Background
BNP und NT-proBNP provide prognostic information in patients with acute coronary syndromes (ACS). Even though it is generally accepted, that gender, age and atrial fibrillation are important determinants for BNP respectively NT-proBNP values, there is no data available evaluating the impact of those factors on the predictive value of those biomarkers. Therefore it was our aim to evaluate the predictive value of NT-proBNP for mortality after an ACS in association to gender, age and rhythm
Methods and results
We included 1123 consecutive patients (age 64±12 years; 342 females) with an ACS within the last 48 hours. Follow up data after median of 204 days were available for 1115 (99%) patients. During the follow up 77 (6.8%) patients died. NT-proBNP values on admission were higher in patients who deceased compared to those who survived (2047 (576 –5624) pg/ml vs. 465 (127–1519) pg/ml; p<0,001). The AUC of the ROC curve for NT-proBNP as a predictor for mortality was 0.714 (p<0.001) and an optimised cut-off value of 1815 pg/ml could be calculated. Patients with NT-proBNP above this cut-off had a significantly higher mortality rate (16% vs. 4%; p<0,001; Log Rank 48; p<0,001)). Even though patients with AF had higher NT-proBNP values as those patients with SR (1952 (770 – 4070) pg/ml vs. 452 (121–1492) pg/ml) NT-proBNP at the same cut-off value of 1815 pg/ml was highly discriminative for mortality (27.9% vs. 7.5%; p<0.022; Log Rank 5.7; p=0,017). Patients with an age above 65 years had higher NT-proBNP values as compared to patients younger than 65 years (894 (255–2642) pg/ml vs. 279 (75–945) pg/ml; p<0,001). However the predictive value of NT-proBNP in both age groups was comparable. Women had higher NT-proBNP values as compared to men (966 (237–2549) pg/ml vs. 407 (102–1273) pg/ml; p<0,001). But in dissimilarity, in women NT-proBNP values above 1815 pg/ml were not associated with a higher mortality and thus were without predictive value (10,6% vs. 6,8%; p<0,304; Log Rank 1,556; p<0,212).
Conclusion
Gender, age and rhythm are important determinants for NT-proBNP values of patients presenting with an ACS. However, only gender had impact on the predictive value of NT-proBNP for mortality. In women cut-off values need to be adopted.