Chronic kidney disease as a risk factor for acute coronary syndromes in patients presenting to the emergency room 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.

Interpretation of positive troponin results among patients with and without myocardial infarction

Measuring cardiac troponins is integral to diagnosing acute myocardial infarction (AMI); however, troponins may be elevated without AMI, and the use of multiple different assays confounds comparisons. We considered characteristics and serial troponin values in emergency department chest pain patients with and without AMI to interpret troponin excursions. We compared serial troponin in 124 AMI and non-AMI patients from the observational Performance of Triage Cardiac Markers in the Clinical Setting (PEARL) study who presented with chest pain and had at least one troponin value exceeding the 99th percentile of normal. Because 8 assays were used during data collection, we employed a method of scaling the troponin value to the corresponding assay's 99th percentile upper reference limit to standardize the results. In 81 AMI patients, 96% had elevated troponin at the first test following initial elevation, compared to 73% of the 43 non-AMI patients (P < 0.001). Scaling troponin to the 99th percentile of normal yielded a median value that was 4.8 [2.2, 14.1] times higher than the 99th percentile cutpoint among AMI patients, compared to 2.3 [1.5, 6.5] times higher among non-AMI patients (P = 0.04). The rise in serial scaled troponin values distinguished the AMI patients. Scaling to the 99th percentile was useful for comparing troponin when different assays were utilized.

Relationship between coronary artery disease and C-reactive protein levels in NSTEMI patients with renal dysfunction: a retrospective study

BACKGROUND

While chronic renal damage is a condition with low-grade inflammation, the potential role of inflammation in kidney disease as a marker of cardiovascular damage is of current interest. This study analyzed the relationship between renal dysfunction, chronic inflammation, and extension of coronary atherosclerosis in patients with non-ST-segment elevation myocardial infarction (NSTEMI).

METHODS

This retrospective study was carried out on consecutive patients presenting with NSTEMI to Maggiore Hospital's emergency department between January 1, 2010 and December 31, 2011. Patients' electronic charts were reviewed to gather information on patients' history, clinical and biochemical variables, with a special focus on inflammatory markers, coronary vessel damage, and drug treatments.

RESULTS

Of the 320 individuals in the study population, 138 (43.1%) had an admission GFR <60 mL/min/1.73 m2. Kidney dysfunction was significantly associated with age (OR = 1.09, 95% CI 1.06 to 1.12), history of heart failure (OR = 2.13, 95% CI 1.08 to 4.17), and hypertension (OR = 2.31, 95% 1.12 to 4.74). C-reactive protein (CRP) and uric acid levels were significantly increased in patients with severe renal dysfunction (SRD) by bivariate and multivariate analyses, adjusted for gender, age and comorbidities at admission. The extent of coronary artery disease (CAD) was significantly higher in the SRD group (p < 0.001). Individuals with SRD were less likely to receive immediate evidence-based therapies (62.9% vs. 76.7% and 82.0% in those with intermediate and no/mild renal dysfunction, p < 0.001). Hospital stay was significantly longer in individuals with a greater extent of CAD, diabetes, and a history of heart failure, and was borderline significantly associated with renal dysfunction (p = 0.08). Older age, CAD severity, and renal function were associated with worsening GFR during hospitalization, whereas immediate evidence-based treatment was unrelated to a GFR change.

CONCLUSIONS

Among individuals hospitalized for NSTEMI, those with SRD had a more extensive CAD and a higher prevalence of pre-existing cardiovascular disease. CRP was positively correlated with renal dysfunction and the number of involved coronary vessels, confirming its potential as a biomarker. Uric acid was associated with renal dysfunction but not with the number of diseased coronary vessels.