AbstractA 12-lead ECG is a simple and less costly measure to assess cardiac amyloidosis and may reflect the infiltrative nature of cardiac amyloidosis and have prognostic value for predicting overall survival in patients with cardiac AL amyloidosis. Therefore, we investigated the associations of surface ECG parameters with left ventricular (LV) global longitudinal strain (GLS) and prognosis in patients with cardiac AL amyloidosis. We performed a multi-center, retrospective analysis of 102 biopsy-proven cardiac AL amyloidosis patients. Baseline studies included 12-lead surface ECG and echocardiography, with two-dimensional strain analysis performed within one month of diagnosis. From the Kaplan-Meier survival analysis, patients with prolonged QTc (≥483 msec) had significantly poorer survival. ECG scores were assigned according to presence of prolonged QTc (≥483 msec) and abnormal QRS axis, and the study participants were divided into three groups according to ECG score. Mean absolute value of LV GLS and regional LV longitudinal strain (LS) differed significantly among the three groups and decreased in a stepwise manner as ECG score increased. Log NT-proBNP increased in a stepwise manner as ECG score increased. Prolonged QTc (≥483 msec) and abnormal QRS axis showed significant incremental values in addition to the revised Mayo stage. The presence of prolonged QTc (≥483 msec) and abnormal QRS axis showed significant incremental values for overall mortality rates. In addition, ECG scores consisting of presence of prolonged QTc (≥483 msec), and abnormal QRS axis showed good association with longitudinal LV dysfunction and NT-proBNP. ECG finding may provide prognostic additional information regarding prognosis of AL amyloidosis with cardiac involvement.