Abstract 2832: Papillary Muscle Infarction is a Predictor of Ischemic Mitral Regurgitation: Novel Insights from Cardiac Magnetic Resonance Study
Introduction Ischemic mitral regurgitation (MR) bodes worsened prognosis and increased mortality in patients with ischemic cardiomyopathy. Various mechanisms of ischemic MR have been purposed, resulting in a spectrum of surgical strategies with varying success rates. Papillary muscle infarction may contribute to ischemic MR, but could not be identified non-invasively until the recent development of chronic infarction specific imaging (delayed-enhancement, or DE-MRI).
Hypothesis We hypothesized that papillary muscle infarction, determined by DE-MRI, was correlated with the presence of ischemic MR.
Methods Contrast-enhanced cardiac MRI for viability assessment was performed in 100 patients with ischemic cardiomyopathy (67 male, mean age 65 years). Papillary muscle infarction was determined from DE-MRI, and left ventricular (LV) functional parameters were calculated from contiguous short-axis cine-MRI images using the disc-summation technique.
Results MR by echocardiography was present in 67%: 30% with mild MR (1+), 27% moderate MR (2+), and 10% severe MR (3– 4+). In patients with no, mild, moderate, and severe MR, there was a positive correlation with the prevalence of posterior papillary muscle infarction (15%, 40%, 52%, and 70%, respectively), but there was no association with anterior papillary muscle infarction (p=NS). There was a significant inverse relationship with LV ejection fraction (LVEF) (29%, 26%, 24%, and 20%, respectively). Both LVEF (p=0.013) and posterior papillary muscle infarction (p=0.006) were significantly associated with ischemic MR on univariate analysis. Using multiple logistic regression analysis, both posterior papillary muscle infarction and LVEF remained independent determinants of MR presence and severity (p<0.001 for both).
Conclusions Patients with ischemic cardiomyopathy demonstrate a significant and positive correlation between the severity of MR and prevalence of posterior, but not anterior papillary muscle infarction identified by DE-MRI, and an inverse relationship with LVEF. The identification of papillary muscle infarction may provide insights into alternative approaches for repair of ischemic MR.