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Predictors of postoperative ventricular dysrhythmias: a multivariate study
V A Ferraris1, S P Ferraris, H S Gilliam
1Department of Surgery, Letterman Army Medical Center, Presidio of San Francisco, California.
Insights
Postoperative ventricular dysrhythmias occurred in 23% of patients after coronary bypass grafting. Advanced age, not using an internal mammary artery graft, and atrial dysrhythmias were identified as key risk factors.
Area of Science:
- Cardiology
- Cardiac Surgery
Background:
- Postoperative ventricular dysrhythmias are a concern following coronary bypass grafting (CABG).
- Identifying risk factors may allow for targeted prophylactic therapy.
Purpose of the Study:
- To determine the incidence of postoperative ventricular dysrhythmias after CABG.
- To identify patient-specific risk factors for these dysrhythmias.
Main Methods:
- Prospective study of 109 patients undergoing CABG.
- Univariate statistical analysis of 15 patient variables.
Main Results:
- 23% of patients developed significant ventricular dysrhythmias.
- Sustained ventricular tachycardia primarily occurred within 36 hours post-operation.
- Advanced age, lack of internal mammary artery use, and concurrent atrial dysrhythmias were associated with increased ventricular dysrhythmia risk.
Conclusions:
- Advanced age, non-use of internal mammary artery grafts, and postoperative atrial dysrhythmias are significant risk factors for ventricular dysrhythmias after CABG.
- These findings may help identify patients who could benefit from prophylactic treatment.
Abstract:
Postoperative ventricular dysrhythmias were studied to document their incidence after coronary bypass grafting and to identify risk factors for their development with the hope of finding a subgroup of patients who might benefit from postoperative, prophylactic drug therapy. One-hundred-nine patients who were undergoing urgent or elective coronary bypass grafting were studied, prospectively. Twenty-five of 109 patients (23%) developed significant postoperative ventricular dysrhythmias that required counter-shock or drug intervention. Seven of eight instances of sustained ventricular tachycardia, the most serious dysrhythmia, occurred within 36 hours of operation. There was no postoperative mortality related to these dysrhythmias. Serious postoperative complications, such as stroke, hemorrhage, or myocardial infarction, were decreased in patients with ventricular dysrhythmias versus those without (8% versus 16%, p = 0.053 for the Fisher's exact test statistic). Univariate statistical analysis was performed using 15 patient variables and revealed that advanced age (p = 0.008 for the unpaired t test), failure to use an internal mammary artery conduit (p = 0.03 for the two-tailed Fisher's exact test), and development of postoperative atrial dysrhythmias (p = 0.02 for the two-tailed Fisher's exact test) were significantly more common in patients with postoperative ventricular dysrhythmias. Variables such as previous myocardial infarction, ejection fraction less than 50%, prolonged operative time, perioperative myocardial infarction, or fewer number of vessels bypassed were not significantly increased in patients with dysrhythmias (the statistical power for these "negative" results was greater than 0.8).(ABSTRACT TRUNCATED AT 250 WORDS)