Myocardial lactate metabolism in relation to preoperative regional wall motion and to early functional recovery after coronary revascularization.
OBJECTIVE
To evaluate myocardial lactate metabolism as a marker of functional status after surgical coronary revascularization.


METHODS
Single-center, prospective, cohort study.


METHODS
Tertiary care teaching hospital.


METHODS
Fifty patients with stable angina, ejection fraction >0.40, undergoing coronary artery bypass surgery for multiple-vessel disease.


RESULTS
Before (T1) and 30 minutes (T2) after coronary artery bypass grafting, the authors simultaneously sampled blood from artery and coronary sinus to determine myocardial lactate dynamics and performed transesophageal echocardiography (TEE) to assess segmental wall motion. Wall motion score index (WMSI) was calculated with an online/offline comparison. At T2, WMSI improved from 1.40 +/- 0.31 to 1.17 +/- 0.23 (p = 0.0001). Preoperatively, 2 patterns of lactate balance were found: 39 patients were lactate extractors (17% +/- 10%) and 11 were lactate producers (-11% +/- 11%). At T2, lactate metabolism was shifted towards a pattern opposite to the baseline: delta lactate extraction was -8% +/- 16% in extractors at T1 versus 7% +/- 9% in producers at T1 (p = 0.003). Changes in WMSI were not correlated with changes in lactate utilization. No single preoperative variable predicted postoperative WMSI or its changes from baseline. Cardiopulmonary bypass (CPB) time was the only significant predictor of postoperative lactate extraction by multivariate regression (r = -0.46, p = 0.001): at T2, patients in the highest CPB time quartile showed frank lactate production (-6% +/- 13%) when compared with those in the lowest quartile (15% +/- 11%, p = 0.005). However, postoperative WMSI was similar in different CPB time groups.


CONCLUSIONS
Myocardial lactate metabolism pattern is not associated with functional status before and early after successful coronary revascularization. CPB time was the only significant predictor of postoperative lactate extraction. Measurement of lactate does not appear to be a valuable tool to assess the coupling of myocardial regional function and metabolism in the setting of coronary artery surgery and mild-to-moderate functional impairment.
Bortone
Franco
F
Department of Anesthesia and Cardiac Surgery, Humanitas Gavazzeni, Bergamo, Italy.
Mazzoni
Maurizio
M
Repossini
Alberto
A
Campolo
Jonica
J
Ceriani
Roberto
R
Devoto
Emmanuela
E
Parolini
Marina
M
De Maria
Renata
R
Arena
Vincenzo
V
Parodi
Oberdan
O
D000368:Aged; D001158:Arteries / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D015415:Biomarkers / Q000032:analysis; D001794:Blood Pressure / Q000502:physiology; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D003326:Coronary Circulation / Q000502:physiology; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D004452:Echocardiography; D017548:Echocardiography, Transesophageal; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009200:Myocardial Contraction / Q000502:physiology; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011446:Prospective Studies; D020127:Recovery of Function / Q000502:physiology; D013223:Statistics as Topic; D013318:Stroke Volume / Q000502:physiology; D013997:Time Factors; D016896:Treatment Outcome; D014655:Vascular Resistance / Q000502:physiology
D015415:Biomarkers; D019344:Lactic Acid