Contrast Volume-to-Estimated Glomerular Filtration Rate Ratio as a Predictor of Short-Term Outcomes Following Transcatheter Aortic Valve Implantation.

Background/Objectives: Contrast-induced acute kidney injury (AKI) is associated with early mortality and adverse events. However, in the setting of transcatheter aortic valve implantation (TAVI), previous literature has failed to establish a correlation between the absolute volume of contrast media administered and mortality. We aimed to investigate the impact of contrast volume administered normalised to estimated glomerular filtration rate (CV/eGFR) on the development of AKI and on 30-day all-cause mortality in TAVI patients. Methods: We retrospectively analysed a cohort of 1150 patients who underwent TAVI at our unit between 2015 and 2018. Results: Follow-up was complete for 1064 patients. There were 23 deaths within the follow-up period and 76 cases of AKI, 9 of which required new renal replacement therapy (RRT). Receiver-operating characteristic (ROC) curve analysis showed fair discrimination for 30-day all-cause mortality at a CV/eGFR ratio of 3.6 (area under the ROC curve (AUC) 0.671). Of patients in whom CV data were available, 86.0% (n = 757) had a CV/eGFR < 3.6 and 14.0% (n = 123) had a CV/eGFR ≥ 3.6. In multivariate logistic regression analysis, CV/eGFR ≥ 3.6 was the strongest predictor of 30-day all-cause mortality (odds ratio 5.06, 95% confidence interval [1.61-15.7], p = 0.004). Other independent predictors were procedural urgency (3.28 [1.04-10.3], p = 0.038) and being under general anaesthesia (4.81 [1.10-17.3], p = 0.023). CV/eGFR ≥ 3.6 was also independently associated with significantly increased odds of AKI (2.28 [1.20-4.17], p = 0.009) alongside significant non-left main stem coronary artery disease (2.56 [1.45-4.66], p = 0.001), and diabetes (1.82 [1.03-3.19], p = 0.037). In supplementary ROC curve analysis, a similar CV/eGFR cut point of 3.6 was found to be an excellent predictor for new RRT (AUC 0.833). Conclusions: In conclusion, a CV/eGFR ≥ 3.6 post-TAVI was found to be a strong predictor of 30-day mortality and AKI. The maximum contrast volume that can be safely administered in each patient without significantly increasing the risk of mortality and AKI can be calculated using this ratio.

A Practical Approach to Preventing Contrast-Associated Renal Complications in the Catheterization Laboratory.

Contrast media use is ubiquitous in the catheterization laboratory. Contrast-associated acute kidney injury (CA-AKI) is a key concern among patients undergoing coronary angiography and percutaneous coronary interventions. The risk of CA-AKI can be minimized by careful attention to hydration status and renal function-based contrast dosing in all patients. In patients with Stage IV chronic kidney disease, ultra low contrast procedure (contrast dose ≤ GFR) may be especially beneficial.

Low Contrast Volume Protocol in Routine Chest CT Amid the Global Contrast Shortage: A Single Institution Experience.

OBJECTIVE: To assess the effectiveness of low contrast volume (LCV) chest CT performed with multiple contrast agents on multivendor CT with varying scanning techniques. METHODS: The study included 361 patients (65 ± 15 years; M: F 173:188) who underwent LCV chest CT on one of the six 64-256 detector-row CT scanners using single-energy (SECT) or dual-energy (DECT) modes. All patients were scanned with either a fixed-LCV (LCVf, n = 103) or weight-based LCV (LCVw, n = 258) protocol. Two thoracic radiologists independently assessed all LCV CT and patients' prior standard contrast volume (SCV, n = 263) chest CT for optimality of contrast enhancement in thoracic vasculature, cardiac chambers, and in pleuro-parenchymal and mediastinal abnormalities. CT attenuations were recorded in the main pulmonary trunk, ascending, and descending thoracic aorta. To assess the interobserver agreement, pulmonary arterial enhancement was divided into two groups: optimal or suboptimal. RESULTS: There was no significant difference among patients' BMI (p = 0.883) in the three groups. DECT had a significantly higher aortic arterial enhancement (250 ± 99HU vs 228 ± 76 HU for SECT, p < 0.001). Optimal enhancement was present in 558 of 624 chest CT (89.4%), whereas 66 of 624 chest CT with suboptimal enhancement was noted in 48 of 258 LCVw (18.6%) and 14 of 103 LCVf (13.6%). Most patients with suboptimal enhancement with LCVw injection protocol were overweight/obese (30/48; 62.5%), (p < 0.001). CONCLUSION: LCV chest CT can be performed across complex multivendor, multicontrast media, multiscanner, and multiprotocol CT practices. However, LCV chest CT examinations can result in suboptimal contrast enhancement in patients with larger body habitus.

