Safety of Same-Day Coronary Angiography in Patients Undergoing Elective Aortic Valve Replacement

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1 Safety of Same-Day Coronary Angiography in Patients Undergoing Elective Aortic Valve Replacement Kevin L. Greason, MD, Lars Englberger, MD, Rakesh M. Suri, MD, PhD, Soon J. Park, MD, Charanjit S. Rihal, MD, Sorin V. Pislaru, MD, PhD, and Hartzell V. Schaff, MD Division of Cardiovascular Surgery and Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota; and Department of Cardiovascular Surgery, University Hospital, Berne, Switzerland Background. Coronary artery imaging is required for most adult patients undergoing aortic valve replacement (AVR). Methods. Between January 1, 2000, and December 31, 2007, 1413 patients underwent elective AVR at Mayo Clinic. Two propensity-matched groups at low risk for acute kidney injury were created: 321 patients with coronary angiography on the same day as AVR (same day) and 321 patients with coronary angiography more than 1 day before AVR (non same day). We defined acute postoperative kidney injury with Acute Kidney Injury Network criteria (> 0.3 mg/dl or a 50% increase in serum creatinine from baseline). Results. The same-day vs non same-day groups were comparable in age (mean [SD] years: 70.6 [11.0] vs 70.8 [11.5]), sex (111 women [34.6%] vs 114 women [35.5%]), preoperative serum creatinine (1.14 [0.22] vs 1.15 [0.23] mg/dl), and ejection fraction (0.62 [0.12] vs 0.61 [0.12]). Coronary artery revascularization was performed in 118 patients (36.8%) in the same-day group and in 123 (38.3%) in the non same-day group (p 0.68). Maximum (30-day) postoperative serum creatinine levels were not significantly different between the same-day and non same day groups (1.30 [0.43] mg/dl vs 1.29 [0.42] mg/dl; p 0.87). Perioperative (30-day) acute kidney injury occurred in 75 patients (23.4%) in the same-day group and in 71 (22.3%) in the non same-day group (p 0.99). Perioperative (30-day) death occurred in 5 patients (1.6%) in the sameday group and in 7 (2.2%) in the non same-day group (p 0.56). Other nonfatal complications rates were comparable between groups. Conclusions: In properly selected patients, coronary angiography can be performed the same day as elective AVR with no increase in perioperative morbidity or death. (Ann Thorac Surg 2011;91:1791 7) 2011 by The Society of Thoracic Surgeons The timing of coronary angiography in relation to a cardiac operation as a risk factor for acute kidney injury is controversial. In a study of patients at low risk for acute kidney injury, Brown and colleagues [1] from Mayo Clinic found that same-day coronary angiography had little affect on renal function in patients undergoing elective valvular heart operations. However, other investigators have reported contrary findings of increased risk of acute kidney injury associated with cardiac operation early (1 to 5 days) after angiography [2 4]. Our experience suggests that not all patients are candidates for operation early after coronary angiography, and we suspect that the studies concluding the risk of renal failure is increased in this circumstance have included patients with other factors that place them at high risk for postoperative acute kidney injury. We hypothesized that in a group of patients without advanced renal or cardiac dysfunction, coronary angiography performed Accepted for publication Feb 21, Address correspondence to Dr Greason, Division of Cardiovascular Surgery, Mayo Clinic, 200 First St SW, Rochester, MN greason.kevin@mayo.edu. on the same day as aortic valve replacement (AVR) would not increase the risk of acute kidney injury compared with patients not having angiography on the same day. Material and Methods Mayo Clinic