Original Paper Cerebrovasc Dis 2014;37:460–469 DOI: 10.1159/000363616

Received: November 7, 2013 Accepted: May 15, 2014 Published online: July 26, 2014

The Risk of Ischemic Stroke after an Acute Myocardial Infarction in Patients with Decreased Renal Function Stina Jakobsson Anna Graipe Daniel Huber Fredrik Björklund Thomas Mooe Department of Public Health and Clinical Medicine, Östersund, Umeå University, Umeå, Sweden

Key Words Ischemic stroke · Myocardial infarction · Chronic kidney disease

Abstract Background: Data on the incidence, trends over time and predictors of ischemic stroke after an acute myocardial infarction (AMI) are sparse for patients with chronic kidney disease (CKD). Methods: Data for unselected AMI patients were obtained from the Swedish Register of Information and Knowledge about Swedish Heart Intensive Care Admissions (RIKS-HIA) between 2003 and 2010. Patients with and without CKD were compared. Multiple logistic regression was performed to identify predictors of ischemic stroke during the hospitalization for AMI, Kaplan-Meier analysis was used to analyze the 1-year postdischarge ischemic stroke trends over time and Cox regression analysis was used to identify predictors. Results: Of 118,434 AMI patients, 40,679 had CKD. The CKD patients had more extensive previous cardiovascular disease and received less reperfusion and secondary preventive therapies than the patients without CKD. An inhospital ischemic stroke occurred in 2.3 and 1.2% of CKD and non-CKD patients, respectively. The incidence of ischemic stroke during hospitalization for AMI was stable during

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the study period. The occurrence of ischemic stroke after hospital discharge decreased between 2003–2004 and 2009–2010 from 4.1 to 2.5% in CKD patients and from 2.0 to 1.3% in non-CKD patients, respectively. Percutaneous coronary intervention (PCI) and statins were independently associated with a reduced risk of stroke after discharge from hospital. Conclusions: Ischemic stroke is a more common complication after an AMI in CKD patients than in non-CKD patients, but the risk has decreased in recent years. The increased use of PCI and statins may have contributed to this reduction. © 2014 S. Karger AG, Basel

Introduction

It is well known that patients with chronic kidney disease (CKD) have an increased risk of cardiovascular disease [1–4]. Furthermore, patients with decreased renal function who suffer an acute myocardial infarction (AMI) have a higher risk of adverse outcomes [5–9]. However, the risk of an ischemic stroke following an AMI in patients with CKD has been poorly investigated. An ischemic stroke is a devastating event with a high mortality rate and a large cost for society [10–16]. Stina Jakobsson Department of Public Health and Clinical Medicine, Umeå University Storgatan 42, 4 tr SE–83130 Östersund (Sweden) E-Mail stina.jakobsson @ medicin.umu.se

In the general population, atrial fibrillation (AF) is one of the most important risk factors for ischemic stroke [17]. Prediction of stroke risk in AF patients has been extensively explored. The dramatically increased risk of ischemic stroke soon after an AMI [15, 18] cannot be explained by the presence of AF, but may be related to changes in the function of platelets, fibrinolysis or coagulation possibly associated with renal function [19]. Few of the studies evaluating the risk of stroke after an AMI have investigated decreased renal function as a potential risk factor. When CKD was considered, most studies did not analyze ischemic and hemorrhagic stroke separately, were performed in selected patient populations or else used different estimates of renal function. To the authors’ knowledge, no previous study has calculated an estimated glomerular filtration rate (eGFR) according to current guidelines [20]. Although CKD is very common [21], particularly in the setting of an AMI [5, 22], little is known about the risk of ischemic stroke in an unselected AMI population treated in coronary care units (CCUs). Our hypothesis was that the risk of an ischemic stroke is increased in CKD patients after an AMI. The aim of this study was therefore to address knowledge gaps by examining the incidence of ischemic stroke during the initial hospitalization and within 1 year after discharge in an AMI population treated in CCUs, stratified by the presence of CKD estimated according to the guidelines. Furthermore, we aimed to analyze temporal trends in the occurrence of ischemic stroke between 2003 and 2010 in this population and identify the predictors for an increased or decreased risk of ischemic stroke.

Materials and Methods The Swedish Web-system for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated according to Recommended Therapies (SWEDEHEART) is a national quality register that includes the Register of Information and Knowledge about Swedish Heart Intensive Care Admissions (RIKS-HIA), from which patient data were obtained. All patients registered with a first-time AMI were eligible for inclusion. In 2008, all 74 Swedish hospitals with CCUs participated in the register, covering almost 100% of CCU admissions [23]. Patient data are reported on caserecord forms that include over 100 variables that are recorded upon hospital admission, inhospital and at discharge. The validity of the entered data is examined annually and there is >95% conformity between the RIKS-HIA data and patient records [23]. The criteria for AMI are standardized according to the European Society of Cardiology/American College of Cardiology/American Heart Association consensus documents [24, 25].

Risk of Stroke after AMI in CKD

Of the 126,822 patients experiencing an AMI for the first time during the period 2003–2010, 118,434 (93.4%) had a recorded inhospital creatinine value and were included in the analysis. In the register, physicians were instructed to enter the inhospital creatinine value that would best reflect the patient’s underlying renal function. The eGFR was calculated with the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine equations [26]. It was assumed that patients were Caucasian. The CKD-EPI formula is recommended by recent guidelines [20]. The National Kidney Foundation’s defined stages of CKD were used [27]. The presence of CKD was defined as an eGFR 10% of the data missing [BMI, systolic blood pressure, diastolic blood pressure, cholesterol, low-density lipoprotein (LDL) and glucose levels]. In the final model, a backward stepwise elimination was

Cerebrovasc Dis 2014;37:460–469 DOI: 10.1159/000363616

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Table 1. Baseline patient characteristics

eGFR ≥90 n = 24,271

eGFR 60 – 89 n = 53,484

eGFR 30 – 59 n = 33,104

eGFR 15 – 29 n = 5,740

eGFR

The risk of ischemic stroke after an acute myocardial infarction in patients with decreased renal function.

Data on the incidence, trends over time and predictors of ischemic stroke after an acute myocardial infarction (AMI) are sparse for patients with chro...
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