Modification of the Outcome of Coronary Thrombo-Embolism by Low and High-Dose Aspirin
Previous work in this laboratory has shown that an occlusive thrombus (O.T.) induced in the left anterior descending coronary artery (L.A.D.) of dogs, by the placement of a segment of magnesium-aluminum wire (M.A.W.) in the lumen of the artery, is associated, with the development of full thickness infarct (F.T.I.). Incomplete (mural) thrombus is associated with focal areas of ischaemic damage, mainly sub-endocardial, in the myocardium of the antero-lateral left ventricle. A 1.0 cm. length of M.A.W., shaped in the form of a tennis racquet, was placed by cardiac catheterization in the proximal L.A.D. of 30 mongrel dogs. Ten dogs received low dose aspirin (L.D.A.); (14 or 29 mgm/Kg daily in a single dose). Ten dogs received high dose aspirin (H.D.A.); (100 mgm/Kg daily in divided doses). Treatment was begun one day before operation and continued until death or killing. Ten control dogs received no drug. All control dogs died within 3 days of operation. Five had O.T. and F.T.I. The remainder showed focal ischaemic myocardial damage. None of the L.D.A. group died. At autopsy 3 or 4 days after operation, none had O.T. or F.T.I. In the H.D.A. group 3 died; 4 had O.T. and F.T.I. Thus L.D.A. provided significant protection from death, O.T., and F.T.I. H.D.A. provided some (P<0.005) but less protection from death but did not significantly affect the incidence of O.T. or F.T.I Supported by Ontario Heart Foundation Grant T15-7.