Congenital Absence of Pericardium: The Largest Systematic Review in the Field on 247 Worldwide Cases (1977-Now)

background: congenital absence of pericardium (CAP), also known as pericardial agenesis, represents an uncommon cardiac abnormality and mostly incidental finding. it can be subdivided into complete and partial (left or right-sided) forms. because of its infrequency, just case reports and a few case series have been released so far. this paper represents the largest systematic review in the field. nine features (age at diagnosis, type, gender, clinical presentation, electrocardiography, imaging (ultrasounds, CT/MRI), concomitant cardiac defects, and out-come) were analysed. methods: the electronic database pubmed was investigated from its establishment up to July 15th, 2023. Just case reports and case series were included. animal studies, papers that were not in english, spanish, and italian, and those manuscripts not reporting at least seven of the nine analysed features. were ruled out. the analysed data were reported mostly in terms of percentage. results: one hundred eighty studies were included encompassing 247 patients. more than half of reviewed CAP cases were in males (63.2%). The mean age at diagnosis was 31.8 ± 19.3 years; a range of 32 weeks of gestation-81 years). 23.5% of the patients did not report any symptoms. the most common clinical presentations were chest pain (35.2%) and dyspnoea (29.2%). the most commonly seen ECG changes were right axis deviation (28.7%) and right bundle branch block (23.9%). CAP was suspected or diagnosed by echocardiography in 20.1% of cases. the diagnosis was made by CT and/or MRI in 61.9% of cases. CAP was left-sided in 71.2%, complete in 23.1%, and right-sided in 5.7%. a concomitant congenital heart defect was found in 22.7%, especially in the form of atrial septal defect (6.5%) and patency of ductus arteriosus (2.8%). the pericardial repair was required in 12.9% of the incomplete forms of the disease. never did the complete form require surgical correction. the outcome appeared favourable in the vast majority of cases, with just 18 deaths (7.3%). discussion: the main limitation of this systematic review is that it is based just on case reports and case series, due to the lack of large studies on CAP. however, it represents the largest analysis in the field. due to the rarity of CAP establishing an International registry is recommended.