Cardiac sarcoidosis is most often clinically silent. When symptomatic, it commonly involves the conduction system. This inflammatory and infiltrative process may be manifest as conduction delays and/or important ventricular ectopy. More diffuse myocardial infiltration may result in congestive heart failure (CHF). This case report illustrates how a more focal infiltrative process in sarcoidosis may cause severe CHF with involvement of the papillary muscle, resulting in worsening of mitral regurgitation. After a cardiac workup that revealed evidence of sarcoidosis, a gadolinium-enhanced magnetic resonance imaging series showed focal infiltration of the left ventricular wall over the region of the posterior papillary muscle, giving a pathophysiologic explanation for the patient's severe mitral regurgitation. This case report depicts sarcoidosis-associated CHF arising in an unusual fashion, resulting not from widespread myocardial infiltration, but rather from focal papillary muscle involvement and, consequently, mitral valve dysfunction. This example suggests that cardiac sarcoidosis should be considered in the differential diagnosis of mitral regurgitation leading to progressive CHF. We briefly review the diagnostic approach to cardiac sarcoidosis, with representative images from this case.