Abstract P318: Why Do Some Patients Not Receive Reperfusion Therapy for ST-Elevation Myocardial Infarction (STEMI)? A Field Evaluation With Expert Core Laboratory Electrocardiographic Analysis

Many apparently eligible patients with ST-elevation myocardial infarction (STEMI) do not receive reperfusion treatment for reasons that remain poorly understood. We explored predictors for not receiving reperfusion treatment, defined as fibrinolysis or urgent referral (≤ 4 hours after triage) for primary angioplasty, in patients with STEMI. A field evaluation systematically reviewed STEMI care in 80 hospitals in 2006-7. Patients with myocardial infarction, acute presenting symptoms, and medical chart mention of STEMI, had a copy of their first electrocardiogram (ECG) interpreted independently at the field evaluation center by 2 cardiologists as being definite STEMI, not STEMI, or uncertain. Left bundle branch block (LBBB) was classified separately. Patients with at least one definite or uncertain ECG interpretation (including LBBB) were considered to have STEMI (n=2,137); of these, 524 (24.5%) did not receive reperfusion therapy. Their 30-day and 1-year mortality was 17.9% and 29.4% compared to 5.6% and 7.8%, respectively, in patients receiving reperfusion treatment (p <0.001). Independent predictors of not receiving reperfusion treatment included: older age, female gender, heart rate >100 beats/min and longer symptom duration. Among patients without LBBB (n=1930), lack of ECG-based agreement for definite STEMI was strongly and independently associated with no reperfusion [OR=6.1; 95% CI: 4.7-8.0]. For only 20.0% of patients not receiving reperfusion treatment did the 2 cardiologists agree on definite STEMI on ECG. Presence of LBBB was also a strong predictor of no reperfusion [OR=13.1 (95% CI: 8.8-19.6)]; only 17.4% of patients with LBBB received reperfusion treatment. Thus, this study confirms the high-risk clinical features and poor prognosis of STEMI patients who do not receive reperfusion and indicates that lack of expert agreement on definite STEMI and presence of LBBB are important predictors of no reperfusion therapy. Further study is needed to determine whether these high-risk patients may benefit from immediate referral for cardiac catheterization.