Interpretation of Serial hsTn in Patients With Suspected ACS

Abstract and Introduction

Abstract

Graphical Abstract

Diagnostic and prognostic interpretation of serial measurement of high-sensitivity cardiac troponin. The figure illustrates the complexity and overlapping nature of current probabilistic algorithms such as the ESC 0/1 h algorithm,^[8] purely diagnostic criteria such as the Fourth Universal Definition of MI^[14] based on the 99th percentile upper reference limit (URL), and focused prognostic assessment that considers both mortality and other cardiovascular events.^[9] The green and red zones reflect higher confidence regarding the definitive exclusion of myocardial injury or identification of acute or chronic myocardial injury, respectively. The yellow zone reflects intermediate probability and criteria that can overlap with the green or red zone depending on the concentration. ^aVery low probabilistic threshold to exclude myocardial infarction (MI) (e.g. from the ESC 0/1 h algorithm). ^bValues <99th percentile URL do not meet criteria for acute myocardial injury but can establish a gradient of risk for future events, with patients overlapping the ESC 'observe' zone having intermediate probability of a final diagnosis of MI. ^cESC 'observe' zone includes values both above and below the 99th percentile URL but below the ESC 'rule in' threshold, and identifies patients with an intermediate probability of a final diagnosis of MI (prevalence 22.5%^[5]) and cardiovascular events through 30 days. ^dThis cohort of patients meet diagnostic criteria for myocardial injury but may overlap with the ESC observe zone. The diagnosis of myocardial infarction is made when acute myocardial injury is in the setting of myocardial ischaemia.

Introduction

Accumulating evidence demonstrates short- and long-term prognostic information offered by serial measurement of high-sensitivity cardiac troponin (hsTn) over varying intervals across a spectrum of cardiovascular diseases, including suspected acute coronary syndromes (ACS), chronic coronary syndromes, heart failure, and atrial fibrillation.^[1–4] In both acute and chronic settings, hsTn concentration not only reflects acute injury but is also associated with risk factors for epicardial and microvascular coronary artery disease and the presence of structural cardiac abnormalities. Thus, hsTn concentration integrates both characteristics of the individual as well as the presence of acute and chronic cardiac disease, and persistent elevation may reflect both chronic and acute contributors to risk.

Algorithms leveraging early serial measurement of hsTn and criteria for dynamic changes have shown both excellent diagnostic and short-term prognostic performance in patients with suspected ACS.^[5–8] In this issue of the European Heart Journal, Pareek and colleagues extend this evidence with a large retrospective observational cohort study of the relationship between serial hsTnT values and 1-year outcomes in patients presenting with suspected ACS.^[9] In a novel approach, they report calculated absolute and relative risks from regression modelling standardizing for a broad group of patient characteristics, including age, sex, cardiovascular history, and renal function. Their report delivers several valuable 'take-home' points for clinical practice. However, some conclusions come with a high level of uncertainty and warrant substantial caution in their interpretation for current clinical practice.