Institutional Review Board approval was obtained for the collection and analysis of data. Between January 1, 2000, and December 31, 2007, 1413 patients underwent AVR with or without coronary bypass grafting (CABG) at our clinic. Our protocol specifically excluded patients who we believed were at higher risk for acute kidney injury; for example, patients with urgent or emergent operative status, acute endocarditis, myocardial infarction within 21 days, previous sternotomy, need for dialysis, or preoperative serum creatinine levels exceeding 1.8 mg/dl. During the study period, 363 patients underwent coronary angiography on the same day as and immediately before AVR, and 1050 had coronary angiography 1 or more days before AVR. Two propensity-matched groups 2011 by The Society of Thoracic Surgeons /$36.00 Published by Elsevier Inc doi: /j.athoracsur

2 1792 GREASON ET AL Ann Thorac Surg CORONARY ANGIOGRAPHY ON SAME DAY AS AVR 2011;91: were created from these cohorts: 321 patients who had coronary angiography on the same day as AVR (sameday angiogram group) and 321 patients who did not receive coronary angiography on the same day as AVR (non same-day angiogram group). We collected baseline demographic data for age, sex, body mass index, and the presence of comorbidities, including diabetes mellitus, chronic lung disease, peripheral vascular disease, and congestive heart failure. In addition, we recorded the number of diseased ( 50% stenosis) coronary artery vessels and ejection fraction. We used the most recently obtained preoperative serum creatinine level to calculate estimated creatinine clearance with the Cockcroft-Gault equation [5]: (140 age [y]) (body weight [kg]) ( 0.85 if female) 72 serum creatinine value (mg/dl). The operative variables collected were cardiopulmonary bypass time, aortic cross-clamp time, performance of CABG, and number of distal anastomoses completed. Postoperative variables collected were length of hospital stay, peak 30-day serum creatinine level recorded, and complications, including vascular complications, myocardial infarction, delirium, stroke, and death. In addition, we analyzed the last recorded serum creatinine level in late follow-up. Same-day coronary angiography catheterization was limited to selective angiography without left ventriculography. Typically, 4 views of the left coronary and 2 views of the right coronary arteries were obtained with a hand injection technique. After angiography, the arterial sheath was sutured into position with a flush bag before patient transfer to the operating room. The sheath was removed postoperatively after the resolution of perioperative coagulopathy. Patients were not routinely given sodium bicarbonate or N-acetylcysteine. We used the criteria of the Acute Kidney Injury Network to classify acute kidney injury on the basis of an absolute rise or magnitude of rise, or both, in the peak postoperative serum creatinine level over the last preoperative serum creatinine level. Stage 1 acute kidney injury was an increase in the postoperative serum creatinine level of 0.3 mg/dl or an increase of 1.5-fold to 1.9-fold from baseline, stage 2 was an increase in the serum creatinine level to 2- to 2.9-fold from baseline, and stage 3 was an increase in the serum creatinine level to more than 4 mg/dl with an acute rise of 0.5 mg/dl or an increase of threefold or greater from baseline [6]. We monitored postoperative serum creatinine levels for 30 days after the surgical procedure, but we did not assess the magnitude of the change in urine output or estimated creatinine clearance. Descriptive statistics for categoric variables reported are frequency and percentage; continuous variables reported are mean (standard deviation) or median (range), as appropriate. We