Decompensated
An individual may be in the compensated phase of MR for years, but will eventually develop left ventricular dysfunction, the hallmark for the chronic decompensated phase of MR. It is currently unclear what causes an individual to enter the decompensated phase of this disease. However, the decompensated phase is characterized by calcium overload within the cardiac myocytes.In this phase, the ventricular myocardium is no longer able to contract adequately to compensate for the volume overload of mitral regurgitation, and the stroke volume of the left ventricle will decrease. The decreased stroke volume causes a decreased forward cardiac output and an increase in the end-systolic volume. The increased end-systolic volume translates to increased filling pressures of the left ventricle and increased pulmonary venous congestion. The individual may again have symptoms of congestive heart failure.The left ventricle begins to dilate during this phase. This causes a dilatation of the mitral valve annulus, which may worsen the degree of MR. The dilated left ventricle causes an increase in the wall stress of the cardiac chamber as well.While the ejection fraction is less in the chronic decompensated phase than in the acute phase or the chronic compensated phase, it may still be in the normal range (i.e. : > 50 percent), and may not decrease until late in the disease course. A decreased ejection fraction in an individual with MR and no other cardiac abnormality should alert the physician that the disease may be in its decompensated phase.
Belzutifan, sold under the brand name Welireg, is a medication used for the treatment of von Hippel–Lindau disease-associated renal cell carcinoma. It is taken by mouth.The most common side effects include decreased hemoglobin, anemia, fatigue, increased creatinine, headache, dizziness, increased glucose, and nausea.Belzutifan is an hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor.Belzutifan is the first drug to be awarded an "innovation passport" from the UK Medicines and Healthcare products Regulatory Agency (MHRA). Belzutifan was approved for medical use in the United States in August 2021. Belzutifan is the first hypoxia-inducible factor-2 alpha inhibitor therapy approved in the U.S.

Medical uses
Belzutifan is indicated for treatment of adults with von Hippel-Lindau (VHL) disease who require therapy for associated renal cell carcinoma (RCC), central nervous system (CNS) hemangioblastomas, or pancreatic neuroendocrine tumors (pNET), not requiring immediate surgery. Belzutifan was also found to be efficacious in an adolescent who had Pacak–Zhuang syndrome with polycythemia and paragangliomas. References
External links
"Belzutifan". Drug Information Portal. U.S. National Library of Medicine. Clinical trial number NCT04195750 for "A Study of Belzutifan (MK-6482) Versus Everolimus in Participants With Advanced Renal Cell Carcinoma (MK-6482-005)" at ClinicalTrials.gov
Clinical trial number NCT03401788 for "A Phase 2 Study of Belzutifan (PT2977, MK-6482) for the Treatment of Von Hippel Lindau (VHL) Disease-Associated Renal Cell Carcinoma (RCC) (MK-6482-004)" at ClinicalTrials.gov