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Outcomes/Effectiveness Research

Heart failure accounts for much of the variation among surgeons in bypass surgery mortality rates

Surgeons typically have varying mortality rates among their coronary artery bypass graft (CABG) surgery patients. Both surgeon and hospital experience have been reported to affect these mortality rates. However, a recent study has uncovered another influence. It found that fatal heart failure accounted for 80 percent of the differences in mortality rates among 23 cardiothoracic surgeons who are members of the Northern New England Cardiovascular Disease Study Group. The study was supported in part by the Agency for Health Care Policy and Research (HS06503, Ischemic Heart Disease Patient Outcomes Research Team [PORT], and HS06813) and led by Gerald T. O'Connor, Ph.D., of Dartmouth Medical School.

The researchers prospectively studied 8,641 consecutive patients undergoing CABG surgery by the 23 study surgeons. A committee determined patient cause of death following CABG. The researchers ranked surgeons according to CABG mortality rates (adjusted for patient risk of death) and divided them into three groups, from the lowest (3.3 percent), middle (4.5 percent), and highest (5.8 percent) CABG mortality rates. Heart failure accounted for nearly 2 percent of mortality rates in the lowest surgeon mortality group to 4 percent in the highest mortality group and for 80 percent of the difference between the lowest and highest mortality group.

Differences in rates of fatal heart failure could not be explained by patient characteristics. For instance, preoperative left ventricular function was virtually identical for patients in all mortality groups. The researchers suggest that variable results may rise from differences in processes of clinical care. Processes of care possibly related to heart failure include preoperative treatment of ischemia, myocardial protection, surgical techniques, perfusion and anesthesia techniques, and the recognition and treatment of perioperative heart failure.

For more information, see "Results of a regional study of modes of death associated with coronary artery bypass grafting," by Dr. O'Connor, John D. Birkmeyer, M.D., Lawrence J. Dacey, M.D., and others, in the Annals of Thoracic Surgery 66, pp. 1323-1328, 1998.

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