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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2016  |  Volume : 27  |  Issue : 4  |  Page : 752-757
Incidence and mortality of acute kidney injury in patients with acute coronary syndrome: A retrospective study from a single coronary care unit

1 Nephrology Unit, Tripoli Central Hospital, Tripoli, Libya
2 Tajoura Cardiology Center, Tripoli, Libya

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Date of Web Publication5-Jul-2016


Acute kidney injury (AKI) is associated with adverse short-and long-term outcomes. The aim of this study was to evaluate the incidence of AKI and the short-term mortality in patients admitted with acute coronary syndrome (ACS) to a single coronary care unit (CCU) in Tripoli, Libya. We retrospectively studied the medical records of ACS patients admitted to the CCU of a referral cardiology center, during the period from January 1, 2014, to December 31, 2014. AKI was defined according to the AKI network criteria. The incidence of AKI and short-term CCU mortality was compared between different types of ACS. Data of patients with and without AKI were compared using Student's t-test and Chi-squared statistic considering P <0.05 statistically significant. Eighty-four patients with ACS were included in the study; their mean age was 57.6 ± 14.4 years [standard deviation (SD)], 75% were males and their mean stay in the CCU was 4.3 ± 3 days (SD). Of them, 71.4% had ST-elevated myocardial infarction (STEMI), 22.6% had non-STEMI, and 6% had unstable angina. About 41.7% had AKI (19% had AKI Stage 1, 17.9% had AKI Stage 2, and 4.8% had AKI Stage 3). The total CCU mortality was 15.5%; mortality among AKI patients in the CCU was 25.7% compared with 6.12% in the non-AKI patients (P = 0.014). The mortality worsened with increasing severity of AKI. Patients with AKI were older (61.6 ± 15 years) than the non-AKI group (54.7 ± 13 years, P = 0.031), their mean blood pressure at admission was lower, their CCU stay was longer, and they more frequently had coexisting acute decompensated heart failure. In this study of ACS patients, the incidence of AKI was high, the CCU mortality among the AKI patients was 25.7% compared with 6.12% in the non-AKI patients, and the mortality worsened with increasing severity of AKI.

How to cite this article:
Buargub M, Elmokhtar ZO. Incidence and mortality of acute kidney injury in patients with acute coronary syndrome: A retrospective study from a single coronary care unit. Saudi J Kidney Dis Transpl 2016;27:752-7

How to cite this URL:
Buargub M, Elmokhtar ZO. Incidence and mortality of acute kidney injury in patients with acute coronary syndrome: A retrospective study from a single coronary care unit. Saudi J Kidney Dis Transpl [serial online] 2016 [cited 2022 Sep 28];27:752-7. Available from: https://www.sjkdt.org/text.asp?2016/27/4/752/185238

   Introduction Top

Acute kidney injury (AKI) occurs in up to 18% of patients admitted to acute medical units and constitutes an independent risk factor of death when the renal replacement therapy is required. [1],[2] Even a minimal increase in serum creatinine (Cr) has been associated with an increased risk of end-stage renal disease and all-cause short and long-term mortality, regardless of whether partial or full recovery of renal function occurred at the time of discharge. [3],[4],[5]

Acute coronary syndrome (ACS) may induce AKI through various mechanisms, including impaired cardiac output, use of contrast media in percutaneous coronary intervention (PCI), and the nephrotoxic effect of drugs. It has been suggested that AKI is not only a marker of severity of the illness but is also a causal factor for acceleration of cardiovascular injury through the activation of neurohormonal, immunological, and inflammatory pathways. [6]

Around 20% of patients hospitalized with acute myocardial infarction in the USA will develop AKI, which can be partly or completely irreversible. [7] The available data indicate that a baseline Cr should be obtained early after admission for ACS and to be closely monitored during hospitalization, which allows early identification of patients at risk of AKI and permits the use of renal protective measures, such as, pre-procedural hydration, limiting contrast volume, use of iso-osmotic contrast agents, and avoiding nephrotoxic medications. [8],[9]

The aim of this retrospective observational study was to evaluate the incidence of AKI, its severity, and the short-term mortality in the coronary care unit (CCU) among ACS patients admitted to a CCU in Tripoli.

   Methods Top

Medical records of all adult patients admitted to the CCU at the Tajoura Cardiology Center, a Referral Cardiology Center in Tripoli, Libya, during the period from January 1, 2014, to December 31, 2014, were reviewed.

