Coronary artery bypass surgery in women and in men; early and long-term results. A study of the Norwegian population adjusted by age and sex

Abstract

OBJECTIVE: We wished to analyse early mortality, postoperative low-output syndrome needing intra-aortic balloon pumping support (IABP), totalmortality, recurrent angina pectoris and total non-fatal myocardialinfarction in women compared with men. Also, the standard mortality ratio(SMR) was estimated to compare the mortality data to the general Norwegianpopulation of comparable sex and age. METHODS: A total of 1025 patients;113 women and 912 men, were submitted to coronary artery bypass surgery atRikshospitalet, Oslo between August 1982 and December 1986. The patientswere followed up until the 1st of January 1993, representing a meanfollow-up time of 7.4 years. An exposed/non-exposed cohort study design wasused. A power study was carried out. The standardized mortality ratios forwomen and men were calculated after adjusting for age and sex. RESULTS:Crude odds ratio (ORC) of early mortality was 2.0 with a 95% confidencelimit (CL95%) of 0.7-5.4. Odds ratio of low output syndrome needingintra-aortic balloon support was 1.7 (CL95% = 0.8-4.2). Statisticalsignificance was not achieved for these end-points. Women did not run anincreased hazard of total mortality (ORC = 0.9; CL95% = 0.5-1.5), recurrentangina pectoris (ORC = 1.4; CL95% = 0.8-2.4) or of total non-fatalmyocardial infarction (ORC = 0.8; CL95% = 0.4-1.6) when compared with men.Adjusting for confounders did not significantly alter the results. Whenmatched on sex and age and compared to the normal Norwegian population, wefound an increased SMR in both men (2.5; CL95% = 2.2-2.9) and women (4.1;CL95% = 2.2-4.9). CONCLUSION: The risk of early mortality and low- outputsyndrome needing intra-aortic balloon support tended to be higher in womencompared with men. Women did not run an increased risk of total mortality,recurrent angina or of total non-fatal myocardial infarction. The standardmortality ratio was increased in both men and women, but in particularhigher in women, suggesting a more aggressive course of coronary arterydisease in operated women than in operated men. However, this differencedid not show in the long term follow-up, due to the beneficial effect ofcoronary artery bypass surgery in both men and women.