Need for Emergency CABG Decreases, But Morbidity and Mortality Remain High
In an era in which interventional cardiologists are pushing the envelope in the kinds of ischemia they can treat, emergency coronary artery bypass surgery has become more rare, according to researchers from the Cleveland Clinic Foundation in Cleveland, Ohio, in a report in this week’s Circulation (Circulation. 2002;106:2346–2350).
The researchers, led by Niranjan Seshadri, MD, from the clinic’s Department of Cardiology, reviewed 18 593 percutaneous interventions performed at the Cleveland Clinic from 1992 through 2000. Emergency coronary artery bypass surgery was performed in 113 (0.61%) patients.
The reasons for the emergency surgery included:
• Extensive dissection in 61 patients (54%)
• Perforation/tamponade in 23 patients (20%)
• Recurrent acute close in 23 patients (20%)
However, the percentage of emergency surgeries performed decreased from 1.5% of all percutaneous interventions performed in 1992 to 0.14% in 2000. Predictors of the need for emergency surgery included the worst American College of Cardiology/American Heart Association scoring of the intervened lesion and female genders. History of prior coronary artery bypass surgery and use of stents resulted in the need for emergency CABG.
Of the patients who underwent emergency CABG, 17 (15%) died in-hospital, 14 (12%) suffered perioperative Q-wave myocardial infarctions, and 6 (5%) had cerebrovascular accidents.
The Foreboding of Cardiac Troponin I
Cardiac troponin I can aid physicians in identifying the risk of short-term mortality and perioperative myocardial infarction in patients who are undergoing or have undergone vascular surgery, according to researchers from Johns Hopkins University School of Medicine in Baltimore, Md, in a report in this week’s issue of Circulation (Circulation. 2002;106:2366–2371).
The study included 229 patients who underwent aortic or infrainguinal vascular surgery or amputation of a lower extremity. Their blood was analyzed for cardiac troponin I immediately after surgery and postoperatively on the mornings of days 1, 2, and 3.
Of the patients, 28 (12%) had increased postoperative cardiac troponin I that was associated with a 6-fold increased risk of mortality by 6 months and a 27-fold increased risk of myocardial infarction. The authors also noted that there was a dose-response relationship between the concentration of cardiac troponin I and mortality.
The authors said, “Postoperative cTn1 [cardiac troponin I] levels provide important prognostic information, and routine surveillance is useful for identifying patients who have an increased risk for morbidity and mortality. Further research is needed to determine whether intervention in patients with elevated cTn1 can improve outcome.”
Aspirin Use After CABG Appears Safe, Risk-Reducing
The use of aspirin as antiplatelet therapy after CABG appears safe and may even reduce the risk of death and damage to major arteries because of decreased blood flow, according to researchers in a report in the October 24, 2002, issue of The New England Journal of Medicine (N Engl J Med. 2002;347:1309–1317).
In this Multicenter Study of Perioperative Ischemia Epidemiology II, investigators from 70 centers in 17 countries studied 5065 patients who underwent CABG surgery. Of these patients, 5022 survived the first 48 hours after surgery. The researchers gathered data on 7500 variables per patient.
Of the 2999 patients who received ≤650 mg of aspirin within 48 hours of the surgery, 40 (1.3%) died, compared with 81 of 2023 of patients (4%) who did not receive aspirin during the first two days. Myocardial infarction occurred in 2.8% of patients who received aspirin versus 5.4% of those who did not. Stroke afflicted 1.3% of the aspirin treated patients versus 2.6% of those who did not receive the medication. Of those who received aspirin, 0.9% of the aspirin patients experienced kidney failure versus 3.4% of those who did not receive aspirin. Bowel infarction afflicted 0.3% of the aspirin group compared to 0.8% of those who were untreated.
The researchers, led by Dennis Mangano, MD, PhD, of the Ischemia Research and Education Foundation in San Francisco, Calif, found that the aspirin did not increase the risk of hemorrhage, gastritis, or infection and did not impair wound healing. The authors concluded: “Given the safety, widespread availability, and minimal cost of aspirin therapy, our data suggest that early aspirin therapy may be considered for patients undergoing coronary bypass surgery unless its use is specifically contraindicated.”
In an accompanying editorial, Eric J. Topol, MD, of the Cleveland Clinic Foundation, wrote: “What is perhaps most intriguing about the report by Mangano et al is the magnitude and breadth of the benefit of early aspirin after CABG in terms of survival, nonfatal ischemic events, and bleeding complications, as well as the comprehensive sweep of benefits for the heart, brain, kidneys, and bowel. Even within each organ system, there is a consistency in the magnitude and direction of the effect of aspirin—for example, its effect on the risk of encephalopathy or the need for dialysis. These findings do indeed reflect a systemic benefit of aspirin and a more profound effect than that found on platelet-mediated thrombosis.”
How Important Is Homocysteine?
The role of homocysteine as a risk factor for ischemic heart disease has been much touted in the past 5 years, but a meta-analysis in the October 23/30, 2002, issue of the Journal of the American Medical Association (JAMA. 2002;288:2015–2022) finds that the chemical may affect heart disease only slightly.
Members of The Homocysteine Studies Collaboration, led by Robert Clarke, MD, of the Clinical Trial Service Unit at the Radcliffe Infirmary in Oxford, England, evaluated 30 studies with 5073 events involving ischemic heart disease and 1113 involving strokes. In their report, the researchers wrote: “Homocysteine level is less strongly related to IHD (ischemic heart disease) and stroke risk in healthy populations than has been suggested. Results from large randomized trials of the effects on vascular disease of lowering homocysteine with folic acid-based vitamin supplementation should provide further information about the relevance of homocysteine levels to the risks of IHD and stroke.”