Ejection fraction and heart rate correlate with diastolic peak filling rate at rest and during exercise

We investigated the independent variables correlating with the multigated radionuclide peak filling rate (PFR) at rest and during supine bicycle exercise in 20 normal individuals. Independent variables were systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), ejection fraction (LVEF), time to PFR (TPFR), peak ejection rate (PER) and time to PER (TPER). Fifteen subjects completed at least five stages of exercise at 25 watts each. Correlating independent variables were selected by a forward-backward stepwise multiple linear regression (BMDP2R). A partial correlation statistical program was also used to allow control of critical independent variables. The final regression equations were: a) resting state, PFR = -2.5 + 0.03HR + 0.05LVEF + 0.02SBP - 0.02DBP, and b) exercise state, PFR = -3.8 + 0.04HR + 0.08LVEF. All independent variables mentioned above correlated with PFR (simple correlations designated as zero partials). However, when LVEF and HR were held constant (second order partials), the correlation of PFR with any of the other independent variables disappeared. In summary, the radionuclide global LV PFR is predominantly correlated to LVEF and HR at rest and during exercise. These correlations should be considered when assessing exercise effects of disease states on PFR.