Correspondence

Continuous-Flow Ventricular Assist Device

N Engl J Med 2007; 357:2305-2306November 29, 2007

Article

To the Editor:

The report by Miller et al. (Aug. 30 issue)1 on the HeartMate II study describes an effective approach to providing hemodynamic support for patients awaiting cardiac transplantation. Although antithrombotic therapy and the risk of thromboembolism are mentioned in the discussion, can the authors comment on heparin use, the incidence of thrombocytopenia, and subsequent evaluation for heparin-induced thrombocytopenia that may have ensued? In a series of 92 consecutive patients receiving a left ventricular assist device (LVAD) before cardiac transplantation, the incidence of heparin-induced thrombocytopenia was 26%.2 Do the authors believe that there may be an association between thrombocytopenia or heparin-induced thrombocytopenia and the hemorrhagic or thrombotic adverse events listed in Table 4 of their article? In addition, was the post-transplantation outcome in this series similar to that in other series with or without an LVAD?

Glen J. Weiss, M.D.
TGen Clinical Research Services, Scottsdale, AZ 85258

2 References

1. 1

   Miller LW, Pagani FD, Russell SD, et al. Use of a continuous-flow device in patients awaiting heart transplantation. N Engl J Med 2007;357:885-896
   Full Text | Web of Science | Medline

2. 2

   Schroder JN, Daneshmand MA, Villamizar NR, et al. Heparin-induced thrombocytopenia in left ventricular assist device bridge-to-transplant patients. Ann Thorac Surg 2007;84:841-846
   CrossRef | Web of Science | Medline

Author/Editor Response

Heparin-induced thrombocytopenia is an important complication after placement of an LVAD, since it predisposes patients to thrombosis.1-3 Data on the presence of heparin-induced thrombocytopenia were not collected as part of the HeartMate II study. Platelet counts decreased from a mean (±SD) preoperative level of 228,000±86,000 per cubic millimeter to 148,000±58,000 per cubic millimeter at 24 hours, with a return to preoperative levels by 1 month (309,000±136,000 per cubic millimeter). Anticoagulation with heparin was recommended but not mandatory in the postoperative period. The five strokes that occurred in the first 48 hours appeared to be related to technical issues of implantation or preexisting neurologic status, not to heparin-induced thrombocytopenia.

Schroder et al.1 identified 26% of 92 LVAD recipients as having heparin-induced thrombocytopenia, and these patients had a greater decrease in the platelet count after transplantation than did the patients without heparin-induced thrombocytopenia, but with no increase in thromboemoblism or mortality. Survival rates among the patients in the HeartMate II study who received a heart transplant were 95% (73 of 77 patients) at 1 month and 84% (51 of 61) at 1 year. These rates are similar to the survival rates reported by the Cardiac Transplant Research Database and International Society for Heart and Lung Transplantation registries for all heart-transplant recipients,4 suggesting that there is no increased risk among patients with previous HeartMate II LVAD support. We do not consider the occurrence of heparin-induced thrombocytopenia to be a major predisposing factor for stroke in the HeartMate II study.

Leslie W. Miller, M.D.
Georgetown University Hospital, Washington, DC 20010
leslie.w.miller@medstar.net

Francis D. Pagani, M.D., Ph.D.
University of Michigan, Ann Arbor, MI 48109

4 References

1. 1

   Schroder JN, Daneshmand MA, Villamizar NR, et al. Heparin-induced thrombocytopenia in left ventricular assist device bridge-to-transplant patients. Ann Thorac Surg 2007;84:841-846
   CrossRef | Web of Science | Medline

2. 2

   Schenk S, El-Banayosy A, Prohaska W, et al. Heparin-induced thrombocytopenia in patients receiving mechanical circulatory support. J Thorac Cardiovasc Surg 2006;131:1373-1381
   CrossRef | Web of Science | Medline

3. 3

   Koster A, Huebler S, Potapov E, et al. Impact of heparin-induced thrombocytopenia on outcome in patients with ventricular assist device support: single-institution experience in 358 consecutive patients. Ann Thorac Surg 2007;83:72-76
   CrossRef | Web of Science | Medline

4. 4

   Taylor DO, Edwards LB, Boucek MM, et al. Registry of the International Society for Heart and Lung Transplantation: twenty-third official adult heart transplantation report -- 2006. J Heart Lung Transplant 2006;25:869-879
   CrossRef | Web of Science | Medline