Pre-Hospital Ambulance Notification for ST Elevation Myocardial Infarction (STEMI) Leads to Rapid Reperfusion But No Effect on Early Mortality: Insights from the Melbourne Interventional Group (MIG) Registry

Abstract

Background: Guidelines for acute coronary syndrome management advocate a 12-lead electrocardiogram should be taken en route and transmitted to prenotify the receiving medical facility. The aim is to obtain a door-to-balloon time (DTBT) <90mins. We sought to analyse the benefits of prenotification. Method: Excluding cardiac arrest, consecutive patients undergoing primary PCI for STEMI between 2011-2016 from the MIG registry were included with analysis separated into prenotified and non-prenotified groups. Results: 1134 prenotified (38.6%) and 1806 non-prenotified (61.4%) cases were compared. The prenotified group has a higher proportion of patients >75yo (29.0% vs 22.8%, p = 0.01) and have an eGFR<60 mL/min/1.73m2 (28.2% vs 22.7%, p<0.01), but a similar cardiogenic shock rate (6.7% vs 5.2%, p = 0.12). The prenotified group has a higher thrombus aspiration use (30.2% vs 22.4%, p < 0.001), glycoprotein IIbIIIa inhibitor use (66.6% vs 53.4%, p < 0.001), RCA intervention (47.1% vs 36.5%, p < 0.001) and bare metal stent use (40.5%vs36.0%, p < 0.05) with similar procedural success (95.7% vs 95.2%, p = 0.54). Prenotification leads to a 36 min shorter DTBT (52mins vs 88mins, p < 0.001). Prenotification increases total DTBT < 90mins (88.9% vs 51.3%, p < 0.001), increases in hours DTBT<90mins (93.3% vs 61.6%, p < 0.001) and after hours DTBT < 90mins (85.6 vs 46.0%, p < 0.001). Prenotification has a higher in-hospital (4.6% vs 2.9%, p < 0.05) and 30-day mortality (5.1% vs 3.6%, p < 0.05). Prenotification is not an independent predictor for 30-day mortality (HR 1.37, 95% CI 0.91-2.07). Conclusion: Although prenotification dramatically improves DTBTs (especially after hours) and reduces total ischaemic time, early mortality is not lower. The effect on long term mortality after STEMI is eagerly awaited.