Is 30-day mortality an adequate outcome statistic for patients considering heart valve replacement?

In-hospital mortality is widely used by clinicians as a benchmark measure of outcome for determining risks/benefits of cardiac surgery. Patients, however, may wish to have information on estimated longer-term outcomes. Mortality risk by 1 year after the operation may be a more meaningful outcome statistic. We therefore undertook to determine 30-day and 365-day postoperative mortality rates in a large series of consecutive patients who have undergone heart valve replacement (HVR) surgery in the United Kingdom since 1986.

Data on 80,757 patients registered on the UK Heart Valve Registry were analyzed. Kaplan-Meier actuarial survival analysis was calculated to determine 30-day (group 1) and 365-day (group 2) mortality. Cox proportional hazards were calculated for each group to identify significant risk factors for mortality less than 1 year.

Thirty-day mortality represents around half (56%) of the 365-day mortality. This ratio was robust for most subdivisions of the total population. Cox proportional hazards demonstrated female sex, age older than 70 years, single tricuspid valve replacement, multiple valve replacement regardless of type of valve, and subsequent valve operation as significant risk factors of early mortality (group 1). However, men were at significantly greater risk of late mortality (group 2). All other factors remained significant with the exception of subsequent valve operation, which was dropped from the model (group 2).

The robustness of these data would allow cardiologists and cardiac surgeons to provide preoperative patients with a reasonably accurate estimate of survival rates at 1 year after valve replacement surgery in addition to the customary short-term 30-day outcome.