Ischaemia monitoring with on-line vectorcardiography during dobutamine stress echocardiography in patients after an episode of unstable coronary artery disease.
OBJECTIVE
This study investigated the ability of on-line vectorcardiography (VCG) to detect myocardial ischaemia as assessed by dobutamine stress echocardiography after an episode of unstable coronary artery disease.


METHODS
Dobutamine stress test (incrementally infused doses of 5, 10, 20, 30 and 40 microg kg(-1) per minute) was performed during simultaneous VCG monitoring. QRS vector difference (QRS-VD), ST vector magnitude (ST-VM), ST change vector magnitude (STC-VM) and T change vector magnitude (TC-VM) were monitored. A new wall motion abnormality or worsening of abnormal wall motion was regarded as indicating a positive dobutamine stress test.


METHODS
Fifty-five patients with unstable angina pectoris and 16 patients with an acute non-Q-wave myocardial infarction were studied 5-8 days after admission.


RESULTS
A positive dobutamine stress test was observed in 37 patients (52%). The sensitivity, specificity and total accuracy of identifying patients with a positive dobutamine stress test by VCG were: 38%, 91% and 63% for QRS-VD; 59%, 88% and 73% for ST-VM; 84%, 79% and 82% for STC-VM; and 86%, 23% and 56% for TC-VM. Patients with a positive dobutamine stress test showed higher maximum VCG values than patients with a negative dobutamine stress test (QRS-VD, P < 0.01; ST-VM, P < 0.001; STC-VM, P < 0.001). The maximum VCG values were related to the number of segments showing new or worsening wall motion abnormality (QRS-VD: r=0.41, P < 0.001; ST-VM: r=0.44, P < 0.001; STC-VM: r=0.57, P < 0.001).


CONCLUSIONS
STC-VM and ST-VM seem to be the best VCG variables for detection of myocardial ischaemia as assessed by dobutamine stress echocardiography.
Lundin
P
P
Department of Medicine, Danderyd Hospital, Sweden.
Eriksson
S V
SV
Andrén
B
B
Lindahl
B
B
Tornvall
P
P
Melcher
A
A
D000368:Aged; D000789:Angina, Unstable / Q000209:etiology*; D002316:Cardiotonic Agents / Q000008:administration & dosage; D017023:Coronary Angiography; D003327:Coronary Disease / Q000175:diagnosis; D004280:Dobutamine / Q000008:administration & dosage; D004452:Echocardiography / Q000379:methods*; D005080:Exercise Test; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications / Q000175:diagnosis*; D012815:Signal Processing, Computer-Assisted; D014672:Vectorcardiography / Q000379:methods
D002316:Cardiotonic Agents; D004280:Dobutamine