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Cold blood cardioplegia or intermittent cross-clamping in coronary artery bypass grafting?
Z Liu1, O Valencia, T Treasure
1Cardiothoracic Unit, St. George's Hospital, London, England.
Insights
Cold blood cardioplegia and ventricular fibrillation with ischemia show similar myocardial protein leakage in coronary artery bypass grafting. Both techniques are viable, with no significant differences in outcomes, though a large trial is impractical.
Area of Science:
- Cardiovascular Surgery
- Cardiac Anesthesia
- Myocardial Protection
Background:
- Cold blood cardioplegia and intermittent ventricular fibrillation with ischemia were compared for myocardial protection.
- A prior prospective study indicated similar enzyme and protein leakage between the two methods.
Purpose of the Study:
- To compare the outcomes of coronary artery bypass grafting (CABG) using cold blood cardioplegia versus intermittent ventricular fibrillation with aortic cross-clamping.
- To evaluate differences in mortality, need for intraaortic balloon pump, and other clinical outcomes.
Main Methods:
- A retrospective review of 1,923 patients undergoing first-time elective or urgent CABG between January 1992 and May 1997.
- Patients were divided into two groups: those receiving cold blood cardioplegia (n=578) and those undergoing ventricular fibrillation with aortic cross-clamping (n=1,345).
- Preoperative factors and intraoperative variables (temperature, cross-clamp time) were analyzed.
Main Results:
- Mortality rates were similar: 2.1% for cardioplegia and 2.5% for ventricular fibrillation (p=0.55).
- Higher use of intraaortic balloon pump was observed in the ventricular fibrillation group (2.4% vs. 1.0%, p=0.04).
- No other significant differences in clinical outcomes were detected between the two techniques.
Conclusions:
- A definitive randomized trial to establish superiority is statistically impractical due to the small observed differences.
- Clinical practice should be guided by available retrospective data, acknowledging the merits of each technique.
- Both cold blood cardioplegia and intermittent ventricular fibrillation are effective methods for myocardial protection during CABG.
Background:
We determined that cold blood cardioplegia and intermittent ventricular fibrillation with ischemia were associated with similar enzyme and myocardial protein leakage in a randomized, prospective study of 40 patients. We have continued to use both methods in our unit, according to surgeons' preference.
Methods:
In our database we have reviewed 1,923 patients who have undergone first-time elective or urgent coronary artery bypass grafting from January 1992 to May 1997.
Results:
Five hundred seventy-eight patients underwent coronary artery bypass grafting with cold blood cardioplegia and 1,345 had ventricular fibrillation and aortic cross-clamping. The preoperative factors were virtually identical. Intraoperative differences were only those inherent to the two techniques: temperature and cross-clamp time. Mortality was 2.5% for ventricular fibrillation and aortic cross-clamping arrest and 2.1% for cardioplegia (p=0.55 by chi2 test). There was a higher use of the intraaortic balloon pump in the ventricular fibrillation and aortic cross-clamping group (2.4% versus 1.0%; p=0.04), but no other differences in outcome were detected.
Conclusions:
A truly randomized trial to demonstrate which technique is superior is impractical at this level of difference because it would require 37,000 patients to avoid a beta error. We have to base our practice on the retrospective data available. Each technique has its merits in practice, which are discussed.