REDUCTION OF THE MYOCARDIAL FRACTION OF C ARDIAC-OUTPUT IN RESPONSE TO VASODILATATION CAUSED BY DIPYRIDAMOLE IS A SIGN OF MULTIVESSEL CORONARY-ARTERY DISEASE

For noninvasive quatification of the myocardial perfusion reserve glob al myocardial Ti-201 uptake was estimated in 19 patients with ischemic heart disease. Ti-201 uptake (TU) was calculated at rest (TUR) and af ter intravenous dipyridamole (TUD). Relative perfusion reserve (PR) wa s calculated from the equation PR=(TUD-TUR) 100/TUR. Perfusion reserve was maximal in patients with 1 vessel disease, minimal in 2 vessel di sease and paradoxically negative both in patients with 3 vessel involv ement and with stenoses of left main coronary artery. Decrease in Ti-2 01 uptake caused by dipyridamole in patients with 3 vessel and left ma in disease probably reflected global myocardial ''coronary steal''. Ch anges of Ti-201 uptake in response to dipyridamole showed that myocard ial perfusion reserve diminished with increase in extent of coronary a therosclerosis. The reduction of Ti-201 uptake in response to dipyrida mole could be used as a sign of multivessel or left main coronary arte ry disease.