Vascular patients who most need treatment are often difficult and risky to treat by open operation or an endovascular intervention. In contrast, patients who least need invasive treatment or need it not at all usually have lesions that are easy to treat with good results. Examples are patients with advanced gangrene versus those with intermittent claudication; symptomatic patients with carotid artery stenosis versus those who are asymptomatic; patients with large abdominal aortic aneurysms versus those with small lesions.
This paradoxical situation occurs because most vascular lesions, particularly those associated with atherosclerosis, are in their early phases benign, cause minimal or no symptoms, and are unassociated with widespread vascular disease.
Moreover, many of these lesions, particularly with statins and other good medical therapy, will remain stable for long periods. These early lesions are technically easy to treat invasively, although such treatment may provide little or no benefit to the patient.
In contrast, only when lesions advance, become more complex and are associated with a widely diseased arterial system do they become threatening to life, limb, and the brain. These latter lesions are usually much harder to treat both by transcatheter or open operative techniques. This situation gives rise to several consequences relating to physician judgment, procedural outcomes, physician and institutional incomes, health care costs and ethical considerations.
Everyone in the vascular field should recognize and face these issues.
To help do so, let us examine some of these issues as they relate to the common problem of carotid bifurcation stenosis. High grade stenosis at this site, even when asymptomatic, can cause some strokes. Level 1 evidence from the so-called landmark asymptomatic trials (ACAS, ACST), which randomized patients from 1990-2003, showed significant stroke prevention from carotid endarterectomy (CEA) compared to medical treatment.
However, the benefit was slight (stroke rates were reduced from about 2% per year to about 1% per year), and there have been substantial improvements in medical treatments over the last decade to prevent strokes with statins and other measures. Carotid artery stenting (CAS) has also become a commonly used treatment to prevent strokes in asymptomatic carotid stenosis patients, although there is no convincing evidence that such treatment is more effective than current medical treatment in most if not all of these patients.
In addition, there is no solid evidence that CEA in asymptomatic patients prevents strokes more effectively than current medical treatment. Yet in the United States, 70%-90% of CEAs and 70%-96% of CAS procedures are performed on asymptomatic patients.
Should this be and how does the vascular disease paradox relate to this situation?
Vascular surgeons and interventionalists from all specialties want to continue to intervene on most of these asymptomatic carotid stenosis patients for several reasons. These include gratifyingly good outcomes from treating these usually simple, low-risk asymptomatic lesions and provision of income to physicians and hospitals.
These good outcomes also provide many accessory benefits to the treating physicians and surgeons by improving their overall results, a desirable goal in view of looming audits and pay-for-performance incentives. Also, increasing case numbers help practitioners to meet credentialing requirements.
However, there are negatives to continuing to perform large numbers of invasive treatments on asymptomatic carotid stenosis patients. One is the high cost to our health care system of providing these large numbers of invasive treatments largely to a group of patients who will derive little or no benefit. Another is the possibility that more patients will be harmed than helped.
Clearly what is needed are better ways to detect the asymptomatic patient at high risk for having a stroke so only those patients can be treated invasively. Although no such method is universally accepted, there are glimmers of hope that one or more will be proven effective.
Also needed are trials to establish the effectiveness of current medical therapy for stroke prevention in patients with asymptomatic carotid stenosis. However, such trials will not be simple to design because of the benign nature of most asymptomatic lesions. Thus, such trials will have to be conducted in patients selected to have more risky lesions.
Until such information is available, all practitioners should exercise restraint in treating patients with asymptomatic carotid stenosis invasively. They should not be seduced into treating simply because of the ease of treatment or the good outcomes – the vascular disease paradox. It is risk-benefit ratio that is more important. Physicians and surgeons should recognize that the landmark trials on this subject are now outdated, and should restrict such invasive treatment in some way to fewer patients than in the past – perhaps those with an increasing or very high grade (pinhole) stenosis or a contralateral occlusion.
Finally, it should be noted that a proposal to provide reimbursement for performing CAS on standard and low-risk carotid stenosis patients, including asymptomatic patients, is currently being considered by Medicare.
It is likely that some support for this proposal stems from the facts that lesions in such patients are easy to treat and the results of treatment are excellent. This is the vascular disease paradox which should be recognized and dealt with by all in the field.n
Dr. Veith is Professor of Surgery at New York University Medical Center and the Cleveland Clinic. He is an associate medical editor for Vascular Specialist.
The ideas and opinions expressed in Vascular Specialist do not necessarily reflect those of the Society or Publisher.