Unfractionated heparin (UFH) plasma protein binding and elimination might be impaired in patients with chronic kidney disease (CKD-defined as creatinine clearance <60 ml/min). It is currently unknown at which UFH bolus dose persistent prolongation of activated partial thromboplastin time (aPTT) occurs in ST-segment elevation myocardial infarction (STEMI) patients with CKD. We investigated the effect of different UFH bolus doses on the first aPTT measured within 6 and 12 h after PPCI in 1071 STEMI patients with and without CKD undergoing primary percutaneous coronary intervention (PPCI) between 1-1-2003 and 31-07-2008. In the first 6 h after PPCI, aPTT ratio was 5.1 for patients with CKD versus 3.4 for those without (p < 0.001). The proportion of patients with markedly high aPTTs (aPTT ratio ≥ 4 times control) increased with increasing heparin bolus and beyond 130 IU/kg there was a marked difference between patients with and without CKD (74.1 and 42.3 % respectively, p < 0.001). By multivariable analysis, CKD was associated with an increased risk of markedly high aPTTs (odds ratio (OR) 2.04; 95 % confidence interval (CI) 1.27-3.27), driven largely by an increased risk of aPTT prolongation in patients treated with UFH boluses ≥130 IU/kg (OR 3.69; 95 % CI 1.85-7.36; p for interaction = 0.009). In conclusion, CKD is associated with severe persistent aPTT prolongation in STEMI patients undergoing PPCI, possibly due to impaired plasma protein binding and reduced UFH elimination. A lower heparin bolus dose might result in lower aPTTs and less bleeding complications in patients with CKD undergoing PPCI.
Keywords: Acute myocardial infarction; Chronic kidney disease; Hemorrhage; Percutaneous coronary intervention; Unfractionated heparin.