Background: The aim of the study was to investigate the potential relationship between A-type (atrial) and B-type (brain) natriuretic peptides (ANP, BNP) and infarct size (IS), left ventricular (LV) function and remodelling as assessed by 99m technetium-hexakis-2-methoxy-isobutyl-isonitrile (99mTc-sestamibi) gated-single photon emission tomography (G-SPET).
Methods: Plasma concentrations of ANP and BNP in peripheral blood were measured in 54 patients with coronary artery disease (CAD) and previous myocardial infarction (MI). Of these, 25 subjects had a recent (<2 weeks) and 29 subjects an old (>6 months) MI. IS, left ventricular ejection fraction (LVEF) and end diastolic (EDV), end systolic (ESV) and stroke volume (SV) were quantitatively calculated from at-rest G-SPET.
Results: In either univariate or multivariate regression analysis that included IS and the other G-SPET derived parameters as co-variables, both BNP and ANP showed a significant association with IS (BNP p<0.002; ANP p<0.01). No significant relationship was found between the two peptides and LVEF, EDV or ESV values. BNP, but not ANP concentrations, were significantly higher in patients with antero-septal vs. infero-lateral (p=0.01) and recent vs. old MI (p=0.003). In these two subgroups, univariate and multivariate analyses confirmed the correlation between BNP and IS, whereas ANP demonstrated a relationship with IS only in subjects with recent MI. CAD extent had no influence on BNP and ANP levels.
Conclusions: The present study showed a positive correlation between BNP and the perfusion defect measured by 99mTc-sestamibi G-SPET in patients with previous MI. Consequently, BNP may reflect the functional significance of myocardial damage and may be considered of prognostic value. ANP was also related to scintigraphic defects in the early phase after MI, but not in the chronic phase, confirming that ANP is a less sensitive marker of LV remodelling, depending also on atrial load conditions and dilatation. These preliminary data based on a small group of subjects need to be confirmed by prospective longitudinal studies involving larger populations.