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Effects of coronary artery bypass grafting on resting and exercise hemodynamics in patients with stable angina
Insights
Coronary bypass surgery significantly improved exercise hemodynamics and treadmill performance in patients with ischemic dysfunction. These improvements were most pronounced in patients with elevated pulmonary arterial wedge pressure at entry.
Area of Science:
- Cardiology
- Cardiovascular Surgery
Background:
- Coronary artery disease often leads to impaired left ventricular function, particularly during exercise.
- Identifying patients who will benefit most from surgical intervention is crucial for optimizing outcomes.
Purpose of the Study:
- To evaluate the impact of coronary bypass surgery on resting and exercise hemodynamics compared to medical management.
- To identify predictors of improved ventricular performance after surgery.
Main Methods:
- Prospective randomized study comparing coronary bypass surgery (38 patients) with medical management (40 patients).
- Hemodynamic measurements (pulmonary arterial wedge pressure, cardiac index) and maximal treadmill exercise tests were performed before and 1 year after intervention.
- Patients were subgrouped based on exercise-induced pulmonary arterial wedge pressure increase at entry.
Main Results:
- The surgical group showed significant improvements in exercise pulmonary arterial wedge pressure and cardiac index, along with increased resting heart rate and mean arterial pressure.
- Maximal treadmill exercise performance significantly improved in the surgical group compared to the medical group.
- A subgroup of 16 surgical patients with marked "ischemic dysfunction" (defined by >10 mm Hg increase in exercise pulmonary arterial wedge pressure) demonstrated substantial improvements in both hemodynamics and exercise capacity.
Conclusions:
- Coronary bypass surgery can lead to significant objective improvements in ventricular performance and exercise capacity.
- Hemodynamic evidence of ischemic left ventricular dysfunction during stress may identify patients who are most likely to benefit from bypass graft surgery.
Abstract:
In this prospective randomized study, resting and exercise hemodynamics were determined in the nonmedicated state before ("entry") and 1 year after coronary bypass surgery in 38 patients, and at entry and 1 year in 40 patients treated medically. The surgical group showed a significant decrease in mean pulmonary arterial wedge pressure during exercise (entry 23.5 +/- 6.1 [standard error of the mean] mm Hg, 1 year 18.9 +/- 1.0, P less than 0.02); an increase in cardiac index during exercise (entry 4.3 +/- 0.1 liter/min per m2, 1 year 4.6 +/- 0.1, P less than 0.05); an increase in resting mean arterial pressure (entry 94.5 +/- 2.2 mm Hg, 1 year 100.2 +/- 2.2, P less than 0.02); and an increase in resting heart rate (entry 68.5 +/- 1.9 beats/min, 1 year: 76.0 +/- 2.0, P less than 0.01). Maximal treadmill exercise performance also improved significantly in the surgical group of patients (entry 285 +/- 24 seconds, 1 year 382 +/- 24, P less than 0.002). There were no significant changes in these variables in the medically treated "control" group. The improvement in pulmonary arterial wedge pressure during exercise and in maximal treadmill exercise time in the surgical group as a whole was due to striking improvement in these variables in a subgroup of 16 surgical patients who had a more than 10 mm Hg increase in pulmonary arterial wedge pressure during exercise in their entry study. In this subgoup, considered to contain those patients with marked "ischemicdysfunction," pulmonary arterial wedge pressure during exercise fell from 31.4 +/- 1.5 mm Hg (entry) to 19.l +/- 1.8 (1 year) (P less than 0.0001) and treadmill time increased from 217 +/- 24 seconds (entry) to 357 +/- 37 (1 year) (P less than 0.001). Thus, hemodynamic evidence of ischemic left ventricular dysfunction during stress may identify those patients who will show objective improvement in ventricular performance after bypass graft surgery.