Background: B-type natriuretic peptide (BNP) levels are known to predict atrial fibrillation (AF) occurrence short-term after cardiac surgery, but no information is available on their predictive potential at a later time point. We evaluated whether BNP levels predict postcardiac surgery AF events occurring during rehabilitation program. AF impact on hospitalization length and rehabilitation program have also been evaluated.
Methods and results: One hundred and forty-nine patients who underwent cardiac surgery were monitored for 'late' AF, defined as AF occurring during the rehabilitation period (20+/-5 days) in contrast to 'early' AF defined as AF documented in the surgical department soon after surgery. BNP was determined at rehabilitative hospital admission (10+/-5 days after surgery). Late AF was observed in 17% of patients. AF patients had higher BNP levels than event-free patients (459+/-209 vs. 401+/-449 pg/ml, P=0.01). Lower kaliemia values (P=0.048), early AF (P<0.001), and combined surgery (coronary artery by pass graft and valve replacement; P=0.016) were also associated with late AF. At multivariate analysis, BNP levels more than 322 pg/ml (P=0.02), and early AF (P=0.003) showed an independent association with late AF occurrence, which did not interfere with the physical training program but prolonged hospitalization (22+/-5 vs. 20+/-5 days, P=0.062) and telemetry monitoring (6+/-5 vs. 1+/-3 days, P<0.001).
Conclusion: BNP levels measured at the beginning of the rehabilitation program are independent predictors of late AF after cardiac surgery. These results suggest a more aggressive therapeutical approach during the rehabilitation period in patients with elevated BNP levels who have already experienced AF in the surgical department.