The acute impact of baseline renal function and contrast medium volume/estimated glomerular filtration rate ratio on reduced renal function following endovascular abdominal aortic aneurysm repair.

OBJECTIVE: The aim of this study was to determine the acute impact of baseline serum creatinine, estimated glomerular filtration rate (eGFR), and contrast medium volume (CMV) on the incidence of reduced renal function (RRF) after endovascular abdominal aortic aneurysm repair (EVAR). We aimed to determine if the CMV/eGFR ratio was a predictor of RRF. METHODS: This study is a retrospective review of EVAR patients in the Society for Vascular Surgery/Vascular Quality Initiative (SVS/VQI) from January 2015 to August 2020. Reduced renal function was defined as > 0.3 mg/dl (26.5 µmol/L), 50% increase from baseline, and temporary or permanent dialysis. Receiver operator characteristic (ROC) curve analyses were conducted for serum creatinine, eGFR, contrast volume, fluid volume, and CMV/eGFR ratio. Two data sets (training and test) were developed followed by multivariate analyses. RESULTS: SVS/VQI data for EVAR contained 38,701 records, of which 30,539 were divided into training (n = 18,283; 60%) and test (n = 12,256; 40%) data sets. RRF rate for the training set was 3.6% (n = 667) and 3.4% (n = 420) for the test data. RRF patients included more females (29.4 vs 19.0%, p < 0.001), were older in age (75.6 + 8.4 vs 73.3 + 8.7 years), had more congestive heart failure (22.3 vs 12.2%, p < 0.001), and more COPD (42.0 vs 34.2%, p < 0.001). An ROC analysis revealed that eGRF, creatinine, contrast, intravenous fluid, and contrast medium volume (CMV)/eGFR ratio were all significantly (p < 0.05) correlated with RRF. The eGFR and CMV/eGFR ratio had the largest area under the curve, (0.26) and (0.65), respectively, while fluid had the lowest (0.54). Negative predictive values were 93.7 (CMV/eGFR), 93.9 (creatinine), 94.2 (eGFR), 92.8 (contrast), and 92.6 (intravenous fluid). Multivariate analysis of the training data set resulted in the CMV/eGFR ratio as an independent predictor of RRF (odds ratio, OR: 1.9 with 95% CI: 1.6, 2.2, p < 0.015). For the test data, the CMV/eGFR ratio was an independent predictor of RRF (OR: 1.8, CI: 1.4 to 2.2, p < 0.001) as well as several other variables. CONCLUSION: RRF after EVAR is a dreaded and potentially devastating complication. Baseline serum creatinine, eGFR, contrast medium volume, and the ratio (CMV/eGFR) were all significantly associated with RRF. The optimal cut-off value for the CMV/eGFR ratio, ≤ 2, provides an easy-to-use equation to provide a suggested contrast target based on initial renal function with caution applied for high-risk patients.

Angiographic predictors of aberrant circumflex artery during cardiac catheterization.

