Myocardial lactate production is not involved in the ischemic preconditioning mechanism in coronary artery bypass graft surgery patients.

OBJECTIVE

To study the relationship between ischemic preconditioning (IP) and lactate production and their impact on coronary artery bypass graft surgery patients.

DESIGN

Prospective, randomized, controlled study.

SETTING

University hospital.

PARTICIPANTS

Eighty 3-vessel disease coronary artery bypass graft surgery patients with stable and unstable angina pectoris.

INTERVENTIONS: The IP patients were preconditioned with 2 periods of 2-minute ischemia followed by 3-minute reperfusion before aortic cross-clamping.

MEASUREMENTS AND MAIN

RESULTS

The cardiac index (CI) after surgery was significantly higher in the IP group than in controls among stable patients (p = 0.013). IP was not effective in CI recovery in unstable patients. The baseline values of lactate production were 11.6%, 20.3%, -7.0%, and -2.9% in stable IP, stable control, unstable IP, and unstable control patients. Compared with baseline, lactate production increased significantly after the IP protocol (39.0% and 47.5% in the stable and unstable patients), and operation (47.5%, 31.7%, 35.4%, and 35.6% in stable IP, stable control, unstable IP, and unstable control patients) but not after 10 minutes of cardiopulmonary bypass (29.7% and 19.0% in the stable and unstable patients). There were no differences among the groups in lactate production after the operation. Lactate production after the IP protocol was negatively associated with CI recovery after surgery in the IP patients (p = 0.026).

CONCLUSION

The IP effects do not include modulation of lactate production. IP induces lactate production, but it seems not to be involved in the triggering process.