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The effect of coronary bypass surgery on exercise-induced ventricular arrhythmias
Insights
Coronary artery bypass surgery improves exercise capacity in patients with stable angina. However, it does not reduce exercise-induced ventricular arrhythmias, which may not be a primary risk factor for sudden cardiac death.
Area of Science:
- Cardiology
- Cardiac Surgery
- Exercise Physiology
Background:
- Coronary artery disease (CAD) and stable angina affect numerous patients worldwide.
- Exercise-induced ventricular arrhythmias are a concern in patients with CAD.
- The relationship between surgical intervention, exercise capacity, and arrhythmias requires further investigation.
Purpose of the Study:
- To compare the effects of surgical versus medical therapy on exercise capacity and ventricular arrhythmias in patients with stable angina.
- To assess the association between exercise-induced ventricular arrhythmias and sudden cardiac death in patients with CAD.
Main Methods:
- Ninety-one patients with angiographically proven CAD and stable angina were randomized to surgical or medical therapy.
- Graded exercise tests were performed at baseline and 1 year to assess exercise capacity and ventricular arrhythmias.
- Arrhythmias were graded by severity, and sudden cardiac death events were recorded.
Main Results:
- Surgically treated patients demonstrated a significant improvement in exercise capacity at 1 year (p < 0.005).
- Ventricular arrhythmia frequency and severity remained unchanged in both groups.
- Sudden death occurred in 12 patients; arrhythmias during exercise were not consistently different in those who died suddenly.
Conclusions:
- Successful coronary surgery enhances exercise capacity in stable angina patients without altering ventricular arrhythmias.
- Exercise-induced ventricular arrhythmias, excluding ventricular fibrillation, may not be a strong predictor of sudden cardiac death in this population.
Abstract:
Ninety-one patients with angiographically proved coronary artery disease and stable angina were randomly assigned into surgical and medical therapy. Graded exercise tests were performed on entry into the study and repeated in 1 year. Ventricular arrhythmias during exercise and 8 minutes of recovery were studied. Arrhythmias were graded on a scale of 0 to 7 by their presumed severity. On entry, both groups were similar in the severity of coronary disease, exercise capacity, and frequency and severity of exercise-induced ventricular arrhythmias. At 1 year, the frequency and severity of arrhythmias remained unchanged in both groups, whereas the surgically treated patients showed a marked improvement in their exercise capacity (p less than 0.005). The medically treated patients had a slight deterioration in their work capacity which, however, did not achieve statistical significance (p = 0.08). Twelve patients died suddenly. In seven medically treated patients who died suddenly, the frequency and severity of ventricular arrythmias on exercise were not different from those of the rest of the medical patients. In the five surgically treated patients who died suddenly, one had multiform premature ventricular beats, a second developed ventricular fibrillation (2 years before dying suddenly), and a third had no arrhythmias during exercise. Two died before the 1 year evaluation. Successful coronary surgery improves exercise capacity without decreasing associated ventricular arrhythmias. Exercise-induced ventricular arrhythmias, with the exception of ventricular fibrillation, may not be closely associated with the risk of sudden death.