High-Sensitive Troponin Measurement in Emergency Department Patients Presenting with Syncope: A Retrospective Analysis

Utility of serial troponin testing for emergency department patients with syncope

BACKGROUND

For emergency department (ED) patients with syncope, cardiac troponin can identify acute coronary syndrome (ACS) and prognosticate for 30-day serious adverse events. However, it is unclear if serial testing improves diagnostic yield and prognostication.

METHODS

This was a secondary analysis of data from two prospective studies conducted to develop the Canadian Syncope Risk Score. Adults (age ≥ 16 years) with syncope were enrolled, and patient characteristics, vital signs, physician diagnostic impression, electrocardiogram and troponin results, and adjudicated 30-day serious adverse event were collected. The primary outcome was the detection of a serious adverse event within 30 days of ED disposition. The secondary outcome was comparison of ED length of stay among patients with single versus serial troponin measurements.

RESULTS

4996 patients [mean age 64.5 (SD 18.8) years, 52.2% male] were included: 4397 (89.8%) with single troponin [232 (5.3%) with serious adverse event in the ED and 203 (4.6%) after ED disposition]; 499 (10.2%) patients with > 1 troponin measurement [39 (7.8%) with serious adverse event in ED and 60 (12.0%) after ED disposition]. Among those with serial measurements, 10 patients (2.0%) had a rise from below to above the 99th percentile threshold, of whom 4 patients (0.8%) suffered serious adverse event: two with arrhythmias diagnosed on electrocardiogram, one with ACS and one suffered respiratory failure. Nine patients (1.8%) had Canadian Syncope Risk Score risk reclassification based on serial measurement, and none suffered 30-day serious adverse event. Median ED length of stay was significantly longer for patients with serial testing (5.6 vs. 3.8 h, p < 0.001).

CONCLUSIONS

The initial troponin measurement was sufficient for serious adverse event detection and in-ED risk stratification. Serial troponin testing does not improve the diagnostic yield or prognostication and should be reserved for patients with ongoing symptoms or electrocardiogram findings suggestive of cardiac ischemia.

Review article: Utility of troponin after syncope: A systematic review and meta-analysis

The role of serum troponin testing in patients presenting to the ED after syncope is unclear. The aim of this systematic review was to examine the practice and utility of troponin testing among patients presenting to the ED after syncope. We conducted a search of MEDLINE, Embase, Cochrane Library, Web of Science and Scopus databases from 1990 to February 2017 using keyword and subject headings for syncope and troponin testing. Design and results of the included studies are extracted. Studies were assessed for heterogeneity and the pooled proportion of measured troponin and positive troponin result described. There were nine studies included for analysis. Significant statistical heterogeneity among studies was observed (P < 0.001). Using the random effects model, the pooled proportion of patients presenting to the ED after syncope who had troponin measured was 0.64 (95% CI 0.46-0.82). Among patients who had been troponin tested, the pooled proportion who had a positive result was 0.19 (95% CI 0.13-0.26). Variability among reported outcomes prevented further meta-analysis. Troponin testing was commonly performed for the assessment of patients with syncope with a substantial proportion returning positive results. The correlation between raised troponin and patient outcomes was not adequately reported. It is possible that an elevated troponin may indicate serious illness, rather than myocardial damage alone.

Prognostic value of cardiac biomarkers in the risk stratification of syncope: a systematic review

The role of cardiac biomarkers in risk stratification of syncope is unclear. We undertook a systematic review to assess their predictive value for short-term major adverse cardiovascular events (MACE). We conducted a systematic review using MEDLINE, EMBASE, DARE and Cochrane databases from inception to July 2014. We included studies involving adult syncope patients that evaluated cardiac biomarker levels for risk stratification during acute management and excluded case reports, reviews and studies involving children. Primary outcome (MACE) included death, cardiopulmonary resuscitation, myocardial infarction (MI), structural heart disease, pulmonary embolism, significant hemorrhage or cardiac procedural interventions. Secondary outcome analysis assessed for prediction of MI, cardiac syncope and death. Two reviewers extracted patient-level data based on the cut-off reported. Pooled sensitivities and specificities were calculated using patient-level data. A total of 1862 articles were identified, and 11 studies with 4246 patients were included. Studies evaluated 3 biomarkers: contemporary troponin (2693 patients), natriuretic peptides (1353 patients) and high-sensitive troponin (819 patients). The pooled sensitivities and specificities for MACE were: contemporary troponin 0.29 (95 % CI 0.24, 0.34) and 0.88 (95 % CI 0.86, 0.89); natriuretic peptides 0.77 (95 % CI 0.69, 0.85) and 0.73 (95 % CI 0.70, 0.76); high-sensitive troponin 0.74 (95 % CI 0.65, 0.83) and 0.65 (95 % CI 0.62, 0.69), respectively. Natriuretic peptides and high-sensitive troponin showed good diagnostic characteristics for both primary and secondary outcomes. Natriuretic peptides and high-sensitive troponin might be useful in risk stratification.

Syncope: the emergency department and beyond

Syncope is a common problem encountered by both emergency and internal medicine physicians. This review focuses on not only the assessment, risk stratification and management of the syncope patient, but also the latest thinking on diagnostic testing including more novel tools such as biomarkers and ambulatory patch monitor recording.

Diagnostic and prognostic value of high-sensitivity cardiac troponin T in patients with syncope

OBJECTIVE

We examined the diagnostic and predictive value of high-sensitivity cardiac troponin T (cTnThs) in patients with syncope.

METHODS

We performed an analysis of consecutive patients with syncope presenting to the emergency department. The primary end point was the accuracy to diagnose a cardiac syncope. In addition, the study explored the prognostic relevance of cTnThs in patients with cardiac and noncardiac syncope.

RESULTS

A total of 360 patients were enrolled (median age, 70.5 years; male, 55.8%; 23.9% aged >80 years). Cardiac syncope was present in 22% of patients, reflex syncope was present in 40% of patients, syncope due to orthostatic hypotension was present in 20% of patients, and unexplained syncope was present in 17.5% of patients. A total of 148 patients (41%) had cTnThs levels above the 99% confidence interval (CI) (cutoff point). The diagnostic accuracy for cTnThs levels to determine the diagnosis of cardiac syncope was quantified by the area under the curve (0.77; CI, 0.72-0.83; P < .001). A comparable area under the curve (0.78; CI, 0.73-0.83; P < .001) was obtained for the predictive value of cTnThs levels within 30 days: Patients with increased cTnThs levels had a 52% likelihood for adverse events, patients with cTnThs levels below the cutoff point had a low risk (negative predictive value, 83.5%). Increased cTnThs levels indicate adverse prognosis in patients with noncardiac causes of syncope, but not in patients with cardiac syncope being a risk factor for adverse outcome by itself.

CONCLUSIONS

Patients with syncope presenting to the emergency department have a high proportion of life-threatening conditions. cTnThs levels show a limited diagnostic and predictive accuracy for the identification of patients with syncope at high risk.