compared categoric variables of same-day and non same-day angiogram groups with the 2 test and continuous variables with the two-sample t test or Wilcoxon rank sum test, where appropriate. All statistical tests were two-sided with 0.05 for statistical significance. Because there were differences between the initial groups in preoperative and intraoperative characteristics, patients with non same-day and same-day angiogram were propensity matched by preoperative and intraoperative risk factors to ensure fair comparison between the two groups. Matched risk factors included age, sex, body surface area, body mass index, diabetes and type of control, hypercholesterolemia, hypertension, chronic lung disease, immunosuppressive treatment, peripheral vascular disease, cerebrovascular disease, myocardial infarction, congestive heart failure, New York Heart Association class, severity of coronary artery disease, left main coronary artery disease, ejection fraction, number of diseased valves, mitral valve disease, tricuspid valve disease, last preoperative serum creatinine level and estimated creatinine clearance, concomitant CABG, number of distal anastomoses, cross-clamp time, and perfusion time. We used logistic regression models to find univariate and multivariate predictors of postoperative renal failure among the matched patients. The multivariable model considered univariate significant variables (p 0.05) with model selection using the stepwise method (backward and forward methods resulted in the same model). Results Baseline patient characteristics are presented in Table 1. The two groups were well matched, with no significant differences with respect to the variables. The median time from angiography to operation in the non same-day coronary angiogram group was 3 days (range, days). Length of stay was 7.4 (5.7) days in the non sameday angiogram group and 7.2 (5.3) days in the same-day angiogram group (p 0.93). Perioperative 30-day morbidity and mortality data are reported in Table 2. No vascular complications occurred in either treatment group. Maximum 30-day postoperative serum creatinine level was 1.29 (0.42) mg/dl in the non same-day angiogram group and 1.30 (0.43) mg/dl in the same-day angiogram group (p 0.87). Acute kidney injury occurred in 71 patients (22.1%) in the non same-day angiogram group and in 75 (23.4%) in the same-day angiogram group (p 0.99). Stage 1 acute kidney injury occurred in 61 patients (19.0%) in the non same-day and in 65 (20.2%) in the same-day angiogram groups. In each group, stage 2 acute kidney injury occurred in 9 patients (2.8%) and stage 3 acute kidney injury occurred in 1 patient (0.3%). The median (range) number of days from operation to the last recorded serum creatinine level was 691 (2 to 3556) days in the non same-day group and 703 (3 to 3556) days in the same-day angiogram group (p 0.28). The last recorded postoperative serum creatinine level was 1.18 (0.57) mg/dl in the non same-day angiogram group and 1.12 (0.38) mg/dl in the same-day angiogram group (p 0.26). Data on contrast medium type and amount administered were available in 173 patients (53.9%) in the non same-day angiogram group and in 211 patients (65.7%) in

