Expert Review of Cardiovascular Therapy
ISSN: 1477-9072 (Print) 1744-8344 (Online) Journal homepage: http://www.tandfonline.com/loi/ierk20
Acute kidney injury after aortic valve replacement: incidence, risk factors and outcomes Marc Najjar, Michael Salna & Isaac George To cite this article: Marc Najjar, Michael Salna & Isaac George (2015) Acute kidney injury after aortic valve replacement: incidence, risk factors and outcomes, Expert Review of Cardiovascular Therapy, 13:3, 301-316, DOI: 10.1586/14779072.2015.1002467 To link to this article: http://dx.doi.org/10.1586/14779072.2015.1002467
Published online: 16 Jan 2015.
Submit your article to this journal
Article views: 373
View related articles
View Crossmark data
Citing articles: 20 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ierk20 Download by: [Cornell University Library]
Date: 15 July 2017, At: 12:51
Review
Acute kidney injury after aortic valve replacement: incidence, risk factors and outcomes Expert Rev. Cardiovasc. Ther. 13(3), 301–316 (2015)
Marc Najjar1, Michael Salna2 and Isaac George*1 1 Division of Cardiothoracic Surgery, College of Physicians and Surgeons of Columbia University – New York Presbyterian Hospital, MHB 7GN-435, 177 Fort Washington Ave, New York, NY 10032, USA 2 School of Medicine, Columbia University, New York, NY 10032, USA *Author for correspondence: Tel.: +1 212 305 4134 [email protected]
The occurrence of acute kidney injury (AKI) following aortic valve replacement (AVR) has very serious clinical implications and has therefore been the focus of several studies. The authors report the results of previous studies evaluating both transcatheter AVR (TAVR) and indirectly surgical AVR (SAVR) through looking at cardiopulmonary bypass (CPB) cardiac surgeries, and identify the incidence, predictors and outcomes of AKI following AVR. In most studies, AKI was defined using the Risk, Injury, Failure, Loss and End Stage, Valve Academic Research Consortium (modified Risk, Injury, Failure, Loss and End Stage) or Valve Academic Research Consortium-2 (Acute Kidney Injury Network) AKI classification criteria. Twelve studies including more than 90,000 patients undergoing cardiac surgery on CPB were considered as well as 26 studies with more than 6000 patients undergoing TAVR. Depending on the definition used, AKI occurred in 3.4–43% of SAVR cases with up to 2.5% requiring dialysis, and in 3.4–57% of TAVR cases. Factors identified as independent predictors of AKI were: baseline kidney failure, EUROSCORE, diabetes mellitus, hypertension, chronic obstructive pulmonary disease, anemia, peripheral vascular disease, heart failure, surgical priority, CPB time, reoperation, use of intra-aortic balloon pump, need for re-exploration, contrast agent volume, transapical access, blood transfusion, postoperative thrombocytopenia, postoperative leukocytosis as well as demographic variables such as age and female gender. The 30-day mortality rate for patients with AKI following SAVR ranged from 5.5 to 46% and was 3- to 16-times higher than in those without AKI. Similarly, patients who developed AKI after TAVR had a mortality rate of 7.8–29%, which was two- to eight-times higher than those who did not suffer from AKI. AKI confers up to a fourfold increase in 1-year mortality. Finally, hospital length of stay was significantly increased in patients with AKI in both SAVR and TAVR groups, with increases up to 3- and 2.5–times, respectively. KEYWORDS: acute kidney injury . cardiac surgery . mortality . renal replacement therapy . surgical aortic valve replacement
.
transcatheter aortic valve replacement
Acute kidney injury (AKI) is a prevalent and prognostically significant complication after aortic valve replacement (AVR), both surgical AVR (SAVR) and transcatheter AVR (TAVR). Depending on the definition and the population studied, it occurs in up to 43% of SAVR and 57% of TAVR cases (TABLES 1 & 2) and is associated with a high mortality, a higher risk of infection and a more complicated hospital course [1–4]. Data on the incidence of AKI after AVR have been for quite some time inconsistent, especially because of the heterogeneity of the populations at risk but most
informahealthcare.com
10.1586/14779072.2015.1002467
importantly because of an inconsistent definition and classification of AKI. Several efforts have been made to address this issue, and the Valve Academic Research Consortium (VARC) introduced criteria in 2011 to standardize definitions of clinical end points for TAVR [5], which was confirmed by a pooled analysis of 16 studies involving 3519 patients [6]. The recently published VARC-2 criteria recommended the use of the AKI Network (AKIN) classification (TABLE 3) [7]. SAVR with cardiopulmonary bypass (CPB) is the standard treatment for patients with
2015 Informa UK Ltd
ISSN 1477-9072
301
Review
Najjar, Salna & George
Table 1. Incidence of acute kidney injury after surgical aortic valve replacement (cardiac surgery). Study (year)
Patients (n)
Incidence of AKI (%)
Incidence of dialysis (%)
Diagnostic criteria
Ref.
