E-Case # 1-B

Tim Crimmins, M.D.

June 11-15, 2001

HPI: 67 year old man complains of three hours of R facial numbness and slurred speech 2 days ago. This is a first time event.  He believes the symptoms have completely resolved, and he notes no other new neurologic symptoms. He has mild hypertension, a 30-pack year history of smoking and hypercholesterolemia. There is no diabetes or clinically apparent cardiovascular disease. He is a retired postman and lives independently with his healthy wife.

PMH

• as above plus
• Erectile Dysfunction
• No history of GI bleeding

Meds

• Atorvastatin 20mg HS
• HCTZ 25 mg qd
• ASA 81 mg qd

SH: no current alcohol or tobacco use (quit in 1991)

PE: T 37.0       BP 135/80       P 74 regular     R 12 SaO2 98% ambient air     WT 160

Cardiac exam: RRR without murmurs, carotid bruits or edema.  Neuro exam reveals no deficits.

Lab review:

Cr 1.3, K 4.1, LDL 145, AST 26

1. Assuming you are concerned about a TIA, what is the appropriate work up?
   Carotid duplex shows less than 30% stenosis on the right, 70-79% on the left (internal carotid artery).  Echo shows normal valve appearance and LVF, no patent foramen ovale by bubble study.  Would you order imaging (CT or MRI)?

2. Does he meet criteria to benefit from carotid endarterectomy for stroke prevention?
   NASCET (North American Symptomatic Carotid Endarterectomy Trial) and ECST (European Carotid Surgery Trial) demonstrate that there is substantial benefit from surgery in symptomatic carotid artery stenosis of greater than 70%. The patients in these studies had either TIA's or non-disabling stroke and ipsilateral carotid stenosis. There was a 65% relative (17% absolute) risk reduction. Thus, 17 strokes were prevented over two years for every 100 surgeries performed. These results are generally applicable to the community if patients are selected appropriately and the surgical center has a <6% risk of perioperative stroke or death.  Additionally, in these studies, patients with 90-99% stenosis had twice the benefit as those with 70-79% stenosis.Symptomatic patients with 0-29% stenosis had no benefit from surgery. There is still debate about symptomatic patients with 30-69% stenosis.  (See attached articles.) Variables that determine which patients with 30-69% stenosis may benefit from surgery include atherosclerotic risks, overall surgical risk and surgical center's CEA complication rate. In addition, type of CVA (cardioembolic, carotid, vertebrobasilar or lacunar) may be important. The assumption is that correcting carotid stenosis will not affect rates of cardioembolic, vertebrobasilar or lacunar CVA's and this makes analysis difficult.  In the right patient, some advocate that surgery for symptomatic stenosis in the 50-69% range is "beneficial" (however, the number needed to treat doubles).

3. What if asymptomatic internal carotid artery stenosis of the same degree is discovered during a vascular evaluation of a different patient?  Would this patient also benefit from carotid endarterectomy to prevent future strokes?
   The ACAS (Asymptomatic Carotid Atherosclerosis Study) shows that patients with asymptomatic stenosis greater than 60% are at a relatively low risk for stroke (11% over five years) With surgery, they demonstrated a 5.9% absolute risk reduction of stroke over five years compared to medical therapy alone and only 2.6% absolute risk reduction of major stroke or death (not statistically significant). These results require a less than 3% rate for perioperative stroke or death.
   
   There are ongoing trials to further address this question. These trials are not using cerebral angiography as part of the pre-surgical evaluation and thus are eliminating a substantial cause of perioperative complications. (See article for details.)

4. Regardless of surgery, how can we maximize his medical therapy?
   Managing atherosclerosis risk factors and antiplatelet therapy are the mainstays of stroke prevention. In this case the patient has stopped smoking. His BP is well controlled. Further LDL lowering (to less than 100) could be advised based on cardiovascular disease studies. Even with good risk factor management, 25% of patients with recent CVA and high grade stenosis will have an ipsilatetaral stroke within 2 years.
   
   As for antiplatelet therapy, has he failed aspirin? Some would say yes and treat with Aggrenox (aspirin/dipyridamole) or clopedogrel. Others may start full dose daily aspirin.Long-term trials of anticoagulation in stroke prevention are underway.

References

Appropriate Use of Carotid Endarterectomy The New England Journal of Medicine -- November 12, 1998 -- Vol. 339, No. 20

Benefit of Carotid Endarterectomy in Patients with Symptomatic Moderate or Severe Stenosis The New England Journal of Medicine -- November 12, 1998 -- Vol. 339, No. 20