Evidence of myocardial ischaemia in patients with chest pain syndromes and normal coronary angiograms.

Patients with chest pain syndromes and normal coronary angiograms were studied with a new set of methods that included thermodilution coronary sinus blood flow and coronary dye dilution curves with special computer analysis, oxygen and lactate determinations, thallium scannings, atrial pacing and dipyridamole tests. The following observations and conclusions were made: Patients with cardiac hypertrophy have a reduced circulating coronary blood volume in relation to the left ventricular mass; this may play a role in patients' vulnerability to ischaemia. During pacing-induced angina a significant imbalance between oxygen supply and demand can be demonstrated in patients with "syndrome X". Dipyridamole-induced chest pain as a result of myocardial ischaemia seems to occur in patients with normal coronary arteries. Marked ischaemia evidenced by a regional intensity reduction of 25% or more in thallium scans results in a significant increase in coronary volume. This is obviously due to mobilization of reserve vasculature as a response to ischaemia. A reduction in the ratio of myocardial oxygen supply to demand was demonstrated even in connection with milder defects, the regional intensity reduction being as low as 12.5%.