Letter by Chung et al Regarding Article, “N-Terminal Pro–B-Type Natriuretic Peptide Testing Improves the Management of Patients With Suspected Acute Heart Failure: Primary Results of the Canadian Prospective Randomized Multicenter IMPROVE-CHF Study”
To the Editor:
We read with interest the article by Moe et al,1 which shows that adding N-terminal pro–B-type natriuretic peptide (NT-proBNP) testing to clinical judgment enhanced the accuracy of diagnosis of acute heart failure in patients presenting to emergency departments with dyspnea. However, NT-proBNP levels were increased in patients with a prior history of heart failure or left ventricular dysfunction even when dyspnea was not due to acute heart failure. This finding may reduce the diagnostic usefulness of NT-proBNP in this group of patients. We have previously shown that although BNP testing reduced diagnostic uncertainty in emergency department patients presenting with dyspnea, the receiver-operating characteristic curve for BNP diagnosis of acute heart failure was significantly worse in patients with a history of heart failure and in those with impaired left ventricular systolic function.2 Compared with the cohort in this study by Moe et al (70±15 years of age, 34% with a history of heart failure), our patients were older (79±10 years) and had a higher incidence of history of heart failure (56%). Unfortunately, the clinical diagnosis of acute heart failure is particularly challenging in elderly patients with comorbidities, and it is in this setting that BNP testing appears least useful. Although we agree with the authors that NT-proBNP testing should be used as a complement rather than an alternative to clinical assessment, the usefulness of NT-proBNP and BNP may be limited in elderly patients with a prior history of heart failure. Knowledge of a baseline clinic NT-proBNP or BNP level may improve diagnostic accuracy in this group.
Moe GW, Howlett J, Januzzi JL, Zowall H. N-Terminal Pro–B-Type Natriuretic Peptide Testing Improves the Management of Patients With Suspected Acute Heart Failure: Primary Results of the Canadian Prospective Randomized Multicenter IMPROVE-CHF Study. Circulation. 2007; 115: 3103–3110.
Chung T, Sindone A, Foo F, Dwyer A, Paoloni R, Janu MR, Wong H, Hall J, Freedman SB. Influence of history of heart failure on diagnostic performance and utility of B-type natriuretic peptide (BNP) testing for acute dyspnea in the emergency department. Am Heart Journal. 2006; 152: 949–955.