Prilocaine-Induced Methemoglobinemia Following Pacemaker and ICD Implantation: A Retrospective Analysis of Incidence and Clinical Characteristics

Abstract

Objectives: This study presents our experience with prilocaine-induced methemoglobinemia in patients undergoing permanent pacemaker (PPM) or implantable cardioverter defibrillator (ICD) implantation. Methodology: We conducted a retrospective analysis of patients who developed clinically significant methemoglobinemia following PPM or ICD implantation between 2019 and 2023. Results: Out of 651 patients who underwent PPM or ICD implantation, 19 patients developed methemoglobinemia after prilocaine administration and were included in the analysis. Of these, 68.4% (13 patients) were female, with a mean age of 75.1 ± 10.1 years, indicating a predominantly elderly population. Regarding comorbidities, 16 patients had hypertension, 10 had diabetes mellitus, 7 had coronary artery disease, and 5 had congestive heart failure. A dual-chamber pacemaker was implanted in 12 patients, a single-chamber pacemaker in 3, a dual-chamber ICD in 2, and a single-chamber ICD in 2. The mean haemoglobin level was 11.5 ± 1.3 g/dL, with 13 patients (68.4%) presenting with anaemia. Mean serum albumin was 32.8 ± 3.7 g/dL, with hypoalbuminemia observed in 9 patients (47.4%). The mean glomerular filtration rate was 67.0 ± 23.3 mL/min/1.73 m², and 15 patients (78.9%) had reduced renal function. The average oxygen saturation among those who developed methemoglobinemia was 87.1 ± 2.0%. The mean MetHb level prior to treatment was 10.2 ± 3.9%, which significantly decreased to 1.9 ± 0.5% following treatment (p < 0.001). Conclusion: Clinicians should consider the possibility of methemoglobinemia in patients with unexplained low oxygen saturation that is inconsistent with their clinical presentation. Prompt administration of methylene blue in patients with comorbidities can lead to rapid clinical improvement.