Usefulness of diastolic phase indexes by gated cardiac blood pool imaging in patients with coronary artery disease

In patients with coronary artery disease (CAD), various left ventricular diastolic phase indexes were obtained from multi-gated blood pool imaging with sup(99m)Tc. As early diastolic phase indexes, during the first third of diastole, filling fraction (1/3 FF), mean filling rate (1/3 FR-mean) and maximal filling rate (1/3 FR-max) were calculated. In addition, maximal filling rate during whole diastole (FR-max) was calculated. These diastolic phase indexes correlated with left ventricular ejection fraction (LVEF) (r >= 0.73, p > 0.001). A good reproducibility was obtained in each of diastolic phase index (r >= 0.96). Subjects were divided into 3 groups: Normal (n = 14), Group I (n = 26); CAD with normal LVEF (>= 55%) and normal wall motion and Group II (n = 29); CAD with reduced LVEF and/or abnormal wall motion. With these diastolic phase indexes, 3 groups could be differentiated (p < 0.001). If we take the mean value minus 2SD of Normal group as the lower limits of normal, diastolic phase indexes were more sensitive to separate CAD from normal subjects (1/3 FR-mean > 1/3 FF > 1/3 FR-max > FR-max in order of sensitivity) than systolic functions such as LVEF, wall motion abnormality and mean first third ejection rate (1/3 ER-mean). Abnormality in 1/3 FR-mean (< 1.70 sec-1) was found in 91% of patients with CAD (81% of Group I, 100% of Group II). The comparison of 1/3 FR-mean with 1/3 ER-mean revealed that early diastolic phase index was sensitive indicator of the left ventricular dysfunction due to myocardial ischemia. (author)