Type of evidence supporting ACC/AHA and ESC clinical practice guidelines for acute coronary syndrome

Aim The aim of clinical practice guidelines for ST elevation myocardial infarction (STEMI) and non-ST elevation acute coronary syndrome (NSTE-ACS) is to assist healthcare professionals in clinical decision-making. We evaluated the type of studies supporting these guidelines and their recommendations.Methods All references and recommendations in the 2013 and 2014 ACC/AHA and 2017 and 2020 (ESC clinical guidelines for STEMI and NSTE-ACS were reviewed. References were classified into meta-analyses, randomised, non-randomised, and other types (e.g., position papers, reviews). Recommendations were classified according to class and their level of evidence (LOE).Results We retrieved 2128 non-duplicated references: 8.4% were meta-analyses, 26.2% randomised studies, 44.7% non-randomised studies, and 20.7% 'other' papers. Meta-analyses were based on randomised data in 78% of cases and used individual-patient data in 20.2%. Compared to non-randomised studies, randomised studies were more frequently multicentre (85.5% vs. 65.5%) and international (58.2% vs. 28.5%). The type of studies supporting recommendations varied as per the LOE of the recommendation. For LOE-A recommendations, the breakdown of supporting recommendations was: 18.5% meta-analyses, 56.6% randomised studies, 16.6% non-randomised studies and 8.3% 'other' papers; for LOE-B this breakdown was 9%, 39.8%, 38.2%, and 12.9%; and for LOE-C; 4.6%, 19.3%, 30.3%, and 45.9%.Conclusions The references supporting the ACC/AHA and ESC guidelines on STEMI and NSTE-ACS consisted of non-randomised studies in similar to 45% of cases, with less than a third of the references consisting of meta-analyses and randomised studies. The type of studies supporting guideline recommendations varied widely by the LOE of the recommendation. [GRAPHICS] .