In a patient with rheumatic valvular disease experiencing chest pain and a new murmur, what is the likely diagnosis?

In a patient with rheumatic valvular disease who presents with chest pain and a new murmur, the likely diagnosis is mitral regurgitation due to the rupture of chordae tendineae. Rheumatic fever can lead to significant valvular heart disease, particularly affecting the mitral valve, which often results in complications such as chordae tendineae rupture.

When the chordae tendineae, which anchor the mitral valve leaflets to the left ventricular wall, are ruptured, it causes the valve to fail to close properly during systole. This leads to retrograde blood flow from the left ventricle into the left atrium, resulting in acute mitral regurgitation, characterized by a new holosystolic murmur. The acute onset of mitral regurgitation can also lead to increased left atrial pressure, pulmonary congestion, and symptoms such as chest pain and dyspnea.

In this clinical setting, it is important to consider the history of rheumatic fever as it indicates the presence of underlying valvular disease, making the rupture of chordae tendineae a plausible and significant complication.