Usefulness of Plasma B-Type Natriuretic Peptide in the Assessment of Disease Severity and Prediction of Outcome after Aortic Valve Replacement in Patients with Severe Aortic Stenosis

Abstract

The diagnostic and prognostic value of plasma B-type natriuretic peptide (BNP) level in isolated aortic stenosis (AS) has not been fully understood. BNP level was determined in 109 consecutive patients with isolated severe AS (68.1 ± 10.6 years; 53 men; transvalvular peak gradient, 87.2 ± 37.0 mm Hg; valve area index, 0.43 ± 0.14 cm(2)/m(2)) and 12 healthy volunteers in their stable state. They were followed up for 36 months. BNP level increased with New York Heart Association (NYHA) class (75.2 ± 95.9 pg/mL, 135.0 ± 112.0 pg/mL, 450.6 ± 366.3 pg/mL, and 1478.9 ± 941.5 pg/mL for NYHA I, II, III, and IV, respectively). Left ventricular (LV) mass index had the best relationship with BNP (r= 0.73, P < .0001). Aortic valve replacement (AVR) was eventually performed in 95 patients (male= 44, age= 67.8 ± 9.3 years). Echocardiography was repeated early (n= 88, 13.2 ± 6.2 day) and late (n= 62, 32 ± 10 months) after AVR. Preoperative BNP level correlated with LV mass index early (r= 0.74, P < .0001) and late (r= 0.78, P < .0001) after AVR. Patients with higher BNP level had a tendency to show cardiac symptoms (NYHA > I) late after AVR (NYHA I vs. > I= 160.8 ± 197.9 pg/mL vs. 504.3 ± 567.3 pg/mL, P < .0001). Preoperative BNP level predicted the occurrence of perioperative complications (P < .0001). During follow-up of the 94 patients (44 ± 10 months after AVR), 10 were readmitted for major cardiac and cerebrovascular events, including 9 patients with congestive heart failure and 1 patient with ischemic stroke. An event-free survival rate was significantly higher in patients with BNP ≤ 312 pg/mL than in patients with BNP > 312 pg/mL (log rank, χ(2)= 10.21, P= .001). Multiple logistic regression analysis revealed that BNP > 312 pg/mL was an independent predictor of AVR complication (odds ratio 5.58; confidence interval, 1.82-20.16; P= .002). Furthermore, BNP was the strongest predictor of major adverse cardiac and cerebrovascular events within 36 months after AVR (odds ratio 8.80; confidence interval, 1.83-42.35; P= .006). Plasma BNP level reflects the degree of heart failure, is associated with LV structure and function in severe AS, and is an independent predictor of complication and outcome after AVR. BNP level may be useful in risk stratification of patients with AS in conjunction with other clinical and echocardiographic parameters.