Worse outcomes after cardiovascular arterial bypass grafting (CABG) in women have been attributed to a number of clinical and nonclinical factors: older age, delayed diagnosis and treatment, more comorbidities, smaller body size, underuse of arterial grafts, and referral bias. However, a team of Cleveland Clinic researchers reported that women were less likely than men to have bilateral–internal thoracic artery (ITA) grafting and complete revascularization, both of which are linked to better long-term survival.
“Women had less favorable preoperative characteristics than men but received fewer bilateral-ITA grafts and less all-arterial grafting as part of their revascularization strategy,” Tamer Attia, MD, MSc, and his coauthors said in the study published in the Journal of Thoracic and Cardiovascular Surgery. They also found that women were more likely to die in the hospital after CABG and had lower risk-adjusted long-term survival than men ().
Survival was lowest in women who were not completely revascularized and had no ITA grafting, while survival was highest in men who were completely revascularized and had bilateral grafting, Dr. Attia and coauthors said.
The researchers’ goal was to use extensive risk adjustment to evaluate how differences in revascularization strategies influenced survival of men and women after CABG. They analyzed 57,943 primary, isolated CABG procedures performed at Cleveland Clinic from 1972 to 2011, including 11,009 procedures in women.
The researchers identified differences between sexes in three key areas: revascularization strategies, in-hospital outcomes, and time-related survival.
With regard to revascularization strategies, while men were significantly more likely to have incomplete revascularization than were women, women received significantly fewer arterial grafts (8.4% vs. 9.3% for men). This included fewer bilateral-ITA grafts and radial artery grafts, less use of total arterial revascularization, and greater use of saphenous vein grafts (SVGs) to the left anterior descending artery. Women were also significantly more likely to receive only SVGs for revascularization (32% vs. 30% for men; P less than .0001). Most operations for both women and men were done with cardiopulmonary bypass, but significantly more women had off-pump procedures (5.4% vs. 2.9%).
In the hospital after operations, women were significantly more prone to postoperative deep sternal–wound infections and septicemias, as well as strokes and renal failure, including dialysis-dependent renal failure. Women also had higher rates of new-onset atrial fibrillation (15% vs. 13% in men), and higher rates of mechanical ventilation for more than 24 hours (13% vs. 9.2%). Women spent more time in the ICU and hospital overall, and their in-hospital death rate was more than double that of men (2.7% vs. 1.1%).
Women also had shorter long-term survival, “and this has persisted since the beginning of CABG at Cleveland Clinic,” Dr. Attia and coauthors said. What’s more, the survival gap between women in the study and women in the general population post CABG was wider than that in men. “After we adjusted for patient and revascularization strategy differences, female sex remained an independent risk factor for death overall and both early and late after CABG.”
Incomplete revascularization had greater consequences for women than for men. At 10 years, 58% of women with incomplete revascularization survived, vs. 70% of men. At 20 years, the rates were 25% for women and 35% for men. “Use of ITA grafts was associated with better survival than use of SVGs alone and was best when bilateral-ITA grafting was performed,” Dr. Attia and coauthors said. However, the study determined that bilateral grafting seems less effective in women long-term. “Hence, a patient’s sex deserves special consideration in operative planning.”
Many questions about CABG in women remain: Identifying which female patients would benefit from more meticulous conduit harvesting, from better coronary artery selection, and from bilateral-ITA grafting and which are less susceptible to sternal would infections could increase appropriate use of bilateral-ITA grafting, the researchers noted. “The difference in effectiveness of bilateral-ITA grafting needs to be considered in women at elevated risk for bilateral-ITA harvesting complications.”
Coauthor Ellen Mayer Sabik, MD, is a principal investigator for Abbott Laboratories and is on the scientific advisory board of Medtronic. Dr. Attia and all other coauthors reported having no relevant financial relationships to disclose.