Article, Cardiology

Hazards with ordering troponin in patients with low pretest probability of acute coronary syndrome

a b s t r a c t

Background: In clinical practice, we progressively rely on biomarkers, without estimating the pretest probability. There is not enough support for the use of cardiac troponin (cTn) I in the management of noncardiac patients. We studied the rate at which this test was ordered, the prevalence of detection of a positive result in noncardiac patients, and the impact of this incidental finding on clinical management.

Methodology: Patients admitted from December 2011 to 2013 to our community hospital with diagnosis of non- cardiac disease who had positive cTn were included. Data collected included final diagnosis, patient disposition, cardiac monitoring, cardiology consult, and cardiac biomarker testing.

Results: Cardiac troponin I was ordered for 1700 patients in our emergency department. Seven hundred fifty pa- tients had a positive cTn. Of the 750 patients, 412 had a positive cTn without any clinical suspicion of an acute coronary syndrome. An incidental finding of a positive cTn leads to ordering of cTn on average 4 times during ad- mission, cardiac monitoring of 379 (91.99%) patients for at least 1 day, and a cardiac consultation for 268 (63.65%) of these patients. None of these patients was candidates for an invasive Cardiac intervention. Seventy-eight (19.17%) patients were admitted to the cardiac care unit and subsequently transferred to the medical intensive care unit.

Conclusions: A positive cTn in patients diagnosed with a nonacute coronary syndrome was associated with in- creased cardiac biomarker testing, Telemetry monitoring, and cardiology consults. This study supports adherence to national guidelines for the use of cTn, to reduce hospital cost and resource utilization.

(C) 2015

Introduction

Despite the widespread use of various highly sensitive tests for the detection of Myocardial necrosis, acute coronary syndrome (ACS) re- mains a clinical diagnosis [1]. It is important to understand under what circumstances it is appropriate to order cardiac troponin (cTn). This test is most useful in confirming ACS, only when strong clinical sus- picion is present [2]. Cardiac Troponin testing is often used to determine the presence of cardiac ischemia in patients hospitalized primarily with a Noncardiac diagnosis. Although a positive cTn in noncardiac disease is predictive of higher mortality and major adverse cardiovascular events [3], there are little data to support the use of cTn as a tool to guide clinical management of Non-ACS cases. Until further data are available on how this test alters patient management, it is not recommended to regularly order cTn during the initial workup of nonischemic condi- tions [4-6]. The additional cardiac testing and the costs associated with an incidental finding of a positive cTn testing have not been

* Corresponding author at: Emergency Department, New York Medical College, Metro- politan Hospital, 1901 1st Ave, New York, NY 10029. Tel.: +1 212 423 6262.

E-mail address: [email protected] (G.W. Hassen).

studied extensively in patients with a noncardiac diagnoses. In this study, we sought to determine how often cTn was ordered in our com- munity hospital and the incidental finding of a positive cTn in nonischemic patients. In those patients who had a positive cTn, it was investigated whether there was a change in their clinical management as a result of cTn testing. We assessed the impact of a positive cTn on subsequent cTn testing, cardiology consults, and cardiac monitoring. The intent and goal of this study were to assess the prevalence of an incidental finding of a positive cTn in noncardiac patients with Low pretest probability of coronary artery disease and the impact of the above finding on ensuing clinical management, while the patient was hospitalized. We hypothesized that routine cTn testing and their subse- quent results do not positively impact the quality of care in non-ACS cases but may adversely affect overall care and resource utilization.

Methods

Retrospective reviews of 1700 electronic patient charts were used to identify patients with an abnormal cTn (>= 0.06 ng/mL, institutional value). Patients who presented with typical, atypical, or an angina equivalent as well as patients with ACS as a primary or secondary

http://dx.doi.org/10.1016/j.ajem.2015.06.006

0735-6757/(C) 2015

S. Talebi et al. / American Journal of Emergency Medicine 33 (2015) 12581260 1259

Table

Demographics and clinical data of patients with abnormal troponin

Troponin Sex Age Abnormal cTn (ng/dL) Length of hospital stay

Total abnormal

Abnormal in non-ACS cases

Female

Male

Max

Min

Avg

Max

Min

Avg.