Ryckwaert et al. (2002)
591
16
1.4
20% increase Cr
[30]
Grayson et al. (2003)
5132
2.9
0.9
Cr >2 mg/dl or dialysis
[10]
Bove et al. (2004)
5068
3.4
1.9
100% increase Cr
[45]
Thakar et al. (2005)
31,677
16
1.8
10% drop in eGFR
[44]
Falvo et al. (2008)
1030
37
2.0
Cr >1.5 mg/dl OR 50% increase Cr
Karkouti et al. (2009)
3500
34
Hobson et al. (2009)
2973
43
D’Onofrio et al. (2010)
2488
23
Robert et al. (2010)
25,086
30 using AKIN 31 using RIFLE
AKIN and RIFLE
Brown et al. (2010)
4987
39
AKIN
Englberger et al. (2011)
4836
26.3 using AKIN 18.9 using RIFLE
Parolari et al. (2012)
3219
8.9
[121]
RIFLE
[46]
2.5
RIFLE
[22]
1.3
RIFLE
[47]
2
[122]
[2]
AKIN and RIFLE
[13]
AKIN
[48]
AKI: Acute kidney injury; AKIN: Acute Kidney Injury Network; Cr: Creatinine; eGFR: Estimated glomerular filtration rate; RIFLE: Risk, Injury, Failure, Loss and End Stage.
severe aortic valve disease. Accounting for 13% of all adult cardiac surgery cases [8], SAVR is the most common cardiac valve operation in the USA [9]. No studies in the past have looked at AKI development specifically following SAVR, most have studied cardiac surgeries in general in the setting of CPB. However, since valvular heart surgery has emerged as an independent risk factor for AKI, conferring a 2.7-times increased risk compared with coronary artery bypass grafting (CABG) [10], it would be reasonable to use the results from cardiac surgery studies to draw conclusions about the effect of SAVR on AKI. Some of the major pathogenic factors involved in the development of AKI after SAVR are anemia, red blood cells (RBC) transfusion as well as CPB-related factors such as hemodilution effect and systemic inflammatory response syndrome (SIRS) [1]. In the case of patients with severe aortic stenosis who are not candidates for surgery, TAVR has emerged as an alternative to SAVR and is now considered as the standard of care in these patients [11,12]. Similar to AKI following SAVR, the pathogenesis of AKI after TAVR is also multifactorial and is often a combination of the use of nephrotoxic contrast media and/or medications, hemodynamic instability perioperatively or more specifically during periods of rapid pacing as well as cholesterol atheroembolization to the renal vascular bed from catheter insertion through a calcified aorta. Several pre-, intra- and postoperative factors have been reported to be associated with and predictors of AKI following AVR (TABLES 4 & 5).
302
Recent advances in cardiac surgery have led to a decrease in general mortality associated with open heart surgery, which over the last decade, ranged between 0.6 and 2% [13,14]. However, mortality rises exponentially and, in some instances, exceeds 40% among those who develop postoperative AKI and may reach 50% in patients requiring dialysis [10,14]. In fact, even small derangements in kidney function have significant prognostic consequences. Minimal changes in postoperative serum creatinine have been associated with increased intensive care unit (ICU) length of stay and mortality [15,16] as well as a higher 1-year risk of mortality independent of whether renal function returned to baseline levels [17,18]. AKI patients are also at a significantly higher risk for infectious complications such as sepsis, which are sometimes the cause of up to 40% of deaths [15,19,20]. We sought in the following review to report the incidence of AKI and need for dialysis following both SAVR and TAVR from studies published on the subject, as well as to identify the major predictors and risk factors of AKI. Data on isolated SAVR were scarce; therefore, we reported studies looking at cardiac surgeries requiring CPB. Outcomes such as 30-day and 1-year mortality and hospital length of stay were also reported according to the different studies. Finally, we discussed some proposed pathogenic mechanisms of AKI along with some preventive and therapeutic measures that should be employed in order to try to minimize both the incidence as well as the impact of AKI following AVR.
