NT-proBNP as a marker for atrial fibrillation and heart failure in four observational outpatient trials.

AIMS: Heart failure (HF) and atrial fibrillation (AF) frequently coexist and are both associated with increased levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP). It is known that AF impairs the diagnostic accuracy of NT-proBNP for HF. The aim of the present study was to compare the diagnostic and predictive accuracy of NT-proBNP for HF and AF in stable outpatients with cardiovascular risk factors.

METHODS AND RESULTS: Data were obtained from the DIAST-CHF trial, a prospective cohort study that recruited individuals with cardiovascular risk factors and followed them up for 12 years. Data were validated in three independent population-based cohorts using the same inclusion/exclusion criteria: LIFE-Adult (n = 2869), SHIP (n = 2013), and SHIP-TREND (n = 2408). Serum levels of NT-proBNP were taken once at baseline. The DIAST-CHF study enrolled 1727 study participants (47.7% female, mean age 66.9 ± 8.1 years). At baseline, patients without AF or HF (n = 1375) had a median NT-proBNP of 94 pg/mL (interquartile range 51;181). In patients with AF (n = 93), NT-proBNP amounted to 667 (215;1130) pg/mL. It was significantly higher than in the first group (P < 0.001) and compared with those with only HF [n = 201; 158 (66;363) pg/mL; P < 0.001]. The highest levels of NT-proBNP [868 (213;1397) pg/mL] were measured in patients with concomitant HF and AF (n = 58; P < 0.001 vs. control and vs. HF, P = 1.0 vs. AF). In patients with AF, NT-proBNP levels did not differ between those with HF and preserved ejection fraction (EF) > 50% [n = 38; 603 (175;1070) pg/mL] and those without HF (P = 1.0). Receiver-operating characteristic curves of NT-proBNP showed a similar area under the curve (AUC) for the detection of AF at baseline (0.84, 95% CI [0.79-0.88]) and for HF with EF < 50% (0.78 [0.72-0.85]; P = 0.18). The AUC for HF with EF > 50% was significantly lower (0.61 [0.56-0.65]) than for AF (P = 0.001). During follow-up, AF was newly diagnosed in 157 (9.1%) and HF in 141 (9.6%) study participants. NT-proBNP was a better predictor of incident AF during the first 2 years (AUC: 0.79 [0.75-0.83]) than of newly diagnosed HF (0.59 [0.55-0.63]; P < 0.001). Data were validated in three independent population-based cohorts (LIFE-Adult, n = 2869; SHIP, n = 2013; and SHIP-TREND, n = 2408).

CONCLUSIONS: In stable outpatients, NT-proBNP is a better marker for prevalent and incident AF than for HF. In AF patients, the diagnostic value of NT-proBNP for HF with EF > 50% is very limited.