Packed Red Blood Cell Transfusion Associates With Acute Kidney Injury After Transcatheter Aortic Valve Replacement

Akeel M. Merchant; Javier A. Neyra; Abu Minhajuddin; Lauren E. Wehrmann; Richard A. Mills; Sarah K. Gualano; Dharam J. Kumbhani; Lynn C. Huffman; Michael E. Jessen; Amanda A. Fox


BMC Anesthesiol. 2019;19(99) 

In This Article

Materials and Methods

Study Population

This retrospective single-center cohort study assessed 116 patients who underwent consecutive TAVRs at the University of Texas Southwestern (UTSW) Medical Center from March 20, 2013 to May 11, 2016. The study was approved by the UTSW Institutional Review Board (IRB), and need for patient written informed study consent was waived by the IRB given that this study involved retrospective review of electronic health records (EHRs). Of the 123 patients who underwent TAVR during the study time period, 6 patients were excluded from analysis because of pre-procedure end-stage renal disease, and one patient was excluded from analysis for being an outlier with regards to need for peri-procedure pRBC transfusion (i.e. massive transfusion protocol).

Data Collection

Patient data regarding demographics, preoperative medical history, TAVR device and approach, and intra-procedure and in-hospital post-procedure events were manually extracted from each patient's electronic health record using a standardized case report form.


The study outcome was the development of AKI within 7 days post-TAVR. Post-TAVR AKI was defined according to Kidney Disease: Improving Global Outcomes (KDIGO) serum creatinine (SCr)-based criteria (i.e. SCr increase by ≥0.3 mg/dl within 48 h after TAVR or an increase in SCr to ≥1.5 times pre-TAVR SCr within the 7 days following TAVR).[20] Pre-TAVR SCr was defined as the SCr measured before and closest to the time of TAVR procedure. Post-TAVR SCr values were compared with the pre-TAVR SCr for purposes of identifying post-TAVR AKI. Post-TAVR SCr values were evaluated through 7 days after TAVR or until hospital discharge if that occurred earlier than 7 days after TAVR.

Need for pRBC transfusion was assessed during the intra-procedure period and during the first 24 h after TAVR (i.e. peri-procedure pRBC transfusion). Transfusion of other blood products such as fresh frozen plasma, platelets, and cryoprecipitate during TAVR and within the first 24 h post-TAVR were also recorded.

Diabetes was defined as requiring insulin or oral agents. Estimated glomerular filtration rate (eGFR) was defined according to the Modification of Diet in Renal Disease (MDRD) 4 variable equation.[21] Pre-TAVR European System for Cardiac Operative Risk Evaluation (EuroSCORE) II mortality risk was retrospectively calculated by entering clinical data available in the medical record into the calculator found at[22–24] TAVR procedure duration was defined as minutes between time of vascular access (skin puncture) and the time of post-procedure dressing placement. Type of TAVR device implanted was defined as Generation 1 (Edwards Sapien), Generation 2 (Edwards Sapien XT or Medtronic CoreValve), and Generation 3 (Edwards Sapien S3 or Medtronic CoreValve Evolut).

Pre-procedural anemia was defined by the World Health Organization definition of anemia: hemoglobin (Hgb) < 12 g/dL for women and Hgb < 13 g/dL for men.[25] Nadir Hgb was defined as the lowest Hgb measured as part of routine clinical care during the TAVR procedure or during the first 24 h after TAVR.

Subjects were recorded as being on a preoperative medication if the medication appeared on their preoperative medication list in the electronic medical record. Data regarding timing of last dose before TAVR procedure was not fully available from retrospective review. However, at our institution patients generally do not take angiotensin converting enzyme-inhibitor (ACE-inhibitor) or angiotensin receptor blocker medications during the 24 h before TAVR. Patients generally receive their beta-blocker medication during the 24 h before TAVR.

Maximum number of concurrent inotropes or vasopressor drugs administered was assessed separately for the intra-procedure period and the post-procedure period, as need for transient vasopressor support during the intra-procedure period is not uncommon secondary to vasodilation under anesthesia as well as to facilitate recovery from transiently low cardiac output during valve deployment. However, need for post-TAVR inotrope and vasopressor drugs was prospectively considered by the investigators to represent a persistent need for inotropes and vasopressor drugs that might have greater impact on renal perfusion. The post-TAVR period for which administration of inotrope or vasopressor infusions was assessed included the first 5 postoperative days or until the patient was discharged from the hospital if that was sooner. Inotropes or vasopressor drugs included continuous infusions of any of the following: dobutamine, dopamine, epinephrine, milrinone, norepinephrine, phenylephrine or vasopressin.

Hypotension during TAVR procedure was defined as having at least one intra-procedural episode of ≥5 consecutive minutes of mean arterial blood pressure (MAP) < 60 mmHg. Intraoperative hypotension was assessed for all patients who had continuous blood pressure monitoring via arterial line that was recorded minute to minute in the electronic operating room anesthesia record throughout the TAVR procedure from before induction of anesthesia to the time of patient departure from the operating room at the end of the TAVR procedure. Two patients did not have intraoperative hypotension data available since their charting was done on paper with every 5 min blood pressure noted.

Statistical Analysis

Statistical analyses were performed using SAS (version 9.3; SAS Institute, Cary, NC), and all P values were two-tailed with threshold for significance set at P < 0.05. Table 1 variables were selected a priori to examine their associations with post-TAVR AKI. Univariate comparisons between patients who did and did not develop AKI were made for clinical and procedural variables using t-tests, Mann-Whitney U tests, Chi-square tests and Fisher's Exact tests for continuous and categorical data, as appropriate. Multivariate logistic regression was used to assess the association of pRBC transfusion (independent variable) with post-TAVR AKI (dependent variable), with adjustments for pre-procedure estimated glomerular filtration rate (eGFR) as well as those variables in Table 1 with univariate associations of P < 0.05. Number of pRBCs transfused and whether patients were transfused any pRBCs are highly collinear variables, so number of pRBCs transfused was the variable ultimately included in the study's final multivariable model, since this variable also gives information about transfusion dose.