Expert Rev. Cardiovasc. Ther. 13(3), (2015)
Acute kidney injury after aortic valve replacement
Review
Table 2. Incidence of acute kidney injury after transcatheter aortic valve replacement. Study (year)
Patients (n)
Incidence of AKI (%)
Incidence of dialysis (%)
Diagnostic criteria
Ref.
Aregger et al. (2009)
60
28
7.4
RIFLE
[71]
Strauch et al. (2010)
28
57
21
RIFLE
[117]
Bagur et al. (2010)
213
12
1.4
RIFLE or need for renal replacement therapy
[37]
Sinning et al. (2010)
70
26
10
AKIN
[33]
Elhmidi et al. (2011)
234
20
10
RIFLE
[32]
Dehedin et al. (2011)
125
8.0
Gotzmann et al. (2011)
145
3.4
Nuis et al. (2011
118
Smith et al. (2011)
348
Sta¨hli et al. (2011)
130
Van Linden et al. (2011)
270
16
Alassar et al. (2012)
79
12
Barbash et al. (2012)
165
15
Durand et al. (2012)
151
Gebauer et al. (2012)
200% increase in SCr or at least 264 mmol/l
[123]
1.4
VARC
[124]
19
2.0
VARC
[35]
8.6
5.4
SCr >3 mg/dl (265 mmol/l)
[12]
6.2
VARC
[125]
16
RIFLE
[90]
VARC
[34]
0
RIFLE
[72]
27
0
VARC
[126]
150
20
4.0
AKIN
[116]
Genereux et al. (2012)
218
8.3
4.1
VARC
[127]
Khawaja et al. (2012)
248
36
10
VARC
[36]
Kong et al. (2012)
52
29
6
RIFLE
[38]
Nuis et al. (2012)
995
21
3.1
VARC
[51]
Scherner et al. (2012)
150
42
5
VARC
[128]
Tchetche et al. (2012)
943
23
VARC
[129]
Ussia et al. (2012)
178
19
VARC
[130]
Frerker et al. (2013)
323
11
VARC
[91]
Saia et al. (2013)
102
42
4.9
VARC
[51]
Yamamoto et al. (2013)
415
15
1.0
VARC
[39]
Schnabel et al. (2014)
458
16
2.4
VARC
[131]
2.2
AKI: Acute kidney injury; AKIN: Acute Kidney Injury Network; RIFLE: Risk, Injury, Failure, Loss and End Stage; SCr: Serum creatinine; VARC: Valve Academic Research Consortium.
Classification
The severity of AKI in patients having undergone AVR is inversely proportional to long-term survival [21]. Previously, studies focused on severe AKI, that is, cases with a significant increase in serum creatinine or those necessitating dialysis [19,20]. However, emerging literature has reported associations with small changes in serum creatinine and adverse outcomes [16,22,23]. An accurate and standardized definition of AKI is crucial for the evaluation of surgical outcomes and comparison between different studies. In fact, depending on this definition, incidence of AKI following SAVR varies between 1 and 30% [1]. Limitations informahealthcare.com
in the prevention and treatment of renal failure after cardiac surgery are compounded by inconsistencies in definitions of injury and a poor understanding of the underlying pathophysiology. To better standardize the definition of AKI, the Acute Dialysis Quality Initiative Group introduced a 5-stage classification system in 2004 known as RIFLE (Risk, Injury, Failure, Loss and End Stage) [24]. The RIFLE staging system classified AKI into 3 grades of increasing severity (risk, injury and failure) on the basis of either change in serum creatinine (50, 100 or 200% increase) or duration of oliguria (6, 12 or 24 h) and 2 outcome stages based on duration of kidney failure. The 303
Review
Najjar, Salna & George
Table 3. Acute kidney injury definitions. Risk, Injury, Failure, Loss and End Stage Risk
[24]
Increase in serum creatinine to 150–200% (1.5–2.0 increase compared with baseline) OR GFR decrease >25% OR Urine output 50% OR Urine output 75% OR Urine output 24 h OR Anuria for ‡12 h
Loss
Persistent acute renal failure: complete loss of kidney function >4 weeks (requiring dialysis)
End-stage renal disease
Complete loss of kidney function >3 months (requiring dialysis)
Valve Academic Research Consortium-2 Kidney Injury Network [28])