Patients were excluded if they were <16 years of age, had a past history of chronic kidney disease, or were admitted to the CCU for <24 h. Data collected included the patients' demographics, diagnosis on CCU admission, associated morbidities, and baseline laboratory data, treatment strategy (PCI), thrombolytic or conservative management, as well as CCU mortality. AKI was defined by either an absolute increase in serum Cr of more than 0.3 mg/dL or the percentage increase in serum Cr according to the AKI network diagnostic (AKIN) criteria. [10]

   Statistical Analysis Top

We used the Statistical Package for the Social Sciences software version 16.0 (SPSS Inc, Chicago, Il, USA). Continuous variables are demonstrated as mean (±standard deviation [SD]) and categorical variables as percentages. The baseline characteristics of the groups were compared using the Student's t-test and the Chi-square test for categorical variables. P was considered as statistically significant when <0.05.

   Results Top

The baseline data of the 84 patients admitted with ACS and were included in the study are shown in [Table 1]; their mean age was 57.6 ± 14.4 years (SD) (range from 16 to 91 years), 75% of them were males, and they were admitted to the CCU for a mean duration of 4.3 ± 3 days (SD). About 48.8% were smokers, 47.6% had a history of diabetes, 34.5% had hypertension, and 19% had ischemic heart disease (IHD). The other details are shown in [Table 1].
Table 1: Baseline clinical characteristics of the 84 study patients with acute coronary syndrome.

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[Table 2] shows the diagnosis and management of the 84 patients; 71.4% had ST-segment elevation myocardial infarction (STEMI), 22.6% had non-STEMI (NSTEMI), and 6% had unstable angina [Figure 1]. Around 15.5% had associated arrhythmia and 20.2% had coexistent acute decompensated heart failure (ADHF). Thrombolytic therapy was used in 51.7% of STEMI patients. PCI was performed in 41.7% of STEMI patients and 26.3% of NSTEMI patients.
Figure 1: Pie diagram showing: Graph 1, distribution of the study patients according to type of ACS and Graph 2, distribution of the study patients according to type of acute kidney injury.

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Table 2: Diagnosis, management, and outcome of the 84 studied patients with the acute coronary syndrome.

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By the AKIN criteria, 41.7% of the patients had AKI (19% had AKI Stage 1, 17.9% AKI Stage 2 and 4.8 % AKI Stage 3) [Figure 1]. The total CCU mortality was 15.5%; the mortality among patients with AKI was high (25.7%) and worsened with increasing severity of AKI (12.5% in AKI Stage 1, 33.3% in AKI Stage 2, and 50% in AKI Stage 3). None of the patients was treated with dialysis.

Comparison of the ACS patients with and without AKI [Table 3] showed statistically significant associations with the age of the patients; AKI patients were older with a mean age of 61.6 ± 15 years compared with 54.7 ± 13 years in the non-AKI group (P 0.031), they had lower mean arterial pressure (MAP) at admission (P = 0.008), their CCU stay was longer (P = 0.020), and they had more frequently coexisting ADHF (P = 0.007). The 25.7% CCU mortality in the AKI group was significantly higher compared with 6.12% in the non-AKI group (P = 0.014). There was no significant statistical association between AKI and the following: gender, history of hypertension, diabetes or IHD, type of ACS (STEMI/NSTEMI), use of thrombolytic therapy, or ACEI/ARB drugs.
Table 3: Comparison between acute kidney injury and nonacute kidney injury subgroups.

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   Discussion Top

Studies of the incidence of AKI and mortality rates in hospitalized patients have shown wide variations attributed to variations in the baseline characteristics of the patient cohorts, and the definition used for the diagnosis of AKI. [11] In this study, the incidence of AKI was 41.7% (19% Stage 1, 17.8% Stage 2, and 4.8% Stage 3), which was higher when compared with other studies that showed rates ranging from 8.7% to 31% [2],[3],[8],[12],[13] but was less than the 62% reported from an Intensive Care Unit in Morocco. [14]

In this study, AKI was significantly associated with the coexistence of ADHF (P = 0.007) which goes with the results from several studies in patients hospitalized for ADHF that have shown a high incidence of AKI (up to 70%) and poor outcomes in ADHF patients. [15],[16],[17] Contrast-induced AKI is the third most common cause of in-hospital AKI, [18] however, in this study, there was a significant association between PCI and the non-AKI group (P = 0.015), which may have been because of selection of younger and stable patients for PCI, while the association between smoking and non-AKI group (P = 0.043) may be explained by the higher percentage of males in the non-AKI group. ACEI/ARB use had no significant statistical association with AKI.

