Compatibility of Carotid Stenting and Cardiac Surgery
To the Editor:
We read with great interest the study by Randall et al1 describing their experience on carotid artery stenting before cardiac surgery. They present 19.2% combined minor stroke, major stroke and death rate, which appears to be higher than previously documented in the literature, as they admit.
The only published trial (investigation performed by the same authors)2 comparing dual antiplatelet regime versus aspirin alone for carotid artery stenting was prematurely interrupted for excess of benefit on the dual antiplatelet arm of the study, confirming the necessity of dual antiplatelet regime before, during and after carotid artery stenting. Stent endothelialization takes between 28 and 96 days.3 During this time the exposed metallic stent continuous to act as a source of platelet activation2 so the dual antiplatelet regime benefits may be explained on the basis of the limitation of this phenomenon.
It is also well known that antiplatelet drugs increase bleeding complications during cardiac surgery, and dual antiplatelet regimes could increase furthermore the risk of bleeding in the perioperative period.
Consequently, in our opinion the 2 procedures are not compatible in their optimal version and compromise is inevitable. That is, the cardiac surgeon must decide to interrupt dual antiplatelet regime for the intervention to minimize bleeding complications, but increasing the risk of neurological adverse events, or perform the operation under dual antiplatelet regime reducing the risk of perioperative stroke, but increasing perioperative bleeding complications.
The third solution, the delay of the cardiac procedure to permit stent endothelialization and a less risky suspension of antiplatelet drugs was shown hazardous in their study, as they observed 3 deaths for cardiac causes (2 documented and 1 presumed) over a total of 52 patients pending for the operation.
In their study they state that the timing of cardiac surgery after stenting was at the discretion of the cardiac surgeon, but it would be very interesting to specify the mean time between the 2 procedures. We also believe that is of great importance to clarify if cardiac surgery was performed under dual antiplatelet therapy or they suspended 1 or both antiplatelet drugs in the perioperative period. This could explain the high rates of combined postoperative neurological adverse events.
We would like to thank Drs Dalainas and Nano for their interest in our recently published article on carotid artery stenting before cardiac surgery. The points they raise in their letter highlight the need for the randomized trial we suggested, and we welcome the opportunity to expand on the points raised.
It is important to point out that the data presented in our article has been collected from our institution’s approved prospective carotid stenting registry of all stenting procedures performed by our radiologists. Therefore, our study methodology did not allow the minimum time between procedures to be stipulated at the outset of data collection. The limits of this methodology have already been discussed. In our series the earliest procedures were more likely to have been performed with only 2 weeks between the initial carotid stent and the subsequent cardiac procedure. However, in the majority of our cases, because of waiting lists in the UK for stable cardiac patients, the operations were >4 weeks apart. In the last 3 years all patients have had at least 4 weeks between the 2 procedures. This change was instigated once the benefits of dual antiplatelet therapy for a minimum of 28 days became clear.1
Problems associated with preoperative clopidogrel use and cardiac surgery remains a subject for much debate. Some studies have suggested that combined antiplatelet therapy increases the risk of cardiac surgery. However, a recent study has suggested that although dual antiplatelet therapy increases perioperative drain blood loss it did not result in an appreciable increase in reoperation rates or complications.2 There is also a growing body of evidence that dual antiplatelet therapy may reduce postoperative complications from off-pump cardiac bypass if started immediately after surgery.3 This is currently under study in a randomized controlled trial.4
In our original manuscript it was stated that almost universally our cardiac surgeons insist on stopping clopidogrel therapy 5 days before surgery, although more recently 2 operators have expressed a willingness to perform operations on clopidogrel if needed.
We agree that it may be shown by future trials that continuing treatment with staged carotid stenting and cardiac bypass surgery may prove incompatible. The need to continue the dual antiplatelet therapy for at least 28 days results in delays to cardiac surgery, which may increase the overall morbidity and mortality of this approach, negating the benefits obtained from the stenting procedure. However, what is not clear from our data are the number of adverse events prevented by this staged approach. It must be remembered that none of our patients undergoing carotid stenting experienced stroke or myocardial infarction at the time of stent insertion or immediate 24-hour follow-up. However, myocardial infarction at the time of carotid endarterectomy is a well recognized complication of staged endarterectomy and cardiac surgery.
What is clear is that the points raised can only be answered by a randomized controlled trial comparing cardiac surgery with prior carotid stent placement under dual antiplatelet therapy and cardiac surgery with no prior carotid intervention. We have been in discussion with investigators from London (Prof Martin Brown) and Leicester (Prof Ross Naylor) to perform a trial that it is hoped will answer this question.
von Heymann C, Redlich U, Moritz M, Sander M, Vargas HO, Grubitzsch H, Konertz WF, Spies C. Aspirin and clopidogrel taken until 2 days prior to coronary artery bypass graft surgery is associated with increased postoperative drainage loss. Thorac Cardiovasc Surg. 2005; 53: 341–345.
Kulik A, Le May M, Wells G, Mesana T, Ruel M. The clopidogrel after surgery for coronary artery disease (CASCADE) randomized controlled trial: clopidogrel and aspirin versus aspirin alone after coronary bypass surgery [NCT00228423]. Current Controlled Trials in Cardiovascular Medicine. 2005; 6: 15.