3 Ann Thorac Surg GREASON ET AL 2011;91: CORONARY ANGIOGRAPHY ON SAME DAY AS AVR 1793 the same-day angiogram group. Patients in the non same-day angiogram group received 72 (41) ml (0.9 [0.6] ml/kg) of contrast medium compared with patients in the same-day angiogram group, who received 63 (30) ml (0.8 [0.6] ml/kg; p 0.007). Of these 384 patients, 349 (90.9%) received iohexol (Omnipaque 350; GE Healthcare Inc, Princeton, NJ) and 35 (9.1%) received iodixanol (Visipaque-320; GE Healthcare Inc). There was no association between acute kidney injury and type of contrast medium administered (p 0.54), the total amount of contrast medium received (p 0.84), or the amount of contrast medium administered per kg of body weight (p 0.90). Univariate predictors of acute kidney injury are reported in Table 3 and multivariate predictors in Table 4. Table 1. Patient Characteristics and Operation Data Variable a Not Same (n 321) Angiogram Same (n 321) p Value Age, mean (SD), y 70.8 (11.5) 70.6 (11.0) 0.58 Female sex 114 (35.5) 111 (34.6) 0.80 Body mass index, 28.7 (5.3) 28.5 (5.9) 0.30 mean (SD) Cerebrovascular disease 37 (11.5) 37 (11.5) 0.99 Chronic lung disease 38 (11.8) 33 (10.3) 0.91 Coronary artery disease 162 (50.5) 157 (48.9) 0.69 Diabetes mellitus 55 (17.1) 51 (15.9) 0.67 NYHA functional class 0.74 I 50 (15.6) 54 (16.8) II 110 (34.3) 118 (36.8) III 139 (43.3) 132 (41.1) IV 22 (6.9) 17 (5.3) Peripheral vascular disease 22 (6.9) 24 (7.5) 0.76 Aortic stenosis 301 (94) 301 (94) 0.99 Aortic insufficiency (grade) (19) 61 (19) (38) 121 (38) 3 36 (11) 39 (12) 4 32 (10) 33 (10) Serum creatinine, mean 1.15 (0.23) 1.14 (0.22) 0.75 (SD), mg/dl Estimated creatinine 68.5 (24.7) 69.5 (25.0) 0.70 clearance, mean (SD), ml/min Ejection fraction, mean (SD) 0.61 (0.12) 0.62 (0.12) 0.81 Aortic cross-clamp time, 48 (18) 47 (19) 0.11 mean (SD), min Cardiopulmonary bypass 67 (27) 65 (28) 0.32 time, mean (SD), min CABG 123 (38.3) 118 (36.8) 0.68 Number of distal anastomoses 0.7 (1.10) 0.7 (1.04) 0.66 a Values are presented as number and percentage of patients unless specified otherwise. AVR aortic valve replacement; CABG coronary artery bypass grafting; NYHA New York Heart Association. Table 2. Postoperative 30-Day Morbidity and Mortality Data a Performance of CABG was a univariate predictor of acute kidney injury (odds ratio [OR], 1.45; 95% confidence interval [CI], 1.45 to 3.14; p 0.001). However, it was not predictive of acute kidney injury in the multivariate model. Importantly, performance of same-day coronary angiogram was not predictive of acute kidney injury in the univariate (OR, 1.06; 95% CI, 0.74 to 1.54; p 0.74) or the multivariate (OR, 1.12; 95% CI, 0.76 to 1.65; p 0.58) model. Comment Not Same Angiogram Same Variable b (n 321) (n 321) p Value Myocardial infarction 2 (0.6) 1 (0.3) 0.56 Stroke 5 (1.6) 8 (2.5) 0.40 Delirium 14 (4.4) 15 (4.7) 0.85 Acute kidney injury 71 (22.3) 75 (23.4) 0.99 Death 7 (2.2) 5 (1.6) 0.56 a No patient had a vascular complication. number and percentage of patients. AVR aortic valve replacement. b Values are presented as The major finding in our propensity-matched study was that coronary angiography performed on the same day as AVR was not associated with acute kidney injury irrespective of the need for CABG. An important aspect of our study was that the amount of contrast agent used was minimized ( 1 ml/kg) because the procedure included only directed coronary angiography; specifically, additional maneuvers such as left ventriculography were not performed. Removing the femoral artery sheath after resolution of the perioperative coagulopathy did not result in an increased number of vascular complications. Importantly, the patients studied in this report represented a homogeneous group of patients in need of AVR Table 3. Univariate Predictors of Acute Kidney Injury Variable OR (95% CI) p Value Increased CPB time 1.01 ( ) Increased aortic cross-clamp time 1.02 ( ) Greater body mass index 1.04 ( ) Older patient age 1.05 ( ) NYHA functional class III/IV 1.74 ( ) Presence of PVD 1.90 ( ) 0.48 CABG 2.11 ( ) Blood transfusion 2.16 ( ) Diagnosis of CAD 2.18 ( ) CABG coronary artery bypass graft; CAD coronary artery disease; CI confidence interval; CPB cardiopulmonary bypass; NYHA New York Heart Association; PVD peripheral vascular disease; OR odds ratio.

