Abstract 17876: NT Pro BNP After Surgery for Constrictive Pericarditis: Does It Increase or Decrease?

Abstract

Background: It has been reported that patients with constrictive pericarditis (CP) have disproportionately lower BNP values compared to their clinical symptoms/signs of heart failure. This has been attributed to lesser stretching of the cardiac myocytes due to constriction. Hence, we hypothesized that surgical correction of constriction would cause an increase in ventricular volume and an elevation in NT pro BNP. Methods: We retrospectively reviewed charts of 221 patients who underwent surgery for CP. Patients were included if they had an NT pro BNP reported <6 weeks before and between 6-52 weeks after surgery; and excluded if they had BNP before but NT pro BNP after surgery. The NYHA class during the encounter for NT pro BNP was noted to minimize selection bias based on symptoms. The NT pro BNP and its logarithm before and after surgery were compared using the Wilcoxon signed rank test. The left ventricular systolic, diastolic volumes and internal diameters on 2D ECHO were compared before and after surgery at dates closest to the NT pro BNP. Results: 17 patients with a median age of 61 [range 33-76, 5 males] met inclusion criteria. NT pro BNP was available a mean 146 days after surgery [range 43-351]. There was a significant increase in the NT pro BNP [mean 877.11 ± 191.1 pg/ml to 3332 ± 1249 pg/ml, p= 0.01] as well as log NT pro BNP [mean 2.715 ± 0.134 to 3.152 ± 0.146, p=0.004] after surgery. At the time of NT pro BNP evaluation post-surgery, the NYHA class was improved in 9, unchanged in 5 and worse in 3 patients. The left ventricular end diastolic volumes showed a trend towards increasing after surgery [103.08 ± 17.23 to 124.08 ± 16.28 ml, p=0.15]. Of the 17 patients, 12 before and 15 after surgery were on diuretics. Conclusions: The NT Pro BNP increases after surgery for CP. This is despite the fact that the NYHA class may remain stable or in fact improve after surgery. This increase in NT pro BNP can likely be explained by the increased cardiac volumes after surgery for CP. Thus post-surgery, an elevation in NT pro BNP can be expected without actual clinical deterioration. The use of diuretic therapy should still be guided by the NYHA class and symptoms. However, the increasing biomarker may reflect ongoing remodeling of the left ventricle after surgery.