± 7 days) after CABG. The CCTA-CABG aSS was evaluated in 45 consecutive patients with 117 bypass grafts and 152 anastomoses. The median native coronary aSS was 35.0 [interquartile range (IQR) 27.0-41.0], whilst the median CCTA-CABG aSS was 13.0 (IQR 9.0-20.5). The inter-observer level of agreement for the native coronary aSS and the CCTA-CABG aSS were both substantial with respective Kappas of 0.67 and 0.61. The CCTA-CABG aSS was feasible in all patients who underwent CABG for complex coronary artery disease with substantial inter-observer reproducibility, and therefore can be used to quantify the completeness of revascularization after CABG.

10 Years of SYNTAX: Closing an Era of Clinical Research After Identifying New Outcome Determinants.

The SYNTAX trial randomized patients equally eligible for coronary artery bypass grafting or percutaneous coronary intervention using the Heart Team approach. The SYNTAXES study achieved a follow-up rate of 93.8% and reported the 10-year vital status. Factors associated with increased mortality at 10 years were pharmacologically treated diabetes mellitus, increased waist circumference, reduced left ventricular function, prior cerebrovascular and peripheral vascular disease, western Europe and North American descent, current smoking, chronic obstructive pulmonary disease, elevated C-reactive protein, anemia, and an increase in HbA1c. Procedural factors associated with higher 10 years mortality include periprocedural myocardial infarction, extensive stenting, small stents, ≥1 heavily calcified lesion, ≥1 bifurcation lesion, residual SYNTAX score >8, and staged percutaneous coronary intervention. Optimal medical therapy at 5 years, use of statins, on-pump coronary artery bypass grafting, multiple arterial grafts, and higher physical component score and mental component score were associated with lower mortality at 10 years. Numerous scores and prediction models were developed to help individualize risk assessment. Machine learning has emerged as a novel approach for developing risk models.

Impact of on-pump and off-pump coronary artery bypass grafting on 10-year mortality versus percutaneous coronary intervention.

OBJECTIVES: The very long-term mortality of off-pump and on-pump coronary artery bypass grafting (CABG) versus percutaneous coronary intervention (PCI) in a randomized complex coronary artery disease population is unknown. This study aims to investigate the impact of on-pump and off-pump CABG versus PCI on 10-year all-cause mortality. METHODS: The SYNTAX trial randomized 1800 patients with three-vessel and/or left main coronary artery disease to PCI or CABG and assessed their survival at 10 years. In this sub-study, the hazard of mortality over 10 years was compared according to the technique of revascularization: on-pump CABG (n = 725), off-pump CABG (n = 128) and PCI (n = 903). RESULTS: There was substantial inter-site variation in the use of off-pump CABG despite baseline characteristics being largely homogeneous among the 3 groups. The crude rate of mortality was significantly lower following on-pump CABG versus PCI [25.6% vs 28.4%, hazard ratio (HR) 0.79, 95% confidence interval (CI) 0.65-0.96], while it was comparable between off-pump CABG and PCI (28.5% vs 28.4%, HR 0.98, 95% CI 0.69-1.40). After adjusting for the 9 variables included in the SYNTAX score II 2020, 10-year mortality remained significantly lower with on-pump CABG than PCI (HR 0.75 against PCI, P = 0.009). CONCLUSIONS: In the SYNTAXES trial, 10-year mortality adjusted for major confounders was significantly lower following on-pump CABG compared to PCI. There was no evidence for unadjusted difference between off-pump CABG and PCI, although the unadjusted estimated HR had a wide CI. Site heterogeneity in the technique used in bypass surgery has had measurable effects on treatment performance.

Impact of periprocedural major adverse events on 10-year mortality after revascularisation.

