Differential Diagnosis for SOB after PCI for Anterior STEMI

Single most likely diagnosis

• Papillary muscle rupture: This condition is a well-known complication of myocardial infarction, particularly after an anterior STEMI. The harsh holosystolic murmur and RV lift palpation are consistent with severe mitral regurgitation, which can occur due to papillary muscle rupture. The timing of 2 days after PCI also fits with this diagnosis.

Other Likely diagnoses

• Ventricular septal rupture (VSR): Although less common than papillary muscle rupture, VSR is another mechanical complication of MI that can present with a new holosystolic murmur. The location of the murmur at the lower left and right sternal borders could be consistent with a VSR.
• Acute severe mitral regurgitation due to chordae tendineae rupture: Similar to papillary muscle rupture, chordae tendineae rupture can lead to severe mitral regurgitation and a harsh holosystolic murmur. This could be a result of the mechanical stress during PCI or the MI itself.

Do Not Miss (ddxs that may not be likely, but would be deadly if missed)

• Cardiac tamponade: Although the presentation does not classically suggest tamponade (e.g., no mention of pulsus paradoxus or distant heart sounds), it is crucial to consider this diagnosis due to its high mortality if missed. Tamponade can occur after PCI due to perforation or bleeding.
• Aortic dissection: This is a rare but potentially fatal complication that could occur after PCI, especially if there was manipulation of the aorta during the procedure. A new murmur could be indicative of aortic regurgitation in the setting of dissection.

Rare diagnoses

• Tricuspid regurgitation due to right ventricular infarction: While less common, right ventricular infarction can occur, especially in the setting of an inferior MI, but it's less likely given the anterior STEMI. However, it could still be considered if other diagnoses are ruled out.
• Prosthetic valve malfunction (if a valve was placed during PCI): If a valve was placed during the PCI procedure (which is not indicated in the question but could be considered in some contexts), malfunction of the prosthetic valve could lead to a new murmur and symptoms. However, this would be extremely rare and context-dependent.