Risk Factors for Acute Kidney Injury in Patients with Acute Myocardial Infarction
Acute kidney injury (AKI) is a severe and often fatal complication of acute myocardial infarction (AMI), associated with high short- and long-term mortality rates and poor prognosis. Despite its potentially preventable nature, the incidence, risk factors, and outcomes of AKI in the Chinese population remain poorly understood. This study aims to fill this gap by identifying high-risk patients who could benefit from preventative care.
The study reviewed the medical data of 1124 hospitalized patients diagnosed with AMI from October 2013 to September 2015. AKI was defined according to the 2012 Kidney Disease Improving Global Outcomes (KDIGO) criteria. Patients were divided into either the AKI group or the non-AKI group. A univariate comparison analysis was performed to identify possible risk factors associated with AKI, followed by a multiple logistic regression analysis to determine independent risk factors.
The overall incidence of AKI was 26.0%. The mortality rate in the AKI group was significantly higher at 20.5%, compared to 0.6% in the non-AKI group. Logistic regression analysis identified several independent risk factors for AKI in patients with AMI: age over 60 years, hypertension, chronic kidney disease (CKD), Killip class ≥3, extensive anterior myocardial infarction, use of furosemide, and non-use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEI/ARB). These factors provide a reliable tool for identifying patients at high risk of developing AKI.
The study found that 26.0% of patients undergoing AMI developed AKI, with a strong correlation between AKI development and in-hospital mortality. The risk factors identified can help clinicians make appropriate clinical decisions and improve patient outcomes.
Introduction
Acute kidney injury (AKI) is a complex disorder triggered by various medical conditions and is generally associated with a poor prognosis. In the United States, the morbidity of AKI has increased from 3/1000 to 5/1000 over the past decades. In China, the situation is equally serious, with 1.4 to 2.9 million patients diagnosed with AKI in 2013 alone, resulting in an estimated medical cost of 13 billion US dollars. Both studies correlated AKI with significant in-hospital mortality.
Acute myocardial infarction (AMI) is one of the critical conditions that trigger AKI, due to comorbid factors, hemodynamic instability, and the use of nephrotoxic medicines. The incidence of AKI during hospitalization in patients with AMI ranges from 7.1% to 29.3%, and it exceeds 50% when AMI is complicated by cardiogenic shock. Patients with AMI and AKI have a 20- to 40-fold higher mortality rate compared to those without AKI. They also experience more long-term complications, including recurrent AMI, heart failure, chronic kidney disease progression, and long-term mortality.
Methods
This retrospective study was approved by the Ethics Committee of Peking University People’s Hospital. Clinical data were collected from 1145 consecutive hospitalized patients diagnosed with AMI in Peking University People’s Hospital and Beijing Jishuitan Hospital between October 2013 and September 2015. The exclusion criteria included incomplete baseline clinical information, death or discharge within 48 hours of admission, complication of septic shock, and prior diagnosis of end-stage renal disease. The final study population included 1124 patients.
AMI was diagnosed based on classical history of chest pain, diagnostic electrocardiographic changes, serial elevation of serum cardiac biomarkers, and wall motion abnormalities on an ultrasonic cardiogram. AKI was defined according to the KDIGO criteria. Cardiac function was classified based on the Killip classification, and left ventricular ejection fraction (LVEF) was assessed within the first 24 hours of hospitalization. In-hospital mortality and length of hospital stay were documented. Comprehensive baseline demographic information, initial vital signs, laboratory tests, and use of medications were reviewed.
Statistical analysis was performed using SPSS 21.0 software. Continuous variables were compared using independent sample t-tests, and categorical data were compared using the Chi-square test or Fisher exact test. Logistic regression analysis was used to identify independent predictors of AKI. A P-value of less than 0.05 was considered statistically significant.
Results
The baseline clinical characteristics of the patients with and without AKI are listed in Table 1. Compared with the non-AKI group, the AKI group was older, more likely to be female, had more comorbidities, and had lower baseline eGFR and higher levels of serum creatinine (SCr), troponin I (TNI), brain natriuretic peptide (BNP), C-reactive protein (CRP), and fasting blood glucose. The AKI group used less ACEI/ARB and statins but received larger doses of diuretics than the non-AKI group. The AKI group also had a higher Killip class and was more likely to have extensive anterior myocardial infarction. The need for coronary artery bypass grafting (CABG) and pacemaker was significantly higher in the AKI group, but in-hospital percutaneous coronary intervention (PCI) was relatively lower.
In our study, 292 (26.0%) patients developed AKI during hospitalization, including 134 (11.9%) with stage 1, 102 (9.1%) with stage 2, and 56 (5.0%) with stage 3 diseases. The length of hospital stay was longer in the AKI group (20 days vs. 12 days), and mortality was higher (20.5% vs. 0.6%). There was a stepwise increase in mortality according to AKI severity (8.2%, 24.5%, and 42.9% from stages 1, 2, and 3, respectively).
Risk factors for AKI were identified through logistic regression analysis. Age over 60 years, hypertension, CKD, Killip class ≥3, extensive anterior myocardial infarction, use of furosemide, and non-use of ACEI/ARB were significant independent risk factors. A risk score for AKI was developed based on these factors, which had good discriminatory capacity and calibration.
Discussion
The study confirmed AKI as a common, serious, and fatal complication of AMI. The incidence of AKI in AMI was 26.0%, with significantly higher mortality rates in patients with AKI. The risk factors identified, including age, hypertension, CKD, Killip class ≥3, extensive anterior myocardial infarction, use of furosemide, and non-use of ACEI/ARB, provide a theoretical basis for prevention and treatment.
Age is an independent risk factor for AKI, likely due to renal atherosclerosis and decreased kidney reserve capacity in elderly patients. CKD is another significant risk factor, with patients with CKD having a 3.52 times higher incidence of AKI. Killip class ≥3 and extensive anterior myocardial infarction are associated with hemodynamic disorders, increasing the risk of cardiogenic shock and acute heart failure, which can lead to renal ischemia and AKI.
The use of furosemide is a risk factor for AKI, as high doses can cause agitation of the sympathetic nervous system and renin-angiotensin system (RAS), leading to decreased renal perfusion. Conversely, ACEI/ARB may be protective against AKI, although its use in patients with AMI-induced AKI remains controversial.
The risk score developed in this study can help emergency physicians identify high-risk patients earlier, allowing for interventions to reduce renal injury and improve outcomes. However, the study has limitations, including its retrospective nature, lack of long-term prognosis data, and absence of information on contrast material volume.
In conclusion, AKI is a perilous and common complication in patients with AMI, associated with adverse in-hospital outcomes. Identifying risk factors and developing a predictive score can aid in early identification and management of high-risk patients, potentially improving outcomes.
doi.org/10.1097/CM9.0000000000000293
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