4 1794 GREASON ET AL Ann Thorac Surg CORONARY ANGIOGRAPHY ON SAME DAY AS AVR 2011;91: Table 4. Multivariate Predictors of Acute Kidney Injury Variable OR (95% CI) p Value Older patient age 1.05 ( ) Greater BMI 1.07 ( ) Diagnosis of CAD 1.76 ( ).006 Blood transfusion 2.00 ( ) BMI body mass index; CAD coronary artery disease; CI confidence interval; OR odds ratio. who were at low risk for perioperative acute kidney injury. In a previous study, we found that same-day coronary angiography was safe and had little affect on renal function in properly selected patients undergoing elective valvular heart operations [1]. In that study, 226 consecutive patients at low risk for acute kidney injury (defined as having a serum creatinine level 1.8 mg/dl) received same-day angiography and valvular repair or replacement. Postoperative serum creatinine levels increased by an average of 0.1 mg/dl, and 4 patients had transient renal failure, of which 2 required temporary hemodialysis. There were no instances of vascular injury related to catheterization, and only 1 patient died. Rates of renal failure (1.8%), dialysis (0.9%), and mortality (0.4%) were within acceptable ranges. These findings are consistent with findings in the present investigation but are contrary to other reports. Several investigators have used multivariate analysis of demographic and perioperative variables after coronary angiography and cardiac operation to identify risk factors for the development of acute kidney injury. Del Duca and colleagues [2] reported that cardiac catheterization performed within 5 days before operation was a risk factor for acute renal failure (OR, 1.82; 95% CI, 1.17 to 2.84; p 0.01), and Ranucci and colleagues [3] reported similar findings with operations performed on the day of cardiac catheterization (OR, 3.1; 95% CI, 1.1 to 8.8; p 0.039). Medalion and colleagues [4] showed operation within 24 hours of catheterization (OR, 3.7; 95% CI, 1.4 to 8.3; p 0.07) was an independent predictor of postoperative acute renal failure, which was also reported by Hennessy and colleagues [7] (OR, 5.3; 95% CI, 1.4 to 19.0; p 0.01). Our review of their demographic and perioperative data leads us to conclude that the patients with postoperative acute renal failure were at much higher risk for the complication because of preoperative risk factors and that many underwent complex operations. Our interpretation of data from these studies is that timing from angiography to operation served as a surrogate measure of the need for the sickest patients to get an early operation. For instance, Del Duca and colleagues [2] showed that patients who had acute renal failure carried much higher risk for the complication because they were older (p ) and had more hypertension (p 0.007), diabetes (p 0.019), chronic lung disease (p 0.006), and peripheral vascular disease (p 0.005) than those who did not have acute kidney injury. Patients who had acute renal failure also had significantly longer cardiopulmonary bypass times than those who did not have renal failure (111 vs 89 minutes; p 0.001). Importantly, the preoperative calculated glomerular filtration rate was significantly less in patients who had acute renal failure (97 ml/min) compared with those who did not have renal failure (106 ml/min; p ). The difference is important when one considers that the OR for development of acute renal failure after isolated CABG (which 62% of patients received in this study) is 3.36 (95% CI, 3.16 to 3.58) for even minor elevations in preoperative creatinine levels (1.5 vs 1.0 mg/dl) [8]. We identified similar differences in risk factors of patients reported in the study by Ranucci and colleagues [3], with patients who had acute renal failure having increased age (p 0.015), more previous heart failure (p 0.001) and previous vascular operations (p 0.021), reduced preoperative ejection fraction (p 0.024), and an increased acute renal failure risk score (p 0.001). The patients who had renal failure were much sicker preoperatively. In this study, patients who had postoperative renal failure were 2.5 times (67% vs 26%; p 0.001) more likely to have a combined coronary and valve operation than those who did not have renal failure. The increased complexity of operation is apparent: these patients had almost double the cardiopulmonary bypass time (111 minutes) compared with those who did not have renal failure (69 minutes; p 0.001). Not surprising, duration of cardiopulmonary bypass was the strongest predictor in this study of postoperative acute renal failure (p 0.001). Finally, patients who had acute renal failure more