[Deviation of activated partial thromboplastin time from optimal level after 12 hours of intravenous infusion of unfractionated heparin -- an independent predictor of recurrence and unfavorable 30-day prognosis in patients with myocardial infarction].

Aim of the study was to assess significance of deviations of activated partial thromboplastin time (APTT) from optimal level (50-75 sec) after 48 hours of intravenous infusion of unfractionated heparin (UFH) in streptokinase treated patients with myocardial infarction (MI) for prognosis of nonfatal reinfarction and cumulative criterion comprising cardiac death, nonfatal MI and early postinfarction angina. Infusion of streptokinase (1,500,000 U in 30-60 min) was carried out after loading dose of aspirin (250 mg) and intravenous bolus (5,000 U) of UFH in 75 patients (age 34-76 years) admitted within 6 hours after onset of acute ST-elevation MI. UFH infusion was started prior to termination of administration of streptokinase and continued for 48 hours. During first 12 hours infusion rate was 1,000 or 800 U/hour in patients with body mass > or = 80 and < 80 kg, respectively. During initial 12 hours infusion rate was corrected if at 6 hours APTT was less than 40 or exceeded 150 sec. After 12 hours a nomogram was used for UFH dose adjustment according to APTT. Maximal number of optimal APTT values during UFH infusion just reached 50%. During first 12 hours prevailed values above 75 sec, after 24 and 36 hours -- values below 50 sec. Deviation of APTT from optimal level in 12 hours after onset of UFH infusion was the only independent predictor of nonfatal recurrent MI during following 30 days (relative risk [RR] 9.01, 95% confidence interval [CI]1.1 to 77.2; p=0.043). Independent predictors of cumulative criterion were level of risk of death according to TIMI scale (RR 1.47, 95% CI 1.-3 to 2.11; p=0.036) and deviation of APTT from optimal level in 12 hours after onset of UFH infusion (RR 3.24, 95%CI 1.05 to 10.5; p=0.046). It should be noted that rather than suboptimal excessive hypocoagulation by 12th hour of UFH infusion was associated with worse prognosis. APTT levels in 6, 24, and 36 hours of UFH infusion had no prognostic significance in relation to events assessed in the study.