CARP Trial Suggests No Benefit to Revascularization Before Vascular Surgery
McFalls, EO, Ward HB, Mortiz TE, et al. Coronary-artery revascularization before elective major vascular surgery. N Engl J Med. 2004;351:2795-2804.
Recent studies have presented evidence that treatment with beta-blockers for patients with CAD could reduce the risk of perioperative cardiac complications. Beta-blockers have since become a critical part of the management plan for the perioperative patient. Evidence-based practice guidelines for cardiac risk assessment have been published by both the American College of Physicians and the American College of Cardiology/American Heart Association. However, practice patterns continue to vary between physicians and cardiologists, particularly for patients clinically stratified into the intermediate-risk category. Some physicians feel comfortable with a conservative approach of medical optimization even in the setting of established CAD, while others favor more aggressive treatment, even though the prospective data supporting cardiac revascularization before major surgery has been lacking. The study investigators sought to clarify this uncertainty.
The prospective trial enrolled 510 patients at 18 VA centers. Patients scheduled for major vascular operations were eligible, and were preoperatively assessed via clinical criteria, stress imaging, and angiography when appropriate. Eligible patients had significant (at least 70%) stenosis of at least one coronary artery. High-risk patients (i.e., those with left main disease, severe aortic stenosis, and LVEF <20%) were excluded. Patients were then randomized to one
of two groups. The first group underwent revascularization with PTCA or CABG plus medical optimization; the second group received only medical optimization. Most patients in both groups received beta-blockers, and more than half in each received statins. The patient populations were appropriately randomized, although overwhelmingly male (98%). Most patients had one- or two-vessel CAD. The primary endpoint was long-term mortality. Secondary endpoints included MI, stroke, renal failure requiring dialysis, and limb loss. Follow-up rates were similar in both groups (86% and 85%).
The major finding of the study was the lack of difference in mortality between the two groups at an average follow-up of 2.7 years (22% vs. 23%, RR= 0.98, 95% CI 0.70 to 1.37, p = 0.92). Analyzing by “treatment-received” instead of “intention-to-treat” did not significantly change this result. Of note, ten patients in the revascularization arm died between the revascularization procedure and the vascular surgery. Not surprisingly, revascularization also delayed the time to surgery for patients in that arm of the study. In the authors’ analysis, the patients were also divided into subgroups based on high-risk variables (prior CABG, category of Revised Cardiac Risk Index, etc.), but the study was not powered to detect mortality differences between the two arms within these subgroups. The authors concluded that there was no benefit to revascularization in patients with stable coronary syndromes prior to elective vascular surgeries.
The results of this study validate the conservative practice recommended by the existing guidelines— that is, to perform revascularization procedures in the preoperative setting only when indicated by clinical criteria such as unstable ischemic symptoms, and if likely to improve long-term survival. Beta-blockers, and based on recent studies probably “statins,” should continue to be the mainstay of perioperative risk optimization for patients with stable coronary disease.
There were, however, several important considerations: first, the study group was exclusively male, although there is little reason to believe that women would have better outcomes from revascularization. And second, the highest-risk patients were excluded, and therefore the results should not be extrapolated to that population. Prospective identification of the group of patients who may benefit from aggressive intervention should remain a target of risk assessment and further research. (BH)