http://www.nlm.nih.gov/databases/alerts/bypass_diabetes.html
Clinical Alert: Bypass Over Angioplasty for Patients With Diabetes Clinical Alert: Bypass Over Angioplasty for Patients With Diabetes National Heart, Lung, and Blood Institute (NHLBI) September 21,1995 Abstract:( The full text of this Alert is_contained in the Abstract. The National Heart, Lung, and Blood Institute (NHLBI), part_of the National_institutes_of_health, today announced that, as a first revascularization procedure, coronary_artery bypass graft (CABG) surgery has_been_shown to have a markedly lower 5-year death_rate than angioplasty for persons with diabetes_mellitus (Type I or II) who are on oral hypoglycemic agents or insulin. The finding came from the NHLBI-funded Bypass Angioplasty Revascularization Investigation (BARI. The multicenter, international, randomized trial studied patients who needed a first revascularization because_of severe ischemia with obstructions in two or more major coronary_arteries. Over 5 years, patients with diabetes_mellitus who were on drug therapy had a significantly lower (p=0. 002) mortality_rate with CABG, compared with percutaneous transluminal coronary angioplasty (PTCA). The 5-year CABG mortality_rate was_compared 19 percent with 35 percent for PTCA. By contrast, in patients without diabetes and in those with diabetes but not on drug treatment, the 5-year mortality_rates for CABG and PTCA were both about 9 percent. The higher death_rate for PTCA was not_due to complications of the procedure itself. Those with diabetes are_known to have an excessive cardiovascular risk and a higher mortality_rate was_expected for them, regardless of revascularization procedure. However, the excess mortality with PTCA had_not_been_anticipated. BARI's results indicate that CABG should be_preferred the treatment for patients with diabetes on drug or insulin therapy who have multivessel coronary_artery_disease and need a first coronary revascularization. These results have a significant impact on the clinical care of these patients. Coronary revascularization plays an important role in the treatment of clinically severe coronary_artery_disease. The two most commonly used methods of revascularization are CABG and PTCA. PTCA is_based a catheter nonsurgical approach that directly targets coronary obstructions by dilation of the vessel at the point of obstruction. The process is_accompanied by local vascular injury and subsequent healing. The extent of injury and the healing process may_be different in diabetic and nondiabetic patients. Not all lesions can be_dilated due largely to technical reasons. CABG is a_major operation, requiring opening of the chest. It provides a new channel, with a lumen frequently larger than the native, diseased lumen. There_is no instrumentation of the local lesion and, therefore, no related vascular injury. While both treatments alleviate the effects of coronary_artery_disease, they do not correct or alter the natural course of the disease. Before PTCA, CABG was the traditional revascularization strategy. But PTCA, first performed in the United_states in 1977, has_grown rapidly in_use. In 1993, about 362,000 PTCAS were_done in the United_states, compared with about 309,000 CABG surgeries. However, PTCA use has_expanded not just in number but_also in the type of patient treated. Initially, PTCA was_done on patients with one obstructed vessel. But, with increased physician expertise and an improved technology, PTCA use has_expanded rapidly to include patients with more complex, multivessel coronary obstructions, once treated exclusively with CABG. This has_led to uncertainties about the longterm effectiveness and safety of PTCA compared with CABG and prompted the NHLBI to fund a rigorous evaluation of the two methods. That rigorous investigation--the BARI study--tests whether the use of PTCA as an initial treatment compromised the clinical outcome for patients with multivessel coronary_artery_disease who needed revascularization and could be_treated by either PTCA or CABG. BARI did not test outcomes for repeat procedures. It also studied only PTCAS performed with the standard balloon technique. The trial is_randomized the largest study of its type, with enough patients to be able to address key endpoints, both overall and in predetermined patient subgroups. The subgroups were based_on patients'anginal status, number of diseased vessels, and left ventricular function. Also studied are various demographic factors such_as gender, age, race, and the presence of diabetes. The primary endpoint is mortality after 5 years of followup. Other important endpoints include the occurrence of a myocardial_infarction, need of repeat revascularization procedures, angina, functional status, quality_of_life, and utilization of healthcare resources. Both quality_of_life and utilization of healthcare resources are_studied in_detail in a separately funded ancillary study. Patients were eligible for the trial if they had coronary_artery_disease with a 50 