text: Long COVID Distinction between Organ Damage and Deconditioning 1 Background Long COVID syndrome refers to long term sequelae of the novel viral disease which occur even in patients with initially mild disease courses However there is still little evidence of the actual organic consequences and their frequency and there is no standardized workup to diagnose long COVID syndrome yet In this study we aim to determine the efficiency of a stepwise diagnostic approach for reconvalescent COVID 19 patients with cardiopulmonary symptoms 2 Methods The diagnostic workup for long COVID syndrome included three steps In the first step the focus was on broad applicability e g blood tests and body plethysmography In the second step cardiopulmonary exercise testing CPET and cardiac MRI CMR were used The third step was tailored to the individual needs of each patient The observation period lasted from 22 February to 14 May 2021 3 Results We examined 231 patients in our long COVID unit mean SD age 47 8 14 9 132 57 1 women Acute illness occurred a mean SD of 121 77 days previously Suspicious findings in the first visit were seen in 80 34 6 patients prompting further diagnostics Thirty six patients were further examined with CPET and CMR Of those 16 44 4 had pathological findings The rest had functional complaints without organ damage functional long COVID Cardiopulmonary sequelae were found in asymptomatic as well as severe courses of the initial COVID 19 disease 4 Conclusions A structured diagnostic pathway for the diagnosis of long COVID syndrome is practicable and rational in terms of resource allocation With this approach manifest organ damage can be accurately and comprehensively diagnosed and distinguished from functional complaints 