It is observed that death rates in cardiac surgery has decreased, however, root causes that behave like triggers of potentially avoidable deaths (AD), especially in low-risk patients (less bias) are often unknown and underexplored, Phase of Care Mortality Analysis (POCMA) can be a valuable tool to identify seminal events (SE), providing valuable information where it is possible to make improvements in the quality and safety of future procedures. Our results show that in São Paul State, only one third of AD in low-risk cardiac surgery was related to specific surgical problems. After a revisited analysis, 75% of deaths could have been avoided, which in the pre-operative phase, the SE was related judgment, patient evaluation and preparation. In the intra-operative phase, most occurrences could have been avoided if other surgical technique had been used. Sepsis was responsible for 75% of AD in the intensive care unit. In the ward phase, the recognition/management of clinical decompensations and sepsis were the contributing factors. Logistic regression model identified age, previous coronary stent implantation, coronary artery bypass grafting + heart valve surgery, ≥ 2 combined heart valve surgery and hospital-acquired infection as independent predictors of AD.