Patients with successful cardioversion and those who remained free from AF on D8 had lower NT-proBNP levels compared to patients with failed cardioversion or with AF recurrence or persistence on D8 [day of cardioversion, D0: SR vs. non-SR, 387 (127–1095) pg/mL vs. 1262 (595–2295), p = 0.004; D8: SR vs. non-SR, 370 (127–1095) vs. 1366 (718–2295), p = 0.002]. Here, NPPB is linked to atrial fibrillation.