Associations between High Sensitivity Troponin in the Emergency Department and Diagnosis of Myocarditis

Research Article

Austin J Clin Cardiolog. 2023; 9(2): 1106.

Associations between High Sensitivity Troponin in the Emergency Department and Diagnosis of Myocarditis

Giladi E1,3*#; Ratzon R2,3#; Arow Z1,3; Losin I1,3; Omelchenko A1,3; Pereg D1,3; Assali A1,3; Arnson Y1,3

¹Department of Cardiology, Meir Medical Center, Tel Aviv University, Tel Aviv, Israel

²Department of Emergency Medicine, Meir Medical Center, Kfar Saba, Israel

³Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel

*Corresponding author: Giladi Ela Department of Cardiology, Meir Medical Center, 59 Tshernichovsky, Kfar Saba, Israel. Tel: +972-9-7472587; Fax: +972-9-7472812 Email: elafi@clalit.org.il

#These authors contributed equally to this work.

Received: June 26, 2023 Accepted: July 25, 2023 Published: August 01, 2023

Abstract

Background: The diagnosis of myocarditis is challenging, and typically relies on clinical presentation, non-invasive imaging, and serum biomarkers. We examine if implementation of hsTnT has affected recognition of myocarditis and patient outcomes.

Methods: Retrospective analysis of >18-year-old patients diagnosed with myocarditis in Meir Medical Center since January 2000 to the end of April 2020. Patients were divided based on their diagnosis date - up to January 2014, for which there was a regular troponin test (REG group) and starting February 2014 for which there was a hsTnT test (HS group). We examined the difference in the rate of myocarditis diagnosis, mortality, and hospitalizations due to heart failure.

Results: We identified 262 patients who were diagnosed with myocarditis. There were no significant differences between the groups. After the implementation of hsTnT there was a two-fold increase in the diagnosis rate (0.0366 vs. 0.0625 cases per day; P<0.0001). The REG group presented with more ST changes (51% vs. 29%; p=0.006) and less cases of normal heart function (69% vs. 79%; P=0.048). There was a higher mortality rate in HS group (6 deaths vs. 2; p=0.011).

Conclusions: hsTnT test leads to increase in myocarditis diagnosis and allows for diagnosing more mild case.

Keywords: Myocarditis; Troponin; Diagnosis; Prognosis

Introduction

Myocarditis is a potentially life-threatening inflammatory condition of the myocardium which most often occurs secondary to an infection but can also be immune-mediated due to exposure to toxic substances. Myocarditis is an uncommon and likely underdiagnosed condition which presents with a wide range of cardiac and extra-cardiac symptoms [1,2]. The incidence of myocarditis is difficult to determine as Endomyocardial Biopsy (EMB), the diagnostic gold standard, is seldom used [3,4]. The Global Burden of Disease study reported an incidence of 22 cases of myocarditis per 100,000 patients based on International Classification of Diseases (ICD) codes on hospital discharge documentation between 1990 and 2013 [5].

Myocarditis prognosis is variable and varies by disease cause and severity. When complicated by Left Ventricular (LV) dysfunction, Heart Failure (HF) or arrhythmia it is associated with a poor prognosis [6]. Most of the available data relies on small series, animal experimental models and case reports [7,8].

Given the lack of consensus regarding the role of EMB and the excellent prognosis of patients with mild uncomplicated myocarditis, a recent agreement statement recommends that EMB be reserved for patients who are likely to have specific myocardial disorders associated with worse prognoses and specific treatment recommendations [9]. Cardiac troponins are sensitive of myocyte injury in patients with clinically suspected myocarditis. However, they are non-specific and when normal do not exclude myocarditis [10,11]. In the past few years, highly sensitive troponin tests allow detection of minimal increase in serum troponin levels and can possibly identify more patients with myocarditis. A small study by Ukena et al. demonstrated that high sensitive troponin-T (hsTnT) is a predictive marker for the diagnosis of acute myocarditis with a sensitivity of 83% and specificity of 80% using a cutoff of 50 ng/L [12].

Highly sensitive troponin test had become feasible at our medical center Since February 1st, 2014. The aims of this study were to detect trends in myocarditis diagnosis with the use of hsTnT, and to determine if different lab studies led to any difference in the clinical characterization and prognosis of the patients diagnosed with myocarditis.

Methods

Study Design

A retrospective single center cohort study. The cohort included patients newly diagnosed with acute myocarditis at Meir Medical Center between January 1st, 2000, and April 30th, 2020. The source of data was Meir Medical Center's computerized records which contain all the medical information, including imaging studies, obtained during an emergency room visit, hospital admissions and outpatient follow-up. Potentially eligible patients were identified by screening for patients with an ICD-9 diagnosis or an imaging report of myocarditis. Eligibility criteria were age 18 years or older and newly diagnosed myocarditis with a positive troponin test. Patients younger than 18 and those with missing data were censored from the cohort.

Clinical diagnosis of acute myocarditis was based on constellation of signs and symptoms, Electrocardiogram (ECG) findings and cardiac biomarkers typically seen in myocarditis, with exclusion of acute coronary syndrome.

All relevant cases were manually retrieved and examined. Baseline characteristics collected were demographic data, lab studies including baseline troponin, cardiovascular risk factors (diabetes mellitus, hypertension, dyslipidemia and smoking), presenting symptoms and vital signs at admission (Table 1). Positive troponin tests were defined as >0.1 mg/L (100 ng/L) for the "regular" troponin test (REG group) and >14 ng/L (0.014 mg/L) for the hsTnT test (HS group).