[5,27]
(Acute
Stage 1
Increase in serum creatinine to 150–199% (1.5–1.99 increased compared with baseline) OR Increase of ‡0.3 mg/dl (‡26.4 mmol/l) OR Urine output 6 but 2.1
2.87 (1.37–6.00)
Diabetes
1.48 (1.08–2.03
CPB duration
1.12 (1.08–1.16)
CPB Hct 1.58 mg/dl
3.9 (1.6–9.5)
Strauch et al. (2010)
Preoperative serum creatinine >1.1 mg/dl
Nuis et al. (2011)
Logistic EuroSCORE
1.08 (1.01–1.14)
Blood transfusion
1.29 (1.01–1.7)
Previous myocardial infarction
5.7 (1.64–19.9)
Van Linden et al. (2011)
[33] [117]
Post-procedural leukocyte count
1.108 (1.01–1.14)
Thrombocytopenia
4.4 (1.6–12.2)
Contrast agent
2.3 (1.0–4.9)
[35]
[90]
Leukocyte count >12 g/l for >2 days postoperatively
2.8 (1.3–6.0)
Baseline creatinine >104 mmol/l
1.04
Diabetes mellitus
6.7
Transapical access
2.9 (1.03–8.29)
Blood transfusion
3.74 (1.36–10.3)
Genereux et al. (2012)
Life-threatening bleeding
5.87 (1.84–14.76)
[127]
Khawaja et al. (2012)
Peripheral vascular disease
2.94 (1.34–6.44)
[36]
Diabetes mellitus
3.17 (1.67–6.05)
Chronic kidney disease
1.57 (1.11–2.21)
Transapical access
9.3 (4.3–23.7)
Blood transfusion
2.4 (2.0–3.1)
Hypertension
6.4 (2.9–17.3)
Blood transfusion (3–4 units)
ISSN: 1477-9072 (Print) 1744-8344 (Online) Journal homepage: http://www.tandfonline.com/loi/ierk20
Acute kidney injury after aortic valve replacement: incidence, risk factors and outcomes Marc Najjar, Michael Salna & Isaac George To cite this article: Marc Najjar, Michael Salna & Isaac George (2015) Acute kidney injury after aortic valve replacement: incidence, risk factors and outcomes, Expert Review of Cardiovascular Therapy, 13:3, 301-316, DOI: 10.1586/14779072.2015.1002467 To link to this article: http://dx.doi.org/10.1586/14779072.2015.1002467
Published online: 16 Jan 2015.
Submit your article to this journal
Article views: 373
View related articles
View Crossmark data
Citing articles: 20 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ierk20 Download by: [Cornell University Library]
Date: 15 July 2017, At: 12:51
Review
Acute kidney injury after aortic valve replacement: incidence, risk factors and outcomes Expert Rev. Cardiovasc. Ther. 13(3), 301–316 (2015)
Marc Najjar1, Michael Salna2 and Isaac George*1 1 Division of Cardiothoracic Surgery, College of Physicians and Surgeons of Columbia University – New York Presbyterian Hospital, MHB 7GN-435, 177 Fort Washington Ave, New York, NY 10032, USA 2 School of Medicine, Columbia University, New York, NY 10032, USA *Author for correspondence: Tel.: +1 212 305 4134 [email protected]
The occurrence of acute kidney injury (AKI) following aortic valve replacement (AVR) has very serious clinical implications and has therefore been the focus of several studies. The authors report the results of previous studies evaluating both transcatheter AVR (TAVR) and indirectly surgical AVR (SAVR) through looking at cardiopulmonary bypass (CPB) cardiac surgeries, and identify the incidence, predictors and outcomes of AKI following AVR. In most studies, AKI was defined using the Risk, Injury, Failure, Loss and End Stage, Valve Academic Research Consortium (modified Risk, Injury, Failure, Loss and End Stage) or Valve Academic Research Consortium-2 (Acute Kidney Injury Network) AKI classification criteria. Twelve studies including more than 90,000 patients undergoing cardiac surgery on CPB were considered as well as 26 studies with more than 6000 patients undergoing TAVR. Depending on the definition used, AKI occurred in 3.4–43% of SAVR cases with up to 2.5% requiring