Atrial fibrillation can raise the level of serum natriuretic peptides, including NT-proBNP, even in the absence of heart failure. This is complicated further in heart failure with preserved ejection fraction, in which 2 echocardiographic diagnostic criteria become unreliable (the left atrial volume and the tissue doppler imaging assessment of diastolic function). These factors contribute to the complexity of the diagnosis and have a potential impact on the usual thresholds for NT-proBNP in people who have atrial fibrillation. This has been recognised in several ongoing randomised controlled trials of heart failure, which are using higher NT-proBNP thresholds for the diagnosis of heart failure in people with atrial fibrillation. 30 of 4 The impact of advanced kidney disease on the natriuretic peptide threshold for diagnosing heart failure What are the optimal NT-proBNP thresholds for diagnosing heart failure in people with stage IIIb, IV or V chronic kidney disease? Why this is important Heart failure incidence and prevalence increase with age, with the rise starting at age 65 and peaking between 75 and 85. Both advancing age and heart failure are associated with a gradual and progressive decline in renal function. In addition, the progression of heart failure and some treatments for heart failure lead to progressive deterioration of renal function. A decline in renal function is associated with increased fluid retention and a rise in the level of the serum natriuretic peptides, including NT-proBNP, even in the absence of heart failure. There is some evidence that the use of higher NT-proBNP thresholds would improve diagnostic accuracy for heart failure in people with significant deterioration of creatinine clearance. 