Association of left anterior descending artery involvement on clinical outcomes among patients with STEMI presenting with and without out-of-hospital cardiac arrest

BACKGROUND: ST-segment elevation myocardial infarction (STEMI) outcomes are influenced by the location of the culprit vessel with worse outcomes portended with a left anterior descending (LAD) culprit lesion. However, relatively little is known about the independent association of LAD involvement with clinical outcomes of patients with STEMI with and without out-of-hospital cardiac arrest (OHCA). METHODS: We identified 91 patients with and 929 without a preceding OHCA within the Vancouver Coastal Health Authority who presented with an acute STEMI and underwent primary percutaneous coronary intervention between 26 June 2007 and 31 March 2016. RESULTS: Patients with STEMI with OHCA had higher rates of in-hospital cardiac arrest (43.3% vs 8.3%, p<0.001), heart failure (50.5% vs 11.3%, p<0.001), cardiogenic shock (49.5% vs 5.7%, p<0.001), mortality (35.2% vs 3.3%, p<0.001) and reduced left ventricular ejection fraction (LVEF; 42.9% vs 47.3%, p<0.001) compared with those without OHCA. Among patients without OHCA, LAD involvement was associated with increased heart failure (18.1% vs 5.2%, p<0.001), in-hospital cardiac arrest (10.7% vs 6.2%, p<0.014), cardiogenic shock (8.4% vs 3.3%, p<0.001), reduced LVEF (43.0% vs 51.2%, p<0.001) and mortality (5.2% vs 1.3%, p=0.003) compared with patients without LAD involvement. With the exception of LVEF, these associations were not seen among patients with STEMI with OHCA and an LAD culprit. The presence of an LAD culprit was not independently associated with increased hospital mortality among patients with OHCA after adjusting for potential confounding factors. CONCLUSION: Our study has demonstrated a differential impact of LAD involvement on clinical outcomes among patients with STEMI who present with and without OHCA. Our data highlight the complexity surrounding the prognostication following OHCA complicating STEMI and demonstrate that other mechanisms other than LAD involvement contribute to the high mortality associated with OHCA as a result of STEMI.