SUMMARY In this study, the interrelationship of regional myocardial perfusion at rest and after exercise, the presence, severity and reversibility of asynergy and the severity of the corresponding coronary arterial obstruction was examined. Forty-five patients underwent exercise testing with thallium-201, cardiac catheterization including intervention (nitroglycerin) ventriculography and coronary arteriography. Of the 45 patients, 13 were normal by catheterization while 32 had coronary heart disease (CHD). Of the 32 with CHD, 21 had asynergy and 11 had normal ventricular contraction. Eighteen of 21 patients with asynergy also had a myocardial perfusion abnormality after exercise, while only three of the 11 without asynergy had a perfusion abnormality (P < 0.001). Of the 21 hypokinetic zones, only 67% had a myocardial perfusion abnormality, while all of the akinetic and dyskinetic zones had a perfusion defect (P < 0.025).
Twenty-seven left ventricular zones demonstrated perfusion abnormalities after exercise, of which 19 had either normal or improved myocardial perfusion at rest. Fifteen of these 19 had reversible asynergy on nitroglycerin ventriculography while three had normal contraction. In contrast, the eight zones with myocardial perfusion defects, both at rest and with exercise, all had associated asynergy which was irreversible.
A significant relationship was also observed between the severity of the coronary arterial obstruction, asynergy and a perfusion abnormality. Thus, of 39 myocardial zones supplied by 2 90% coronary arterial lesions, 24 had asynergy and 21 of these also had a corresponding myocardial perfusion defect. However, of the remaining 15 without asynergy, only three had a perfusion abnormality (P < 0.001). In addition, of 17 zones subserved by coronary vessels having 75-89% obstructive lesions, three of seven with asynergy had an associated perfusion abnormality, while none of the 10 without asynergy had a perfusion defect (P < 0.025).
In summary, the findings of the present study indicate that there is a close interrelationship between the severity of a coronary arterial obstruction and both decreased regional myocardial perfusion and contraction in man. Myocardial perfusion, which is adequate at rest but abnormal with stress, is associated with less severe and reversible asynergy, while perfusion, which is abnormal even at rest, appears to be associated with more severe and irreversible asynergy.