Evaluation of Cardiac Function Using Transthoracic Echocardiography in Patients with Myocardial Injury Secondary to Methomyl Poisoning

Generally, the mortality rate for cases of carbamate poisoning is low, but fatalities secondary to methomyl poisoning have been reported including a case report of cardiac toxicity following short-term exposure to methomyl. There have been no reports, however, regarding patterns of cardiac toxicity after exposure to methomyl. Therefore, we investigated the prevalence and patterns of myocardial injury using a biochemical marker, troponin I (TnI), and evaluated cardiac function using transthoracic echocardiography (TTE). We conducted a retrospective review of 14 consecutive methomyl poisoning cases that were diagnosed and treated at the emergency department of the Wonju Severance Christian Hospital between January 2009 and December 2013. On ECG analysis, ST depression and T-wave inversion were seen in five patients (35.7 %) and one patient (7.1 %), respectively. On cardiac biochemical marker analysis, initial TnI was elevated in 11 patients (78.6 %). TTE was performed in nine patients among the 11 patients in whom TnI was found to be elevated. Of the nine patients that underwent TTE, three patients (33.3 %) showed a reduced ejection fraction (EF), and RWMA was noted in two patients. There were two patients (22.2 %) that had both reduced systolic function and RWMA. One patient did not regain normal systolic function on admission. None of the three patients with reduced EF received any specific treatment to support cardiac function. One patient expired due to pneumonia, and one patient was transferred as moribund. We followed up on 12 patients who survived to discharge for 6–44 months. One patient (8.3 %) was died to follow-up, and 11 patients survived without any further complications. Methomyl exposure can cause direct myocardial injury and reversible cardiac dysfunction. Monitoring of TnI levels and TTE for evaluation of cardiac function may be useful in the workup of patients suffering from methomyl poisoning.