DO RADIONUCLIDE AND ECHOCARDIOGRAPHIC TECHNIQUES GIVE A UNIVERSAL CUT-OFF VALUE FOR LEFT-VENTRICULAR EJECTION FRACTION THAT CAN BE USED TO SELECT PATIENTS FOR TREATMENT WITH ACE-INHIBITORS AFTER MYOCARDIAL-INFARCTION

Objective-To determine whether echocardiography and radionuclide angio graphy give comparable results when the left ventricular ejection frac tion is measured early after myocardial infarction and thus whether, i rrespective of the method used, a single value for the ejection fracti on could be used as a guide for starting treatment with an angiotensin converting enzyme inhibitor. Design-Prospective comparison of measure ment of left ventricular ejection fraction by echocardiography and rad io-nuclide angiography. Setting-Coronary care units of two university teaching hospitals in Glasgow. Patients-99 patients studied within 36 hours of acute myocardial infarction. Outcome measures-left ventricula r ejection fraction assessed by echocardiography and radionuclide angi ography. Results-70 (77%) of the 99 patients had ejection fraction mea sured by both echocardiographic and radionuclide techniques, 30 in cen tre 1 and 40 in centre 2. In centre 1 the mean difference (SD) in ejec tion fraction (radionuclide angiography - echocardiography) was -8 (10 %); 95% CI-12 to -4%. In centre 2 the mean difference was -14 (11%); 9 5% CI -17 to -11%. If patients had been treated with an ACE inhibitor on the basis of a radionuclide ejection fraction of <40% then 93% in c entre 1 (28 of 30) and 98% in centre 2 (39 of 40) would have been trea ted. This compares with 63% (19 of 30) and 50% (20 of 40), respectivel y if echocardiography had been used as a guide. Conclusion-Measurement of ejection fraction is highly dependent on the method used and it is therefore impossible to quote a universally applicable figure for lef t ventricular ejection fraction below which an ACE inhibitor should be used after myocardial infarction.