Prognostic Value of Long Corrected QT Interval on Electrocardiogram in Acute Organophosphate Poisoning: A Cohort Study

Abstract

Introduction: According to data available from National Poison Information Centre India, suicidal poisoning with household agents (organophosphates, carbamates etc.) is the most common modality of poisoning. There are reports suggesting relationship between prolonged corrected QT interval and the severity of Organophosphate (OP) poisoning. Corrected QT (QTc) interval is measured in 12 lead electrocardiograms taken on admission. Aim: To assess prognosis of acute organophosphate poisoning patients by studying association of corrected QT interval with its complications and mortality. Materials and Methods: The cohort study was conducted at Medicine Department of Medical College, Baroda and Sir Sayaji General Hospital, Vadodara, Gujarat, India, from December 2017 to November 2018. The study included 60 patients with a history of OP poisoning. The QTc interval in electrocardiogram was determined by using the Bazett formula. Prognostic importance of QTc interval was assessed by correlating it with Paradeniya Organophosphorus Poisoning Scale score, hospital stay, atropine requirement, requirement of ventilatory support and mortality. Data was analysed by using descriptive statistics and Chi-square test. Results: The organophosphate poisoning was seen more in younger age group, between 18-29 years (68.4%). The QTc prolongation was seen in 12, 80% of patients in moderate grade of Paradeniya Organophosphorus Poisoning Scale and in 9 (20%) patients among mild grade of Paradeniya Organophosphorus Poisoning Scale (p-value=0.0001). Amongst patients who needed hospital stay for more than 7 days, QTc prolongation was seen in 43% of patients, and in patients who needed hospital stay for less than 7 days QTc prolongation was seen in 9% of patients (p-value=0.0223). Statistically significant association was seen between atropine ampule requirement and QTc prolongation. Total 29 (48.3%) patients developed respiratory depression, and amongst them 19 (65.5%) had QTc prongation (p-value <0.0001). Thirteen (22%) patients died and amongst them 12 (92.31%) had QTc prolngation. In those who survived (47,78%) only 9 (19.15%) had QTc prolongation (p-value <0.0001). Conclusion: Prolonged QTc interval in electrocardiogram is a good prognostic indicator in patients with organophosphorus poisoning. Early identification of prolonged QTc interval and subsequent timely shifting of patients to Intensive Care Unit (ICU) and subsequent intensive management in a patient of OP poisoning would be of profound value at any level of health care setting for favourable outcomes.