S-20-3: PLASMA ATRIAL AND BRAIN NATRIURETIC PEPTIDES LEVELS AND THE RISK OF INCIDENT ATRIAL FIBRILLATION: THE SUITA STUDY

Abstract

Background: Atrial fibrillation (AF), a common cardiac rhythm abnormality, is associated with significantly increased morbidity and mortality risk. We developed the risk prediction of incident AF using traditional risk factors. It is essential to consider the residual risk to increase risk predictions. Heart failure is not a factor that appeared in the Suita AF score but others. There is no prospective study on the relationship between plasma atrial and brain natriuretic peptide (ANP and BNP) levels and incident AF in non-Western residents. Objectives: We hypothesized the association between ANP, BNP, and incident AF in the Suita Study. Methods: A total of 2,828 participants (mean age 66.7 ± 10.4 years without AF at the baseline) have been prospectively followed-up for incident AF since November 2005. AF was diagnosed when AF or atrial flutter was present on ECG at a biannual health examination or when AF was indicated as a current illness or was in the medical records during follow-up. ANP and BNP were measured by the CLEIA methods at the baseline survey examination. Cox proportional hazard ratios (HRs) and 95% confidence intervals (CIs) were analysed after adjusting for the risk components of the recently published Suita AF risk score. Statistical analyses were performed using Cox proportional hazards regression methods and evaluated using C statistics and net reclassification improvement. Results: The baseline prevalence of hypertension according to the BNP levels were 34.5%, 50.1%, and 78.8% in BNP < 18.5 pg/dL, 18.5–99 pg/dL, and P ≧ 4100 pg/dL, respectively. During the 16,584 person-years of follow-up, we observed 65 incidents of AF. Compared to the subjects with ANP< 42 pg/dL and BNP< 18.4 pg/dL, the adjusted HRs (95% confidence intervals) of incident AF were 2.70 (1.53–4.78) for the subjects with ANP ≧ 42 pg/dL and 2.09 (1.09–4.01) and 9.75 (3.82–24.87) for the subjects with BNP = 18.5–99 pg/dL and BNPP ≧ 4100 pg/dL, respectively. The addition of ANP and BNP to variables recently combined in the Suita AF risk score showed an integrated discrimination improvement of 0.061 (0.035–0.087) and 0.068 (0.036–0.100), with 13.3% and 19.1% relative improvement in reclassification analysis, respectively. Furthermore, the addition of ANP to the Suita AF score with BNP showed a significant but slight integrated discrimination improvement of 0.007 (0.001–0.012) (P = 0.01). Conclusions: Each elevated ANP and BNP contributed significantly to the predictive for incident AF to calculate the Suita Risk Score, but adding ANP to the Suita AF score with BNP improved the risk prediction slightly.