Prevalence, clinical profile and prognostic implications of interatrial block in patients admitted for heart failure

Introduction and objectives: To describe the prevalence, clinical profile, and prognostic significance of interatrial block (IAB) in heart failure (HF) inpatients. Methods: We included prospectively 557 hospitalized HF patients with sinus rhythm from nationwide registry. Partial IAB was defined as a P wave duration ≥120 ms, and advanced IAB as a P wave duration ≥120 ms with biphasic morphology in inferior electrocardiogram (ECG) leads. Clinical, blood test, and echocardiographic data were analyzed in a Cox regression to determine the impact of IAB at discharge on prognosis. The primary outcome was a composite of mortality or readmission for HF at 1-, 6-, and 12-month. Results: Normal P wave, partial, and advanced IAB were identified in the discharge ECG in 336 (60.3%), 118 (21.1%), and 103 (18.5%) patients, respectively. The independent factors related to IAB at discharge were previous history of HF (OR, 1.78; 95%CI, 1.23–2.57), valvular HF etiology (OR, 1.88; 95%CI, 1.18–3.00), heart rate at admission (OR, 1.10 per 10 beats; 95%CI, 1.03–1.17) and left atrial diameter (OR, 1.24 per 5 mm; 95%CI, 1.11–1.38). The incidence of 1-, 6-, and 12-month mortality/readmission for HF was 4.8%, 7.7%, and 33.0% in normal P wave, 1.7%, 7.6%, and 33.2% in partial IAB, and 3.9%, 9.7%, and 36.9% in advanced IAB. Multivariable analysis showed no significant effect of IAB in major acute cardiovascular events. Conclusions: IAB is found in 40% of patients in sinus rhythm discharged after a HF hospitalization. This ECG pattern at discharge does not imply a greater risk of readmission or death during the first year.