Do you need to clamp a patent left internal thoracic artery-left anterior descending graft in reoperative cardiac surgery?

BACKGROUND

Dogma suggests optimal myocardial protection in cardiac surgery after prior coronary artery bypass graft surgery (CABG) with patent left internal thoracic artery (LITA) pedicle graft requires clamping the graft. However, we hypothesized that leaving a patent LITA-left anterior descending (LAD) graft unclamped would not affect mortality from reoperative cardiac surgery.

METHODS

Data were collected on reoperative cardiac surgery patients with prior LITA-LAD grafts from July 1995 through June 2006 at our institution. With the LITA unclamped, myocardial protection was obtained initially with antegrade cardioplegia followed by regular, retrograde cardioplegia boluses and systemic hypothermia. The Society of Thoracic Surgeons National Database definitions were employed. The primary outcome was perioperative mortality. Variables were evaluated for association with mortality by bivariate and multivariate analyses.

RESULTS

In all, 206 reoperations were identified involving patients with a patent LITA-LAD graft. Of these, 118 (57%) did not have their LITA pedicle clamped compared with 88 (43%) who did. There were 15 nonsurvivors (7%): 8 of 188 (6.8%) in the unclamped group and 7 of 88 (8.0%) in the clamped group (p = 0.750). Nonsurvivors had more renal failure (p = 0.007), congestive heart failure (p = 0.017), and longer perfusion times (p = 0.010). When controlling for independently associated variables for mortality, namely, perfusion time (odds ratio 1.014 per minute; 95% confidence interval: 1.004 to 1.023; p = 0.004) and renal failure (odds ratio 4.146; 95% confidence interval: 1.280 to 13.427; p = 0.018), an unclamped LITA did not result in any increased mortality (odds ratio 1.370; 95% confidence interval: 0.448 to 4.191). Importantly, the process of dissecting out the LITA resulted in 7 graft injuries, 2 of which significantly altered the operation.

CONCLUSIONS

In cardiac surgery after CABG, leaving the LITA graft unclamped did not change mortality but may reduce the risk of patent graft injury, which may alter an operation.