OBJECTIVES: To identify angiographic predictors of aberrant left circumflex artery (LCx) by comparing left main (LM) length and bifurcation angle between patients with aberrant LCx and normal anatomy. BACKGROUND: Failure to recognize aberrant LCx during a cardiac catheterization may hamper correct diagnosis, delay intervention in acute coronary syndromes, and result in increased contrast volume, radiation exposure, and infarct size. METHODS: We retrospectively analyzed angiograms of aberrant LCx patients and normal anatomy matched controls, in three-participating centers. LM-length, bifurcation angle between the left anterior descending (LAD) and the first non-LAD branch of the LM, and procedural data were compared. RESULTS: Between 2003 and 2020, 136 patients with aberrant LCx and 135 controls were identified. More catheters (2.4 ± 0.6 vs. 2.2 ± 0.9, p = 0.009), larger contrast volumes (169 ± 94 ml vs. 129 ± 68 ml, p < 0.0005), and prolonged fluoroscopy time (652.9 ± 623.7 s vs. 393.1 ± 332.1 s, p < 0.0005), were required in the aberrant LCx-group compared with controls. Patients with aberrant LCx had a longer LM-length and a more acute bifurcation angle, both in caudal and cranial views, compared with controls (24.7 ± 8.1 vs. 10.8 ± 4.5 mm, p < 0.0005 and 26.7 ± 7.4 vs. 12 ± 5.5 mm, p < 0.0005, respectively, and 45.2° ± 12° vs. 88.8° ± 23°, p < 0.0005 and 51.9° ± 21° vs. 68.2° ± 28.3°, p < 0.0005, respectively). In ROC analysis, LM-length showed the best diagnostic accuracy for detecting aberrant LCx. In multiple logistic regression analysis, a cranially measured LM-length > 17.7 mm was associated with a 5.3 times greater probability of predicting aberrant LCx [95% CI (3.4-8.1), p < 0.0001]. CONCLUSIONS: Our study suggests that a long LM-length and an acute bifurcation angle can indicate the presence of aberrant LCx. We present a practical algorithm for its rapid identification.

Comparison of Safety and Efficiency between Tiger-2 Catheter with Right Radial Artery Access and Judkins Catheter with Left Radial Artery Access.

We sought to compare the safety and efficiency of Tiger-2 in the right radial and Judkins catheter in the left radial access. We retrospectively collected data of 487 patients, involving 172 patients after coronary angiography with Judkins on the left radial artery and 315 patients with Tiger-2 on the right radial artery access. There were no differences in baseline characteristics, except for hypertension ratio and mean age. There was a difference in pulse absence on the radial artery. The volume of contrast used was higher in the Judkins group. Both groups differed in the amount of drugs administered (NTG and heparin). Fluorescence times were comparable between groups. Radiation dosage and AK was significantly greater in the Tiger-2 group. The Tiger-2 catheters were significantly more often changed to another type of catheter (100 changes) than the Judkins (12 changes). However, there was no statistical difference in access site change. Judkins with left radial access seems to be a safer option because of the lower radiation exposure and less incidence of complications than Tiger-2 with right radial access, however, it requires a higher volume of contrast.

Evidence-to-Practice Gap for Preventing Procedure-Related Acute Kidney Injury in Patients Undergoing Percutaneous Coronary Intervention.

Background Acute kidney injury (AKI) is a common complication of percutaneous coronary intervention. This risk can be minimized with reduction of contrast volume via preprocedural risk assessment. We aimed to identify quality gaps for implementing the available risk scores introduced to facilitate more judicious use of contrast volume. Methods and Results We grouped 14 702 patients who underwent percutaneous coronary intervention according to the calculated NCDR (National Cardiovascular Data Registry) AKI risk score quartiles (Q1 [lowest]-Q4 [highest]). We compared the used contrast volume by the baseline renal function and NCDR AKI risk score quartiles. Factors associated with increased contrast volume usage were determined using multivariable linear regression analysis. The overall incidence of AKI was 8.9%. The used contrast volume decreased in relation to the stages of chronic kidney disease (168 mL [SD, 73.8 mL], 161 mL [SD, 75.0 mL], 140 mL [SD, 70.0 mL], and 120 mL [SD, 73.7 mL] for no, mild, moderate, and severe chronic kidney disease, respectively; P<0.001), albeit no significant correlation was observed with the calculated NCDR AKI risk quartiles. Of the variables included in the NCDR AKI risk score, anemia (7.31 mL [1.76-12.9 mL], P=0.01), heart failure on admission (10.2 mL [6.05-14.3 mL], P<0.001), acute coronary syndrome presentation (10.3 mL [7.87-12.7 mL], P<0.001), and use of an intra-aortic balloon pump (17.7 mL [3.9-31.5 mL], P=0.012) were associated with increased contrast volume. Conclusions The contrast volume was largely determined according to the baseline renal function, not the patients' overall AKI risk. These findings highlight the importance of comprehensive risk assessment to minimize the contrast volume used in susceptible patients.

