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Prophylactic Revascularization Before Vascular Surgery
Abstract & Commentary
By Michael H. Crawford, MD, Professor of Medicine, and Chief of Clinical Cardiology, at the University of California, San Francisco. Dr. Crawford is on the speaker's bureau for Pfizer.
Source: Poldermans D, et at. A clinical randomized trial to evaluate the safety of a noninvasive approach in high-risk patients undergoing major vascular surgery. J Am Coll Cardiol. 2007;49:1763-1769. Moscucci M, Jones N. J Am Coll Cardiol 2007;42:1770-1771.
The value of revascularization before major vascular surgery in patients with stress induced myocardial ischemia has not been tested. Thus, the Dutch Echocardiographic Cardiac Risk Evaluation Applying Stress Echocardiography (DECREASE) study was conducted in 5 European and 1 Brazilian hospitals. Among 1880 patients undergoing elective abdominal aorta or infrainguinal vascular surgery, 430 with 3 or more risk factors for coronary artery disease underwent dobutamine echo or dypridamole perfusion scintigraphy. The major inclusion criteria were extensive stress-induced ischemia which was present in 101 of the 430 patients. They were randomized to medical or revascularization therapy prior to surgery. All patients received perioperative beta-blockers at a dose to keep the resting heart rate between 50 and 65 beats/minute, as long as systolic blood pressure was > 100 mm Hg. Antiplatelet therapy was continued during vascular surgery. The primary endpoint was the composite of all-cause death and myocardial infarction (MI) until 30 days post surgery. The one-year death and MI rate was a secondary endpoint. Results: Two patients died between coronary artery bypass surgery (CABG) and vascular surgery of a ruptured aortic aneurysm. The primary endpoint was 43% in the revascularization group and 33% in the medical therapy group (OR 1.4, 95% CI 0.7-2.8, p = 0.3). Also, the primary endpoint was not different between those treated with CABG (performed in one-third) or percutaneous coronary revascularization (41% vs 44% during the 1-year follow-up). The authors concluded that perioperative coronary revascularization in vascular surgery patients with extensive stress-induced myocardial ischemia did not improved post operative or 1-year outcome.
The publication of the Goldman index in the 1970s lead to an industry of preoperative testing for patients with CAD or likely to have it, based upon risk factors, to detect those with myocardial ischemia who were at highest risk of a perioperative coronary event. But detection implied treatment was necessary which spawned such absurdities as doing CABG so someone could have their gallbladder out. Then came perioperative beta-blocker therapy which demonstrated that many patients considered at risk would do well on such therapy. The Coronary Artery Revascularization Prophylaxis (CARP) trial showed that pre operative revascularization of stable CAD patients did not improve the outcome of major vascular surgery. However, there was a trend in CARP that favored revascularization for very high-risk patients. This hypothesis was tested in the current trial where only those with extensive stress-induced myocardial ischemia were randomized to revascularization or medical therapy alone. Although the trial was small (101 patients) the results were not encouraging that a larger study would demonstrate the value of revascularization. Thus, it will not likely be done.
The question now is where does this leave pre-operative testing? If revascularization does not make a difference, why look for ischemia? These studies did exclude those with significant left main stenosis, but we cannot justify cardiac catheterization in all stable patients for that reason. The only reason to delay surgery for cardiac catheterization would be for the unstable cardiac patient; those with unstable angina, resting ischemia, and stress tests done for symptoms that show high-risk features. Cardiac catheterization in stable or asymptomatic patients — whatever their risk profile — would seem unjustified.
Another interesting feature of this trial is that delaying surgery for cardiac revascularization lead to death from ruptured aneurysms for 2 patients (4%). So the urgency of the surgical situation needs to be considered. Also, aspirin and clopidogrel were not stopped for vascular surgery after coronary stenting and there was no difference between those on these drugs and those not in bleeding complications. We have to ask our surgeons to rise to the occasion as they do in Europe and Brazil. Almost half the patients in this study had significantly reduced left ventricular ejection fraction. Although this is a legitimate indication for cardiac catheterization if ischemic heart disease is the suspected cause, this study would suggest that this does not have to be done before vascular surgery if the patient is stable. For those interested, the implications of this study are consistent with the ACC/AHA Guidelines. So, experienced clinicians knew these things before this study was done.