Stress-induced ischaemia in patients with ischaemic heart disease
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.