NPPB and cardiac arrhythmia: While searching for noninvasive alternatives, N-terminal pro-B-type natriuretic peptide (NT-proBNP)10–12 and autonomic function tests became of value as markers of cardiomyopathy and cardiac autonomic neuropathy, respectively.13,14 However, both noninvasive alternatives have limitations: loss of renal function and arrhythmias may cause elevated NT-proBNP levels irrespective of the presence of cardiomyopathy,15 and autonomic function tests mainly assess cardiac parasympathetic function.13,14