Ever since Cannon and Epstein1 coined the term “microvascular angina” to describe syndrome X in 1988, the theory that a significant proportion of patients with syndrome X have microvascular dysfunction that leads to ischaemia, ST-depression, and chest pain has dominated the field of syndrome X research. This is surprising in view of the fact that the studies looking at the presence of ischaemia and microvascular dysfunction are poorly conducted and have inconsistent results. Despite publication bias, there are numerous negative studies demonstrating the lack of ischaemia in syndrome X patients when compared to controls. Indeed when Cannon himself did a well conducted study into microvascular dysfunction and found negative results, he concluded that invasive measurements of endothelium-dependent and endothelium-independent agonists is unlikely to be of value …