Prevalence and Significance of Interatrial Block in Takotsubo Syndrome (from the RETAKO Registry).

Interatrial block (IAB) represents a conduction delay between right and left atria and is associated with an increased risk of atrial fibrillation and stroke. IAB has not been previously assessed in patients with Takotsubo syndrome (TS). Our aim was to describe the prevalence and prognostic significance of IAB in patients with TS. Data come from the Spanish National prospective registry of patients with definitive TS diagnosis. IAB was defined as a P-wave ≥120 ms and was considered partial when the P-wave was positive in inferior leads and advanced when it was biphasic (+/-). A total of 246 patients were included, normal P-wave was found in 151 (61%), partial IAB in 58 (24%), atrial fibrillation in 18 (7%), advanced IAB in 13 (5%), and 6 (2%) were pacemaker dependent. During a mean follow up of 12 months the composite of all-cause mortality and hospital readmission was significantly higher in patients with advanced IAB (31%) or atrial fibrillation (33%) than in the rest of the cohort (pacemaker stimulation 17%, normal P-wave 13%, partial IAB 12%), p < 0.01. The data regarding P wave characteristics were an independent predictor of the composite end point all-cause death and hospital readmission. IAB has a high prevalence in patients with TS. Advanced IAB and atrial fibrillation are associated with a poor prognosis.