A 75-year-old man presents with worsening shortness of breat…

A 75-year-old man presents with worsening shortness of breath, fatigue, and weight gain. The symptoms have progressed over the past month. He has a history of coronary artery disease and is on aspirin 81mg daily, atorvastatin 40mg daily, and metoprolol 50mg twice daily. His vital signs are as follows: BP 138/83, HR 97, RR 18, T 98.5F and 02 95% on RA. Physical exam reveals a previously undetected grade 2/6 holosystolic murmur most prominently heard at the apex. There is 2+ pitting edema to the shins.Which of the following conditions would be highest on the differential diagnosis?