The scale of scientific evidence behind the current ESC clinical guidelines

Background: European Society of Cardiology (ESC) clinical practice guidelines are currently considered as an essential tool supporting many cardiologists in clinical decision-making not only in Europe but all-over the world. In this study we analyzed these recommendations regarding their class of recommendations (COR) and level of evidence (LOE) to detect how solid is the scientific background behind these recommendations. Methods: We have abstracted all the current guidelines defined as "the guidelines available on the ESC website by 01 October 2022". All recommendations were classified according to their COR (Class I, IIa, IIb, or III) and LOE (A, B, or C). As every topic has different number of recommendations, we have used the median values in comparisons between different topics to give all the topics the same weight. Results: Current ESC guidelines consist of 37 clinical topics including a total of 4289 recommendations. Their distribution was 2140 with a median of 49.9% in Class I, Class II and Class III were 1825 with a median of 42.6% and 324 with a median of 7.5% respectively. LOE A was only present in 667(15.5%) recommendations, 1285(30%) in LOE B, while LOE C was behind the majority of the recommendations, 2337 with a median of 54.5%. Conclusion: Although ESC guidelines are considered a gold standard for management of cardiovascular diseases, but surprisingly more than half of its recommendations are based on such scientific evidence. Deficiency in clinical trials is not the same across all guideline's topics, some are needier for clinical research.