Incidence and management of methemoglobinemia following cardiac implantable electronic device (CIED) implantation

Methemoglobinemia is a known, albeit uncommon, complication that may arise from various surgical procedures and medications. This condition occurs when hemoglobin is oxidized to methemoglobin, leading to reduced oxygen-carrying capacity and potential tissue hypoxia. Clinically, methemoglobinemia may present with symptoms ranging from mild cyanosis to severe hypoxemia, depending on methemoglobin levels. While methemoglobinemia associated with certain drugs and surgical procedures has been widely documented, no study has evaluated its incidence or management in patients undergoing cardiac implantable electronic device (CIED) implantation. This study aims to examine the incidence, clinical presentation, diagnostic considerations, and management outcomes in these patients.

This prospective study included 21 patients undergoing CIED implantation at our center. Patient demographics and clinical characteristics, including age, sex, comorbidities, and ejection fraction (EF), were recorded. Methemoglobin levels were assessed in patients presenting with cyanosis, oxygen desaturation, or other unexplained symptoms during the immediate postoperative period. Levels exceeding 1.5% were considered abnormal, with therapeutic intervention determined by clinical severity.

The study included 21 patients undergoing CIED implantation, with a mean age of 68.3 years and a male-to-female ratio of 7:14 (Table 1). 80% (n=17) of our patient group had methemoglobin levels above 1.5% and 2 of these patients showed symptoms requiring treatment. One patient, experiencing only mild symptoms, was treated with intravenous vitamin C alone. The other patient, who presented with significant dyspnea, received both vitamin C and methylene blue, resulting in rapid symptom relief and normalization of methemoglobin levels within 24 hours. Blood gas data (Table 2) indicated slight improvements in oxygen saturation (SpO2) and pO2 over the course of treatment, confirming effective management. The average hospital stay was 2.2 days, and no patient required readmission or experienced adverse effects from methemoglobinemia.

This study highlights methemoglobinemia as an uncommon yet relevant underreported complication following CIED implantation, primarily manifesting as mild, asymptomatic cases that typically resolve with observation. For the small subset requiring intervention, treatment with vitamin C alone or in combination with methylene blue provided rapid recovery, underscoring effective management options based on symptom severity.

Importantly, mild oxygen desaturation post-cardiac device implantation should prompt consideration of methemoglobinemia in differential diagnosis, especially when symptoms do not respond to oxygen therapy. Raising awareness about this rare, manageable complication can support timely diagnosis and intervention, ultimately enhancing patient safety in CIED implantation settings.

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