Image Fusion During Standard and Complex Endovascular Aortic Repair, to Fuse or Not to Fuse? A Meta-analysis and Additional Data From a Single-Center Retrospective Cohort.

PURPOSE: To determine if image fusion will reduce contrast volume, radiation dose, and fluoroscopy and procedure times in standard and complex (fenestrated/branched) endovascular aneurysm repair (EVAR). MATERIALS AND METHODS: A search of the PubMed, Embase, and Cochrane databases was performed in December 2019 to identify articles describing results of standard and complex EVAR procedures using image fusion compared with a control group. Study selection, data extraction, and assessment of the methodological quality of the included publications were performed by 2 reviewers working independently. Primary outcomes of the pooled analysis were contrast volume, fluoroscopy time, radiation dose, and procedure time. Eleven articles were identified comprising 1547 patients. Data on 140 patients satisfying the study inclusion criteria were added from the authors' center. Mean differences (MDs) are presented with the 95% confidence interval (CI). RESULTS: For standard EVAR, contrast volume and procedure time showed a significant reduction with an MD of -29 mL (95% CI -40.5 to -18.5, p<0.001) and -11 minutes (95% CI -21.0 to -1.8, p<0.01), respectively. For complex EVAR, significant reductions in favor of image fusion were found for contrast volume (MD -79 mL, 95% CI -105.7 to -52.4, p<0.001), fluoroscopy time (MD -14 minutes, 95% CI -24.2 to -3.5, p<0.001), and procedure time (MD -52 minutes, 95% CI -75.7 to -27.9, p<0.001). CONCLUSION: The results of this meta-analysis confirm that image fusion significantly reduces contrast volume, fluoroscopy time, and procedure time in complex EVAR but only contrast volume and procedure time for standard EVAR. Though a reduction was suggested, the radiation dose was not significantly affected by the use of fusion imaging in either standard or complex EVAR.

Low contrast volume dual-energy CT of the chest: Quantitative and qualitative assessment.

PURPOSE: To evaluate the image quality of chest CT performed on dual-energy scanners using low contrast volume for routine chest (DECT-R) and pulmonary angiography (DECTPA) protocols. MATERIALS AND METHODS: This retrospective study included dual-energy CT scans of chest performed with low contrast volume in 84 adults (34M:50F; Age 69 ± 16 years: Weight 71 ± 16kg). There were 42 patients with DECT-R and 42 patients with DECT-PA protocols. Images were reviewed by two thoracic radiologists. Qualitative assessment was done on a four-point scale, for subjective assessment of contrast enhancement and artifacts (1 = Excellent, 2 = optimal, 3 = suboptimal, and 4 = Limited) in the pulmonary arteries and thoracic aorta, on virtual monoenergetic and material decomposition iodine (MDI) images. Quantitative assessment was performed by measuring the CT (Hounsfield) units in aorta and pulmonary arteries. The estimated glomerular filtration rate (eGFR) was calculated before and after CT scans. Two tailed student's t-test was performed to assess the significance of findings, and strength of correlation between readers was determined by Cohen's kappa test. RESULTS: DECT-PA and DECT-R demonstrated excellent/adequate contrast density within the pulmonary arteries (up to segmental branch), and aorta. There was no suboptimal or limited examination. There was strong interobserver agreement for arterial enhancement in pulmonary arteries (kappa = 0.62-0.89) and for thoracic aorta (kappa = 0.62-0.94). Pulmonary emboli were seen in 3/42(7%) in DECT-R and in 5/42(12%) in DECT-PA. There was no significant change in eGFR before and after IV contrast injection (p = 0.46-0.52). CONCLUSION: DECT-R and DECT-PA performed with low contrast volume provide diagnostic quality opacification of the pulmonary vessels and aorta vessels.

Comparing Trimetazidine with Allopurinol in Prevention of Contrast Induced Nephropathy After Coronary Angiography.

