NPPB and atrial fibrillation: Thirdly, due to the retrospective nature of the study, several potentially residual confounders related to additional pharmacological treatment, relevant chronic conditions such as paroxysmal/persistent atrial fibrillation, mitral regurgitation, history of important events—e.g., stroke—and certain biochemical markers including estimated glomerular filtration rate, creatine phosphokinase, brain natriuretic peptide, troponin, and reperfusion status were unavailable.