The incidence of heparin-induced thrombocytopenia Type II in patients with subarachnoid hemorrhage treated with heparin versus enoxaparin.

OBJECT: Heparin-induced thrombocytopenia Type II (HIT II) is a serious complication that occurs in 0.2-3% of patients treated with heparin and is associated with a high risk of thrombotic events. One center recently reported an incidence of HIT II of 15% in a population of patients with aneurysmal subarachnoid hemorrhage (aSAH). Because these patients are typically exposed to heparin during angiography, controversy exists regarding whether prophylaxis with enoxaparin rather than heparin affords any reduction in the risk of developing HIT II. In this study, the authors investigated the effect of heparin compared with enoxaparin on the incidence of HIT II in patients with aSAH. METHODS: The authors reviewed the medical records of 300 patients treated for aSAH who received thromboprophylaxis with either heparin or enoxaparin, and identified patients who developed HIT II. The incidences of HIT II in the 2 treatment groups were then compared. RESULTS: One hundred sixty-six patients with aSAH were treated with heparin, and 134 patients were treated with enoxaparin. Sixteen (5.3%) of 300 patients met the diagnostic criteria for HIT II. Of those treated with heparin, 8 (4.8%) of 166 developed HIT II, compared with 8 (6%) of 134 treated with enoxaparin (difference not significant). CONCLUSIONS: The authors report a lower incidence of HIT II in patients with aSAH than has previously been reported. The data also suggest that patients with aSAH who receive heparin are at no greater risk of developing HIT II than those who receive enoxaparin. This finding challenges the merit of choosing enoxaparin rather than heparin for thromboprophylaxis in patients with a SAH.

Doppler ultrasonography screening of poor-grade subarachnoid hemorrhage patients increases the diagnosis of deep venous thrombosis.

BACKGROUND: Prophylactic anticoagulation greatly decreases the prevalence of deep venous thrombosis (DVT) in neurosurgical patients. Using Doppler ultrasonography (USG), recent studies demonstrate a 1% DVT detection rate following microsurgery or endovascular treatment for aneurysmal subarachnoid hemorrhage (aSAH). We hypothesize that reported statistics underestimate the DVT detection rate in this high risk cohort by accounting for only symptomatic thromboses. This study utilizes Doppler USG to examine the prevalence of DVT in a large population of aSAH patients and attempts to identify a high-risk subgroup within this cohort. METHODS: We retrospectively examined 178 aSAH patients who underwent screening lower extremity Dopplers (LEDs) and 57 who did not undergo screening LEDs. All received pharmacologic and mechanical DVT prophylaxis. We analysed DVT prevalence within these two groups and compared rates to the literature. We then segregated patients according to Hunt-Hess grade and determined DVT prevalence within subgroups. RESULTS: Patients who underwent LED screening demonstrated a 3.4% (6/178) DVT rate, compared to 0% (0/57) in the unscreened cohort. Our screening protocol yielded a thrombosis rate almost triple that reported in the literature (3.4% versus 1.2%). A significantly greater (p<0.05) percentage of screened Hunt-Hess III-V patients (6.5%, 6/93) had positive LEDs compared to Hunt-Hess I-II patients (0%, 0/85). CONCLUSION: These data suggest that while pharmacologic prophylaxis lowers the prevalence of symptomatic DVTs in aSAH patients, the number of asymptomatic DVTs remains significant, particularly in patients with formidable neurological deficits. While a formal cost-effective analysis is warranted, our data suggest that screening high-risk patients may increase the diagnosis of asymptomatic DVTs and potentially prevent serious medical complications.