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Prolonged ischemic heart disease and coronary artery bypass - relation to contractile reserve
Klaus F Kofoed1, Regitze Bangsgaard, Steen Carstensen
1Division of Cardiology, Medical Department B, The Heart Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. kkofoed@pet.rh.dk
Insights
Coronary artery bypass grafting (CABG) benefits patients with chronic ischemic heart disease and impaired left ventricular (LV) function, even without significant myocardial viability. Post-CABG, patients experienced symptom relief and improved exercise capacity.
Area of Science:
- Cardiology
- Cardiac Surgery
- Nuclear Cardiology
Background:
- Coronary artery bypass grafting (CABG) is often expected to improve left ventricular (LV) function by recovering viable myocardium.
- Recent evidence suggests a time limitation for myocardial recovery after ischemic events.
- The extent of viable myocardium and its impact on post-CABG outcomes in patients with prolonged medical treatment require further investigation.
Purpose of the Study:
- To investigate the extent of viable myocardium in patients with impaired LV function due to ischemic heart disease after prolonged medical treatment.
- To assess the relationship between viable myocardium and clinical changes after CABG.
- To evaluate the benefits of CABG in patients with chronic ischemic heart disease and impaired LV function despite limited functional reserve.
Main Methods:
- Included 45 patients with ischemic heart disease, LV ejection fraction (EF) <45%, and a mean symptom duration of 9 years, referred for CABG.
- Preoperative assessment of LV viable myocardium using glucose metabolism-blood flow positron emission tomography (PET) and dobutamine stress echocardiography.
- Evaluation of symptoms, exercise capacity, and LV function before and 7 months after surgery in event-free survivors.
Main Results:
- The LV extent of myocardial viability was less than 30% in most patients.
- In event-free survivors, LV ejection fraction (LVEF) decreased from 31+/-7% to 26+/-8% 7 months post-CABG.
- Despite the LVEF decrease, most patients reported improved angina, heart failure symptoms, and exercise capacity, with a 3-year survival rate of 77%.
Conclusions:
- Patients with chronic ischemic heart disease and impaired LV function who have undergone prolonged conservative treatment benefit from CABG.
- The benefits of CABG in this patient group persist even in the absence of significant LV functional reserve.
- CABG can lead to symptomatic improvement and enhanced exercise capacity in selected patients with chronic ischemic heart disease and reduced LV function.
Objective:
A major effect of coronary artery bypass grafting (CABG) in patients with ischemic heart disease and impaired left ventricular (LV) contractile function is believed to be an improvement in LV function due to recovery of dysfunctional, but viable myocardium. However, recent studies have indicated a time limit for such a recovery. We therefore investigated the extent of viable myocardium in patients with impaired LV function due to ischemic heart disease after a prolonged strategy of medical treatment and its relation to changes in clinical variables after CABG.
Methods:
Forty-five consecutive patients with a mean duration of ischemic heart symptoms of 9 years and LV ejection fraction (EF) <45% referred for CABG were included and LV extent of viable myocardium was measured preoperatively by glucose metabolism--blood flow positron emission tomography imaging and dobutamine stress echocardiography. Symptoms, exercise-capacity and LV function were evaluated before and 7 months after surgery in event-free survivors.
Results:
LV extent of myocardial viability was <30% in most patients. In event-free survivors, LVEF decreased from 31+/-7 to 26+/-8% 7 months after CABG. The decrease in LVEF was correlated to the LV extent of myocardial metabolism--blood flow reverse mismatch. Most of the patients experienced an improvement in their angina pectoris, heart failure symptoms and exercise capacity after CABG; the overall 3-year survival was 77%.
Conclusions:
Patients with chronic ischemic heart disease and impairment of LV function, in whom an initial long-standing conservative treatment has been practiced, benefit from CABG, despite a lack of LV functional reserve.