Author + information
- Received July 29, 1992
- Revision received January 14, 1993
- Accepted March 2, 1993
- Published online September 1, 1993.
- Marc D. Tischler, MD,FACC∗,
- Joelyn Niggel, RN,
- David T. Borowski, MD and
- Martin M. Lewinter, MD, FACC
- ↵∗Address for correspondence: Marc D. Tischler, MD, Medical Center Hospital of Vermont, McClure 1, Burlington, Vermont 05401.
Objectives. The aim of this study was to identify dynamic predictors of exercise duration in patients with systolic left ventricular dysfunction and to test the hypothesis that left ventricular shape is an independent determinant of exercise duration in these patients.
Background. Measurements of left ventricular volumes and ejection fraction at rest do not predict exercise capacity in patients with systolic left ventricular dysfunction. Left ventricular shape at rest has been reported to be an independent determinant of exercise duration in these patients. The significance of alterations in left ventricular shape that occur during dynamic exercise has not been investigated.
Methods. Twenty-one patients with a documented ejection fraction <40% performed symptom-limited graded upright bicycle exercise with simultaneous quantitative two-dimensional echocardiography. End-diastolic volume, end-systolic volume, stroke volume, ejection fraction and sphericity index were measured at rest and peak exercise.
Results. Eleven patients exercised beyond stage II (6 min, 50 W), averaging 8.9 ± 1.9 min; 10 patients were unable to complete stage II, averaging 4.9 ± 0.9 min. No patient developed clinical evidence of ischemia during the exercise period. Of the echocardiographic variables considered, only end-systolic and end-diastolic sphericity indexes at peak exercise (r = 0.809 and 0.711, respectively) and the change in end-systolic sphericity index during exercise (r = 0.697) were strongly correlated with exercise duration.
Conclusions. Conventional descriptors of left ventricular function are poor predictors of exercise capacity. Dynamic changes in heart shape correlate strongly with exercise duration and may be important determinants of exercise capacity in patients with systolic left ventricular dysfunction.
- Received July 29, 1992.
- Revision received January 14, 1993.
- Accepted March 2, 1993.