Background: Methyl alcohol poisoning (MAP) is a common commercial compound that can lead to significant morbidity and mortality when exposed to high levels. This study aims to describe MAP-related electrocardiography (ECG) changes and post-acute late complications. Materials and Methods: The study was conducted through a retrospective data review between 2017 and 2023. Patient data were recorded, including demographic information, medication use, and laboratory results. Twelve-lead ECG recordings were evaluated and the results were recorded. The cases included in the study were grouped according to QTc distance, ECG findings, late-term complications, treatment status, and mortality. Results: The mean age of all cases included in the study (n = 227) was 43.23 +/- 11.11 years, 8 (3.5%) cases were female, and the age distribution was between 19 and 68 years (p = 0.792). The age distribution of QTc groups was not significant (p = 0.792). The mean QTc distance was 442.7 +/- 60.1 ms in all cases (n = 227) and 514.08 +/- 5.45 ms in cases with mortality (n = 49) (p < 0.001). The mean time to application of the patients to the hospital (n = 227) was 19.1 +/- 4.61 h, and blood sugar was 130.7 +/- 32.09 mg/dL (p < 0.001). In addition, the mean pH of the cases (n = 227) was 7.14 +/- 0.2, bicarbonate was 17.17 +/- 4.86 mmol/L, the base deficit was -6.21 +/- 3.18 mmol/L, the anion gap was 19.36 +/- 7.31 mmol/L, and lactate was 4.82 +/- 2.45 mmol/L (p < 0.001). Mortality occurred in 49 (21.6%) of the patients, and all of them were in-hospital deaths. In all cases where mortality occurred, pH was below 6.93 +/- 0.22 and severe acidosis was directly related to death. MAP, sinus tachycardia in 31 (13.7%) cases, bradycardia in 8 (3.5%), atrial fibrillation in 5 (2.2%), accelerated idioventricular rhythm in 3 (1.3%), and 11 (4.8%), left bundle branch block, and right bundle branch block were detected in 22 (9.7%). All of these ECG findings were newly developed conditions with no previous history. In the 6-month follow-up after discharge, 4 (1.8%) of the cases developed neurological deficit, 15 (6.6%) had acute coronary syndrome and severe heart failure, 23 (10.1%) had permanent blindness, 6 (2.7%) had renal failure, and 6 (2.7%) had pancreatitis. Conclusions: Methyl alcohol poisoning can cause various ECG changes; sinus tachycardia, nonspecific changes, and QTc prolongation are the most common findings. These changes are more pronounced in cases of severe acidosis. Patients should be warned of late signs of MAP.