Max

Min

Avg

750

412

189

223

103

21

65

13

0.06

0.2

90

1

7

Abbreviations: Max, maximum; Min, minimum; Avg, average.

diagnosis upon discharge and an abnormal electrocardiogram were ex- cluded from this study. Finally, we only included the patients who based on the latest guidelines did not have any indication for ordering a cTn. Information about demographic, clinical presentation, downstream car- diac testing, change in clinical management based on the cardiology consult, patient disposition, and length of hospital stay was obtained from patients’ charts (Table). A change in clinical management was defined as the addition of medication, cardiac Stress testing before dis- charge, or cardiac catheterization. No attempt was made to evaluate outcomes in this limited study.

Results

Cardiac troponin I was ordered for 1700 patients in the emergency department (ED) over the 24-month period of the study. Of this popu- lation, cTn was positive in 750 patients (44.11%). Of the 750 patients for whom cTn testing was positive, 412 patients (24.23%) did not have any clinical diagnosis of ACS during admission or upon discharge. This latter subgroup was the focus of our study. The primary diagnosis in- cluded Hypertensive emergency (87, 21.11%), heart failure exacerbation (63, 15.29%), chronic kidney disease (51, 12.37%), syncope (28, 6.79%), septic shock (26, 6.31%), asthma or chronic obstructive pulmonary disease exacerbation (24, 5.82%), infections (cellulitis, pneumonia, and

pyelonephritis) (24, 5.82%), tachycardia (20, 4.85%), acute abdomen

(20, 4.85%), gastrointestinal bleeding (15, 3.64%), stroke (14, 3.39%),

rhabdomyolysis (13, 3.15%), alcohol intoxication or withdrawal (8, 1.94%), seizure (8, 1.94%), pulmonary embolism (6, 5.35%), and cardiac arrest (5, 1.21%). Cardiac troponin was measured 4 times on average during the hospital stay, and 268 (65%) patients received a cardiology consult. Based on the cardiology consult, aspirin was started for 65 (15.75%) patients, and no patient was a candidate for inpatient cardiac stress testing or invasive cardiac intervention. Seventy-eight (18.93%) patients were initially admitted in the coronary care unit and subse- quently transferred to the medical intensive care unit because the first diagnosis was not cardiac. Three hundred seventy-nine patients (91.99%) were monitored for at least 1 day in a telemetry unit (Figure).

Discussion

Based on this limited study, we found a significant number of pa- tients with abnormal troponin levels in whom clinical suspicion of ACS did not exist. Physicians’ fear of litigation from a missed myocardial infarction along with the incidental abnormal Troponin elevation can lead to inappropriate subsequent testing, telemetry monitoring, un- necessary cardiology consultations, and admissions to the coronary care unit [7]. Cardiac troponin Testing was not associated with a change

Figure. Study flow diagram.

1260 S. Talebi et al. / American Journal of Emergency Medicine 33 (2015) 12581260

in cardiac management, assessed by the use of cardiac catheterization, stress testing, or the initiation of antiischemic medications. The above approach increases hospital costs with no improvement in patient care and exacerbates a well-known problem, ED overcrowding, and long waits. A study by Bernstein et al [8] recently reported that ED crowding contributed to a 5% higher chance of death, 1% longer hospital stay, and 1% higher cost per admission.

Troponin testing is only a helpful tool when appropriately ordered. The major challenge of properly ordering troponins in clinical practice is similar to that of ordering of a D-dimer test because an inappropriate request can lead to misinterpretation of the results [1]. Nonselective use of cardiac testing in patients without a clinical suspicion for cardiovas- cular disease not only leads to unnecessary testing but ultimately does not lead to a Change in management [9].

Proper use of Troponin tests requires a good history, physical exami- nation, appropriate laboratory tests, and electrocardiographic results. Overordering of cTn is of particular concern and should be addressed, as it will become more problematic in the near future with the introduc- tion of high sensitivity cardiac biomarkers [10]. However, abnormal tro- ponin levels are related to adverse outcomes, and larger prospective studies would be required to evaluate the short- and long-term outcomes based on an abnormal cTn in this cohort of patients.

References

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