OBJECTIVE: Short-term (30 days) mortality frequently is used as an outcome measure after cardiac surgery, although it has been proposed that the follow-up period should be extended to 120 days to allow for more accurate benchmarking. The authors aimed to evaluate whether mortality rates 120 days after surgery were comparable to general mortality and to compare causes of death between the cohort and the general population.

DESIGN: A multicenter descriptive cohort study using prospectively entered registry data.

SETTING: University hospital. The cohort was obtained from the Western Denmark Heart Registry and matched to the Danish National Hospital Register as well as the Danish Register of Causes of Death. A weighted, age-matched general population consisting of all Danish patients who died within the study period was identified through the central authority on Danish statistics.

PARTICIPANTS: A total of 11,988 patients (>15 years) who underwent cardiac-surgery at Aarhus, Aalborg and Odense University Hospitals from April 1, 2006 to December 31, 2012 were included.

INTERVENTIONS: Coronary artery bypass grafting, valve surgery and combinations.

MEASUREMENTS AND MAIN RESULTS: Mortality after cardiac surgery matches with mortality in the general population after 140 days. Mortality curves run almost parallel from this point onwards, regardless of The European system for cardiac operative risk evaluation (EuroSCORE) and intervention. The causes of death in the cohort differed statistically significantly from the background population (p<0.0001; one-sample t-test) throughout the first postoperative year. The leading cause of death in the cohort was cardiac (38%); 53% of which was categorized as heart failure. A total of 54% of these patients were assessed preoperatively as having normal or mildly impaired heart function (EuroSCORE).

CONCLUSIONS: This study supported an extended follow-up period after cardiac surgery when benchmarking cardiac surgery centers. Regardless of preoperative heart function, heart failure was the consistent leading cause of death.