   Limitations of the study Top

Our study was a retrospective analysis with the following limitations:

  1. Data that could help us to decide which factor(s) contributed to AKI and mortality were missing including; the volume status of the patients on admission, the volume and type of contrast used in PCI, duration from the onset of ACS to the start of treatment, the time of onset of ACEI/ARB therapy in relation to the Cr rise (57% of the study patients were started on these medications while in the CCU)
  2. AKI incidence and mortality were limited to the duration of CCU stay. However, the change in serum Cr may not be apparent for a few days, for example, in contrast-induced AKI or in ACEI/ARB therapy which would underestimate the true AKI incidence
  3. We were not able to assess the long-term outcome or renal recovery.

Conflict of interest: None declared.

   References Top

Metnitz PG, Krenn CG, Steltzer H, et al. Effect of acute renal failure requiring renal replacement therapy on outcome in critically ill patients. Crit Care Med 2002;30:2051-8.  Back to cited text no. 1
Uchino S, Kellum JA, Bellomo R, et al. Acute renal failure in critically ill patients: A multinational, multicenter study. JAMA 2005;294:813-8.  Back to cited text no. 2
Mehta RL, Pascual MT, Soroko S, et al. Spectrum of acute renal failure in the intensive care unit: The PICARD experience. Kidney Int 2004;66:1613-21.  Back to cited text no. 3
Lassnigg A, Schmidlin D, Mouhieddine M, et al. Minimal changes of serum creatinine predict prognosis in patients after cardiothoracic surgery: A prospective cohort study. J Am Soc Nephrol 2004;15:1597-605.  Back to cited text no. 4
Lafrance JP, Miller DR. Acute kidney injury associates with increased long-term mortality. J Am Soc Nephrol 2010;21:345-52.  Back to cited text no. 5
Ronco C, Haapio M, House AA, Anavekar N, Bellomo R. Cardiorenal syndrome. J Am Coll Cardiol 2008;52:1527-39.  Back to cited text no. 6
Amin AP, Salisbury AC, McCullough PA, et al. Trends in the incidence of acute kidney injury in patients hospitalized with acute myocardial infarction. Arch Intern Med 2012;172:246-53.  Back to cited text no. 7
Marenzi G, Cabiati A, Bertoli SV, et al. Incidence and relevance of acute kidney injury in patients hospitalized with acute coronary syndromes. Am J Cardiol 2013;111:816-22.  Back to cited text no. 8
KDIGO clinical practice guideline for acute kidney injury. Kidney Int Suppl 2012;2:8-12.  Back to cited text no. 9
Mehta RL, Kellum JA, Shah SV, et al. Acute Kidney Injury Network: Report of an initiative to improve outcomes in acute kidney injury. Crit Care 2007;11:R31.  Back to cited text no. 10
Hoste EA, De Corte W. Epidemiology of AKI in the ICU. Acta Clin Belg 2007;62 Suppl 2:314-7.  Back to cited text no. 11
Fox CS, Muntner P, Chen AY, Alexander KP, Roe MT, Wiviott SD. Short-term outcomes of acute myocardial infarction in patients with acute kidney injury: A report from the national cardiovascular data registry. Circulation 2012;125:497-504.  Back to cited text no. 12
Kim MJ, Choi HS, Oh SH, et al. Impact of acute kidney injury on clinical outcomes after ST elevation acute myocardial infarction. Yonsei Med J 2011;52:603-9.  Back to cited text no. 13
Nechba RB, El M'barki KM, Mesfioui A, Zeggwagh AA. Epidemiology of acute kidney injury in Moroccan medical intensive care patients: A regional prospective, observational study. Sci J Public Health 2014;2:1-6.  Back to cited text no. 14
Samimagham HR, Kheirkhah S, Haghighi A, Najmi Z. Acute kidney injury in intensive care unit: Incidence, risk factors and mortality rate. Saudi J Kidney Dis Transpl 2011;22:464-70.  Back to cited text no. 15
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Barros LC, Silveira FS, Silveira MS, Morais TC, Nunes MA, Bastos Kde A. Acute kidney injury in hospitalized patients with decompensated heart failure. J Bras Nefrol 2012;34:122-9.  Back to cited text no. 16
Jose P, Skali H, Anavekar N, et al. Increase in creatinine and cardiovascular risk in patients with systolic dysfunction after myocardial infarction. J Am Soc Nephrol 2006;17:2886-91.  Back to cited text no. 17
James MT, Ghali WA, Knudtson ML, et al. Associations between acute kidney injury and cardiovascular and renal outcomes after coronary angiography. Circulation 2011;123:409-16.  Back to cited text no. 18

Correspondence Address:
Mahdia Buargub
Nephrology Unit, Tripoli Central Hospital, Tripoli
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1319-2442.185238

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  [Figure 1]

  [Table 1], [Table 2], [Table 3]

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