Introduction: Patients with secondary mitral regurgitation (SMR) often show extra-mitral valvular cardiac damage which can influence the prognosis. SMR can be defined according to stages of extra-mitral valvular cardiac damage. The present study evaluated the prevalence of different stages of extra-mitral valvular cardiac damage and the prognostic implications in moderate and severe SMR patients. Methods: A total of 648 patients with moderate and severe SMR were classified according to the extent of cardiac damage on echocardiography: left ventricular damage (Stage 1), left atrial damage (Stage 2), pulmonary artery vasculature damage (Stage 3) or right ventricular damage (Stage 4). Cox proportional hazards analyses were performed, both on, non-censored and censored data (included till the occurrence of mitral valve intervention). The primary endpoint was all-cause mortality. Results: The prevalence of each stage of the proposed classification was, 10% in Stage 1, 7% in Stage 2, 16% in Stage 3 and 67% in Stage 4. In the censored data, cardiac damage classification was independently associated with all-cause mortality (HR: 1.182, CI :1.019-1.370; P=0.027), and this was mainly driven by Stage 4 (HR: 1.726 CI: 1.034-2.881; p=0.037, Figure 1A). The non-censored data, showed that Stage 3 was independently associated with all-cause mortality (HR: 1.795 CI:1.121-2.876; P= 0.015), whereas Stage 4 showed an increased non-significant risk for all-cause mortality (HR: 1.472 CI:0.973-2.227; P=0.067, Figure 1B). Conclusions: A new proposed staging classification for moderate and severe SMR showed, that cardiac damage staging was independently associated with all-cause mortality in patients censored for mitral valve intervention, and this was mainly determined by RV dysfunction.