Study shows high-sensitivity cardiac troponin I concentrations is an independent predictor of obstructive coronary artery disease in patients with suspected stable angina

Use of this test may improve the selection of patients for further investigation and treatment.

ALAMEDA, CA, February 28, 2018–Measurement of cardiac troponin I in stable patients with chest pain using the ultrasensitive Singulex cTnI assay and Single Molecule Counting technology can independently predict moderate and severe coronary artery disease (CAD), suggesting its clinical utility for accurate, safe, and cost-effective evaluation of patients in an outpatient setting, according to the findings of a study published in Circulation: Cardiovascular Quality and Outcomes (Feb 2018).

Most patients presenting with suspected stable angina do not ultimately have obstructive CAD identified as a cause for their symptoms. Despite this, current guideline-endorsed, risk-based approaches to the assessment of these patients result in the majority having to undergo noninvasive cardiac imaging tests to exclude this diagnosis. The SCOT-HEART (Scottish Computed Tomography of the Heart) trial showed that measuring cardiac troponin concentrations in patients with suspected stable angina using a simple blood test run on ultrasensitive Single Molecule Counting technology can safely increase the proportion of patients determined to be at low risk of CAD, reducing the need for more costly imaging investigations.

With up to 1000 times more sensitivity than existing technologies, Single Molecule Counting technology reveals the presence or absence of disease more clearly and definitively than was possible before. The Singulex cTnI assay, using proprietary Single Molecule Counting technology, is the first test to measure cardiac troponin down to femtogram per milliliter levels, far lower than existing high-sensitivity troponin immunoassays, enabling unprecedented insight into cardiovascular disease. The Singulex Clarity system and Singulex Clarity cTnI assay have the CE mark and are commercially available in Europe. The cTnI assay is currently indicated for use in ruling out cardiac ischaemia in patients with suspected CAD.

“There is widespread interest in, and recognized need to, improve diagnostic accuracy in patients with suspected stable coronary artery disease,” said Nicholas Mills, PhD, Consultant Interventional Cardiologist at the Royal Infirmary of Edinburgh, a British Heart Foundation Senior Clinical Research Fellow, and Professor of Cardiology at the University of Edinburgh and primary investigator. “A role may emerge for this most recent generation of ultra-sensitive cardiac troponin assay because it offers the ability to reliably measure troponin in the majority of the population. Testing has transformed the efficiency and safety of our assessment of patients with acute coronary syndrome and use of these assays is likely to have a similar impact in stable coronary artery disease.”

About SCOT-HEART
The SCOT-HEART trial was a prospective, multicenter, randomized controlled study of 4,146 patients recruited from 12 cardiology chest pain clinics across Scotland between 2010 and 2014. SCOT-HEART investigated the role of coronary computed tomographic angiography (CCTA) in patients referred to a specialist clinic with suspected stable angina.

Method and Findings
In a pre-specified sub study of the SCOT HEART trial, plasma cardiac troponin was measured using a high-sensitivity single-molecule counting assay in 943 adults with suspected stable angina who had undergone CCTA. Rates of obstructive CAD were compared with the pretest probability determined by the CAD Consortium (CADC) risk model with and without cardiac troponin concentrations. By including cardiac troponin, there was a net 10.5% reduction in the number of patients determined to be at intermediate or high risk according to the CADC model but without obstructive CAD on CCTA. Furthermore, higher cardiac troponin concentrations were associated with obstructive CAD with a 5-fold increase across quintiles (9%–48%; P<0.001), independent of known cardiovascular risk factors (odds ratio 1.35 per doubling of cardiac troponin). External validation was undertaken in an independent study population from Denmark comprising 487 patients with suspected stable angina.

Plasma concentrations of cardiac troponin I independently predict the presence of obstructive CAD in patients with suspected stable angina. The authors concluded that using this test within the chest pain clinic may improve the selection of patients for further investigation and treatment of CAD.

“This simple investigation has potential to improve the appropriate use of diagnostic imaging tests by reducing unnecessary testing in 1 in 10 patients without disease,” Dr. Mills concluded. “One notable strength of our study is that we use a troponin assay with exceptional analytic characteristics that was able to detect cardiac troponin concentrations in 99.6% of our population, and to accurately quantify cardiac troponin concentrations in 96.8% of patients.”

About Singulex
Singulex is an immunodiagnostics company at the forefront of Single Molecule Counting technology, a novel immunoassay technology recognized for unprecedented ultra sensitivity in the precision measurement of biomarkers. Singulex is the developer of the Singulex Clarity system, a fully-automated, in vitro diagnostics platform powered by Single Molecule Counting technology. In 2017, Singulex filed a 510(k)-pre-market notification submission with the U.S. Food and Drug Administration. The Singulex Clarity system and Singulex Clarity cTnI assay have the CE mark and are commercially available in Europe. Additional assays to detect and rule out infectious and inflammatory diseases are in development. Singulex is also developing a point-of-care platform and exploring applications beyond the clinical setting. For more information, please visit www.singulex.com or singulexclarity.eu.