dialysis, and in 3.4–57% of TAVR cases. Factors identified as independent predictors of AKI were: baseline kidney failure, EUROSCORE, diabetes mellitus, hypertension, chronic obstructive pulmonary disease, anemia, peripheral vascular disease, heart failure, surgical priority, CPB time, reoperation, use of intra-aortic balloon pump, need for re-exploration, contrast agent volume, transapical access, blood transfusion, postoperative thrombocytopenia, postoperative leukocytosis as well as demographic variables such as age and female gender. The 30-day mortality rate for patients with AKI following SAVR ranged from 5.5 to 46% and was 3- to 16-times higher than in those without AKI. Similarly, patients who developed AKI after TAVR had a mortality rate of 7.8–29%, which was two- to eight-times higher than those who did not suffer from AKI. AKI confers up to a fourfold increase in 1-year mortality. Finally, hospital length of stay was significantly increased in patients with AKI in both SAVR and TAVR groups, with increases up to 3- and 2.5–times, respectively. KEYWORDS: acute kidney injury . cardiac surgery . mortality . renal replacement therapy . surgical aortic valve replacement
.
transcatheter aortic valve replacement
Acute kidney injury (AKI) is a prevalent and prognostically significant complication after aortic valve replacement (AVR), both surgical AVR (SAVR) and transcatheter AVR (TAVR). Depending on the definition and the population studied, it occurs in up to 43% of SAVR and 57% of TAVR cases (TABLES 1 & 2) and is associated with a high mortality, a higher risk of infection and a more complicated hospital course [1–4]. Data on the incidence of AKI after AVR have been for quite some time inconsistent, especially because of the heterogeneity of the populations at risk but most
informahealthcare.com
10.1586/14779072.2015.1002467
importantly because of an inconsistent definition and classification of AKI. Several efforts have been made to address this issue, and the Valve Academic Research Consortium (VARC) introduced criteria in 2011 to standardize definitions of clinical end points for TAVR [5], which was confirmed by a pooled analysis of 16 studies involving 3519 patients [6]. The recently published VARC-2 criteria recommended the use of the AKI Network (AKIN) classification (TABLE 3) [7]. SAVR with cardiopulmonary bypass (CPB) is the standard treatment for patients with
2015 Informa UK Ltd
ISSN 1477-9072
301
Review
Najjar, Salna & George
Table 1. Incidence of acute kidney injury after surgical aortic valve replacement (cardiac surgery). Study (year)
Patients (n)
Incidence of AKI (%)
Incidence of dialysis (%)
Diagnostic criteria
Ref.
Ryckwaert et al. (2002)
591
16
1.4
20% increase Cr
[30]
Grayson et al. (2003)
5132
2.9
0.9
Cr >2 mg/dl or dialysis
[10]
Bove et al. (2004)
5068
3.4
1.9
100% increase Cr
[45]
Thakar et al. (2005)
31,677
16
1.8
10% drop in eGFR
[44]
Falvo et al. (2008)
1030
37
2.0
Cr >1.5 mg/dl OR 50% increase Cr
Karkouti et al. (2009)
3500
34
Hobson et al. (2009)
2973
43
D’Onofrio et al. (2010)
2488
23
Robert et al. (2010)
25,086
30 using AKIN 31 using RIFLE
AKIN and RIFLE
Brown et al. (2010)
4987
39
AKIN
Englberger et al. (2011)
4836
26.3 using AKIN 18.9 using RIFLE
Parolari et al. (2012)
3219
8.9
[121]
RIFLE
[46]
2.5
RIFLE
[22]
1.3
RIFLE
[47]
2
[122]
[2]
AKIN and RIFLE
[13]
AKIN
[48]
AKI: Acute kidney injury; AKIN: Acute Kidney Injury Network; Cr: Creatinine; eGFR: Estimated glomerular filtration rate; RIFLE: Risk, Injury, Failure, Loss and End Stage.