often received same-day angiography than those that did not have renal morbidity (42% vs 20%; p 0.018). In the study by Medalion and colleagues [4], patients who received an operation within 1 day or less of the coronary angiogram group had more unstable angina (p 0.01), urgent operations (p 0.001), diabetes (p 0.02), hypertension (p 0.02) and a higher European System for Cardiac Operative Risk Evaluation (Euro- SCORE; p 0.001) score, each of which is indicative of more risk for postoperative acute renal failure. The authors stated in their Discussion that they excluded patients who had conditions that might have increased the risk of acute renal failure. We disagree and would argue that patients in the early angiogram group had a higher risk of renal failure according to their preoperative risk factors (individual OR, 1.12 to 1.8 in the Society of Thoracic Surgeons study) [1]. Despite the authors conclusion to delay operation for at least 5 days after contrast agent administration, they also state that indeed... elective patients who had near normal preoperative renal function and received low contrast dose could undergo surgery safely immediately after angiography. The most recent analysis to characterize the risk of same-day angiography was by Hennessy and colleagues [7], who showed again that patients who were at higher risk for acute renal failure did indeed have increased rates of postoperative acute renal injury. For instance, patients in their study who had postoperative acute renal failure had higher preoperative creatinine levels of 1.21 vs 1.12 mg/dl (p 0.06) and Society of Thoracic Surgeons

5 Ann Thorac Surg GREASON ET AL 2011;91: CORONARY ANGIOGRAPHY ON SAME DAY AS AVR 1795 scores of 8 vs 6, although this was not statistically significant ( p 0.31), than patients who did not have renal injury. Patients who had acute renal failure also had significantly longer cardiopulmonary bypass times (156 vs 133 minutes; p 0.03) and significantly more postbypass vasoplegia, as evidenced by need for treatment with norepinephrine (p 0.005) or vasopressin (p 0.002). Cardiac catheterization took place within 24 hours of operation in 31% of patients who had acute renal failure vs in 9% of patients who did not have renal failure, which highlights our argument that the sicker patients received an earlier operation. Interestingly, in this study, cardiac catheterization within 24 to 48 hours of operation was protective of acute renal failure (OR, 0.4; 95% CI, 0.1 to 2.8), whereas catheterization before 24 hours (OR, 5.3; 95% CI, 1.4 to 19.0) or within 48 to 72 hours (OR, 3.1; 95% CI, 0.8 to 12.3) was not. It is axiomatic that the risk of perioperative acute kidney injury is not equal among all cardiac surgical procedures. The database of the Society of Thoracic Surgeons reports that rates of associated acute renal failure differ fourfold by type of procedure, ranging from 2.6% (mitral valve repair) to 13.6% (mitral valve replacement with CABG) [8 10]. The studies of Del Duca [2], Ranucci [3], and Hennessy [7] and their colleagues included many operations, such as CABG, reoperative cardiac procedures, combined procedures, and a plethora of valve procedures (eg, aortic, mitral, repair, replacement) done under elective, urgent, and emergent status. Quite possibly, the sickest patients or those requiring the most complex operations ended up in the early operation groups. It is difficult to account for this potential event, which would significantly bias the results against early operation after angiography. All of these previous studies support the notion that patients at high risk for postoperative renal failure should not have a cardiac operation early after the contrast agent load from cardiac catheterization. But these investigations do not address the safety of sameday angiography in the large group of patients who have a low risk of acute postoperative kidney injury, or at least 47% (662 of 1413) of the patients who underwent operations at our institution from 2000 to The present study eliminated many of the biases that are apparent in previous reports. We identified two groups of propensity-matched patients at low risk for postoperative renal failure who were undergoing only a specific, first-time, elective valve procedure and introduced the single variable of timing of coronary angiography in relation to the operation. We determined it was important to include patients having concomitant CABG because the status of the coronary arteries in a patient referred for AVR is unknown before angiography, regardless of whether the coronary angiogram