Case report: recurrent heart failure with preserved ejection fraction but markedly elevated BNP in a 51-year-old female on hemodialysis with oversized AV fistula.

We hereby report a case that appeared to have had recurrent clinical heart failure secondary to high-output state due to oversized arteriovenous fistula. Patient started to have dyspnea on exertion approximately 4 months after the creation of the fistula, and subsequently had two episodes of heart failure exacerbation. On both occasions, she had normal left ventricular systolic function as demonstrated by echocardiogram. The shunt was estimated to be as large as 1.9 L/min. B-type natriuretic peptide (BNP) levels were markedly elevated. To our knowledge, this is the first case in which BNP level was reported and used in the diagnosis of high-output heart failure.