A single-center trial looked at patients with ST-segment-elevation myocardial infarction who had symptoms for six hours or less. Researchers randomized 298 patients to receive unfractionated heparin at the first prehospital medical contact plus a supplemental dose before the procedure. Another group of 295 patients received standard heparin only at the time of the procedure.
The main result showed that pretreatment with unfractionated heparin was associated with a higher rate of good blood flow in the blocked artery. Specifically, 43 percent of patients in the pretreatment group had improved flow compared to 27 percent in the control group. This represents an absolute increase of 16 percent in artery patency.
Safety was also monitored during the hospital stay. The rate of serious bleeding was 2.4 percent in the pretreatment group versus 2.0 percent in the control group. This difference was not statistically significant. The study found no increased risk of bleeding and no serious adverse events were reported. Readers should note that this was a single-center trial, so results may vary in other settings.