The use of negative dromotropic agents for the treatment of symptoms in patients with rheumatic MS in normal sinus rhythm has been controversial. Although a reduction in heart rate and prolonga- tion of the diastolic filling period will decrease the transmitral mean gradient, studies have shown that treatment with beta blockade may not improve or may even decrease exercise tolerance, most likely because of the limitation of the cardiac output attributable to a limited stroke volume and Nonetheless, there are now several randomized trials that have exam- ined beta blockers and ivabradine in patients with rheumatic MS and have shown that either drug can increase exercise duration and improve symp- To explain these differences, the earlier trials that found no benefit of beta blockers were performed in older patients with underlying chro- notropic incompetence, whereas the randomized trials showing benefit were performed primarily in younger patients with higher resting and exercise- induced heart rates. Thus, the use of beta blockers or ivabradine to improve symptoms may be effec- tive only in patients who do not have underlying chronotropic incompetence. When medical ther- apy is considered for relief of symptoms in patients with rheumatic MS, it must be remembered that intervention with PMBC relieves symptoms in those patients with an appropriate valve morphology. Recommendations for Intervention for Rheumatic MS Referenced studies that support the recommendations are summarized in Online Data Supplements 21 to 24. 