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Background: Accurate identification of patients at high risk for acute coronary syndromes among those seen in the emergency department (ED) with possible myocardial ischemia and nonischemic electrocardiograms is problematic. Both 2-dimensional echocardiography and myocardial perfusion imaging with technetium-99m sestamibi can identify patients at low and high risk; however, comparative studies are lacking., Methods and Results: Patients initially considered at low or moderate risk for myocardial ischemia on the basis of the presenting history, physical examination, and electrocardiogram underwent both echocardiography and myocardial perfusion imaging within 4 hours of ED presentation. Positive echocardiography was defined as the presence of segmental wall motion abnormalities or moderate to severe global systolic dysfunction; positive perfusion imaging was defined as a perfusion defect in association with abnormal wall motion, thickening, or both. End points included MI, percutaneous transluminal coronary angioplasty, and positive stress perfusion imaging. Both imaging procedures were performed in the ED on 185 patients. Six patients had MI, and an additional 4 patients underwent percutaneous transluminal coronary angioplasty. Echocardiography and perfusion imaging were positive in all 10. Overall agreement between the 2 techniques was high (concordance 89%, kappa coefficient 0.74) in the 27 patients who had MI or underwent coronary angiography. For all patients, concordance was 89%, with a kappa coefficient of 0.66., Conclusions: Agreement between echocardiography and perfusion imaging with technetium-99m sestamibi is high when used in patients in the ED with possible myocardial ischemia. Both techniques identified patients at high risk who required admission and those who could be safely discharged directly from the ED.

A completely noninvasive method for estimating left atrial pressure in patients with congestive heart failure and mitral regurgitation has been devised with the use of continuous-wave Doppler echocardiography and brachial sphygmomanometry. Of 46 patients studied with mitral regurgitation, 35 (76%) had jets with distinct Doppler spectral envelopes recorded. The peak ventriculoatrial gradient was obtained by measuring peak mitral regurgitant velocity in systole and using the modified Bernoulli equation. This gradient was then subtracted from peak brachial systolic blood pressure, an estimate of left ventricular systolic pressure, to yield left atrial pressure (left atrial pressure = systolic blood pressure - mitral regurgitant pressure gradient). Noninvasive estimates of left atrial pressure from 35 patients were plotted against simultaneous recordings of mean pulmonary capillary wedge pressure resulting in the correlation y = 0.88x + 3.3, r = 0.88, standard error of estimate = +/- 4 mm Hg (p less than 0.001). Therefore, continuous-wave Doppler echocardiography and sphygmomanometry may be used in selected patients with congestive heart failure and mitral regurgitation for noninvasive estimation of left atrial pressure.

Left ventricular ejection fraction (EF) at rest and during exercise was measured in 19 patients with hypertrophic cardiomyopathy (HCM) by means of radionuclide angiography. The results were compared to those in 20 normal subjects. Based on hemodynamic data, patients with HCM were divided into three groups. In group I, no demonstrable left ventricular outflow obstruction, there were five patients; their mean EF increased from 68% +/- 8.9 (+/- SD) at rest to 74% +/- 9.2 during exercise (p less than 0.05). In group II, latent obstruction, there were six patients; their mean EF at rest (75.2% +/- 8.2) and at peak exercise (78.7% +/- 6.7) was not statistically different (p greater than 0.05). Group III, obstruction present at rest, consisted of eight patients; EF at rest (82.6% +/- 8.5) decreased significantly during exercise (75.6% +/- 7.7, p less than 0.01). In normal subjects resting EF was 66.3% +/- 7.6; it increased to 76.4% +/- 7 (p less than 0.001). Exercise duration and heart rate-blood pressure product were lower in groups II and III. Thus there are significant differences in left ventricular systolic function both at rest and during exercise between these three major hemodynamic subgroups. These findings emphasize the importance of such a hemodynamic classification of HCM.