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Short-term fluctuations of plasma NT-proBNP levels in patients with new-onset atrial fibrillation: a way to assess time of onset?

Objective The objective of this study was to characterise short-term kinetics of plasma amino-terminal pro-B natriuretic peptide (NT-proBNP) levels in patients with new-onset atrial fibrillation (AF) without heart failure. Design Prospective cohort study. Setting Emergency departments and inpatient services of three large community hospitals. Patients 31 consecutive patients with new-onset atrial fibrillation (<24 h before presentation) persisting at least 48 h, without evidence of heart failure. Main outcome measures Plasma NT-proBNP levels were obtained at presentation and then 6, 12, 18, and 24 h after presentation. A final sample was obtained 48 h after onset of AF. Results Mean plasma NT-proBNP levels and 95% CIs (pg/ml) during the 48-h period following onset of AF were: 0–6 h: 636 (395 to 928), 6–12 h: 1364 (951 to 1778), 12–18 h: 1747 (1412 to 2083), 18–24 h: 1901 (1549 to 2253), 24–36 h: 1744 (1423 to 2066) and 36–48 h: 1101 (829 to 1373). Mean time to peak NT-proBNP levels was 16.7 (0.7) h; 29 patients reached their peak levels within 24 h. The mean peak NT-proBNP level was significantly higher than those obtained at 0–6 h and at 36–48 h after onset of AF (p<0.001 for both). There was no correlation between ventricular rate and plasma NT-proBNP levels during any time period after onset of AF. Conclusion In patients with new-onset AF but no clinical or radiographic evidence of heart failure, plasma NT-proBNP levels rise progressively to a peak during the first 24 h and then rapidly fall. This pattern may serve as an aid to assess the time from AF onset.