Relationship between systolic and diastolic function with improvements in forward stroke volume following reduction in mitral regurgitation

Efforts to improve mitral regurgitation (MR) are often performed in conjunction with coronary revascularization. However, the independent effects of reduced MR area (MRa) are difficult to quantify. Using a previously developed cardiovascular model, ventricular contractility (elastance 1-8 mmHg/ml) and relaxation (tau: 40-150 msec) were independently adjusted for 4 grades of MR orifice areas (0.0 to 0.8 cm²). Improvements in forward stroke volume (fSV) were determined for the permutations of reduced MRa. For all conditions, LV end-diastolic pressure and volumes ranged from 7.3-24.2 mmHg and 64.8-174.3 ml, respectively. Overall, fSV ranged from 36.0-89.4 (mean: 64.2±12.8) ml, improved between 6.4 and 35.3% (mean: 15.6±8.1%), and was best predicted by (r=0.97, p<0.01): %Δ(fVS) = 34 [MRa_inital] - 46 [MRa_final] - 0.5 [elastance]. Reduced MRa, independent of relaxation and minimally influence by contractility, yield improved fSVs.