BACKGROUND: The long-term prognostic impact of a composite of periprocedural major adverse events (PMAE) following revascularisation for patients with complex coronary artery disease (CAD) has not yet been established. AIMS: This study aimed to assess the impact on 10-year mortality of non-fatal PMAE following percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). Other objectives were to evaluate 1) whether PMAE affect mortality predicted by the SYNTAX score II 2020 (SSII-2020) and 2) whether optimal medical therapy (OMT) positively affects the prognosis of patients with non-fatal PMAE. METHODS: The association between 10-year mortality and non-fatal PMAE occurring within 30 days of PCI or CABG in patients with three-vessel disease and/or left main disease enrolled in the SYNTAXES study was investigated. RESULTS: The main findings are that non-fatal PMAE occurred less frequently following PCI than CABG (11.2% vs 28.2%; p<0.001) and that non-fatal PMAE were an independent predictor of all-cause mortality in the first year post-procedure, but not at 5 or 10 years, in both treatment modalities. PMAE substantially alter the individual predictions of 10-year mortality by the SSII-2020. In patients with non-fatal PMAE, OMT may provide survival benefits during the first year post-procedure as well as in the long term. CONCLUSIONS: In patients with complex CAD, non-fatal PMAE were more common following CABG than PCI, but their prognostic impact was similar, being significant in the first year and then diminishing out to 10 years. Patients with non-fatal PMAE may therefore require more careful follow-up and additional preventive treatment in the first year post-procedure.

Appropriateness of the Modality of Revascularization According to the SYNTAX Score II 2020 in the FASTTRACK CABG Study: An Interim Report on Patient Selection.

BACKGROUND: Personalized long term vital prognosis plays a key role in deciding between percutaneous coronary intervention (PCI) and CABG in patients with complex coronary artery disease. The FASTTRACK CABG trial enrolls patients with the sole guidance of coronary computed tomographic angiography (CCTA) and fractional flow reserve CCTA (FFRCT). The feasibility/non-feasibility of this approach is determined by the surgeon request to have access to the invasive coronary angiography. METHODS: This interim analysis, which was requested by the Data and Safety Monitoring Board (DSMB), compared the treatment decision of the "on site" Heart team to the recommended treatment as per the SYNTAX Score II 2020 (SS-2020), which was prospectively assessed by the central core laboratory in the first 57 consecutive patients (half of the planned population) enrolled in this First in Man study. RESULTS: The average anatomical SYTAX Score is 35.6 ± 11.5. The SS-2020 predicted 5-year MACE and 10-year all-cause mortality are 14.7 % and 21.6 % following CABG, and 23.0 % and 30.4 % following PCI. Among the enrolled patients the SS-2020 predicts long-term PCI outcomes similar to CABG (absolute risk difference ≤0 % in favor of PCI) in only two patients whilst the remaining 55 patients had a predicted survival benefit with CABG. CONCLUSIONS: According to the SS-2020, the first 57 patients recruited into the FASTTRACK CABG trial received the appropriate modality of revascularization and the DSMB allowed the investigators to complete the study.

Geographic disparity in 10-year mortality after coronary artery revascularization in the SYNTAXES trial.

AIMS: To investigate geographic disparity in long-term mortality following revascularization in patients with complex coronary artery disease (CAD). METHODS AND RESULTS: The SYNTAXES trial randomized 1800 patients with three-vessel and/or left main CAD to percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) and assessed their survival at 10 years. Patients were stratified according to the region of recruitment: North America (N-A, n = 245), Eastern Europe (E-E, n = 189), Northern Europe (N-E, n = 425), Southern Europe (S-E, n = 263), and Western Europe (W-E, n = 678), which also served as the reference group. Compared to W-E, patients were younger in E-E (62 vs 65 years, p < 0.001), and less frequently male in N-A (65.3% vs 79.6%, p < 0.001). Diabetes (16.0% vs 25.4%, p < 0.001) and peripheral vascular disease (6.8% vs 10.9%, p = 0.025) were less frequent in N-E than W-E. Ejection fraction was highest in W-E (62% vs 56%, p < 0.001). Compared to W-E, the mean anatomic SYNTAX score was higher in S-E (29 vs 31, p = 0.008) and lower in N-A (26, p < 0.001). Crude ten-year mortality was similar in N-A (31.6%), and W-E (30.7%), and significantly lower in E-E (22.5%, p = 0.041), N-E (21.9%, p = 0.003) and S-E (22.0%, p = 0.014). Compared to W-E, adjusted mortality in N-E (HR 0.85, p = 0.019) and S-E (HR 0.72, p = 0.043) remain significantly lower after adjustment for pre- and peri-procedural factors, but no significant interaction (Pinteraction = 0.728) between region and modality of revascularization was seen. CONCLUSION: In the era of globalization, knowledge, and understanding of geographic disparity are of paramount importance for the correct interpretation of global studies.

