Çagdas M, et al. - The diagnostic value of QRS and S wave variation was investigated in patients admitted to the Emergency Department with suspicion of acute pulmonary embolism (APE). The comparison of patients with APE and those without APE showed that increased heart rate, right axis deviation of QRS axis, complete or incomplete right bundle branch block, prominent S wave in lead D1, increased QRS duration, percentage of QRS, S wave variation and ΔS wave amplitude were significantly associated with APE, however, there appeared no relationship with respect to the presence of atrial arrhythmias, clockwise rotation of the horizontal axis, fragmentation, ST segment deviation, T wave inversion, and S1Q3T3 and S1S2S3 patterns. Findings thereby suggested that QRS and S wave variation could be useful electrocardiographic signs for the diagnosis of APE.