Ischaemia detection in Intermediate Risk
patients with Acute Coronary Syndromes On-line by Vectorcardiography. B Aliprandi-Costa*, V.Solanki, D.Breiger. Dept of Cardiology, University of Sydney, Concord RG Hospital, Sydney. Background: Continuous on-line vectorcardiography (VCG) provides an
alternative non-invasive method for identifying intermediate risk patients with
recurrent ischaemia in the presence of coronary artery disease. As patient
presentations suggestive of unstable angina vary, combined clinical risk
evaluation and ischaemia monitoring is needed in order to identify patients for
early investigation and treatment. Method: The prognostic information from 24 hr monitoring with on-line VCG
was assessed in 93 consecutive patients with UA (n=67) or non Q-wave MI (n=26). On admission patients were classified into the
intermediate risk group as defined by the National Health and Medical Research
Council (NHMRC). The occurrence and duration of ischaemia was measured by ST
vector magnitude (ST-VM60) and ST change vector magnitude (STC-VM). Ischaemia
was defined as a change of >50 mV on either parameter. Results: On VCG, 12 of the 39 (31%) intermediate risk patients had
detectable ischaemia.The mean duration of ischaemia was 204.1±219.5mins and 31 patients underwent coronary angiography. 10 of the 12 patients with detectable ischaemia had evidence of coronary
artery disease (CAD),. In addition there were 8 patients with no evidence of
ischaemia on the VCG, and a positive angiogram. This reflects a positive
predictive value of 90% for the detection of ischaemia by VCG in the presence
of CAD and a negative predictive value of 60% in intermediate risk patients. Conclusions: The predictive value of continuous on-line VCG for detection
of ischaemia is a reliable method for clinical stratification of intermediate
risk patients with acute coronary syndromes. Patients identified in the first
24hrs of admission may be referred for early risk modification strategies.
