Acute Coronary Syndrome vs Nonspecific Troponin Elevation

Abstract

Background: Although troponin is considered a specific marker for the diagnosis of acute coronary syndrome (ACS), recent studies have shown troponin elevation in a variety of nonischemic conditions. Our aim was to determine the predictors for the diagnosis of ACS in the presence of an abnormal troponin level.Methods: All patients with abnormal troponin T levels were analyzed. Demographic and clinical data were collected and death was recorded. The study group was divided into 2 subgroups: ACS vs nonthrombotic troponin elevation. A multivariate logistic regression analysis was performed to define variables that predict the diagnosis of ACS. The positive predictive value (PPV) for ACS diagnosis was calculated, and a survival analysis was performed.Results: During the study period, 615 patients had elevated troponin T levels. Only 326 patients (53%) received a main diagnosis of ACS, while 254 (41%) had nonthrombotic troponin elevation; for 35 patients (6%), the diagnosis was not conclusive. Positive predictors for the diagnosis of ACS were age between 40 and 70 years, history of hypertension or ischemic heart disease, normal renal function, and a troponin T level higher than 1.0 ng/ mL. The overall PPV of troponin T for ACS diagnosis was only 56% (95% CI, 52%-60%). The PPV of troponin T level higher than 1.0 ng/mL in the presence of normal renal function was 90% but was as low as 27% for values of 0.1 to 1.0 ng/mL for elderly patients with renal failure. In-hospital and long-term survival rates were significantly better (PϽ.001) for patients with ACS.Conclusions: Nonspecific troponin elevation is a common finding among hospitalized patients and correlates with worse prognosis. The diagnosis of myocardial infarction should still mostly be based on the clinical presentation. The predictors and algorithm suggested in this study might increase the diagnostic accuracy of ACS and direct the appropriate treatment.

A Review of Causes and Systemic Approach to Cardiac Troponin Elevation

“…The predictors that can help rule in or rule out the diagnosis of ACS in the presence of an elevated Tn level are age, hypertension, and history of ischemic heart disease, renal function, and a maximal cTn level. 52 These predictors can increase diagnostic accuracy and guide the appropriate treatment.The high early and late mortality rate among the patients with non-ACScTn elevation indicates that Tn level serves as an indicator of a critical state in a noncardiac condition. 17 …”

“…age 40-70 years, history of hypertension or ischemic heart disease, normal renal function, anda cTn level >1 ng/mL favors ACS, extreme age (<40 y, >80 y) and impaired renal function favors non-ACScTn elevation. 52 A diagnosis of MI requires combination of clinical history, ECG changes, Tn increase, and/or a new wall-motion abnormality on echocardiogram or nuclear scan showing new loss of viable myocardium. A Tn elevation should be divided into ACS and non-ACS based on clinical history and available diagnostic tools.…”

False Positive Troponin – A True Problem

“…The overall PPV of cTnT for ACS diagnosis was only 56% (95% CI, 52%-60%). The PPV of cTnT level >1,000 ng/L in the presence of normal renal function was 90%, but was as low as 27% for values of 100 -1,000 ng/L for elderly patients with renal failure (42). Thus, the rate of »FP« in terms of AMI directly depends upon the cTn cut-off value used.…”

“…Cardiac troponin is often (but erroneously) considered a specific marker for the diagnosis of ACS (42). The tissue specificity of cardiac cTn should not be confused with specificity for the mechanism of injury (e.g., AMI vs. myocarditis) (43,44).…”

A Hypertrophic Cardiomyopathy-associated MYBPC3 Mutation Common in Populations of South Asian Descent Causes Contractile Dysfunction

“…Moreover, HCM is the most frequent cause of acute cardiac arrest in young people (1). In particular, mutations in the MYBPC3 gene are responsible for ϳ40% of all HCM cases (2,3). MYBPC3 encodes the thick filament protein cardiac myosin binding protein-C (cMyBP-C).…”