RS time: A novel electrocardiographic parameter for diagnosis of pulmonary embolism

Background: Pulmonary embolism [PE] is one of the leading causes of cardiovascular mortality worldwide. PE which presents itself with various symptoms and clinical severities, sometimes is detected incidentally, while other times may cause sudden death. The heterogeneous clinical presentation of PE may lead to difficulties in recognition, and thus delays in the initiation of life-saving treatments. In order to overcome these difficulties, several risk scoring systems and diagrams have been developed, based on history, physical examination, and laboratory findings, to assess the clinical probability of PE. The aim of our study was to assess the relationship between diagnosis of acute PE with QRS duration and prolonged RS time measured from the inferolateral leads in surface ECG. Methods: Our study had a prospective and retrospective design that was conducted on multi-centres. This study was conducted on 140 patients presented to Benha university hospitals, Dar-Elshefaa hospital and International medical center with suspected pulmonary embolism, in the period from January 2019 till November 2020. Patients of the study were classified into two groups; Group A with confirmed PE and group B excluded from PE. Patients with confirmed PE were subdivided into 2 groups [massive and sub massive PE] according to the distribution of the filling defect in CT pulmonary angiography and hemodynamic instability . RS time was calculated and compared between the 2 groups. Results: The normal and confirmed PE patients were compared according to risk factors and we found that diabetes mellitus and hypertension were with significant importance [p value 0.017 for both]. Patients with history of malignancy or history of recent surgery were more in confirmed patients with PE than normal group but without significant value. Also in confirmed PE patients. In the current study, Geneva score [REV] was estimated to all patients. Geneva score [REV] was significantly higher among patients with confirmed PE . P value [< 0.001]. In the current study, Patients with confirmed PE had significant elevation in Troponin and D-dimer . In the current study, RS time and QRS duration in ECG were obtained from all patients and comparison between patients with confirmed PE and normal was done. Patients with confirmed PE had significant prolongation in mean RS time [63.5 ± 3.9 SD]. In our study the confirmed group with diagnosis of PE were reclassified into massive and sub massive PE . RS time was compared between the 2 groups. RS time in surface ECG was more prolonged in patients with massive PE than submassive PE. Also in the current study S1Q3T3 pattern , sinus tachycardia and incomplete RBBB were compared between the 2 groups. S1Q3T3 pattern and sinus tachycardia were more obvious and significant in patients with confirmed PE. Conclusion: ECG is a fast non invasive easily accessible in-expensive diagnostic tool . Early detection of specific ECG changes could help in early diagnosis of PE . There is a difficulty in diagnosis of PE through a single ECG parameter . Our study doesn’t hypothesize that prolonged RS time alone is enough to diagnose PE . However , our findings indicate prolonged RS time on surface ECG is a novel and effective parameter that can be very beneficial [ with other parameters and in correlation with clinical data ] for predicting the diagnosis of acute PE in the ER.