Brain natriuretic peptide and magnetic resonance imaging in tetralogy with right ventricular dilatation

Abstract

Background: Cardiac volumetry by magnetic resonance imaging can guide the timing for reoperation in minimally symptomatic or asymptomatic patients with pulmonary insufficiency after corrected tetralogy of Fallot. Pro-brain natriuretic peptide (BNP) is a marker of ventricular dysfunction and wall stress, and levels may complement magnetic resonance imaging in cardiac assessment before and after pulmonary valve replacement.

Methods: Between May 2004 and October 2005, 23 consecutive patients with corrected tetralogy, severe pulmonary insufficiency, and right ventricular end-diastolic volume index greater than 150 mL/m2 underwent elective pulmonary valve replacement. Plasma proBNP levels and magnetic resonance imaging were obtained before and 6 months after pulmonary valve replacement.

Results: There was no surgical mortality or morbidity. Preoperative right ventricular end-diastolic volume index correlated with pulmonary insufficiency, and inversely so with left ventricular ejection fraction, reflecting interventricular interaction. Preoperatively (r = -0.47) and 6 months postoperatively (r = -0.54), log BNP was inversely correlated with right ventricular ejection fraction. Mean preoperative proBNP levels, right ventricular end-diastolic volume index, and pulmonary insufficiency significantly (p < 0.0001) diminished 6 months after pulmonary valve replacement (231 versus 114 ng/L, 184 versus 109 mL/m2, and 44% versus 2%, respectively).

Conclusions: Plasma proBNP is elevated in patients with corrected tetralogy, severe pulmonary insufficiency, and right ventricular dilatation, and it significantly diminishes 6 months after pulmonary valve replacement, mirroring magnetic resonance imaging-documented better right ventricular ejection fraction and smaller right ventricular end-diastolic volume index. Pro-brain natriuretic peptide complements magnetic resonance imaging for cardiac assessment in patients requiring pulmonary valve insertion. Future validation of cutoff levels are required to establish proBNP as a useful diagnostic and follow-up tool in patients with chronic pulmonary insufficiency and failing right ventricles.