OBJECTIVES: Contrast-induced nephropathy is considered a serious complication following coronary angiography increasing morbidity and mortality. Various drugs have been assessed to reduce the incidence of contrast-induced nephropathy. In this study, we compared trimetazidine and allopurinol as a pharmacological measure to reduce the incidence of contrast-induced nephropathy. METHODS: One hundred and twenty patients undergoing coronary angiography with baseline creatinine clearance more than 30 ml/minute were divided into three groups, 40 patients each. Group 1 received standard parenteral intravenous hydration in the form of isotonic saline at a rate of 1 ml/kg body weight per hour started 12 hours before angiography and up to 12 hours after the procedure. Group 2 received trimetazidine 35 mg twice per day for 72 hours starting 48 hours before the procedure in addition to intravenous hydration. Group 3 received allopurinol 300 mg once daily for 72 hours starting 48 hours before the procedure in addition to intravenous hydration. Serum creatinine and creatinine clearance were measured before and 72 hours after the procedure in addition to the volume of contrast media used. RESULTS: Trimetazidine and allopurinol failed to reduce contrast-induced nephropathy significantly. Among patients with contrast-induced nephropathy volume of contrast media was significantly higher. CONCLUSION: Adding trimetazidine or allopurinol in addition to regular intravenous hydration with isotonic saline without targeting selectively high-risk patients did not reduce contrast-induced nephropathy following coronary angiography.

Image quality and radiation exposure with low-contrast-dose computed tomography angiography of the lower extremities.

INTRODUCTION: Multidetector computed tomography is the reference standard for the diagnosis of peripheral arterial disease (PAD). The aim of this study is to optimise the image quality of computed tomography (CT) scanning for the diagnosis of PAD with the lowest possible radiation and contrast volume. MATERIAL AND METHODS: Seventy-two patients were referred for evaluation of suspected PAD with CT angiography. Patients were randomly assigned to an optimise care dose of kVp - group A, n = 36; 18 men, 18 women; mean age, 63 years with standard deviation 15; range, 20-88 years (contrast volume 80-85 ml was injected automatically with bolus tracking, and group B, n = 36; 18 men, 18 women; mean age, 61 years with standard deviation 16; range, 26-88 years (contrast volume 120-140 ml was injected automatically with bolus tracking). Other scanning parameters were kept constant. Lower extremities vessel enhancement and image noise were quantified, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective vessel contrast was assessed by two radiologists in consensus. RESULT: A total of 16 cases of PAD (22.2%) were found in the evaluated of subjects (10 in group A, and six in group B).All PAD cases were detected by the two readers. There was no significant difference in the size or location of the PAD between the two groups; the average image noise was 19 HU for group A and 16 HU for group B. The difference was not statistically significant (p = 0.183). Overall, the SNR and CNR were slightly higher in group B (25.5 and 24.1, respectively) compared with group A (20 and 17.4, respectively), but those differences were not statistically significant (p = 061 and p = 0.38, respectively). CONCLUSIONS: All patients were evaluated by lower extremities CTA protocol allowing similar image quality to be achieved in both groups, with optimised care dose for both protocols, and contrast volume was reduced by 40% in the new protocol group compared to the conventional protocol group.

A Practical Approach to Preventing Renal Complications in the Catheterization Laboratory.

Contrast-induced acute kidney injury is a common complication in patients undergoing invasive procedures and is associated with increased mortality and morbidity. There is no effective approach to the management of this complication, and prevention remains of paramount importance. The 3 pillars of prevention are identification of high-risk patients, appropriate hydration before and after contrast exposure, eGFR-based contrast dosing and use of ultra-low contrast volume in high-risk patients. Most evidence supporting these practices is derived from patients undergoing coronary angiography or percutaneous coronary intervention but these basic principles can be applied to most patients undergoing contrast-based procedures in the catheterization laboratory.

Contrast Volume to Glomerular Filtration Ratio and Acute Kidney Injury among ST-Segment Elevation Myocardial Infarction Patients Treated with Primary Percutaneous Coronary Intervention.

