Determinants of Reversible Asynergy

Abstract

To determine which factors may be of value in determining whether or not asynergic zones have residual contractile ability, the responsiveness of these zones to sublingual nitroglycerin (1/150 grs) was studied angiographically in 36 patients. The responsiveness of asynergy was correlated with the presence or absence of pathologic Q waves and coronary collaterals in the corresponding zones, as well as with anatomic location. Of the 25 asynergic segments which had corresponding pathologic Q waves, 11 (44.0%) responded to nitroglycerin while 14 (56%) remained unresponsive. In contrast, 30 (83.3%) of the 36 segments which did not have associated Q waves improved while only 6 (16.4%) did not (P < 0.005). Akinetic segments with Q waves were associated with a significant decrease in responsiveness (P < 0.02) compared to hypokinetic segments. Of the 26 segments with angiographically demonstrable collaterals, 22 (84.6%) improved and only 4 (15.4%) remained unchanged (P < 0.02). In contrast, of the 35 segments without collaterals, 19 (54.3%) were responsive and 16 (45.7%) did not respond. Seven (77.8%) of the 9 akinetic segments with collaterals exhibited improvement compared to only 5 (33%) of the 15 segments without collaterals (P < 0.05). In segments with pathologic Q waves, 70% of those associated with collaterals improved compared to only 27% without collaterals (P < 0.02). Relative to anatomic location, of 29 anterior wall segments, 24 (82.8%) responded compared to only 11 (45.8%) of 24 apical segments (P < 0.005). These data indicate that the presence of coronary collaterals and absence of pathologic Q waves in the corresponding zones are associated with a higher incidence of residual contractile ability of asynergic segments. Apical asynergy responds less frequently than asynergy in other anatomic zones.