Lowest hematocrit on bypass and adverse outcomes associated with coronary artery bypass grafting. Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Cardiac surgery patients' hematocrits frequently fall to low levels during cardiopulmonary bypass. METHODS: We investigated the association between nadir hematocrit and in-hospital mortality and other adverse outcomes in a consecutive series of 6,980 patients undergoing isolated coronary artery bypass graft surgery. The lowest hematocrit during cardiopulmonary bypass was recorded for each patient. Patients were divided into categories based on their lowest hematocrit. Women had a lower hematocrit during bypass than men but both sexes are represented in each category. RESULTS: After adjustment for preoperative differences in patient and disease characteristics, the lowest hematocrit during cardiopulmonary bypass was significantly associated with increased risk of in-hospital mortality, intra- or postoperative placement of an intraaortic balloon pump and return to cardiopulmonary bypass after attempted separation. Smaller patients and those with a lower preoperative hematocrit are at higher risk of having a low hematocrit during cardiopulmonary bypass. CONCLUSIONS: Female patients and patients with smaller body surface area may be more hemodiluted than larger patients. Minimizing intraoperative anemia may result in improved outcomes for this subgroup of patients.

Improved in-hospital mortality in women undergoing coronary artery bypass grafting. Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Few studies have examined the changes in in-hospital mortality for women over time. We describe the changing case mix and mortality for women undergoing coronary artery bypass grafting (CABG) from 1987 to 1997 in northern New England. METHODS: Data were collected on 8,029 women and 21,139 men undergoing isolated CABG. The study consisted of three time periods (1987 to 1989, 1990 to 1992, and 1993 to 1997) to account for regional efforts to improve quality of care that occurred during 1990 to 1992. RESULTS: Compared with 1987 to 1989, women undergoing CABG in 1993 to 1997 were older, had poorer ventricular function, and more often required urgent or emergency operations. The crude and adjusted mortality rates for both women and men decreased significantly over time. The absolute magnitude of the change in adjusted rates was greater for women (3.1%) than for men (1.5%). Although women represented only 28% of the study population, the decrease in their mortality accounted for 44% of the total decrease in adjusted mortality during the study period. CONCLUSIONS: Over the last decade there has been a marked decrease in CABG mortality for women, despite a worsening case mix.