Detection of silent ischemia adds to the prognostic value of coronary anatomy and left ventricular function in predicting outcome in unstable angina patients.

BACKGROUND

Patients with unstable angina are at increased risk of unfavourable outcomes such as myocardial infarction, death and urgent revascularization. Early risk stratification may improve subsequent outcome. Recently the presence and duration (at least 60 mins) of silent ischemia as measured by Holter monitoring has been shown to be of prognostic value. The incremental value of this information over that provided by coronary angiography and assessment of left ventricular function is not known.

OBJECTIVE

To determine whether detection of silent ischemia is of independent and additional prognostic significance beyond that provided by the angiographic extent of coronary artery disease and left ventricular dysfunction.

METHODS

One hundred and thirty-five unstable angina patients with 24 h of ST segment monitoring in addition to early cardiac catheterization (4 +/- 3 days) were assessed. Eighty-nine patients (66%) had ST segment shift for a total of 593 episodes (mean duration of 18 +/- 30 mins per episode) of which 92% were asymptomatic. Ten patients had a myocardial infarction and six patients died during the hospitalization. In addition, there were 33 urgent revascularization procedures.

RESULTS

With the generalized additive logistic model, various clinical variables were assessed for predicting unfavourable outcomes. Duration of ST shift (P = 0.02) was second only to angiographic severity of coronary artery disease (P = 0.004) as a predictor. In the presence of these two variables left ventricular function did not have independent prognostic significance (P = 0.16). Event-free survival curves show that duration of ST shift of at least 60 mins was of incremental value in predicting unfavourable in-hospital outcomes compared with both the extent of coronary artery disease and left ventricular dysfunction.

CONCLUSION

In patients with unstable angina, further stratification can be achieved early with Holter monitoring in addition to coronary angiography and assessment of left ventricular function.