Impact of intraoperative myocardial cellular damage on early hemodynamics after off-pump versus on-pump coronary artery bypass surgery

Abstract

Background: Due to the surgical trauma a small amount of myocardial cellular damage is inherent during coronary artery bypass grafting (CABG). The purpose of the present study was to assess the degree of myocardial cellular damage after off-pump (OPCAB) and on-pump CABG (ONCAB) as measured by cardiac troponin I (cTnI), creatine kinase (CK), its MB isoenzyme (CK-MB) and myoglobin (Myo) and to examine its impact on early hemodynamics after surgery.

Methods: Ninety-nine consecutive OPCAB patients, operated between 01/1999 and 01/2004, were enrolled in the present study and compared to 99 ONCAB patients operated during the same period of time, who were matched for baseline data and mean number of grafts per patient. Early hemodynamics, cTnI, CK/CK-MB and Myo were measured preoperatively and at 1, 6, 12, 24 and 48 hours (h) postoperatively. Perioperative inotropic support, clinical data and potoperative outcome were recorded prospectively.

Results: The two groups were similar concerning preoperative characteristics. The mean number of distal grafts/patient was 2.1 +/- 1.0 in OPCAB and 2.1 +/- 0.8 in ONCAB patients (mean +/- SD). There was no significant difference among the groups regarding early hemodynamics in terms of cardiac index (CI), systemic vascular resistance index (SVRI), and left ventricular stroke work index (LVSWI), and inotropic support. However, cTnI, CK/CK-MB but not Myo levels were significantly lower in OPCAB compared to ONCAB patients at 1, 6, 12, 24, 36 and 48 h postoperatively (P<0.05).

Conclusions: Off-pump surgery results in equal early hemodynamics despite a significantly lower release of cTnI and CK, suggesting a reduced myocardial cell damage as compared to ONCAB surgery.