Abstract:
Background. Frederick’s syndrome is a rare cardiac conduction disorder, characterized by
the simultaneous presence of atrial fibrillation and complete atrioventricular block, with
extremely low incidence in young patients, especially as a complication following
myopericarditis, reported in less than 1% of cases.
Objective(s). Presentation of a rare case of Frederick’s syndrome following mixed
myopericarditis in a 46-year-old patient, treated with pacemaker implantation and
symptom improvement.
Materials and methods. A detailed evaluation was performed including patient history,
thorough clinical examination, routine laboratory tests and paraclinical investigations,
electrocardiogram (ECG), and transthoracic echocardiography to establish an accurate
diagnosis and monitor the progression of Frederick’s syndrome in mixed postmyopericarditis.
Results. A 46-year-old man with no cardiovascular history developed influenza A
pneumonia in February 2024, complicated by viral and bacterial myopericarditis. Four
months later, he developed atrial fibrillation resistant to cardioversion, treated with betablockers and anticoagulants. He later reported vertigo, frequent presyncope, weakness, and
dyspnea. ECG showed atrial fibrillation and third-degree AV block with a ventricular rate of
30–50 bpm. Echocardiography revealed moderate cardiac dilation and pulmonary
hypertension (PASP 48 mmHg). A single-chamber Vitatron Medtronic pacemaker was
implanted, improving symptoms with continued medical therapy.
Conclusion(s). Frederick’s syndrome following myopericarditis is a rare cardiac
complication resulting from impaired cardiac electrical conduction, requiring careful
monitoring, an individualized therapeutic approach, and strict adherence to guidelines for
managing third-degree AV block.