INTRODUCTION: The ratio of contrast media volume to glomerular filtration rate (contrast/GFR) has been shown to correlate with the occurrence of contrast-induced acute kidney injury (CI-AKI) in unselected patient populations who underwent percutaneous coronary intervention (PCI). OBJECTIVE: We evaluated the possible utilization of this marker and optimal cutoff among ST-elevation myocardial infarction (STEMI) patients undergoing primary PCI. METHODS: We retrospectively included 419 patients with STEMI treated with primary PCI. The occurrence of CI-AKI was defined by the KDIGO criteria as an increase in serum creatinine of ≥0.3 mg/dL within 48 h following PCI. A receiver-operator characteristic (ROC) curve was used to identify the optimal cutoff value of contrast/GFR ratio to predict CI-AKI. This value was then assessed using multivariable logistic regression. RESULTS: The overall incidence of CI-AKI was 9%. The contrast/GFR ratio was significantly higher among patients with CI-AKI (2.7 ± 1.2 vs. 1.9 ± 0.9; p < 0.001). According to the ROC curve analysis, the optimal cutoff value of contrast/GFR ratio to predict AKI was measured as ≥2.13, with 70% sensitivity and 60% specificity (AUC 0.65, 95% CI 0.56-0.74; p = 0.002). In a multivariate logistic regression model, contrast/GFR ratio ≥2.13 was independently associated with CI-AKI (OR 2.46, 95% CI 1.09-5.57; p = 0.03). CONCLUSIONS: Among STEMI patients undergoing primary PCI, contrast/GFR ratio ≥2.13 was independently associated with CI-AKI.

Angioplasty with Stenting in Acute Coronary Syndromes with Very Low Contrast Volume Using 6F Diagnostic Catheters and Bench Testing of Catheters.

AIM: To safely perform angioplasties in acute coronary syndromes with low contrast volume using Cordis 6F diagnostic catheters and to perform mechanical bench tests on the diagnostic and guide catheters in a radial path model. METHODS: In 191 patients (242 lesions/268 stents) with acute coronary syndromes angioplasty were performed with cordis 6F diagnostic catheters. RESULTS: The lesions were present at left anterior descending (121), Left main (5), left circumflex (51), ramus (5) and right coronary artery (60). In 72% of cases, Iodixanol was used. All contrast injections were given by hand. Regular follow-up of the patients was performed at 30 days. The procedures were performed in the femoral route only. Pre-dilatation was performed in 43 cases. Successful revascularization of the target lesion was achieved in all cases. The mean contrast volume used per patient was 28 ml (± 8 ml). Mild reversible contrast-induced nephropathy (CIN) was observed in two patients. Cardiogenic shock was seen in 7 cases, and one death was observed. Pushability and trackability tests showed good force transmission and hysteresis in diagnostic catheters compared to guide catheters. CONCLUSIONS: Angioplasty with stenting could be performed safely in patients using cordis 6F diagnostic catheters using a low volume of contrast in acute coronary syndromes. Low contrast volume usage would result in a lower incidence of contrast-induced nephropathy and cardiac failures.

Evaluation of neutrophil gelatinase-associated lipocalin and cystatin C as biomarkers of acute kidney injury after ST-segment elevation myocardial infarction treated by percutaneous coronary intervention.

BACKGROUND: Two biomarkers of early acute kidney injury-plasmatic neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C-are not used in routine clinical practice in patients with ST-segment elevation myocardial infarction (STEMI) treated by percutaneous coronary intervention (PCI) because of a lack of supporting data. AIMS: To evaluate the predictive value of NGAL and cystatin C regarding the incidence of contrast-induced acute kidney injury (CI-AKI) and clinical outcomes after STEMI in patients treated by primary PCI. METHODS: Plasmatic NGAL and cystatin C were measured on admission, before any contrast exposure, in 701 unselected patients with STEMI. Associations between biomarker concentrations and incidence of CI-AKI (assessed at 48h), haemodialysis requirement at 1 year and all-cause mortality at 1 year were assessed by logistic regression analyses and receiver operating characteristic area under the curve analysis (c-statistic). Discrimination performance comparison was performed using the DeLong test. RESULTS: NGAL and cystatin C had mild discrimination regarding CI-AKI, with c-statistics of 0.60 (P=0.001) and 0.60 (P=0.002), respectively. Combining NGAL and cystatin C did not improve their discrimination (c-statistic 0.61; P=0.001). There was no significant difference in discrimination between NGAL, cystatin C and baseline creatinine (P=0.57). Regression analyses showed no independent association between NGAL and CI-AKI, haemodialysis or 1-year mortality. Similarly, cystatin C was not associated with these clinical outcomes. CONCLUSIONS: In this cohort of patients with STEMI treated by primary PCI, plasmatic NGAL and cystatin C did not provide additional value regarding CI-AKI prediction compared with known risk factors such as baseline creatinine.