occurs on the same day. Indeed, many patients requiring AVR have coronary artery disease, as we noted in about 50% of our patients, which is comparable with other reported series [11]. Of importance to our hypothesis, the addition of CABG was not predictive of acute kidney injury in our report, with similar findings noted by Mistiaen and colleagues [12] in their review of risk factors for acute kidney injury in patients treated with AVR and CABG. We agree that the increased amount of contrast medium given is a risk factor for acute renal failure, as reported by Medalion and colleagues [4] (OR, 3.4; 95% CI, 1.5 to 7.7; p 0.004) and Ranucci and Ballotta [13] (OR, 1.81; 95% CI, 1.01 to 3.23; p 0.045). Understanding this association, we specifically use a protocol for angiography that minimizes the amount of contrast agent given by limiting the views of the coronary anatomy and omitting left ventriculography, internal mammary angiography, or aortography, or a combination of these. As a result, the amount of contrast agent given to our same-day angiogram group (0.8 ml/kg) was significantly less than the amount given to our non same-day angiogram group (0.9 ml/kg; p 0.007). Larger volumes of contrast agent were reported by Medalion and colleagues [4] (1.1 to 1.3 ml/kg) and Ranucci and colleagues [3] (1.33 to 1.68 ml/kg), where no specific efforts were made to minimize the amount of contrast agent. The reduced volume of contrast agent given in our study may have substantial clinical importance to the outcome of this study. Our study used the Acute Kidney Injury Network criteria for acute kidney injury, modified only by the fact that we analyzed renal function (serum creatinine levels) out to 30 days postoperatively rather than the more widely reported 48 hours. We used this longer time because almost 40% of renal dysfunction occurs greater than 48 hours after the contrast study. Furthermore, the 30-day timeframe is the accepted one for which surgeons report perioperative cardiac complications [14]. We did not use volume of urine output as a part of the criteria for acute kidney injury because the hourly recorded urine output was not consistently available before the existence of the electronic record, and most patients received diuretics in the perioperative period that may have artificially elevated urine output. We also did not use estimated creatine clearance in the postoperative period because the Cockcroft-Gault equation is based on weight and our experience is that patient weights can be unreliable in the initial postoperative period when thoracostomy drainage catheters are still in place or when bed-weights are used. Our study has several limitations, including the retrospective design. However, the propensity-matched analysis mitigates some inherent selection bias associated with the retrospective nature of how patients were assigned to non same-day or same-day coronary angiography. It would be costly and difficult to complete a randomized prospective study to determine the risk of acute kidney injury in patients undergoing same-day coronary angiography. In addition, the study findings apply only to patients undergoing elective AVR who were at low risk for postoperative acute kidney injury. The results are most likely not applicable to other types of cardiac patients or procedures, such as mitral valve replacement, nonelec-

6 1796 GREASON ET AL Ann Thorac Surg CORONARY ANGIOGRAPHY ON SAME DAY AS AVR 2011;91: tive operations, other combined operations, or reoperations, or a combination of these. In conclusion, coronary artery disease is present in approximately 50% of adult patients treated with elective AVR a prevalence that necessitates coronary artery imaging before valve operations. In a select but large group of patients with a low risk of acute kidney injury, sameday coronary angiography eliminated additional hospital stay and was not associated with increased morbidity, including acute kidney injury, or death. The strategy required measures to minimize the dose of contrast agent during coronary angiography and the delayed removal of the vascular sheath after AVR. This is an integrated approach that can be easily established between cardiology and cardiac surgery services. Same-day limited coronary angiography is safe in selected patients referred for elective AVR. The convenience of a single hospital stay is an added benefit that patients have accepted readily. References 1. Brown ML, Holmes DR, Tajik AJ, Sarano ME, Schaff HV. Safety of same-day coronary angiography in patients undergoing elective valvular heart surgery. Mayo Clin Proc 