In patients with moderate calcific mitral stenosis, possible HFpEF and dyspnea on exertion, how would you differentiate the etiology of the symptoms?   

I would consider a dobutamine stress echocardiogram to evaluate the flow across the valve as well as diastolic parameters. If this does not answer the question, an exercise right heart catheterization could be helpful and could also look into concomitant pulmonary hypertension as a cause of dyspnea....