Predicted and Observed Mortality at 10 Years in Patients With Bifurcation Lesions in the SYNTAX Trial.

BACKGROUND: Percutaneous coronary intervention (PCI) of bifurcation lesions is associated with higher rates of adverse events, and currently it is unclear whether PCI or coronary artery bypass grafting (CABG) is the safer treatment for these patients at very long-term follow-up. OBJECTIVES: The aim of this study was to investigate the impact of bifurcation lesions on individual predicted and observed all-cause 10-year mortality in the SYNTAX (Synergy Between PCI With Taxus and Cardiac Surgery) trial. METHODS: In the SYNTAXES (SYNTAX Extended Survival) study, 10-year observed and individual predicted mortality derived from the SYNTAX score 2020 (SS-2020) was compared between patients with ≥1 bifurcation (n = 1,300) and those with no bifurcations (n = 487). RESULTS: Among patients treated with PCI, patients with >1 bifurcation lesion compared with those without bifurcation lesions had a significantly higher risk for all-cause death (19.8% vs 30.1%; HR: 1.55; 95% CI: 1.12-2.14; P = 0.007), whereas following CABG, mortality was similar in patients with and those without bifurcation lesions (23.3% vs 23.0%; HR: 0.81; 95% CI: 0.59-1.12; P = 0.207; Pinteraction = 0.006). In PCI patients, a 2-stent vs a 1-stent technique was associated with higher mortality (33.3% vs 25.9%; HR: 1.51; 95% CI: 1.06-2.14; P = 0.021). According to the SS-2020, among those with ≥1 bifurcation, there was equipoise for all-cause mortality between PCI and CABG in 2 quartiles of the population, whereas CABG was superior to PCI in the 2 remaining quartiles. CONCLUSIONS: Bifurcation lesions require special attention from the heart team, considering the higher 10-year all-cause mortality associated with PCI. Careful evaluation of bifurcation lesion complexity and calculation of individualized 10-year prognosis using the SS-2020 may therefore be helpful in decision making. (Synergy Between PCI With TAXUS and Cardiac Surgery: SYNTAX Extended Survival [SYNTAXES], NCT03417050; Taxus Drug-Eluting Stent Versus Coronary Artery Bypass Surgery for the Treatment of Narrowed Arteries [SYNTAX], NCT00114972).

Successful Coronary Artery Bypass Grafting Based Solely on Non-Invasive Coronary Computed Tomography Angiography.

An 81-year-old female presented with chronic coronary disease (Canadian Cardiovascular Society angina severity grading III). The patient underwent coronary computed tomography angiography (CCTA) that revealed three-vessel coronary artery disease (3VD). This case illustrates that in a patient with 3VD, planning and execution of coronary artery bypass grafting (CABG) were successfully performed based solely on CCTA combined with fractional flow reserve derived from computed tomography angiography (FFRCT). Coronary artery bypass grafting (CABG) was planned and executed as follows: left internal mammary artery grafted to the left anterior descending artery (LAD), saphenous vein graft (SVG) to the right coronary artery (RCA), and SVG to the obtuse marginal artery (OM). Repeat imaging assessment with non-invasive CCTA and FFRCT at 30-day follow-up confirmed the safety of this approach. The FFRCT values of the RCA and LAD were normalized, whereas a borderline pressure drop was observed in the distal run-off of the OM (FFRCT=0.79). Notably, this is the first case in which post-CABG FFRCT assessment was performed. Post-CABG FFRCT is an investigational novel non-invasive tool for assessing the functional improvement of the epicardial conductance vessels following surgical revascularization.

Delayed bleeding complication due to internal mammary artery injury after ultrasound-guided percutaneous catheter drainage for liver cyst infection.

BACKGROUND: Ultrasound-guided percutaneous catheter drainage (PCD) is widely accepted as a primary treatment for pyogenic liver abscess. Severe PCD-related complications have been reported; however, delayed bleeding complications due to internal mammary artery injury are unknown. CASE PRESENTATION: An 84-year-old man undergoing hemodialysis owing to chronic kidney disease due to focal segmental glomerulosclerosis was admitted to our hospital for liver cyst infection. Ultrasound-guided PCD was carried out through the normal liver at the upper abdominal midline at the level of the sixth intercostal space. Two days later, an abdominal hematoma occurred at the puncture site. Contrast-enhanced computed tomography revealed extravasation of the distal right internal mammary artery, which was successfully treated with percutaneous coil embolization. CONCLUSION: Internal mammary artery injury should be considered as a differential diagnosis when a progressing hematoma develops after PCD.

