Vasodilator stress echocardiography for risk stratification of medically stabilized unstable angina

The aims of this study were to assess the safety, feasibility and prognostic value of dipyridamole-atropine stress echo in patients with medically stabilized unstable angina.

The initial population consisted of 173 patients consecutively admitted at two different Coronary Care Units with class IIIB unstable angina. Of these, 56 were excluded: five had poor acoustic window, 24 did not stabilize with medical therapy and underwent urgent coronary angiography, 26 evolved in non-Q wave myocardial infarction and one patient died. The remaining 117 patients underwent dipyridamole-atropine stress echo after 48 h without symptoms or electrocardiographic evidence of myocardial ischaemia.

No complications or side effects occurred. An ischaemic response was found in 61 patients. During follow-up (10+/-9 months), three cardiac deaths, eight infarctions, 13 unstable anginas, and seven late (>3 months from stress testing) revascularizations occurred. There were 22 events (36%) in patients with, and nine events (16%) in patients without, inducible ischaemia (P=0.01). At Cox analysis peak-stress wall-motion score index (HR=5.5; 95% CI, 1.9 to 15.5; P=0.0015), and admission ST-segment depression (HR=4.2; 95% CI, 1.7 to 10.7; P=0.0022) were independent predictors of spontaneous events (cardiac death, infarction, unstable angina). The 12-month event-free survival was 69% for ischaemic and 83% for non-ischaemic group (P=0.03). In considering major events as end-points (spontaneous events, and late revascularization), again multivariate prognostic indicators were peak-stress wall-motion score index (HR=14.2; 95% CI, 2.6 to 76.6; P=0.0021), and admission ST-segment depression (HR=3.1; 95% CI, 1.4 to 6.9; P=0.0055). The 12-month event-free survival rate was 58% for ischaemic and 81% for non-ischaemic group (P=0.002). With an interactive stepwise procedure, stress echo findings were found to provide incremental prognostic contribution to that of clinical data alone.

With proper selection of patients, dipyridamole-atropine stress echo is extremely safe and feasible in patients with medically stabilized unstable angina, and can be useful in identification of subjects at risk for future cardiac events.