Impact of renal dysfunction on acute coronary syndrome evaluation in observation unit patients

Prevalence and Significance of Renal Dysfunction Among Emergency Department Observation Patients With Chest Pain

OBJECTIVES

Previous studies have demonstrated increased risk of acute coronary syndrome among patients with chest pain and renal dysfunction. The objective of this study was to investigate the impact of renal dysfunction on cardiac outcomes in patients with chest pain in an emergency department observation unit (EDOU).

METHODS

We conducted a 5-year prospective evaluation of patients evaluated in the EDOU for chest pain. We collected baseline information and data from the emergency department visit, EDOU stay, inpatient admission, and the 30-day period after presentation to the emergency department. We calculated glomerular filtration rate (GFR) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. We stratified patients as having mild (GFR 60-89 mL/min per 1.73 m) or at least moderate (GFR <60) renal dysfunction. We evaluated the rate of major adverse cardiac events (MACE: myocardial infarction, stent, coronary artery bypass graft, and death).

RESULTS

Of 1067 enrolled EDOU patients, the majority had at least mild renal dysfunction: 39% [95% confidence interval (95% CI): 36.1%-42%] had a GFR between 60 and 89, and 16% (95% CI: 14%-18.4%) had a GFR <60. MACE rates increased with decreasing GFR: 3.3% (95% CI: 2.1%-5.3%) for GFR ≥90, 7.3% (95% CI: 5.2%-10.2%) for GFR 60-89, and 9.1% (95% CI: 5.7%-14.3%) for GFR <60 (P = 0.005). In multivariate analysis, patients with at least mild renal dysfunction (GFR < 90) were at greater risk of MACE (P = 0.028).

CONCLUSIONS

We noted a high prevalence of renal dysfunction among EDOU patients evaluated for chest pain. Even those with mild renal dysfunction demonstrated an increased risk of MACE. Clinicians may wish to consider renal dysfunction in selecting appropriate patients for EDOU placement.

Provocative biomarker stress test: stress-delta N-terminal pro-B type natriuretic peptide

Objective

Stress testing is commonly performed in emergency department (ED) patients with suspected acute coronary syndrome (ACS). We hypothesised that changes in N-terminal pro-B type natriuretic peptide (NT-proBNP) concentrations from baseline to post-stress testing (stress-delta values) differentiate patients with ischaemic stress tests from controls.

Methods

We prospectively enrolled 320 adult patients with suspected ACS in an ED-based observation unit who were undergoing exercise stress echocardiography. We measured plasma NT-proBNP concentrations at baseline and at 2 and 4  hours post-stress and compared stress-delta NT-proBNP between patients with abnormal stress tests versus controls using non-parametric statistics (Wilcoxon test) due to skew. We calculated the diagnostic test characteristics of stress-delta NT-proBNP for myocardial ischaemia on imaging.

Results

Among 320 participants, the median age was 51 (IQR 44-59) years, 147 (45.9%) were men, and 122 (38.1%) were African-American. Twenty-six (8.1%) had myocardial ischaemia. Static and stress-deltas NT-proBNP differed at all time points between groups. The median stress-deltas at 2  hours were 10.4 (IQR 6.0-51.7) ng/L vs 1.7 (IQR -0.4 to 8.7) ng/L, and at 4  hours were 14.8 (IQR 5.0-22.3) ng/L vs 1.0 (-2.0 to 10.3) ng/L for patients with ischaemia versus those without. Areas under the receiver operating curves were 0.716 and 0.719 for 2-hour and 4-hour stress-deltas, respectively. After adjusting for baseline NT-proBNP levels, the 4-hour stress-delta NT-proBNP remained significantly different between the groups (p=0.009).

Conclusion

Among patients with ischaemic stress tests, static and 4-hour stress-delta NT-proBNP values were significantly higher. Further study is needed to determine if stress-delta NT-proBNP is a useful adjunct to stress testing.

Impaired renal function is associated with adverse outcomes in patients with chest pain discharged from internal medicine wards

BACKGROUND

Assessment of chest pain is one of the most common reasons for hospital admissions in internal medicine wards. However, little is known regarding predictors for poor prognosis in patients discharged from internal medicine wards after acute coronary syndrome (ACS) rule-out.

OBJECTIVE

To assess the association of kidney function with mortality and hospital admissions due to ACS in patients with chest pain who were discharged from internal medicine wards following ACS rule-out.

METHODS

Included were patients admitted to an internal medicine ward who were subsequently discharged following an ACSrule-out during 2010-2016. The primary endpoint was the composite of all-cause mortality and hospital admission due to ACS at 30-days following hospital discharge.

RESULTS

Included in the study were12,337 patients who were divided into 3 groups according to renal function. Considering patients with an eGFR ≥ 60 ml/min/1.73m² as the reference group yielded adjusted hazard ratios for the composite of 30-day all-cause mortality and hospital admission for ACS that increased with reduced eGFR (HR = 2, 95%CI = 1.3-3.3, HR = 4.8, 95%CI = 3-7.6, for patients with eGFR of 45 to 59.9 or <45 ml/min/1.73m², respectively, p < 0.001). Similarly, reduced renal function was associated with increased 1-year all-cause mortality (HR = 1.6, 95%CI = 1.2-2.2, HR = 4.5, 95%CI = 3.4-5.9, for patients with eGFR of 45-59.9 or <45 ml/min/1.73m², respectively, p < 0.001).

CONCLUSION

We found an independent graded association between lower eGFR and the risk of death and ACS among patients with chest pain who were discharged from internal medicine wards following an ACS rule-out. The eGFR may be combined in the risk stratification of patients with chest pain.

Novel Emergency Department Risk Score Discriminates Acute Coronary Syndrome Among Chest Pain Patients With Known Coronary Artery Disease

BACKGROUND

Patients with known coronary artery disease presenting to the emergency department (ED) with chest pain are often admitted, yet may not be having an acute coronary syndrome (ACS).

METHODS

We assessed whether the use of a novel risk score and a modified thrombolysis in myocardial infarction risk score obtained in the ED could discriminate which of these high-risk patients have ACS. Chart review was performed on a cohort of 285 patients with known coronary artery disease presenting to the ED with chest pain thought to be of ischemic origin and admitted to the hospital. The ED variables were assessed with logistic regression for their association with eventual ACS diagnosis at hospital discharge. ACS was diagnosed in 74 (26%) of the patients.

RESULTS

Non-ACS patients had a 2-day median length of stay and $6875 median inpatient (post ED) hospital charges (not including physician fees), totaling 566 hospital bed days and $1,871,250 for the 211 (74%) non-ACS patients. A novel risk score, including (1) history of prior revascularization, (2) comorbid chronic kidney disease, (3) onset of chest discomfort at rest, (4) dynamic electrocardiogram changes in the ED, (5) elevated troponin I (>0.05 ng/mL) in the ED, and (6) associated illness at presentation, discriminated ACS and non-ACS with a c statistic of 0.767; the c statistic for a modified thrombolysis in myocardial infarction risk score was 0.712.

CONCLUSIONS

Application of these risk scores may reduce the number of potentially avoidable admissions and their associated hazards and costs.