Regional myocardial ischaemia is commonly expressed as exertional angina in patients with stable coronary artery disease (CAD). It also associates with prognosis, risk tending to increase with the severity of ischaemia. The validity of myocardial ischaemia as a surrogate for adverse clinical outcomes, however, has not been well established. Thus, in cohort studies, ischaemia testing has failed to influence rates of myocardial infarction and coronary death. Moreover, in clinical studies, pharmacological and interventional treatments that are effective in correcting ischaemia have rarely been shown to reduce cardiovascular (CV) risk. This contrasts with statins and other anti-inflammatory drugs that have no direct effect on ischaemia but improve CV outcomes by modifying the atherothrombotic disease process. Despite this, and with little evidence of patient benefit, stress testing is commonly used during the follow-up of patients with stable CAD when the demonstration of ischaemic change may be seen as a target for treatment, independently of symptomatic status. Substitution of a symptom-driven management strategy has the potential to reduce rates of non-invasive stress testing, unnecessary downstream revascularisation procedures and use of valuable resources in patients with stable CAD without adverse consequences for CV risk.
Strange times indeed: the evolving significance of myocardial ischaemia and the dwindling importance of functional imaging
