Clinical significance of papillary muscle late enhancement detected via cardiac magnetic resonance imaging in patients with single old myocardial infarction

BackgroundContrast-enhanced cardiac magnetic resonance imaging (MRI) can depict papillary muscle (PM) necrosis or fibrosis by late enhancement (LE) of PM, but its clinical significance in old myocardial infarction (OMI) has been little understood.MethodsMyocardial LE and PM-LE were detected with contrast imaging in 60 patients with OMI caused by a single culprit coronary artery lesion. Left ventricular (LV) morphology and function, mitral valve geometry, and severity of mitral regurgitation were also evaluated by cine imaging. Sphericity index was calculated for the assessment of LV remodeling.ResultsPM-LE was detected in 32 of 60 (53.3%) OMI patients. Unilateral PM-LE was detected in 22 patients and bilateral PM-LE in 10 patients. Patients with bilateral PM-LE demonstrated more severe LV remodeling and functional mitral regurgitation than those with unilateral or no PM-LE (sphericity index; bilateral PM-LE, 1.60 ± 0.15, unilateral PM-LE, 1.71 ± 0.29, no PM-LE, 1.85 ± 0.27, p ≤ 0.05) (mitral regurgitation; bilateral PM-LE, 1.10 ± 0.57, unilateral PM-LE, 0.41 ± 0.73, no PM-LE, 0.54 ± 0.84, p ≤ 0.05). In cases of unilateral PM-LE, posteromedial PM-LE resulting from right coronary artery-related OMI was accompanied by less severe mitral regurgitation, while anterolateral PM-LE resulting from left coronary artery-related OMI was not associated with severity of mitral regurgitation.ConclusionsMore than half of patients with OMI showed unilateral or bilateral PM-LE, and bilateral PM-LE was closely related to more severe LV remodeling and functional mitral regurgitation.