1Universitätsmedizin Göttingen Herzzentrum, Klinik für Kardiologie und Pneumologie Göttingen, Deutschland; 2Universitätsmedizin Göttingen Institut für Medizinische Statistik Göttingen, Deutschland; 3St. Bernward-Khs. Hildesheim Med.Klinik I Hildesheim, Deutschland; 4Universitätsmedizin Göttingen Klinik für Psychosomatische Medizin und Psychotherapie Göttingen, Deutschland
Background: In patients with out-of-hospital cardiac arrest (OHCA), prehospital administration of heparin has been reported to have a lower mortality. The beneficial effect of heparin may be limited to the subgroup of OHCA patients with an ST-segment elevation myocardial infarction (STEMI), in whom prehospital administration of heparin may result in improved patency of the infarct artery and reduced ischemic damage in the infarct area. However, there are few data to support this hypothesis and nothing is known about the prognostic role of prehospital heparin in the subgroup of STEMI patients with OHCA.
Methods: To analyze the impact of prehospital heparin administration on TIMI flow grade prior to primary percutaneous coronary intervention (PCI) in STEMI patients with OHCA, we used data from two hospitals participating in the prospective Feedback Intervention and Treatment Times in ST-segment Elevation Myocardial Infarction (FITT-STEMI) trial.
Results: Of a total cohort of 2,442 patients with acute STEMI, 394 study participants had OHCA, of whom 272 (69%) received heparin from EMS personnel in the prehospital setting. Multivariable regression analysis confirmed collapse witnessed by EMS (OR=3.03, 95% CI=1.41-6.50, p=0.004), prehospital ECG recording (OR=5.65, 95% CI=1.95-16.40, p=0.001) and the TIMI risk score (OR=0.87, 95% CI=0.77-0.97, p=0.016) as independent predictors of prehospital heparin use in STEMI with OHCA. In-hospital mortality differed significantly between the heparin group (73 deaths of 272 patients, 26.8%) and the group not receiving heparin (52 deaths of 122 patients, 42.6%, p=0.002). A regression model adjusted for clinically relevant confounders showed that a no-flow time of >5 minutes (p=0.022) and a low-flow time of 30-60 minutes and >60 minutes were strongly associated with mortality in our cohort of STEMI patients with OHCA. In contrast, prehospital use of heparin had no effect on mortality (p=0.976). Moreover, preprocedural TIMI-flow grade of the infarct artery was not associated with early administration of heparin (p=0.950).
Conclusions: In STEMI patients with OHCA, prehospital use of heparin is neither associated with a better prognosis nor with improved patency of the infarct artery. Our results do not support the assumption of a positive effect of heparin administration in the prehospital treatment phase in STEMI patients with OHCA.