HIGH-DOSE BOLUS HEPARIN AS INITIAL THERAPY BEFORE PRIMARY ANGIOPLASTYFOR ACUTE MYOCARDIAL-INFARCTION - RESULTS OF THE HEPARIN IN EARLY PATENCY (HEAP) PILOT-STUDY

Objectives. We sought to determine the effect of high dose intravenous bolus heparin on early coronary patency before primary angioplasty. B ackground. Early coronary angiography after thrombolysis for acute myo cardial infarction has shown better patency when intravenous heparin i s used as an adjunct. The present study explores whether heparin alone can induce reperfusion. Methods. In the Heparin in Early Patency (HEA P) pilot study, 108 patients,vith signs and symptoms of acute myocardi al infarction <6 h eligible for primary angioplasty received a single intravenous bolus of 300 U/kg of heparin together with aspirin (160 mg chewed) in the emergency room. The median dose of bolus heparin given was 27,000 U. Patency of the infarct related artery (IRA) was assesse d by coronary angiography at a median of 85 min after the heparin bolu s, Results. In 55 patients (51%, 95% confidence interval 38% to 64%), Thrombolysis in Myocardial Infarction (TIMI) flow grade 2 or 3 was obs erved at 90 min: TIMI flow grade 3 in 33 patients (31%); TIMI flow gra de 2 in 22 (20%). Thirty-two (64%) of 50 patients with symptoms less t han or equal to 2 h had TIMI bow grade 2 or 3 versus 23 (40%) of 58 pa tients with symptoms >2 h (p = 0.02). No significant bleeding was seen . Two patients (2%) died in the hospital. The patency results obtained in patients treated with the high dose bolus heparin were compared wi th those in 108 patients from a large primary angioplasty database, wh o were treated with standard therapy, including aspirin but not intrav enous heparin, and were matched for clinical and angiographic characte ristics with the HEAP pilot study patients, They showed an 18% patency rate (p < 0.001) of the IRA (TIMI flow grade 3 in 9%, TIMI flow grade 2 in 9%) before primary angioplasty. Conclusions. Early therapy with high dose heparin is associated with full coronary reperfusion in a co nsiderable number of patients with acute myocardial infarction, especi ally in those treated early (<2 h). This simple, inexpensive, probably safe and easily antagonizable treatment may be an attractive first tr eatment of acute myocardial infarction both before and during the hosp ital stay in conjunction with primary angioplasty. (C) 1998 by the Ame rican College of Cardiology.