severe aortic valve disease. Accounting for 13% of all adult cardiac surgery cases [8], SAVR is the most common cardiac valve operation in the USA [9]. No studies in the past have looked at AKI development specifically following SAVR, most have studied cardiac surgeries in general in the setting of CPB. However, since valvular heart surgery has emerged as an independent risk factor for AKI, conferring a 2.7-times increased risk compared with coronary artery bypass grafting (CABG) [10], it would be reasonable to use the results from cardiac surgery studies to draw conclusions about the effect of SAVR on AKI. Some of the major pathogenic factors involved in the development of AKI after SAVR are anemia, red blood cells (RBC) transfusion as well as CPB-related factors such as hemodilution effect and systemic inflammatory response syndrome (SIRS) [1]. In the case of patients with severe aortic stenosis who are not candidates for surgery, TAVR has emerged as an alternative to SAVR and is now considered as the standard of care in these patients [11,12]. Similar to AKI following SAVR, the pathogenesis of AKI after TAVR is also multifactorial and is often a combination of the use of nephrotoxic contrast media and/or medications, hemodynamic instability perioperatively or more specifically during periods of rapid pacing as well as cholesterol atheroembolization to the renal vascular bed from catheter insertion through a calcified aorta. Several pre-, intra- and postoperative factors have been reported to be associated with and predictors of AKI following AVR (TABLES 4 & 5).
302
Recent advances in cardiac surgery have led to a decrease in general mortality associated with open heart surgery, which over the last decade, ranged between 0.6 and 2% [13,14]. However, mortality rises exponentially and, in some instances, exceeds 40% among those who develop postoperative AKI and may reach 50% in patients requiring dialysis [10,14]. In fact, even small derangements in kidney function have significant prognostic consequences. Minimal changes in postoperative serum creatinine have been associated with increased intensive care unit (ICU) length of stay and mortality [15,16] as well as a higher 1-year risk of mortality independent of whether renal function returned to baseline levels [17,18]. AKI patients are also at a significantly higher risk for infectious complications such as sepsis, which are sometimes the cause of up to 40% of deaths [15,19,20]. We sought in the following review to report the incidence of AKI and need for dialysis following both SAVR and TAVR from studies published on the subject, as well as to identify the major predictors and risk factors of AKI. Data on isolated SAVR were scarce; therefore, we reported studies looking at cardiac surgeries requiring CPB. Outcomes such as 30-day and 1-year mortality and hospital length of stay were also reported according to the different studies. Finally, we discussed some proposed pathogenic mechanisms of AKI along with some preventive and therapeutic measures that should be employed in order to try to minimize both the incidence as well as the impact of AKI following AVR.
Expert Rev. Cardiovasc. Ther. 13(3), (2015)
Acute kidney injury after aortic valve replacement
Review
Table 2. Incidence of acute kidney injury after transcatheter aortic valve replacement. Study (year)
Patients (n)
Incidence of AKI (%)
Incidence of dialysis (%)
Diagnostic criteria
Ref.
Aregger et al. (2009)
60
28
7.4
RIFLE
[71]
Strauch et al. (2010)
28
57
21
RIFLE
[117]
Bagur et al. (2010)
213
12
1.4
RIFLE or need for renal replacement therapy
[37]
Sinning et al. (2010)
70
26
10
AKIN
[33]
Elhmidi et al. (2011)
234
20
10
RIFLE
[32]
Dehedin et al. (2011)
125
8.0
Gotzmann et al. (2011)
145
3.4
Nuis et al. (2011
118
Smith et al. (2011)
348
Sta¨hli et al. (2011)
130
Van Linden et al. (2011)
270
16
Alassar et al. (2012)
79
12
Barbash et al. (2012)
165
15
Durand et al. (2012)
151
Gebauer et al. (2012)
200% increase in SCr or at least 264 mmol/l
[123]
1.4
VARC
[124]
19
2.0
VARC
[35]
8.6
5.4
SCr >3 mg/dl (265 mmol/l)
[12]
6.2
VARC
[125]
16
RIFLE
[90]
VARC
[34]
0
RIFLE
[72]
27
0
VARC
[126]
150
20
4.0
AKIN
[116]
Genereux et al. (2012)
218
8.3
4.1
VARC
[127]
Khawaja et al. (2012)
248
36
10
VARC
[36]
Kong et al. (2012)
52
29
6
RIFLE
[38]
Nuis et al. (2012)
995
21
3.1
VARC
[51]
Scherner et al. (2012)
150
42
5
VARC
[128]
Tchetche et al. (2012)
943
23
VARC
[129]
Ussia et al. (2012)
178
19
VARC
[130]
Frerker et al. (2013)
323
11
VARC
[91]
Saia et al. (2013)
102
42
4.9
VARC
[51]
Yamamoto et al. (2013)
415
15
1.0
VARC
[39]
Schnabel et al. (2014)
458
16
2.4
VARC
[131]
2.2
AKI: Acute kidney injury; AKIN: Acute Kidney Injury Network; RIFLE: Risk, Injury, Failure, Loss and End Stage; SCr: Serum creatinine; VARC: Valve Academic Research Consortium.
