Related Experiment Videos
[Evaluation of the effects of coronary artery bypass grafting on left ventricular function in patients with previous
H Imagawa1, T Yoshino, T Kobayashi
1Department of Circulatory Dynamics, Center for Adult Diseases, Osaka, Japan.
Insights
Coronary artery bypass grafting improved left ventricular function in myocardial infarction patients. However, extensive infarction may limit recovery of exercise capacity even after complete revascularization.
Area of Science:
- Cardiology
- Cardiac Surgery
- Cardiovascular Physiology
Background:
- Assessing left ventricular (LV) function post-coronary artery bypass grafting (CABG) is crucial for patients with prior myocardial infarction (MI).
- Understanding the impact of MI size on LV functional recovery after CABG is essential for optimizing treatment strategies.
Purpose of the Study:
- To evaluate changes in left ventricular function after CABG in patients with and without previous myocardial infarction.
- To analyze the influence of myocardial infarction size on post-CABG left ventricular performance during rest and exercise.
Main Methods:
- Utilized radionuclide angiography to assess stroke index (SI), ejection fraction (EF), systolic pressure/end-systolic volume index (SP/ESVI), and end-diastolic volume index (EDVI).
- Evaluated LV function at rest and during exercise, both preoperatively and postoperatively, in MI(+) and MI(-) groups.
- Correlated myocardial infarction size, assessed by ECG scoring, with postoperative functional recovery.
Main Results:
- Postoperatively, CABG improved EF and SP/ESVI during exercise in MI patients, normalizing function in those without prior MI.
- Patients with prior MI showed significantly different exercise EF and SP/ESVI compared to those without MI and controls.
- Larger MI size negatively correlated with exercise-induced improvements in postoperative EF and SP/ESVI.
Conclusions:
- Complete revascularization via CABG enhances left ventricular function in MI patients, normalizing it in non-MI individuals.
- Extensive myocardial infarction can impair functional reserve during exercise, limiting recovery potential despite complete revascularization.
- ECG-derived MI size is a significant predictor of incomplete functional recovery post-CABG.
Abstract:
The present study was designed to assess a left ventricular function following coronary artery bypass grafting (CABG) in patients with previous myocardial infarction (MI). The subject was consisted of 10 patients with MI (MI(+) group) and 6 without it (MI(-) group). Both groups underwent complete revascularization. Stroke index (SI), ejection fraction (EF), systolic pressure/end-systolic volume index (SP/ESVI) and end-diastolic volume index (EDVI) were evaluated utilizing radionuclide angiography at rest and during exercise (Ex) before and after CABG. The influence of size of myocardial infarction on left ventricular function were also analyzed. Preoperatively during Ex, EF showed decrease, SP/ESVI no change and EDVI increase in both MI(+) and MI(-) group compared with those at rest. Postoperatively during Ex, SI, EF and EDVI showed no change and SP/ESVI increase in both MI(+) and MI(-) group compared with those at rest. Ejection fraction and SP/ESVI during Ex in MI(+) group had significant differences compared with those in both MI(-) group and control group. Ejection fraction and SP/ESVI during Ex in MI(-) showed no difference compared with those in control group. The size of MI suggested by ECG scoring system (proposed by Wagner GS et al, Circulation '82) had negative correlations with both Ex-induced increment of postoperative EF and Ex-induced increase ratio of postoperative SP/ESVI. These data indicated that complete revascularization improved EF and SP/ESVI in patients with MI, and moreover normalized those in patients without MI. But in the case of extensive MI, even complete revascularization might not recover poor functional reserve during Ex.