RELATION BETWEEN ACTIVATED CLOTTING TIME DURING ANGIOPLASTY AND ABRUPT CLOSURE

Background The purpose of this study was to determine whether the degr ee of heparin anticoagulation during coronary angioplasty, as measured by the activated clotting time, is related to the risk of abrupt vess el closure. Methods and Results Sixty-two cases of in- and out-of-labo ratory abrupt closure in patients in whom intraprocedure activated clo tting times were measured were identified from a population of 1290 co nsecutive patients who underwent non-emergency coronary angioplasty. T his group was compared with a matched control population of 124 patien ts who did not experience abrupt closure. Relative to the control popu lation. patients who experienced abrupt closure had significantly lowe r initial (median, 350 seconds [25th to 75th percentile, 309 to 401 se conds] versus 380 seconds [335 to 423 seconds], P=.004) and minimum (3 45 seconds [287 to 387 seconds] versus 370 seconds [321 to 417 seconds ], P=.014) activated clotting times. Higher activated clotting times w ere not associated with an increased likelihood of major bleeding comp lications. Within this population, a strong inverse linear relation ex isted between the activated clotting time and the probability of abrup t closure. Conclusions This study demonstrates a significant inverse r elation between the degree of anticoagulation during angioplasty and t he risk of abrupt closure. A minimum target activated clotting time co uld not be identified; rather, the higher the intensity of anticoagula tion, the lower the risk of abrupt closure.