Role of exercise echocardiography as a predictor of coronary artery disease. Detection of exercise-induced asynergy by M-mode echocardiography.

Left ventricular asynergy has been shown to occur commonly in patients with coronary artery disease (CAD) and to be induced or exaggerated by exercise. The purpose of this study is to report on a method to detect asynergy and estimate its severity by M-mode echocardiographic analysis of left ventricular wall motion at rest and during supine ergometric exercise. Sixteen patients with CAD underwent graded supine ergometric exercise until anginal pain occurred or apparent ischemic changes were noted on ECG. This study was done using the following criteria: 1) Asynergy at rest was defined as occurring when the amplitudes of the interventricular septum and/or the posterior left ventricular wall were below normal values at rest. 2) Asynergy during exercise was defined as occurring when one or both of the two amplitudes were more than 2 mm below the values at rest (severe) or were unchanged in spite of sufficient exercise load (mild). The results were as follows: 1) In the normal subjects, the septal and posterior wall amplitudes increased during exercise (ranging from 7 mm to 9 mm for the septum, and from 13 mm to 16 for the posterior wall). In patients with CAD, asynergy at rest was demonstrated in only 3 cases (19%), whereas septal and/or posterior wall asynergy during exercise was noted in 75% of cases. 2) The location of exercise-induced asynergy detected by echocardiography showed a good correlation with that of coronary artery lesions (greater than or equal to 75% stenosis) recognized by angiography. 3) Significant differences were observed between changes in left ventricular dimensions in patients with CAD and those of normals during exercise. In the normal subjects, left ventricular end-systolic dimension (ESD) decreased without significant change in end-diastolic dimension (EDD) during exercise. On the other hand, both ESD and EDD increased during exercise in patients with CAD. Although echocardiographic analysis of left ventricular wall motion during exercise has some limitations, this study suggests that asynergy induced or exaggerated by ergometric exercise can be successfully detected by M-mode echocardiography.