Clinical implications of elevated plasma b-type natriuretic peptide in cardiac arrest

Abstract

Study objectives: Plasma B-type natriuretic peptide (BNP) is a useful diagnostic and prognostic biomarker for patients with congestive heart failure. In victims with cardiac arrest, plasma BNP level might reflect the presence of congestive heart failure before the occurrence of cardiac arrest. Influence of cardiac arrest on plasma BNP level remains to be investigated. The aim of this study is to know whether the occurrence of cardiac arrest influences plasma BNP level and to define clinical significance of increased plasma BNP level in patients with cardiac arrest. Methods: Seventy patients (mean age 63±16 years, 49 male patients) with out-of-hospital cardiac arrest were enrolled in this study. Blood samples for BNP testing were obtained on arrival (time 0), 30 minutes after initiation of cardiopulmonary resuscitation (CPR) (time 1), and 3 hours (time 2) and 12 hours (time 3) after restoration of spontaneous circulation. Patients were grouped by plasma BNP level as normal BNP group (<100 pg/mL) and high BNP group (≥100 pg/mL). Results: Plasma BNP was not changed along elapsed time from cardiac arrest (482±866 pg/mL at time 0, 484±396 at time 1, 510±959 at time 2, 587±599 at time 3, <i>P</i>>.01). Mean plasma BNP was 41±29 pg/mL in the normal BNP group (n=33) and 876±1,049 pg/mL in the high BNP group (n=37). Plasma BNP was elevated in 24 (75%) of 32 patients with presumed cardiac etiology and 13 (34%) of 38 patients with noncardiac etiology (<i>P</i>=.01). Mean plasma BNP of the patients with presumed cardiac etiology was higher than that of patients with noncardiac etiology during CPR (709±924 pg/mL versus 292±777 pg/mL at time 0, <i>P</i>=.067; 438±463 versus 101±180 pg/mL at time 1, <i>P</i>=.001; 701±561 versus 382±1,151 pg/mL at time 2, <i>P</i>=.878; 974±623 versus 290±381 pg/mL at time 3, <i>P</i>=.122). There was no difference in plasma BNP level according to initial presenting cardiac rhythm or resuscitation outcome. Conclusion: Plasma BNP is not affected by occurrence of cardiac arrest or performing CPR. Elevated plasma BNP in patients with cardiac arrest suggests presence of preexisting heart disease.