Influence of haemodynamics and myocardial ischaemia on Doppler transmitral flow in patients undergoing dobutamine echocardiography

To examine whether pulsed Doppler left ventricular filling indicescan reliably detect myocardial ischaemia in patients with coronaryartery disease undergoing dobutamine stress echocardiographywe studied three groups matched for age and global indices ofleft ventricular function. Group 1 patients (n=10) had normalcoronary arteries whereas those in Groups 2 (n=12) and 3 (n=15)had significant coronary disease (70% diameter stenosis) atangiography. After stopping cardiouctive treatment, patientsunderwent incremental dobutamine stress (5, 10, 15 and 20 µg.kg^–1. min^–1) during pulsed Doppler interrogationof diastolic filling with simultaneous heart rate and bloodpressure measurements. Only Group 3 patients developed myocardialischaemia using electrocardiographic and cross sectional echocardiographiccriteria, subset 3A (n=4) comprised those with inducible mitralregurgitation on colour Doppler. Electrocardiographic R-R intervaldecreased (–311 ± 123 ms, P<0·001) andmean blood pressure altered (5±17 mmHg, P=ns) uniformlyacross groups. The respective changes in peak early velocity,peak atrial velocity and their ratio for Groups 1 (0·08± 0·09 m. s^–1, 0·26 ± 0·18m.s^–1 and – 0·32 ± 0·36), 2(0·07 ± 0·07 m.s^–1 0·18±0·15m.s^–1 and –0·13±0·21) and 3(0·09±0·12 m.s^–1, 0·20±0·13m.s^–1 and –0·17±0·21) weresimilar (all P=ns between groups). Corresponding data for subset3A (0·23 ± 0·04 m.s^–1 0·20± 0·10 m.s^–1and 0·00 ± 0·16)revealed a significantly greater increase in peak early velocityand normalized velocity ratio in these patients. Overall, changesin peak early (r= –0·47, P<0·01) andatrial velocity (r–0·65, P<0·001) andtheir ratio (r=0·35, P<0·05) correlated withreduction in R-R interval but not alterations in blood pressure.In conclusion, tachycardia during dobutamine stress masks theeffects of myocardial ischaemia on Doppler diastolic indicesalthough a minority of patients with inducible mitral regurgitationmanifest a relatively distinct filling profile.