A systematic review including 12 studies with a total of 26,831 subjects was abstracted in DARE. Enoxaparin was statistically superior to placebo regarding medium-term death, reinfarction and angina rate in 2 RCTs. It was also superior to UFH for in-hospital and medium-term occurrence of death, reinfarction and angina in 2 RCTs. Study results varied regarding IRA patency rates. One trial reported a higher incidence of intracranial haemorrhage, twice that obtained with UFH. One RCT found that dalteparin was superior to placebo on left ventricular thrombosis and arterial thromboembolism on day 9, with no effects on the reinfarction or mortality rates; however, dalteparin was associated with a higher risk of major and minor bleedings. A second RCT found no significant effect on Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow in the infarct related artery (IRA), but TIMI 0 to 3 flow and its combination with intraluminal thrombus were significantly less frequent in the dalteparin group; the rate of clinical events were also lower in the dalteparin group compared with placebo. Compared with UFH, dalteparin had no significant effect on clinical events and on the IRA late patency, but less thrombus.
A systematic review including 6 RCTs with a total of 1,735 subjects was abstracted in DARE . In all analyses, heparin led to non-significantly lower odds of death (OR 0.91, 95% CI 0.59 to 1.39), corresponding to an absolute difference of 5 deaths/1000 treated. For t-PA only the OR was 0.84 (95% CI 0.43 to 1.64). For streptokinase/APSAC only the OR was 0.96 (95% CI 0.55 to 1.66). With aspirin the OR was 1.01, and without aspirin it was 0.72 (95% CI 0.36 to 1.45). The risk of bleeding of any severity was significantly higher (OR 1.55, 95% CI 1.21 to 1.98).
Comment: The quality of evidence is downgraded limitations in review quality.