Electrocardiographic findings of methanol toxicity: a cross-sectional study of 356 cases in Iran

Abstract

Background Methanol is widely used in industry; however, methanol poisoning is not common. In this regard, a number of outbreaks have been recently reported due to inappropriate processing of alcoholic beverages. Shiraz, a city located in the southern part of Iran, faced one of such outbreaks in 2020 during COVID-19 pandemic. There is no sufficient literature on the electrocardiographic findings in methanol toxicity. This study aimed to address this gap in the literature. Method A total of 356 cases with methanol toxicity referred to Shiraz University of Medical Science Tertiary Hospitals (Faghihi and Namazi) in March and April, 2020. The clinical findings of blindness and impaired level of consciousness, lab data such as arterial blood gas, electrolytes, and creatinine, and the most common findings from ECGs were collected. Results The most common ECG findings were J point elevation (68.8%), presence of U wave (59.2%), QTc prolongation (53.2% in males and 28.6% in females), and fragmented QRS (33.7%). An outstanding finding in this study was the presence of myocardial infarction in 5.3% of the cases. This finding, to the best of our knowledge, has only been reported in a few case reports. Brugada pattern (8.1%) and Osborn wave (3.7%) were the other interesting findings. In multivariate analysis, when confounding factors were adjusted, myocardial infarction, atrioventricular conduction disturbances, sinus tachycardia, and the prolonged QTC > 500 msecond were four independent factors correlated with methanol toxicity severity measured with arterial blood PH on arterial blood gas measurements, with odds ratios of 12.82, 4.46, 2.32 and 3.15 (P < 0.05 for all), respectively. Conclusion Electrocardiographic variations during methanol intoxication are remarkable and well-correlated with poisoning severity. Myocardial infarction was an egregious and yet a common concerning finding in this sample, which need to be ruled out in methanol toxicity.

Useful Electrocardiographic and Laboratory Findings in Shiraz Outbreak of 356 Methanol Poisoned Patients

“…Based on previous studies, the most remarkable nding was positive associations between various ECG ndings such as QTc > 500, QTD > = 40, AVB, sinus tachycardia, Brugada pattern, J point elevation, STEMI, BBB and Osborn wave and increased mortality rate in methanol toxicity [19,22,23]. However, multivariate analysis, after adjustment for sex and age revealed the signi cance T slope, Brugada pattern and low voltage remained signi cantly associated with mortality.…”

“…Besides, our recent publication on this topic revealed noteworthy results. J point elevation, presence of U wave, fragmented QRS and STEMI are the prominent ECG changes among methanol poisoning patients [19]. However, none of these evidences reported an ECG nding as an independent predictor of mortality.…”

“…Furthermore, there are even more limited published studies (Jaff et al [17] and Sanaei-zadeh et al [18]) about the electrocardiographic manifestations in patients with methanol poisoning; On the other hand, it has not been established yet whether or not the electrocardiographic ndings can predict mortality [18]. A recent study on one of the largest outbreaks of methanol poisoning by authors of this paper described the most common ECG ndings among patients with methanol toxicity and analyzed their association with the severity of intoxication [19]. Subsequently, current study aimed to re-examine the possible prognostic factors associated with the mortality risk and more precisely to investigate the ECG ndings associated with mortality in methanol toxicity.…”

“…The laboratory investigations were arterial blood gas measurements (PH, Bicarbonate (meq/l), Partial Pressure of Carbon Dioxide (torr) and Oxygen saturation (%)), renal function tests, electrolytes, and blood sugar. Severe acidosis is de ned as PH less than 7.2 [19]. Dedicating from Winter's formula (PaCO2 = 1.5 × [HCO3] + 8 ± 2), marked mixed metabolic and respiratory acidosis was marked as lack of hyperventilation in our patients [23].…”

“…Exclusion criteria were previous myocardial infarction, supra-ventricular or ventricular arrhythmias, CABG, any known genetic cardiac disease such as Brugada, long QT syndrome, and short QT syndrome. The de nition of ECG parameters, renal failure, and myocardial infarction were described in our pervious study [19]. Finally, we calculated an angle, which will be named as T slope in this article, in the following way.…”