Classification
The severity of AKI in patients having undergone AVR is inversely proportional to long-term survival [21]. Previously, studies focused on severe AKI, that is, cases with a significant increase in serum creatinine or those necessitating dialysis [19,20]. However, emerging literature has reported associations with small changes in serum creatinine and adverse outcomes [16,22,23]. An accurate and standardized definition of AKI is crucial for the evaluation of surgical outcomes and comparison between different studies. In fact, depending on this definition, incidence of AKI following SAVR varies between 1 and 30% [1]. Limitations informahealthcare.com
in the prevention and treatment of renal failure after cardiac surgery are compounded by inconsistencies in definitions of injury and a poor understanding of the underlying pathophysiology. To better standardize the definition of AKI, the Acute Dialysis Quality Initiative Group introduced a 5-stage classification system in 2004 known as RIFLE (Risk, Injury, Failure, Loss and End Stage) [24]. The RIFLE staging system classified AKI into 3 grades of increasing severity (risk, injury and failure) on the basis of either change in serum creatinine (50, 100 or 200% increase) or duration of oliguria (6, 12 or 24 h) and 2 outcome stages based on duration of kidney failure. The 303
Review
Najjar, Salna & George
Table 3. Acute kidney injury definitions. Risk, Injury, Failure, Loss and End Stage Risk
[24]
Increase in serum creatinine to 150–200% (1.5–2.0 increase compared with baseline) OR GFR decrease >25% OR Urine output 50% OR Urine output 75% OR Urine output 24 h OR Anuria for ‡12 h
Loss
Persistent acute renal failure: complete loss of kidney function >4 weeks (requiring dialysis)
End-stage renal disease
Complete loss of kidney function >3 months (requiring dialysis)
Valve Academic Research Consortium-2 Kidney Injury Network [28])
[5,27]
(Acute
Stage 1
Increase in serum creatinine to 150–199% (1.5–1.99 increased compared with baseline) OR Increase of ‡0.3 mg/dl (‡26.4 mmol/l) OR Urine output 6 but 2.1
2.87 (1.37–6.00)
Diabetes
1.48 (1.08–2.03
CPB duration
1.12 (1.08–1.16)
CPB Hct 1.58 mg/dl
3.9 (1.6–9.5)
Strauch et al. (2010)
Preoperative serum creatinine >1.1 mg/dl
Nuis et al. (2011)
Logistic EuroSCORE
1.08 (1.01–1.14)
Blood transfusion
1.29 (1.01–1.7)
Previous myocardial infarction
5.7 (1.64–19.9)
Van Linden et al. (2011)
[33] [117]
Post-procedural leukocyte count
1.108 (1.01–1.14)
Thrombocytopenia
4.4 (1.6–12.2)
Contrast agent
2.3 (1.0–4.9)
[35]
[90]
Leukocyte count >12 g/l for >2 days postoperatively
2.8 (1.3–6.0)
Baseline creatinine >104 mmol/l
1.04
Diabetes mellitus
6.7
Transapical access
2.9 (1.03–8.29)
Blood transfusion
3.74 (1.36–10.3)
Genereux et al. (2012)
Life-threatening bleeding
5.87 (1.84–14.76)
[127]
Khawaja et al. (2012)
Peripheral vascular disease
2.94 (1.34–6.44)
[36]
Diabetes mellitus
3.17 (1.67–6.05)
Chronic kidney disease
1.57 (1.11–2.21)
Transapical access
9.3 (4.3–23.7)
Blood transfusion
2.4 (2.0–3.1)
Hypertension
6.4 (2.9–17.3)
Blood transfusion (3–4 units)