Dynamic CTA in Native Kidneys Using a Multiphase CT Protocol-Potential of Significant Reduction of Contrast Medium.

RATIONALE AND OBJECTIVE: The objective of this study was to assess an optimized renal multiphase computed tomography angiography (MP-CTA) protocol regarding reduction of contrast volume. MATERIALS AND METHODS: Thirty patients underwent MP-CTA (12 phases, every 3.5 seconds, 80 kV/120 mAs) using 30 mL of contrast medium. The quality of MP-CTA was assessed quantitatively measuring vessel attenuation, image noise, and contrast-to-noise ratio. MP-CTA was evaluated qualitatively regarding depiction of vessels, cortex differentiation, and motion artifacts (grades 1-4, 1 = best). Mean effective radiation dose was registered. Results were compared to standard renal computed tomography angiography (CTA) (80 mL). Student t test was applied, if variables followed normal distribution. For other variables, nonparametric Mann-Whitney U test was used. RESULTS: All acquisitions were successfully performed, and no patient had to be excluded from the study. MP-CTA enabled high attenuation (aorta: 503 ± 91 HU, renal arteries: 450 ± 73 HU/456 ± 72 HU) at adequate image noise (13.7 ± 1.5) and good contrast-to-noise ratio (34.2 ± 10.2). Good attenuation of renal veins was observed (286 ± 43 HU/282 ± 42 HU). Arterial enhancement was significantly higher compared to renal CTA (aorta: 396 ± 90 HU, renal arteries: 331 ± 74 HU/333 ± 80 HU; P < .001). MP-CTA protocol enabled good image quality of renal arteries (1.5 ± 0.6) and veins (1.7 ± 0.6). Cortex differentiation and motion artifacts were ranked 1.8 ± 0.8 and 1.6 ± 0.8. The mean effective radiation dose was 9 mSv (MP-CTA). CONCLUSIONS: Compared to standard renal CTA, the renal MP-CTA enabled the significant reduction of contrast volume and simultaneously provided a significantly higher arterial attenuation.

The ratio of contrast volume to glomerular filtration rate predicts acute kidney injury and mortality after transcatheter aortic valve implantation.

OBJECTIVE: The aim of this study was to assess the impact of the ratio of volume of contrast medium to the glomerular filtration rate (V/GFR) on acute kidney injury (AKI) after transcatheter aortic valve implantation (TAVI) and its impact on long-term mortality. METHODS: We retrospectively calculated V/GFR in 397 patients undergoing TAVI. AKI was defined as VARC-modified Risk, Injury, Failure, Loss and End-stage (RIFLE) kidney disease score≥2. RESULTS: The incidence of AKI was 17.9%. The mean V/GFR ratio was 3.0±2.7 in patients without AKI and 7.8±8.8 in patients with AKI (p<0.001). The receiver-operator characteristic curve analysis showed fair discrimination between patients with and without AKI (C-statistic 0.85) at a V/GFR ratio of 3.2. Multivariable regression analysis indicated that V/GFR>3.2 was an independent predictor of both AKI (OR 3.4, 95% CI 1.0-6.1, p<0.001) and long-term mortality (OR 3.3, 95% CI 2.0-5.2, p<0.001). CONCLUSIONS: A V/GFR > 3.2 was found to be correlated with a higher incidence of AKI and mortality after TAVI. Therefore, this ratio could potentially be used to calculate the maximum volume of contrast medium that can be administered without significantly increasing the risk of AKI and mortality. Further larger studies are needed to validate these findings.

Very low intravenous contrast volume protocol for computed tomography angiography providing comprehensive cardiac and vascular assessment prior to transcatheter aortic valve replacement in patients with chronic kidney disease.

