LATE THROMBOLYSIS FOLLOWED BY ANTITHROMBOTIC TREATMENT IN ACUTE MYOCARDIAL-INFARCTION - EFFECT OF THERAPY EVALUATED WITH TL-201 SPECT

Perfusion abnormalities and infarct size evaluated by thallium-201 SPECT after late thrombolysis followed by anti-thrombotic treatment in acute myocardial infarction were studied in 111 patients. Patients were prospectively randomized to a treatment group (n = 54) receiving streptokinase initiated 12-49 h after onset of symptoms, followed by heparin for at least 5 days and warfarin and dipyridamole for at least 3 months, or to a control group (n = 57) treated routinely without any of these drugs.Thallium-201 scintigraphy was performed within 3 months of follow-up in 40 (74%) of the patients in the treatment group and 46 (81%) in the control group. During a symptom-limited bicycle test the isotope was injected at peak exercise. SPECT was acquired 10 min later (exercise SPECT) and after 3 h (redistribution SPECT). A computerized quantitative analysis was performed. Defects were defined as regions with activity below 40% of the maximum. In the exercise SPECT defects were significantly smaller in the treatment group than among control patients (9±12% vs 15±15% of the left ventricle; P<0.05). The djfference was more apparent in patients with Q-wave than in those with non-Q-wave infarctions and the entire difference was accounted for by patients without a previous history of infarct or angina pectoris. There was no statistically significant difference in defect size in the redistribution SPECT (5±10% vs 9±11%, ns). Multiple defects (two or three defects) in the exercise SPECT were less prevalent in patients in the treatment group (15/40; 37%) than in the control group (29/46; 63%, P<0.05). For the redistribution SPECT the corresponding figures were 11/40 (28%) vs 23/46 (50%) (P=0.05).In conclusion, the extent and numbers of defects in exercise thallium-201 SPECT was reduced after late thrombolysis followed by antithrombotic treatment in patients with acute myocardial infaction. The results may indicate fewer perfusion abnormalities and/or a reduction in size of infarcted segments. © 1993 The Europen Society of Cardiology.