percent or more luminal obstruction (as measured by calipers) in at_least two of the coronary vessels supplying two or three major coronary territories. They also had to have clinically severe ischemia but not a prior revascularization. Patients were ineligible for the trial if they had, for_example, insufficient angina or ischemia, required emergency revascularization, left main stenosis of 50 percent or greater, a noncardiac illness expected to result in limited survival, primary coronary spasm, or a poor quality angiogram. Baseline angiograms were_reviewed and classified by the Central Radiographic Laboratory (Dr. Edwin L. Alderman, director) at the Stanford_university Medical_center in Palo_alto, CA. Between August 1988 and August 1991,18 clinical centers randomized 1, 829 patients, ages 17 to 80 and including 353 on drug treatment for diabetes. Half of the patients were_assigned randomly to PTCA and the other half to CABG. At baseline, the mean age of the randomized patients was 61 years. Thirty-nine percent of the randomized patients were age 65 or older, 27 percent were women, 25 percent were_classified as having diabetes (of these, 76 percent were being_treated with oral hypoglycemic agents or insulin), 60 percent had two-vessel disease and 40 percent had three-vessel disease, and 98 percent had angina (of these, 64 percent had unstable angina and 17 percent had class 3-4 angina). At the time of this alert, 66 percent of patients had_completed followup. Patients will_be_followed for a minimum of 7 years. The trial is_expected to finish followup on all patients by November 1998. Followup includes annual functional status assessments and an electrocardiogram (ECG), and a biennial exercise stress_test. As_required by the protocol, risk factor modification was_initiated for all patients after their enrollment. This includes help with smoking cessation, exercise, and diet. Patients also were_treated as_needed for hypertension, elevated blood cholesterol, and diabetes. Risk factors and medical problems were_managed by each patient's primary care physician. The trial has_been_monitored closely by both the study chairman (Dr. Robert Frye Mayo Clinic Foundation), the Clinical Coordinating Center (Dr. Katherine Detre, University of Pittsburgh), and the independent Data and Safety Monitoring Board (chaired by Dr. J. David Bristow, Oregon Health Sciences University). The Data and Safety Monitoring Board is_composed of PTCA experts, cardiovascular surgeons, clinical cardiologists, and experts in biostatistics and ethics. The Board regularly reviews the monitoring reports. ECG analyses are being_done by the Central ECG Laboratory (Dr. Bernard R. Chaitman, director) at the St_louis University Medical_center. An independent Mortality and Morbidity Classification Committee (chaired by Dr. Ronald Prineas, University of Miami) categorizes fatal events in the trial. On September 13,1995, the Data and Safety Monitoring Board held an urgent session to review the 5-year mortality data. The Board concluded that the unfavorable mortality results for the patients on drug treatment for diabetes and first treated with PTCA were unlikely to be_due to chance. The Board recommended to the National_institutes_of_health that physicians and other health_care professionals and the public be_informed promptly of the results. In summary: BARI's findings should not be_applied to all persons with diabetes. They apply only to those on oral hypoglycemic agents or insulin for diabetes and who have multivessel coronary_artery_disease and are undergoing an initial revascularization procedure. The data offer the following guidelines for such patients: They will probably fare better with CABG than PTCA as an initial treatment. For patients who have_had already a PTCA and are asymptomatic--experiencing no ischemia, angina, or other symptom--they should take no special action but continue their regular care. Alternatively, if they have_had already a PTCA and had their ischemia return (e_g.,, reappearance of angina), they should consult their physicians to assess their current health status and review optimal strategies for further care. Close physician monitoring is particularly important for patients with diabetes who have coronary_artery_disease, since they may_not experience symptoms during periods of ischemia. Finally all patients who have evidence of coronary_artery_disease, with or without a prior PTCA or CABG, should receive an aggressive approach to medical management of known risk factors for coronary_artery_disease, including smoking cessation for smokers, appropriate control of elevated blood_pressure or serum cholesterol, and optimal control of diabetes. The full text of this alert has_been_mailed to all libraries that are members of the National Network of Libraries of Medicine. U_s. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894 National_institutes_of_health, Department_of_health & Human Services Copyright, Privacy, Accessibility Last updated: 15 March 1996