The ischaemic cascade¹ describes the temporal sequence of pathophysiological events initiated by an imbalance between myocardial oxygen supply and demand. Depending on severity and duration, an ischaemic episode may manifest as metabolic disturbance, mechanical dysfunction, electrical changes, angina pectoris or, ultimately, as myocardial infarction. Although being the primary sequelae of coronary artery disease (CAD), quantitative relationships between myocardial perfusion changes and their consequences such as metabolic, mechanical or electrical dysfunction are not well defined. In particular, the existence of an absolute perfusion threshold preventing short-term ischaemia has not been investigated so far.

Percutaneous coronary intervention (PCI) provides an elegant model to deal with this issue in patients with CAD. During angioplasty, myocardial blood supply is diminished below normal depending on the collateral supply from adjacent vascular regions. Absolute perfusion or myocardial blood flow (MBF, ml/min/g) can be obtained from positron emission tomography and, of late, from myocardial contrast echocardiography (MCE).² However, only MCE is applicable during PCI owing to its mobility and short acquisition time.

Our study aimed to determine the absolute perfusion threshold that prevents myocardial ischaemia using MBF measurements by contrast echocardiography during angioplasty in humans.

METHODS

Twenty eight consecutive patients with stable CAD eligible for PCI …