Comparison of 0.9-mm and 1.4-mm catheters in excimer laser coronary angioplasty for acute myocardial infarction.

Excimer laser coronary angioplasty (ELCA) is a unique revascularization modality that can vaporize plaque and thrombus. Compared to thrombus aspiration therapy, ELCA is reported to provide better microcirculation and reduced peripheral embolism in treatment for acute coronary syndrome. Excimer laser catheters come in various sizes, and we sought to compare the 0.9- and 1.4-mm-diameter catheters. We retrospectively enrolled 90 acute myocardial infarction (AMI) patients who underwent primary percutaneous coronary intervention with excimer laser from August 2013 to March 2017 in our hospital. Patients were grouped by diameter of catheter that had been used, the 0.9 mm group (n = 51) and 1.4 mm group (n = 39). We evaluated myocardial perfusion, procedural success rate, short-term outcome, lesion crossability, and complications between the two groups. The percentage of patients whose final thrombolysis in myocardial infarction (TIMI) grade was 3 (0.9 mm 86.3% vs 1.4 mm 89.7% p = 0.75) and final myocardial blush grade (MBG) was 3 (0.9 mm 72.5% vs 1.4 mm 69.2% p = 0.82) was similarly high for both groups. Procedural success rate, in-hospital major adverse cardiac events (MACE), lesion crossability, and complications were also similar. This study showed that efficacy of 0.9 and 1.4 mm excimer laser catheter was equivalent in ELCA for AMI patients. If one takes into account lesion crossability, debulking effects, and the stunned platelets phenomenon, the 0.9 mm excimer laser catheter is sufficient for ELCA in AMI patients.

Sodium Bicarbonate-Ascorbic Acid Combination for Prevention of Contrast-Induced Nephropathy in Chronic Kidney Disease Patients Undergoing Catheterization.

BACKGROUND: Sodium bicarbonate and ascorbic acid have been proposed to prevent contrast-induced nephropathy (CIN). The present study evaluated the effect of their combined use on CIN incidence.Methods and Results:We prospectively enrolled 429 patients with chronic kidney disease (CKD: baseline estimated glomerular filtration rate <60 mL/min/1.73 m2) prior to elective coronary catheterization. CIN was defined as absolute (≥0.5 mg/dL) or relative (≥25%) increase in serum creatinine within 72 h. In the saline hydration (n=218) and combined sodium bicarbonate+ascorbic acid (n=211) groups, a total of 1,500-2,500 mL 0.9% saline was given before and after the procedure. In addition, the combination group received 20 mEq sodium bicarbonate and 3 g ascorbic acid i.v. before the procedure, followed by 2 g ascorbic acid after the procedure and a further 2 g after 12 h. There were no significant differences between the basic characteristics and contrast volume in the 2 groups. CIN occurred in 19 patients (8.7%) in the saline group, and in 6 patients (2.8%) in the combined treatment group (P=0.008). CONCLUSIONS: Combined sodium bicarbonate and ascorbic acid could prevent CIN following catheterization in CKD patients.

Enhanced angiotensin receptor-associated protein in renal tubule suppresses angiotensin-dependent hypertension.

We have previously shown that angiotensin II type 1 receptor-associated protein (ATRAP/Agtrap) interacts with the angiotensin II type 1 receptor and promotes constitutive internalization of the receptor so as to inhibit the pathological activation of its downstream signaling but preserve baseline physiological signaling activity. The present study was designed to investigate the role of renal ATRAP in angiotensin II-dependent hypertension. We generated transgenic mice dominantly expressing ATRAP in the renal tubules, including renal distal tubules. The renal ATRAP transgenic mice exhibited no significant change in blood pressure at baseline on normal salt diet. However, in the renal ATRAP transgenic mice compared with wild-type mice, the following took place: (1) the development of high blood pressure in response to angiotensin II infusion was significantly suppressed based on radiotelemetry, (2) the extent of daily positive sodium balance was significantly reduced during angiotensin II infusion in metabolic cage analysis, and (3) the renal Na+ -Cl- cotransporter activation and α-subunit of the epithelial sodium channel induction by angiotensin II infusion were inhibited. Furthermore, adenoviral overexpression of ATRAP suppressed the angiotensin II-mediated increase in the expression of α-subunit of the epithelial sodium channel in mouse distal convoluted tubule cells. These results indicate that renal tubule-dominant ATRAP activation provokes no evident effects on blood pressure at baseline but exerts an inhibitory effect on the pathological elevation of blood pressure in response to angiotensin II stimulation, thereby suggesting that ATRAP is a potential target of interest in blood pressure modulation under pathological conditions.

