NPPB and atrial fibrillation: Patients from the derivation cohort had a lower prevalence of ischaemic heart disease [23 (11.9%) vs. 61 (27.6%)], atrial fibrillation [94 (48.5%) vs. 130 (59.4%)], and smoking [68 (35.1%) vs. 118 (54.1%)]; lower haemoglobin, sodium, and creatinine levels; and higher NT-pro BNP level than those from the validation cohort.