Objectives: To study the influence of the variable “experience” on the early risk in off-pump coronary surgery(OPCAB).
Methods: We prospectively analyzed a consecutive cohort of 3054 patients undergoing OPCAB between January 2000 and December 2007; same day infarct patients were excluded. Significant predictors, identified in univariate analysis, were inserted in a multivariate logistic regression analysis for the 30-day and the 3-month mortality. The variable “experience” was defined as a continuous variable, tallying the OPCAB procedures from the beginning of the experience in 1997, thereby excluding the first 196 patients.
Results: The crude 30 days and 3 months mortality were respectively 1.47% (95% CI 1.10-1.96) and 2.05%(95% CI 2.05-3.17). The 30-day analysis (ROC=75 %, R²= 10 %) identified as significant predictors: age, concomitant vascular disease (either peripheral or of supra-aortic vessels), preoperative atrial fibrillation and the OPCAB “experience”. The 3-month analysis identified: age, presence of vascular disease, preoperative creatinine, FEV1 and the OPCAB “experience”(ROC= 78 %, R²= 10 %).
Conclusions: This study identified, in addition to clinical variables, the significant effect on mortality after OPCAB of the tally of the procedures. “Experience” could and is probably a surrogate for tacit variables, not included in the model as there are: completeness and complexity of the concept, completeness of transfer from tacit to codified knowledge, optimized interface between virtual and organizational learning. This observation is even more interesting since the positive learning effect was simultaneous with the learning processes of the senior residents who performed most of these procedures under very close supervision.