Renal Functional Recovery Confounding the Assessment of Contrast Nephropathy: Propensity Score Analysis.

BACKGROUND: Large data analyses confirm the relative safety of contrast-enhanced computed tomography (CT), except for those with advanced renal failure. However, the prevalence of post-contrast acute kidney injury may be masked by acute kidney functional recovery (AKR) in unstable inpatients, irrespective of contrast-enhanced imaging. METHODS: In this work we aimed to assess AKI and AKR along with need for dialysis and mortality, among inpatients undergoing contrast-enhanced or non-enhanced CT. We performed a large-scale retrospective data analysis using propensity score matching (PSM) that compared patients undergoing contrast-enhanced and non-enhanced imaging. We also performed a subgroup analysis of subjects stratified by baseline renal function. RESULTS: A total of 41,456 patients were analyzed. PSM resulted in well-balanced groups. AKR occurred substantially more often than AKI among hospitalized patients following CT imaging, especially among those with low baseline renal function. Yet, in this population, whereas the rate of AKI significantly increased, the rate of AKR significantly decreased following contrast-enhanced studies as compared to patients that underwent non-enhanced CT. A significantly higher proportion of patients with baseline advanced renal failure that underwent contrast-enhanced imaging required dialysis. CONCLUSIONS: The increased incidence of AKI and AKR as seen in patients with lower pre-imaging kidney function possibly suggests that both entities reflect impaired renal functional reserve. Unstable kidney function in inpatients, as demonstrated by rates of AKR and AKI, is an important confounder which requires attention in similar observational studies on the renal effects of contrast media and of various other renal injurious events.

Transesophageal echocardiography and computerized tomography angiography mismatch in left atrial appendage thrombus evaluation.

BACKGROUND: Transesophageal echocardiography (TEE) is the gold standard test for the diagnosis of left atrial appendage (LAA) thrombus. Nonetheless, computerized tomography angiography (CTA) is readily used to exclude LAA thrombus before pulmonary vein isolation (PVI) and LAA closure procedures. We aimed to assess the comparability of LAA thrombus diagnosis using chest CTA scans in patients with atrial fibrillation who underwent TEE. METHODS: Retrospective collection of consecutive patients with atrial fibrillation who underwent TEE and chest CTA within 30 days and had evidence of spontaneous echo contrast (SEC) or LAA thrombus on TEE. Clinical, demographic, and echo data were collected. Prospective analysis of the CTA for evidence of LAA thrombus in the same group of patients was performed. We compared the findings of the two modalities. RESULTS: Out of 1550 patients with atrial fibrillation who underwent TEE examinations in the study period, 63 patients underwent TEE within 30 days of a chest CTA scan. Twenty-three patients had LAA thrombus and 40 had some degree of SEC according to TEE. On CTA, 11 were interpreted as positive with a high level of suspicion for the presence of an LAA thrombus. Six patients (26.1%) had LAA thrombus according to both CT and TEE. Therefore, low concordance was found between test results (chi-squared continuity correction = 5.5, df  = 1, and P -value = 0.01902). CONCLUSION: The discrepancy between CTA and TEE results suggests these examinations might be more suitable as complementary examinations to exclude LAA thrombus.

Changing serum creatinine in the detection of acute renal failure and recovery following radiocontrast studies among acutely ill inpatients: Reviewing insights regarding renal functional reserve gained by large-data analysis.

A rise in serum creatinine (SCr) is widely used for the detection and definition of evolving acute kidney injury (AKI). Yet, it takes time for SCr to re-adjust in response to changes in glomerular filtration rate (GFR), and subtle transient changes in GFR may remain concealed. Additionally, it cannot differentiate altered glomerular hemodynamics and pre-renal failure from true renal tissue injury, necessitating additional clinical and laboratory diagnostic tools. While these features limit the usefulness of SCr and subsequently estimated GFR (eGFR) at a single time point for the individual patient, their overall pattern of changes along time in a large cohort of hospitalized patients may provide a powerful perspective regarding the detection and assessment of shifting kidney function in this population. Herein we review our experience running large data analyses, evaluating patterns of day-to-day changes in SCr among inpatients, occurring around the exposure to iodinated radiocontrast agents. These large data evaluations helped substantiating the existence of contrast-induced nephropathy in patients with advanced renal failure, underscoring the impact of predisposing and confounding factors. It also provides novel insights regarding a phenomenon of "acute kidney functional recovery" (AKR), and illustrate that the incidence of AKI and AKR along the scale of baseline kidney function co-associates and is inversely proportional to kidney function. This can be attributed to renal functional reserve, which serves as a buffer for up-and-down changes in GFR, forming the physiologic explanation for concealed subclinical AKI.

