Abstract 1108: Impact of Pre-existing Ischemic Heart Disease on Hip Surgery Outcomes: A Population-Based Study
Background: Pre-existing ischemic heart disease (IHD) is a known clinical risk factor of hip surgery, but the degree of conferred risk of MI as compared to non IHD patients has not been examined at the population level. Also, though all orthopedic surgery is considered intermediate risk according to ACC/AHA preoperative guidelines, patients undergoing hip fracture repair likely have a worse outcome than patients undergoing elective total hip arthroplasty (THA), especially those with IHD.
Hypothesis/Aims: In a population based cohort of patients undergoing hip surgery, we sought to assess one-year post-operative mortality and seven-day post-operative MI rate among patients with IHD as compared to patients without IHD. Furthermore, we hypothesized that patients undergoing hip fracture repair as compared to those undergoing elective THA will have significantly greater rates of MI and death.
Methods: Using the Rochester Epidemiology Project, we assembled a population-based cohort of 1,593 Olmsted County, MN residents undergoing 1,844 hip surgeries from 1988 through 2002. IHD was defined by a history of positive stress testing, evidence of ischemia or prior infarct on imaging, results of cardiac catheterization, or prior PCI or CABG. We excluded individuals with active coronary disease or pre-operative MI during hospitalization.
Results: There were 1212 hip fracture repairs and 632 elective THAs during the study period. The 7 day MI rate was 17.43% in patients with prior IHD as compared to 6.71% in patients without IHD. The odds ratio for post-operative MI in patients with pre-existing IHD was 2.97 (95% CI 2.11 to 4.17), after adjustment for age, sex, ASA score, and type of surgery. The adjusted odds ratio for one-year post-operative mortality for patients with IHD was 1.54 (95% CI 1.19 to 1.99). The post-operative rate of MI in patients undergoing hip fracture repair was 14.25% as compared to 3.96% in patients undergoing elective THA.
Discussion: Stable pre-existing IHD confers three times the risk of post-operative MI and a 50% increase in one-year mortality among patients undergoing hip surgery. Additionally, given the higher post-operative rate of MI associated with hip fracture repair, it should not be considered an intermediate risk procedure.
This research has received full or partial funding support from the American Heart Association, National Center.