The influence of time on the characteristics and risk factors for patients submitted to myocardial revascularization.

Objective: To compare the clinical and surgical profile between two groups of patients submitted to Myocardial Revascularization (MCR) surgery at the Instituto de Cardiologia of Rio Grande do Sul with a ten year interval, to observe its influence upon MCR hospital mortality and to verify the predictability of this result using the risk score.

Methods: A retrospective cohort study involving 307 patients who underwent MCR surgery within a six month period during 1991/92 (INITIAL group, n=153) or 2001/02 (CURRENT group, n=154). Demographic characteristics, heart disease, comorbidities and surgical events were analyzed to compare the groups and to define the hospital mortality risk score (based on the Cleveland Clinic method).

Results: The CURRENT group was older, had more severe heart condition (functional class, incidence of heart failure and number of vessels with severe lesions) and a greater prevalence of comorbidities. The INITIAL group had a higher prevalence of nonelective surgery. Both groups had similar mean risk scores (2.8 +/- 3.1 for INITIAL and 2.2 +/- 2.5 for CURRENT) and hospital mortality rates (3.3% and 1.9% respectively). These figures are comparable to those for reported by Cleveland Clinic (for a risk score of 3 the predicted mortality range between 2.0 %; using a confidence level of 95% the predicted mortality is between 0 and 4.3%; and actual mortality confirmed by the study was 3.4%).

Conclusion: Patients currently submitted to MCR are older and in worse clinical condition (heart and systemic) than those operated on ten years ago; however, the risk scores and hospital mortality rates were slightly higher in the INITIAL group. The higher number of nonelective surgical interventions could have contributed to this. A risk score can be used to identify patients that require a higher level of care and to predict surgical outcomes.