| Abstract|| |
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 2021 Oct 18];27:752-7. Available from: https://www.sjkdt.org/text.asp?2016/27/4/752/185238
| Introduction|| |
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. , 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. ,,
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. 
Around 20% of patients hospitalized with acute myocardial infarction in the USA will develop AKI, which can be partly or completely irreversible.  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. ,
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|| |
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. 
| Statistical Analysis|| |
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|| |
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|| |
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.  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% ,,,, but was less than the 62% reported from an Intensive Care Unit in Morocco. 
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. ,, Contrast-induced AKI is the third most common cause of in-hospital AKI,  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|| |
Our study was a retrospective analysis with the following limitations:
- 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)
- 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
- We were not able to assess the long-term outcome or renal recovery.
Conflict of interest: None declared.
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Nephrology Unit, Tripoli Central Hospital, Tripoli
[Table 1], [Table 2], [Table 3]