BACKGROUND: Transcatheter aortic valve replacement (TAVR) is a lifesaving procedure for many patients high risk for surgical aortic valve replacement. The prevalence of chronic kidney disease (CKD) is high in this population, and thus a very low contrast volume (VLCV) computed tomography angiography (CTA) protocol providing comprehensive cardiac and vascular imaging would be valuable. METHODS: 52 patients with severe, symptomatic aortic valve disease, undergoing pre-TAVR CTA assessment from 2013-4 at Columbia University Medical Center were studied, including all 26 patients with CKD (eGFR<30 mL/min) who underwent a novel VLCV protocol (20 mL of iohexol at 2.5 mL/s), and 26 standard-contrast-volume (SCV) protocol patients. Using a 320-slice volumetric scanner, the protocol included ECG-gated volume scanning of the aortic root followed by medium-pitch helical vascular scanning through the femoral arteries. Two experienced cardiologists performed aortic annulus and root measurements. Vascular image quality was assessed by two radiologists using a 4-point scale. RESULTS: VLCV patients had mean (±SD) age 86 ± 6.5, BMI 23.9 ± 3.4 kg/m(2) with 54% men; SCV patients age 83 ± 8.8, BMI 28.7 ± 5.3 kg/m(2), 65% men. There was excellent intra- and inter-observer agreement for annular and root measurements, and excellent agreement with 3D-transesophageal echocardiographic measurements. Both radiologists found diagnostic-quality vascular imaging in 96% of VLCV and 100% of SCV cases, with excellent inter-observer agreement. CONCLUSIONS: This study is the first of its kind to report the feasibility and reproducibility of measurements for a VLCV protocol for comprehensive pre-TAVR CTA. There was excellent agreement of cardiac measurements and almost all studies were diagnostic quality for vascular access assessment.

The importance of contrast volume/glomerular filtration rate ratio in contrast-induced nephropathy patients after transcatheter aortic valve implantation.

BACKGROUND/AIM: Transcatheter aortic valve implantation (TAVI) is a method which is increasingly applied in severe aortic stenosis treatment. The development of contrast-induced nephropathy (CIN) after TAVI increases morbidity and mortality rates. Within the scope of this study, the importance of the contrast medium volume to glomerular filtration rate (CV/GFR) ratio in determining the development of CIN and the amount of CV that could be applied was evaluated. METHODS: Seventy-two patients (aged 78.6 ± 11.6 years; 38 females) who underwent aortic valve replacement with the TAVI method between June 2013 and August 2014 were included in the study. CIN was defined as an absolute increase in serum creatinine of >0.5 mg/dl or a relative increase of >25% within 48-72 h after TAVI. CIN+ and CIN-patients were classified into two groups. The χ(2) test, t test, Mann-Whitney U test, ROC analysis, and univariate and multivariate regression analyses were applied for statistical analyses. RESULTS: CIN was detected in 16 patients (22%) in our study. Baseline creatinine, baseline GFR, the Mehran risk score, CV, and the CV/GFR ratio were determined as the predictive factors of CIN development. A CV/GFR ratio of 3.9 was specified to predict CIN development with 71% sensitivity and 80% specificity. CONCLUSION: After TAVI, CIN may develop due to various reasons. In patients to whom TAVI was applied, the CV/GFR ratio may be a guideline helping to prevent the development of renal pathologies. The amount of contrast medium that can be given to a patient can be calculated in terms of baseline GFR.

Do Cardiovascular Risk Factors and Coronary SYNTAX Score Predict Contrast Volume Use During Cardiac Catheterization?

The association of cardiovascular risk factors and complexity and severity of coronary artery disease with contrast volume (CV) remains unknown. We assessed the predictive factors of CV use during elective and emergent cardiac catheterization (CC). Electronic medical records from 2010 to 2013 were retrospectively reviewed. A total of 708 patients were eligible. On multivariable regression analysis, the presence of obstructed coronary arteries was associated with CV (P = .01, ß = -14.17), with greater CV used in patients with single or double vessel disease compared to those with triple vessel disease. The presence of lesions with >70% stenosis in major epicardial arteries (P = .019, ß = 24.39) and ST-segment elevation myocardial infarction (P = .001, ß = 36.14) was associated with increased CV use. Elevated B-type natriuretic peptide (P = .036, ß = -17.23) and increase in Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery score (P = .024, ß = -29.06) were associated with decreased CV use. These aforementioned associations were attenuated after adjusting for percutaneous coronary intervention. Our findings may help predict patient populations who could be exposed to increased CV during CC, thereby possibly increasing their risk of contrast-induced nephropathy.