Expression of angiotensin II type 1 receptor-interacting molecule in normal human kidney and IgA nephropathy.

The intrarenal renin-angiotensin system plays a crucial role in the regulation of renal circulation and sodium reabsorption through the activation of vascular, glomerular, and tubular angiotensin II type 1 (AT(1)) receptor signaling. We previously cloned a molecule that specifically interacted with the murine AT(1) receptor to inhibit AT(1) receptor signaling, which we named ATRAP (for AT(1) receptor-associated protein). Since murine ATRAP was shown to be highly expressed in the kidney, in the present study we investigated expression and distribution of human ATRAP in normal kidney and renal biopsy specimens from patients with IgA nephropathy. In the normal human kidney, both ATRAP mRNA and protein were widely and abundantly distributed along the renal tubules from Bowman's capsule to the medullary collecting ducts. In all renal tubular epithelial cells, the ATRAP protein colocalized with the AT(1) receptor. In renal biopsy specimens with IgA nephropathy, a significant positive correlation between ATRAP and AT(1) receptor gene expression was observed. There was also a positive relationship between tubulointerstitial ATRAP expression and the estimated glomerular filtration rate in patients with IgA nephropathy. Furthermore, we examined the function of the tubular AT(1) receptor using an immortalized cell line of mouse distal convoluted tubule cells (mDCT) and found that overexpression of ATRAP by adenoviral gene transfer suppressed the angiotensin II-mediated increases in transforming growth factor-ß production in mDCT cells. These findings suggest that ATRAP might play a role in balancing the renal renin-angiotensin system synergistically with the AT(1) receptor by counterregulatory effects in IgA nephropathy and propose an antagonistic effect of tubular ATRAP on AT(1) receptor signaling.

Novel regulatory effect of angiotensin II type 1 receptor-interacting molecule on vascular smooth muscle cells.

We have recently cloned a novel molecule that interacts with the angiotensin II type 1 receptor (AT1R)-associated protein (ATRAP). In this study, we tested the hypothesis that ATRAP modulates angiotensin II-induced responses in vascular smooth muscle cells. The results of immunoprecipitation and bioluminescence resonance energy transfer assay demonstrated a direct interaction between ATRAP and AT1R at baseline and showed that angiotensin II enhanced the interaction of these proteins >2-fold. The results of immunofluorescence analysis also demonstrated that >65% of ATRAP constitutively colocalized with an endosome marker. Although only 36% of ATRAP colocalized with AT1R at baseline, angiotensin II enhanced the colocalization of these molecules and made 92% of ATRAP colocalize with AT1R on a quantitative fluorescence analysis. Overexpression of ATRAP by adenoviral transfer decreased the cell surface AT1R number from 4.33 to 2.13 fmol/10(6) cells at baseline and from 3.04 to 1.26 fmol/10(6) cells even after removal of angiotensin II. ATRAP also suppressed angiotensin II-mediated increases in c-fos gene transcription and transforming growth factor-beta production. Furthermore, this suppression was accompanied by inhibition of angiotensin II-induced activation of 5-bromodeoxyuridine incorporation. Finally, ATRAP knockdown by small-interference RNA activated angiotensin II-induced c-fos gene expression, which was effectively inhibited by valsartan, an AT1R-specific antagonist. These results indicate that ATRAP promotes internalization of AT1R and attenuates the angiotensin II-mediated c-fos-transforming growth factor-beta pathway and proliferative response in vascular smooth muscle cells, suggesting a novel strategy to inhibit vascular fibrosis and remodeling through a novel and specific blockade of AT1R signaling.