Mycoplasma pneumoniae is a common cause of upper and lower respiratory tract infections, while extrapulmonary manifestations are less frequent. Cardiac complications are uncommon and may include myocarditis, pericarditis, and arrhythmias. We report the case of a 77-year-old male with baseline conduction disease but no prior history of advanced atrioventricular (AV) block who presented with acute hypoxemic respiratory failure due to Mycoplasma pneumoniae pneumonia and developed progressive high-grade AV block. Despite appropriate antimicrobial therapy and initial clinical improvement in respiratory status, conduction abnormalities persisted; follow-up electrocardiography (ECG) performed one month after discharge demonstrated complete heart block requiring permanent dual-chamber pacemaker implantation. This case adds to the limited adult literature describing persistent high-grade AV block temporally associated with M. pneumoniae infection, including rare cases requiring permanent pacemaker implantation, and underscores the importance of careful cardiac evaluation, monitoring, and follow-up in patients with underlying conduction disease. • Cardiac involvement of mycoplasma pneumoniae infections is rare roughly occurring in 4-5% of infections, but can lead to serious complications, including myocarditis, cardiac thrombus, pericarditis, heart failure, and heart block. • The mainstay treatment of extra-pulmonary complications of M. pneumoniae is treatment of the underlying infection but complications can persist despite treatment phase. • Cardiac involvement has been primarily described in children, with only four reported cases in adults, and just one other case resulting in the need for a permanent pacemaker, similar to the outcome observed in our patient.
Monsanto et al. (2026) studied this question.