Effect of time delay on the diagnostic use of contrast echocardiography in patients presenting to the emergency department with chest pain and no S-T segment elevation.

BACKGROUND: The purpose of this study was to assess the effect of time delay on the diagnostic and prognostic use of contrast echocardiography (CE) in patients presenting to the emergency department (ED) with chest pain (CP) and no S-T segment elevation.
METHODS: Patients (n = 957, 498 men) presenting to the ED within 12 hours of suggested cardiac CP underwent CE. Regional function (RF) and myocardial perfusion were interpreted separately by expert readers blinded to all other clinical data. Primary (acute myocardial infarction and total mortality) and secondary (unstable angina and revascularization) events within 24 hours of enrollment were determined.
RESULTS: Patients were divided into 4 quartiles based on the time interval between their last episode of CP and CE. Patients in quartile I had CE during CP (time delay of 0 minutes). The time delay in quartiles II, III, and IV were 54 +/- 45, 213+/-54, and 556 +/- 184 minutes, respectively (P < .001). The incidence of events was similar among the 4 quartiles. In each quartile, patients with normal RF had the lowest incidence of events, whereas those with both abnormal RF and myocardial perfusion had the highest incidence of events. Patients with abnormal RF but normal myocardial perfusion had an intermediate event rate.
CONCLUSIONS: In patients presenting to the ED within 12 hours of CP, the timing of CE does not influence its ability to predict events that occur 24 hours later. These findings have important implications in the performance of CE in the ED.