Influence of dobutamine or exercise stress on the results of pulsed-wave Doppler assessment of myocardial velocity

Background Pulsed-wave Doppler assessment of myocardial velocity (MDV) may permit a more quantitative interpretation of stress echocardiography. This technique has been used with dobutamine echo (DbE), but exercise echo (ExE) may be preferred in patients who are able to exercise maximally. The influence of these stressors on the results of MDV are undefined. Purpose This study sought to determine whether differences between the physiology of DbE and ExE could influence the MDV responses to stress and whether interpretative criteria should be different with exercise or dobutamine stress. Methods DbE or ExE was performed in 105 patients tested for known or suspected coronary artery disease. Pulsed-wave MDV was obtained in basal segments of anteroseptal, septal, anterior, posterior, lateral, and inferior walls in the apical views at rest and at peak doses of dobutamine or immediately after exercise. Segments were classified as normal or abnormal (ischemia or scar) according to results of 2-dimensional echocardiography, and MDV obtained at rest and stress was compared by using analysis of variance. Results Resting heart rate was similar before both dobutamine and exercise, but heart rate at peak dobutamine exceeded that after exercise (137 +/- 10 vs 115 +/- 22, P < .01). For both ExE and DbE, MDV was significantly greater at rest and stress in normal than in abnormal segments. Stress MDV in both normal and abnormal segments was greater with DbE than with ExE (17.0 +/- 4.8 cm/s vs 10.3 +/- 3.4 cm/s, P < .001 for normal segments and 10.7 +/- 4.4 cm/s vs 7.9 +/- 3.3 cm/s, P < .001 for abnormal segments, Increase in MDV/Delta heart rate induced by DbE was greater than by ExE in normal (0.14 +/- 0.07 cm/s . beat for DbE and 0.09 +/- 0.08 cm/s . beat for ExE; P < .05) but similar in abnormal segments (0.06 +/- 0.07 cm/s . beat for DbE and 0.05 +/- 0.09 cm/s . beat for ExE). MDV correlated better with peak heart rate at ExE (r = 0.56, P < .01) than at DbE (r = 0.28, P < .01). Conclusions MDV responses to exercise and pharmacologic stress appear to be different, reflecting differences in inotropy, loading, and the timing of imaging. These findings may influence the ability of MDV to differentiate normal from abnormal stress echocardiography responses.