Incidence, Relevant Patient Factors, and Clinical Outcomes of the Misdiagnosis of ST‐Segment–Elevation Myocardial Infarction: Results From the Korea Acute Myocardial Infarction Registry

Background Data on the incidence, relevant patient factors, and clinical outcomes of the misdiagnosis of ST‐segment–elevation myocardial infarction (STEMI) in the modern era of percutaneous coronary intervention are limited. Methods and Results Data from KAMIR (Korea Acute Myocardial Infarction Registry) between November 2011 and June 2020 were analyzed. Out of 28 470 patients with acute myocardial infarction, 11 796 were eventually diagnosed with STEMI following a coronary angiogram. They were classified into 2 groups: patients with an initial working diagnosis of STEMI before starting the initial treatment and patients with an initial working diagnosis of non‐STEMI (misdiagnosed group). Out of 11 796 patients with a final diagnosis of STEMI, 165 (1.4%) were misdiagnosed. The door‐to‐angiography time in the misdiagnosed group was 5 times longer than that in the timely diagnosed group (median 220 [interquartile range {IQR}, 66–1177] versus 43 [IQR, 31–58] minutes; P <0.001). In a multivariable adjustments model, patients with a history of heart failure, atypical chest pain, anemia, or symptom‐to‐door time ≥4 hours had significantly higher odds, whereas those with systolic blood pressure <100 mm Hg or anterior ST elevation or left bundle‐branch block on ECG had lower odds of STEMI misdiagnosis. For patients with culprit lesions in the left anterior descending artery (n=5838), the adjusted 1‐year mortality risk for STEMI misdiagnosis was 1.84 (95% CI, 1.01–3.38). Conclusions Misdiagnosis of STEMI is not rare and is associated with a significant delay in coronary angiography, resulting in increased 1‐year mortality for patients with culprit lesions in the left anterior descending artery.