Objectives: We sought to assess the relationship between infarct status and systolic contractile function of papillary muscle (PM) for patients with inferior wall myocardial infarction (MI).
Methods: Peak systolic velocity (V) of posteromedial PM, systolic strain (epsilon) of posteromedial PM (epsilonPM), V of adjacent inferior wall, and of adjacent inferior wall (epsilonW) were calculated from color Doppler tissue imaging images obtained at apical views in 25 patients with inferior MI and in 13 healthy control subjects. All 25 patients with MI underwent magnetic resonance imaging to assess the infarct status of PM.
Results: Compared with the control subjects, patients with MI had significantly lower V of adjacent inferior wall (5.0 +/- 0.8 vs 4.4 +/- 1.1 cm/s, P = .049) and V of posteromedial PM (4.9 +/- 0.8 vs 4.0 +/- 1.2 cm/s, P = .005), and less systolic deformation, as demonstrated by epsilonW (-17 +/- 3 vs -6 +/- 5%, P < .001) and epsilonPM (-24 +/- 5 vs -11 +/- 6%, P < .001). There was a weak positive correlation between epsilonW and epsilonPM (r = 0.393, P = .052) for patients with MI. Magnetic resonance imaging showed total infarct of PM in 14 patients (group A), with the remaining 11 revealing either normal perfusion or partial infarct of PM (group B). Although epsilonW was similar in groups A and B (-5 +/- 5% vs -8 +/- 6%, P = .20), epsilonPM was significantly lower in group B (-7 +/- 4% vs -16 +/- 4%, P = .004).
Conclusions: In patients with inferior wall MI, infarct status of the PM is variable and determines its systolic contractile function, which can be quantified by epsilon measurement using Doppler tissue imaging.