Steve Parker of Quantum Imaging comments on Journal of American Cardiology

Steve Parker of Quantum Imaging comments on a paper in the Journal of American College of Cardiology’s (JACC) on whether the use of high-sensitivity troponin will increase the frequency of MI diagnoses.

 

A paper recently published in the Journal of American College of Cardiology (JACC) illustrates the  challenges associated with the increasing use of high-sensitivity troponin tests in the diagnosis and detection of acute cardiac events in emergency departments.

 

Cardiac troponin is a protein released into the blood when there is physical damage to the heart muscle itself. While troponin is a very effective way of identifying cardiac cell damage and it has a role to play in detecting heart attacks and the whole range of Acute Coronary Syndromes (ACS), the challenge comes when smaller and smaller amounts of the protein are identified. High-sensitivity troponin tests are undoubtedly more specific, but they begin to identify trace amounts of the protein that may be present naturally in a person’s body. The JACC paper cites that approximately 10% of men over 65 years would test positive for troponin when they had no cardiac event symptoms. Given people in this age range are more likely to come to hospital complaining of chest pain and the fact that they are likely to have troponin occurring naturally, there is likely to be an increasing number of false positive troponin tests. Once a patient has received a positive troponin result they must be thoroughly investigated, meaning longer hospital stays, unnecessary therapies and investigation. This ultimately results in adding further strain and expense to already overstretched healthcare systems.

Cardiac troponin tests have an important place alongside all of the other tools available to a physician in the emergency detection of acute coronary events. But, as more and more sensitive tests become available, there is a corresponding increase in the need for tools to identify the false positives from the system. That’s where Magnetocardiography (MCG), the technology utilised by Quantum Vitalscan, comes in as it has the potential capability to identify these ‘false positive’ patients as well as those identified at initial triage, quickly, safely  and reliably in a simple, fast and non-invasive test.

Troponin tests are a ‘rule in’ test, meaning that a negative troponin test cannot rule out unstable angina, or an early evolving heart attack before any muscle damage can be detected (because troponin only appears in the blood several hours after the onset of heart damage). A positive test, regardless of whether the levels represent natural cell demise or a potential cardiac event, requires thorough investigation which means longer hospital stays and additional tests to be carried out on potentially healthy patients. Whether positive or negative, it is clear that troponin tests, including high-sensitivity tests, are not accurate enough to be used in isolation.

MCG, however, is a ‘rule out’ test. This means it looks for normal (non ischemic) heart function and can do so with near 100% accuracy. It ‘rules out’ cardiac-related problems and therefore enables non-cardiac patients to be identified quickly, potentially saving hospitals valuable time and resources. Where normal heart function is not detected, patients can then go on to be tested using ‘rule in’ tests, such as troponin to determine the specific problem and subsequent treatment. MCG is not a replacement for troponin tests, but it helps to support ‘rule in’ tests by ensuring that patients with normal heart function are identified early and not sent for these types of test. We believe that this will reduce the additional financial burden due to levels of false positive troponin tests because those with normal heart function would not be tested in the first place.

High sensitivity troponin tests do represent a significant technological milestone in the diagnosis and management of cardiac events. The JACC paper states that this technological advancement will likely increase the frequency of correct diagnosis and make more efficient the care of some heart-related problems. It believes that the implications for the entire health care system must be considered because the identification of elevated troponin levels from conditions other than heart-related problems will also increase, with the potential to increase subsequent testing and prolong inpatient care. That is why we believe that MCG as found in Quantum Vitalscan will be a key tool to work in conjunction with other tests to ensure that heart problems are diagnosed and detected as accurately as possible, potentially helping to save lives.

’Will the use of high-sensitivity troponin increase the frequency of diagnosis of MI?’ was published on the American College of Cardiology’s website in June 2016 by Purav Mody MD and James A. de Lemos MD. It is available to read in full here.