Hyperglycemia on Admission Predicts Acute Kidney Failure and Renal Functional Recovery among Inpatients.

BACKGROUND: Hyperglycemia is associated with adverse outcomes in hospitalized patients. We aimed to assess the impact of glucose levels upon admission on the subsequent deterioration or improvement of kidney function in inpatients with a focus on diabetes or reduced baseline kidney function as possible modifiers of this effect. METHODS: Running a retrospective cohort analysis, we compared patients with normal vs. high glucose levels upon admission. We applied multivariable logistic regression models to study the association between baseline glucose levels with subsequent renal and clinical outcomes. Interaction terms were used to study a possible modifier effect of diabetes. RESULTS: Among 95,556 inpatients (52% males, mean age 61 years), 15,675 (16.5%) had plasma glucose higher than 180 mg/dL, and 72% of them were diabetics. Patients with higher glucose at presentation were older, with a higher proportion of co-morbid conditions. Rates of acute kidney injury (AKI), acute kidney functional recovery (AKR), and mortality were proportional to reduced renal function. AKI, AKR, and mortality were almost doubled in patients with high baseline glucose upon admission. Multivariable analysis with interaction terms demonstrated an increasing adjusted probability of all events as glucose increased, yet this association was observed principally in non-diabetic patients. CONCLUSIONS: Hyperglycemia is associated with AKI, AKR, and mortality in non-diabetic inpatients in proportion to the severity of their acute illness. This association diminishes in diabetic patients, suggesting a possible impact of treatable and easily reversible renal derangement in this population.

Acute Kidney Injury After Radiocontrast-Enhanced Computerized Tomography in Hospitalized Patients With Advanced Renal Failure: A Propensity-Score-Matching Analysis.

BACKGROUND: The overall risk of postcontrast acute kidney injury (PC-AKI) after computerized tomography (CT) is negligible, likely because of the small volume of injected iodinated contrast media required. However, the safety of contrast media-enhanced CT in patients with advanced renal functional impairment, an established major risk factor for PC-AKI, is unknown. MATERIALS AND METHODS: This is a retrospective study using large data analysis of hospitalized patients at a single center. Adults undergoing CT or magnetic resonance imaging were included in the study and were stratified by estimated glomerular filtration rate (eGFR) (≤30 or >30 mL/min/1.73 m) and by either contrast-enhanced or nonenhanced imaging. Only patients with serial determination of creatinine before and after imaging were included. Demographic, clinical, and laboratory data between groups were analyzed and compared using univariate analysis, propensity score matching, and multivariate logistic regression analysis. RESULTS: A total of 22,319 imaging studies were included. Patients with an eGFR of 30 mL/min/1.73 m or lower undergoing contrast-enhanced CT (n = 403) had an increased risk to develop PC-AKI than did similar patients undergoing enhanced or nonenhanced magnetic resonance imaging (n = 96) or nonenhanced CT (n = 1576) or patients undergoing contrast-enhanced CT with a preprocedural eGFR higher than 30 mL/min/1.73 m (n = 9173). These findings remained robust after propensity matching for demographic, procedural, and clinical parameters. Multivariate regression analysis of all patients undergoing CT with preimaging eGFR of 30 mL/min or lower (n = 1979) revealed that iodine-based contrast enhancement increased the likelihood of post-CT AKI by 51% (confidence interval, 1.23-2.05). CONCLUSION: Although radiocontrast-enhanced CT is considered safe in most hospitalized patients and in ambulatory settings, the risk of PC-AKI remains significant among inpatients with substantial preimaging renal functional impairment. Caution is warranted using iodine-based enhanced CT in hospitalized patients with an eGFR of 30 mL/min/1.73 m or lower.