Anti-PF4/heparin antibody responses after heparin reexposure
| Pt . | Interval (weeks) . | Rechallenge (postoperative antithrombotic therapy) . | SRA pre/post . | IgG pre/post . | IgA pre/post . | IgM pre/post . | Seroconversion by . | |
|---|---|---|---|---|---|---|---|---|
| SRA . | EIA . | |||||||
| Reexposure in medical patients of a full anticoagulant course of treatment (n = 3) | ||||||||
| 1 | 703 | UFH × 11-day course | NA/− | NA/− | NA/− | NA/− | No | No |
| 2 | 477 | UFH × 17-day course | NA/− | NA/− | NA/− | NA/− | No | No |
| 7 | 408 | LMWH × 10-day course | −/− | +*/+* | −/− | −/− | No | No |
| Reexposure in surgical patients (post-cardiac/vascular surgery)—intraoperative UFH use only (n = 17) | ||||||||
| 3 | 132 | CPB UFH (danaparoid) | −/+++ | −/+++ | −/++ | −/+ | Yes | Yes |
| 4 | 8 | Vasc UFH (danaparoid) | −/− | −/− | −/− | −/− | No | No |
| 5 | 8 | CPB UFH (nil) | −/− | −/− | −/− | −/− | No | No |
| 6 | 307 | Vasc UFH (danaparoid) | −/− | −/− | −/− | −/− | No | No |
| 8 | 180 | CPB UFH (danaparoid) | −/+++ | −/+++ | −/++ | −/+ | Yes | Yes |
| 9 | 21 | Vasc UFH (clopid/ASA) | −/− | +/+ | −/− | −/− | No | No |
| 10 | 37 | CPB UFH (danaparoid) | −/++ | +/+++ | +/++ | −/− | Yes | Yes |
| 11 | 47 | Vasc UFH (clopid/ASA) | −/+++ | +*/+++* | −/− | −/− | Yes | Yes* |
| 12 | 62 | Vasc UFH (danaparoid) | −/− | −/− | −/− | −/− | No | No |
| 13 | 22 | CPB UFH (danaparoid) | −/− | ++/++ | −/+* | −/− | No | Yes* |
| 14 | 22 | Vasc UFH (nil) | −/+++ | +/+++ | −/+++ | −/− | Yes | Yes |
| 15 | 515 | CPB UFH (danaparoid) | −/+++ | ++/+++ | −/+ | +*/++* | Yes | Yes |
| 16 | 422 | Vasc UFH (danaparoid) | −/+++ | +/+++ | −/− | −/+ | Yes | Yes |
| 17 | 597 | CPB UFH (fondaparinux) | −/+++ | −/+++ | −/− | −/+* | Yes† | Yes |
| 18a | 414 | Vasc UFH (fondaparinux) | −/− | −/− | −/− | −/+ | No | Yes |
| 18b | +132 | Vasc UFH (fondaparinux) | −/− | −/− | −/− | −/+ | No | Yes |
| 19 | 166 | CPB UFH (warfarin) | −/− | ++/++ | −/− | −/− | No | No |
| 20 | 20 | CPB UFH (fondaparinux) | −/− | ++/+++ | −/+ | −/− | No | Yes |
| Pt . | Interval (weeks) . | Rechallenge (postoperative antithrombotic therapy) . | SRA pre/post . | IgG pre/post . | IgA pre/post . | IgM pre/post . | Seroconversion by . | |
|---|---|---|---|---|---|---|---|---|
| SRA . | EIA . | |||||||
| Reexposure in medical patients of a full anticoagulant course of treatment (n = 3) | ||||||||
| 1 | 703 | UFH × 11-day course | NA/− | NA/− | NA/− | NA/− | No | No |
| 2 | 477 | UFH × 17-day course | NA/− | NA/− | NA/− | NA/− | No | No |
| 7 | 408 | LMWH × 10-day course | −/− | +*/+* | −/− | −/− | No | No |
| Reexposure in surgical patients (post-cardiac/vascular surgery)—intraoperative UFH use only (n = 17) | ||||||||
| 3 | 132 | CPB UFH (danaparoid) | −/+++ | −/+++ | −/++ | −/+ | Yes | Yes |
| 4 | 8 | Vasc UFH (danaparoid) | −/− | −/− | −/− | −/− | No | No |
| 5 | 8 | CPB UFH (nil) | −/− | −/− | −/− | −/− | No | No |
| 6 | 307 | Vasc UFH (danaparoid) | −/− | −/− | −/− | −/− | No | No |
| 8 | 180 | CPB UFH (danaparoid) | −/+++ | −/+++ | −/++ | −/+ | Yes | Yes |
| 9 | 21 | Vasc UFH (clopid/ASA) | −/− | +/+ | −/− | −/− | No | No |
| 10 | 37 | CPB UFH (danaparoid) | −/++ | +/+++ | +/++ | −/− | Yes | Yes |
| 11 | 47 | Vasc UFH (clopid/ASA) | −/+++ | +*/+++* | −/− | −/− | Yes | Yes* |
| 12 | 62 | Vasc UFH (danaparoid) | −/− | −/− | −/− | −/− | No | No |
| 13 | 22 | CPB UFH (danaparoid) | −/− | ++/++ | −/+* | −/− | No | Yes* |
| 14 | 22 | Vasc UFH (nil) | −/+++ | +/+++ | −/+++ | −/− | Yes | Yes |
| 15 | 515 | CPB UFH (danaparoid) | −/+++ | ++/+++ | −/+ | +*/++* | Yes | Yes |
| 16 | 422 | Vasc UFH (danaparoid) | −/+++ | +/+++ | −/− | −/+ | Yes | Yes |
| 17 | 597 | CPB UFH (fondaparinux) | −/+++ | −/+++ | −/− | −/+* | Yes† | Yes |
| 18a | 414 | Vasc UFH (fondaparinux) | −/− | −/− | −/− | −/+ | No | Yes |
| 18b | +132 | Vasc UFH (fondaparinux) | −/− | −/− | −/− | −/+ | No | Yes |
| 19 | 166 | CPB UFH (warfarin) | −/− | ++/++ | −/− | −/− | No | No |
| 20 | 20 | CPB UFH (fondaparinux) | −/− | ++/+++ | −/+ | −/− | No | Yes |
Positive anti-PF4/heparin EIA not inhibited by >30% in the presence of high heparin.
Patient 17 developed HIT based upon both clinical picture and SRA+ status.
Yes* Any/all EIA seroconversion(s) for that patient were not inhibited >30% by high heparin.
Strength of assay results: EIA: –, negative; +, weak positive (0.40 [or 0.45] to 0.99 OD units), ++, moderate positive (1.00-1.99 OD units); +++, strong positive (≥2.00 OD units). SRA: –, negative (<20% serotonin release); +, weak positive (20.0-49.9% release); ++, moderate positive (50.0-79.9% release); +++, strong positive (≥80% release).
Clopid/ASA, clopidogrel/acetylsalicylic acid (aspirin); CPB, cardiopulmonary bypass; NA, not available; pre/post, test results of blood samples available shortly before heparin reexposure and after heparin reexposure, respectively; Pt, patient; Vasc, vascular surgery.