2007; 82: Del Duca D, Iqbal S, Rahme E, Goldberg P, de Varennes B. Renal failure after cardiac surgery: timing of cardiac catheterization and other perioperative risk factors. Ann Thorac Surg 2007;84: Ranucci M, Ballotta A, Kunkl A, et al. Influence of the timing of cardiac catheterization and the amount of contrast media on acute renal failure after cardiac surgery. Am J Cardiol 2008;101: Medalion B, Cohen H, Assali A, et al. The effect of cardiac angiography timing, contrast media dose, and preoperative renal function on acute renal failure after coronary artery bypass grafting. J Thorac Cardiovasc Surg 2010;139: Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron 1976;16: Mehta RL, Kellum JA, Shah SV, et al; Acute Kidney Injury Network. Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury. Crit Care 2007;11:R Hennessy SA, LaPar DJ, Stukenborg GJ, et al. Cardiac catheterization within 24 hours of valve surgery is significantly associated with acute renal failure. J Thorac Cardiovasc Surg 2010;140: Shahian DM, O Brien SM, Filardo G, et al; Society of Thoracic Surgeons Quality Measurement Task Force. The Society of Thoracic Surgeons 2008 cardiac surgery risk models: part 1 coronary artery bypass grafting surgery. Ann Thorac Surg 2009;88 (1 suppl):s O Brien SM, Shahian DM, Filardo G, et al; Society of Thoracic Surgeons Quality Measurement Task Force. The Society of Thoracic Surgeons 2008 cardiac surgery risk models: part 2 isolated valve surgery. Ann Thorac Surg 2009;88 (1 suppl):s Shahian DM, O Brien SM, Filardo G, et al; Society of Thoracic Surgeons Quality Measurement Task Force. The Society of Thoracic Surgeons 2008 cardiac surgery risk models: part 3 valve plus coronary artery bypass grafting surgery. Ann Thorac Surg 2009;88 (1 suppl):s Iung B. Interface between valve disease and ischaemic heart disease. Heart 2000;84: Mistiaen W, Van Cauwelaert P, Muylaert P, De Worm E. A thousand pericardial valves in aortic position: risk factors for postoperative acute renal function impairment in elderly. J Cardiovasc Surg (Torino) 2009;50: Ranucci M, Ballotta A. Contrast media dose, angiography timing, and acute renal failure after coronary operations. J Thorac Cardiovasc Surg 2010;140: Weisbord SD, Hartwig KC, Sonel AF, Fine MJ, Palevsky P. The incidence of clinically significant contrast-induced nephropathy following non-emergent coronary angiography. Catheter Cardiovasc Interv 2008;71: INVITED COMMENTARY Greason and colleagues [1] have shown that minimizing contrast in a subset of patients undergoing elective aortic valve replacement (AVR) has allowed a sameday cardiac catheterization and cardiac procedure program with a low incidence of acute kidney injury (AKI) an advantage in terms of patient convenience and reduced cost. As the authors point out, not all patients are candidates for early operation after coronary angiography. There is much evidence albeit with heterogeneous groups and varying definitions of AKI that early cardiac surgery in higher risk patients is associated with a greater risk of AKI and increased morbidity and mortality [2 4]. For patients who have early cardiac operations, contrast nephropathy combined with the patient s presenting circumstances may be compounded by intraoperative and postoperative events, further increasing the likelihood of AKI [3]. For instance, some patients may have recently received angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, or nonsteroidal antiinflammatory drugs. Some may have been exposed to other potential renal insults such as inflammation and endotoxemia. Subsequently, cardiopulmonary bypass and other intraoperative events may contribute to or be responsible for AKI through a variety of mechanisms: 1. Hemodynamic alterations may cause decreased renal perfusion. 2. Ischemic injury may occur secondary to generation of macroscopic and microscopic emboli. 3. Exposure of blood components to the bypass circuit may induce a systemic inflammatory response syndrome, activation of neutrophils, oxidative injury from free hemoglobin released from injured erythrocytes, and ischemia reperfusion injury. Intraoperative events are followed by volume shifts, vasoactive drugs, and other perturbations in the postoperative period [3]. Greason and coworkers are clear that same-day limited coronary angiography is safe in selected patients referred for elective AVR. We must be cautious with regard to generalizing this information. The Northern New England Cardiovascular Diseases Study Group registry has 2011 by The Society of Thoracic Surgeons /$36.00 Published by Elsevier Inc doi: /j.athoracsur