Re: Antiplatelet and Anticoagulative Medication During Shockwave Lithotripsy

Dear Editor:

It is with great interest that we read the article by Schnabel and associates in the September issue of the Journal of Endourology concerning antiplatelet and anticoagulation treatment in shockwave lithotripsy (SWL). While the authors venture in a structured and detailed summary of the relevant literature in the absence of well-designed trials and quality evidence, the main issue of finding the balance between the risk of bleeding from the procedure against risk of thromboembolic events from stopping medication is not addressed.

We agree that SWL is a procedure of low to intermediate rather than high risk of significant hemorrhage, because it can cause visible hematuria and renal hematoma that resolve with conservative management in the majority of cases and do not necessitate transfusion. ¹ It is also important to point out that SWL carries a very low risk of deep vein thrombosis/pulmonary embolism because it avoids prolonged immobilization and use of anesthetic.

We believe, however, that the most critical step is to integrate the individual thromboembolic risk in the management plan and consent process of SWL in particular. The American College of Chest Physicians has published guidelines for the perioperative management of antithrombotic therapy that can serve as a guide for risk stratification of thromboembolic events. ² According to the consensus, patients at low risk can safely stop high-dose aspirin and clopidogrel for 3 to 7 days and anticoagulants for 5 days without bridging and resume 48 to 72 hours post-treatment. Low-dose aspirin prophylaxis (75 mg) is no longer considered a factor for bleeding during major surgery, and discontinuation is not necessary. ²

On the other hand, patients in the intermediate and high-risk groups pose a different challenge. Patients receiving warfarin or dabigatran (a thrombin inhibitor) can be safely bridged with low molecular weight heparin when surgical intervention is needed. ² Ureteroscopy is preferable in patients at high risk. If SWL is considered, power ramping with the use of the lowest energy possible for fragmentation is recommended. ³

The biggest problem arises with new generation antiplatelets (clopidogrel, prasugrel, ticagrelor) and combination regimens (dual antiplatelet treatment) after coronary artery stent placement, especially with drug eluting stents. Because SWL is minimally invasive, it is an appealing solution for patients with comorbidities in general. In the case of complex cardiac disease, however, we advise that withholding antiplatelets be directed by specialist review and in accordance to strict subspecialist guidelines, because the consequences can be severe. Another option is to defer treatment and consider expectant management until such time that it would be safe to modify the antiplatelet regime. ³ As the authors rightfully point out, special antiplatelet bridging agents are still investigational; again, ureterorenoscopy can be considered if stone removal is absolutely necessary, with respect to anesthetic tolerance.

Taking the above into consideration, we believe there is a need for a collaborative effort that includes endourology, anesthetics, and cardiology specialists to design appropriate prospective studies that will yield high quality evidence and work toward a consensus for perioperative antithrombotic planning in minimally invasive stone surgery for all patient risk groups.