Relation Between Regional Contraction and Perfusion During Stress and 15 to 45 Minutes After Stress in Ischemic and Nonischemic Myocardial Regions We wished to determine how quickly stress-induced changes in MBF and contractile function subsided following cessation of stress. For this purpose, 10 normal volunteers and 7 pts with CAD and normal resting LV function (mean LVEF=50+/-6%) were studied. All 7 pts exhibited stress-induced wall motion abnormality (WMA). The 17 subjects underwent gated blood pool (GBP) and positron emission tomography (PET) with O-15 water. GBP and PET images were acquired at rest, during stress (supine bicycle exercise or dobutamine), and approximately 15-45min post-stress. CAD pts also underwent stress thallium (Tl) scintigraphy and data were analyzed in 9 regions per subject. All ischemic regions on stress Tl also exhibited stress-induced WMA. However, none of the abnormal regions exhibited post-stress persistent dysfunction. Mean absolute regional MBF (ml/min/g) computed from the dynamic O-15 water data follow. CAD pts rest stress 15min-post 30min-post ischemic 0.90+/-0.08 1.25+/-0.14* 0.99+/-0.05 0.90+/-0.07 nonisch 1.03+/-0.07 1.79+/-0.18** 1.10+/-0.08 1.08+/-0.09 Normal volunteers normal 0.95+/-0.08 2.10+/-0.31** 1.17+/-0.15 1.00+/-0.08 *p<0.05 and **p<0.01, rest vs stress MBF was similar in ischemic, nonischemic and normal regions at rest. With stress, MBF increased in normal and nonischemic regions by 122% and 73%, respectively while the increase in MBF in the ischemic regions was attenuated (38%). MBF returned to baseline 15min and 30min post-stress in all groups. These preliminary data suggest that in pts with CAD and normal resting LV function, stress-induced perfusion and WMAs return quickly to baseline after the termination of stress.
