DOBUTAMINE STRESS ECHOCARDIOGRAPHY WITH AUTOMATED BORDER DETECTION AND COLOR KINESIS IDENTIFIES IMPROVED DIASTOLIC LEFT VENTRICULAR FUNCTION AND VIABLE MYOCARDIUM IN ISCHEMIC CARDIOMYOPATHY.

Since the effects of dobutamine on left ventricular systolic and diastolic function are related to the presence of myocardial viability, we attempted to establish if improvement of diastolic wall motion abnormalities assessed with automated border detection (ABD) and color kinesis (CK) has an adjunctive value in detecting hibernating but viable myocardium. 21 patients (pts) with ischemic cardiomyopathy (left ventricular ejection fraction -LVEF-: 0.31 +/- 0.11) were studied with low dose (5-10 mcg/Kg/min) dobutamine stress echocardiography (DSE). ABD waveforms of LV area change and the rate of area change were displayed along with the electrocardiogram and the concurrent cross sectional image. CK digitized LV end-systolic and end-diastolic images were evaluated by reviewing the stored loops obtained in all pts. Endocardial tracking was considered adequate when the visually assessed systolic excursion matched the color-encoded images. Viability was defined as akinetic or hypokinetic segments becoming normokinetic with systolic wall thickening. At baseline and during peak infusion LVEF, peak ejection rate (PER: ml/s), peak filling rate (PFR: ml/s) and mean time of diastolic endocardial motion (tDEM: ms) were calculated. In 10 pts viability was present (group 1), in 11 pts viability was absent (group 2). In group 1 pts there was a significantly increase from baseline to peak infusion in LVEF (0.28 +/- 0.11 vs 0.42 +/- 0.8, p<0.005), PER (1.64 +/- 0.61 vs 2.98 +/- 0.97, p<0.005), PFR (1.52 +/- 0.53 vs 2.69 +/- 0.92, p<0.05) and significant decrease in mean tDEM (304 +/- 41 vs 205 +/- 23, p<0.001). In group 2 pts a significantly increase was shown in LVEF (0.27 +/- 0.9 vs 0.38 +/- 0.10, p<0.05) and PER (1.41 +/- 0.72 vs 2.11 +/- 0.83, p<0.05); no significant difference was found in PFR (1.39 +/- 0.61 vs 1.74 +/- 0.73, p=NS) and tDEM ( 315 +/- 39 vs 304 +/- 31, p=NS). Thus, ABD and CK parameters of diastolic function (PFR, tDEM) improved only in pts with hibernating but viable myocardium whereas global systolic function can improve in the presence of both viability and non viability.