Besides the EDICA trial, iSCOR is being evaluated in other clinical conditions to further validate its potential application in the management of cardiac ischemia
Patients with typical stable angina who have no obstructive coronary artery disease (NOCAD) at angiography constitute a heterogeneous group of patients. Most of these patients show coronary microvascular dysfunction (CMD) potentially responsible for myocardial ischemia and angina symptoms, thus defining primary stable microvascular angina (MVA).
The demonstration of myocardial ischemia in these patients is challenging. The ischemic origin of MVA is suggested by the occurrence of typical ischemic ECG alterations during exercise stress test or during normal daily activities on ambulatory ECG Holter recordings. Moreover, reversible defects of myocardial perfusion on stress scintigraphy, compatible with myocardial ischemia, are detectable in more than half of the patients.
There is a patchy distribution of ischemic regions dispersed within the myocardium and surrounded by normally perfused myocardium that makes difficult to detect metabolic and functional myocardial alterations in patients with MVA during ischemia.
Beside the scattered distribution of coronary microvascular dysfunction, the difficulty in demonstrating myocardial ischemia in MVA patients may also include the inappropriateness of the ischemic stimuli, the limitations of contemporary technics in detecting minor degrees of ischemia and the variable mechanisms of coronary microvascular dysfunction.
Diagnosing cardiac ischaemia remains a challenge. Assays for cardiac-specific troponin are the gold standard test to diagnose non-ST-segment elevation myocardial infarction. However, some patients present with troponin-negative chest pain and are discharged from hospital without invasive investigation for coronary artery disease (CAD), being re-admitted within a few weeks later with a definite acute myocardial infarction (AMI).
Tests for CAD in patients without AMI are more contentious and diagnostic pathways in stable coronary disease are less well-defined. CAD diagnostic method uses pre-test probability considerations before determining which non-invasive or invasive investigation should be carried out (exercise stress test, stress echocardiography, CT coronary angiography (CTCA), myocardial perfusion imaging (MPS), or invasive coronary angiography).
Some of these tests have low sensitivity and specificity. This may result in underdiagnosis and missed therapeutic opportunities as well as unnecessary extra tests and anxiety.
Moreover, other tests use ionising radiation, which carries risk, pharmacological stressors that can cause arrhythmias, and/or contrast agents that pose risks of allergy and nephropathy.
