DIAGNOSTIC AND PROGNOSTIC VALUE OF DIPYRIDAMOLE-ECHOCARDIOGRAPHY IN PATIENTS WITH SUSPECTED CORONARY-ARTERY DISEASE - COMPARISON WITH EXERCISE ELECTROCARDIOGRAPHY

Background Before any new diagnostic test is accepted in clinical prac tice, such a test should be compared with established diagnostic tools in an appropriately large series of patients encompassing the complet e spectrum of challenges to which the test is exposed. The aim of the present study was to assess the relative diagnostic and prognostic acc uracies of high-dose dipyridamole echocardiography (two-dimensional ec hocardiographic monitoring during dipyridamole infusion up to 0.84 mg/ kg over 10 hours) versus maximal symptom-limited bicycle exercise ECG test in patients with angina. Methods and Results We studied 429 conse cutive in-hospital patients who met the following inclusion criteria: history of chest pain, off antianginal therapy for at least 2 days (1 week for beta-blockers), no previous myocardial infarction and/or obvi ous regional left ventricular dyssynergy of contraction (akinesis or d yskinesis) at baseline, and acceptable acoustic window under resting c onditions. Ah patients underwent dipyridamole echocardiography and exe rcise ECG-on different days and in random order-within 1 week of coron ary angiography (which was performed independent of test results) and were followed up for 37.8+/-14 months (range, 1 to 73 months). Criteri a of positivity were for dipyridamole echocardiography, a transient re gional dyssynergy absent in the baseline examination; for exercise ECG , an ST-segment shift of greater than or equal to 0.1 mV from baseline ; and for coronary angiography, a luminal reduction of greater than or equal to 75% in at least one major coronary vessel (50% for left main ). There were 183 patients without and 246 with coronary artery diseas e; 132 had one-, 70 had two-, and 44 had three- and/or left main vesse l disease. The specificity was higher for dipyridamole echocardiograph y than for exercise ECG (90% versus 51%, P<.001). The overall sensitiv ity of dipyridamole echocardiography was similar to that of exercise E CG (75% versus 74%, P=NS), with no significant differences in the subs et with one- (67% versus 69%, P=NS), two- (79% versus 77%, P=NS), or t hree- (93% versus 86%, P=NS) vessel disease. During the follow-up, the re were 20 deaths, 13 nonfatal myocardial infarctions, and 126 revascu larization procedures. In the univariate analysis, dipyridamole result ed in higher chi(2) values than did exercise stress testing. A Cox for ward stepwise survival analysis identified the dipyridamole time as th e most powerful prognostic predictor of death (chi(2)=19.4, P<.0001) o f all invasive and noninvasive parameters. The dipyridamole time also provided independent and additional prognostic information when it was adjusted for age, diabetes, resting ECG, and exercise stress test acc ording to a modified, interactive stepwise procedure. This is true whe n death only, death and myocardial infarction, and death, myocardial i nfarction, and revascularization procedures were considered end points . Conclusions In patients with no previous myocardial infarction and g ood resting left ventricular function, compared with exercise ECG, dip yridamole echocardiography has a similar sensitivity and a higher spec ificity for the noninvasive detection of angiographically assessed cor onary artery disease. Dipyridamole echocardiography also provides info rmation in addition to that provided by exercise ECG for predicting de ath, infarction, and all events when the presence as well as the timin g, severity, and extension of dipyridamole-induced wall motion abnorma lities are considered.