Lewis Lead Enhances Atrial Activity Detection in Wide QRS Tachycardia

The differential diagnosis of wide QRS tachycardia is a challenge for the emergency physician. The major tool is the electrocardiogram (ECG), even though the sensitivity and specificity may be variable, depending on presentation. Additional leads could be used to improve the diagnostic accuracy of the ECG.To document the use of the Lewis lead in improving the diagnostic accuracy of the ECG in wide QRS tachycardia.A 52-year-old woman with rheumatoid arthritis, in treatment with methotrexate, was admitted with progressive dyspnea that evolved to acute respiratory distress and shock at arrival. Pneumonia was diagnosed as the infection and she received antibiotics, and respiratory and inotropic support. She was also using amiodarone for more than 10 years, but she couldn't state the reason. On cardiac monitoring, wide QRS tachycardia was detected and ventricular tachycardia was considered on the differential diagnosis. The standard 12-lead ECG was complemented with the Lewis lead, obtained with higher speed and amplitude, demonstrating atrioventricular concordance and excluding ventricular tachycardia. The patient was treated for septic shock, and she died 2 days later.The Lewis lead is a simple and easy strategy to enhance atrial activity detection in wide QRS tachycardia.