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Right Ventricular Systolic Function in Organic Mitral Regurgitation: Impact of Biventricular Impairment
Study Questions:
What are the prevalence, determinants, and prognosis value of right ventricular ejection fraction (RVEF) impairment in chronic organic mitral regurgitation (MR)?
Methods:
A cohort of 208 patients (62 ± 12 years, 138 males) with chronic organic MR referred to surgery underwent echocardiography and biventricular radionuclide angiography with assessment of regional function.
Results:
Mean RVEF was 40.4 ± 10.2%, ranging from 10% to 65%. RVEF was severely impaired (≤35%) in 63 patients (30%); biventricular impairment (left ventricular [LV] EF <60% and RVEF ≤35%) was found in 34 patients (16%). Pathophysiologic correlates of RVEF were LV septal function (β = 0.4, p < 0.0001), LV end-diastolic diameter index (β = −0.22, p = 0.002), and pulmonary artery systolic pressure (β = −0.14, p = 0.05). Mitral effective regurgitant orifice size (n = 84) influenced RVEF (β = −0.28, p = 0.01). In 68 patients examined after surgery, RVEF increased strongly (27.5 ± 4.3 to 37.9 ± 7.3, p < 0.0001) in patients with depressed RVEF, whereas it did not change in others (p = 0.91). RVEF ≤35% impaired 10-year cardiovascular survival (71.6 ± 8.4% vs. 89.8 ± 3.7%, p = 0.04). Biventricular impairment dramatically reduced 10-year cardiovascular survival (51.9 ± 15.3% vs. 90.3 ± 3.2%, p < 0.0001; hazard ratio [HR], 5.2; p < 0.0001) even after adjustment for known predictors (HR, 4.6; p = 0.004). Biventricular impairment also reduced 10-year overall survival (34.8 ± 13.0% vs. 72.6 ± 4.5%, p = 0.003; HR, 2.5; p = 0.005) even after adjustment for known predictors (p = 0.05).
Conclusions:
In patients with chronic organic MR referred to surgery, RV function impairment is frequent (30%), and only weakly associated with pulmonary artery systolic pressure, but more so with LV remodeling and septal function. RV function is a predictor of postoperative cardiovascular survival, whereas biventricular impairment is a powerful predictor of both cardiovascular and overall survival.
Perspective:
It has been presumed that RV systolic dysfunction that occurs in the setting of chronic severe MR is a result of elevated left atrial pressure and reflexive pulmonary vasoconstriction, leading to pulmonary hypertension and increased RV afterload. Notably, this study revealed only a weak correlation between pulmonary artery systolic pressure and RVEF. Rather, RVEF appeared to be more strongly influenced by the effect of MR on the interventricular septum, which in turn likely was a function of LV enlargement and unfavorable LV remodeling. The finding of a strong association between decreased RVEF and postoperative cardiovascular survival provides further support for intervention for chronic severe MR prior to the development of substantial LV dilation.
Keywords: Prognosis, Ventricular Function, Right, Mitral Valve Insufficiency, Radionuclide Angiography, Echocardiography
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