We report on a 69-year-old man suffering from chronic progressive oligoarthritis (localized in metacarpal and knee joints), which clinically was interpreted as steroid-sensitive seronegative chronic arthritis. The patient died from sudden death at the emergency department after a 4-week history of increasing cough and dyspnea (meanwhile obtaining negative testing results for SARS-CoV-2). During the autopsy, we found massive pancarditis affecting all cardiac compartments, in particular exhibiting constrictive pericarditis, myocarditis, and multivalvular endocarditis. Microscopically, interstitial myocarditis could be observed. Performing extensive molecular analyses, we detected Tropheryma whipplei in the tissue specimens of the heart, but not in various duodenal tissue probes or in the synovial membrane. Taken together, in the present case the cause of death was acute cardiac failure due to multivalvular pancarditis due to T. whipplei. Besides from classical symptoms and morphological signs, Whipple's disease may present with various features. Regarding the differential diagnosis of a chronic multisystem disorder with aspects of hitherto unknown arthralgia, Whipple's disease should be considered.