[Comparison of exercise capacity with resting left ventricular function evaluated by various non-invasive methods in patients with old myocardial infarction].

The purpose of this study was to investigate the relationship between exercise capacity and resting left ventricular function assessed by several non-invasive methods in patients with old myocardial infarction. Subjects were 25 male patients whose endpoint was either dyspnea or general fatigue at the symptom-limited maximal graded treadmill exercise test according to Bruce protocol. The indices obtained by non-invasive cardiac examinations included left ventricular fractional shortening (% FS), scintigraphic infarct size (% SIS) by 201Tl myocardial scintigraphy and PEP/ET (so-called Weissler's index). A significant correlation of exercise duration with % FS (r = 0.67, p less than 0.001) or with % SIS (r = -0.55, p less than 0.02) indicated that the more was impaired resting left ventricular function, the more was decreased exercise capacity. Also, a significant correlation of systolic blood pressure at the end-point in exercise test with % FS (r = 0.58, p less than 0.005) or with % SIS (r = 0.69, p less than 0.001) indicated that inadequate blood pressure response might be partially attributed to impaired left ventricular function during exercise. The response of heart rate at the Bruce protocol stage I correlated with % FS (r = -0.67, p less than 0.001) and with % SIS (r = 0.53, p less than 0.02), respectively. These findings may be interpreted as chronotropic compensatory mechanism for limited stroke volume during exercise in patients with imparied left ventricular function. Thus, it was concluded that resting left ventricular function assessed by non-invasive cardiac examinations may predict exercise capacity prior to the test to some extent. These informations can be utilized for the decision of the planning at cardiac rehabilitation and also for the guidance in daily activities. Additionally, low level exercise test with treadmill is considered to be valuable for screening cases with impaired left ventricular function in old myocardial infarction.