Background

Mechanical circulatory support device (MCSD) patients with positive heparin-induced thrombocytopenia (HIT) screening pose a unique challenge, as clinicians must make rapid decisions about their anticoagulation and whether they can safely undergo cardiopulmonary bypass. We identified screening practices at our institution and other institutions nationwide that differed from American Society of Hematology (ASH) guidelines. This discovery prompted a data review to confirm the applicability of guidelines to this unique population and to highlight complications of "gestalt" screening.

Methods

Our study included MCSD patients with HIT testing from April 2014 to August 2020. We evaluated 510 PF4 IgG ELISA results.

Results

HIT was confirmed in 4.2% of patients. There was an increased prevalence of HIT in patients with nondurable (5.3%) vs durable devices (2.9%) or those in the preimplantation setting (1.3%), however this difference was not statistically significant (p = 0.26). None of the patients with a low probability 4T Score had HIT. All patients with a high probability 4T Score and PF4 immunoassay OD >2.0 had HIT. False positive results occurred in 22% of assays ordered for patients with a low probability 4T Score. Twelve patients with a low probability 4T Score and a false positive immunoassay were switched to a direct thrombin inhibitor (DTI) while awaiting confirmatory results. Two patients experienced clinically significant bleeding after conversion to a DTI. An organ was refused in one patient with false positive HIT screening.

Conclusions

Our findings demonstrate that an opportunity exists to improve clinical outcomes by re-emphasizing the utility of established guidelines and highlighting their safe use in the MCSD patient population.

中文翻译：

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诊断机械循环支持装置患者肝素诱导的血小板减少症

背景

肝素诱导的血小板减少症 (HIT) 筛查阳性的机械循环支持装置 (MCSD) 患者构成了独特的挑战，因为临床医生必须快速决定他们的抗凝药物以及他们是否可以安全地接受体外循环。我们确定了我们机构和全国其他机构与美国血液学会 (ASH) 指南不同的筛查实践。这一发现促使对数据进行审查，以确认指南对这一独特人群的适用性，并强调“完形”筛查的并发症。

方法

我们的研究包括 2014 年 4 月至 2020 年 8 月期间进行 HIT 检测的 MCSD 患者。我们评估了 510 例 PF4 IgG ELISA 结果。

结果

HIT 在 4.2% 的患者中得到证实。非耐用设备（5.3%）与耐用设备（2.9%）或植入前患者（1.3%）相比，HIT 的患病率增加，但这种差异无统计学意义（p  = 0.26）。具有低概率 4T 评分的患者均未发生 HIT。所有具有高概率 4T 评分和 PF4 免疫测定 OD > 2.0 的患者都有 HIT。为低概率 4T 评分的患者订购的检测中有 22% 出现假阳性结果。12 名具有低概率 4T 评分和假阳性免疫测定的患者被转换为直接凝血酶抑制剂（DTI），等待确认结果。两名患者在转换为 DTI 后出现临床显着出血。一名假阳性 HIT 筛查患者的器官被拒绝。

结论

我们的研究结果表明，通过重新强调既定指南的实用性并强调其在 MCSD 患者群体中的安全使用，存在改善临床结果的机会。