Diagnostic Challenges on the Laboratory Detection of Lupus Anticoagulant

Cardiac involvement in the catastrophic antiphospholipid syndrome (CAPS): Lessons from the "CAPS registry"

OBJECTIVE

To analyze the demographic, clinical, and laboratory characteristics of catastrophic antiphospholipid syndrome (CAPS) patients with cardiac involvement, and to identify the factors associated with this cardiac involvement.

MATERIAL AND METHODS

Based on the analysis of the "CAPS Registry", the demographic, clinical, and serological characteristics of patients with cardiac involvement were analyzed. Cardiac involvement was defined as heart failure, valvular disease, acute myocardial infarction, pericardial effusion, pulmonary arterial hypertension, systolic dysfunction, intracardiac thrombosis, and microvascular disease. Univariate and multivariate analysis was used for multiple comparisons.

RESULTS

749 patients (293 [39 %] women and mean age 38.1 ± 16.2 years) accounting for 778 CAPS events were included, of them 404 (52 %) had cardiac involvement. The main cardiac manifestations were heart failure in 185/377 (55 %), valve disease in 116/377 (31 %), and acute myocardial infarction in 104/378 (28 %). Of 58 patients with autopsy/biopsy, 48 (83 %) had cardiac thrombotic microangiopathy, Stroke (29% vs. 21 %, p = 0.012), transient cerebral vascular accident (2% vs. 1 %, p = 0.005), pulmonary infarction (26% vs. 3 %, p = 0.017), renal infarction (46% vs. 35 %, p = 0.006), acute kidney injury (70% vs. 53 %, p < 0.001), and livedo reticularis (24% vs. 17 %, p = 0.016) were significantly more frequent during CAPS events with versus without heart involvement. Multivariate analysis identified acute kidney injury (OR 1.068, IC 95 % 1.8-4.8, p < 0.001) as the only clinical characteristics that were, independently, associated with cardiac involvement in CAPS events. Cardiac involvement was not related to higher mortality.

CONCLUSIONS

Cardiac involvement is frequent in CAPS, with association with kidney involvement, and it is not related to higher mortality. The presence of cardiac microthrombosis was demonstrated in most biopsies/autopsies performed.

Lupus Anticoagulant Detection under the Magnifying Glass

Diagnosis of antiphospholipid syndrome (APS) requires the presence of a clinical criterion (thrombosis and/or pregnancy morbidity), combined with persistently circulating antiphospholipid antibodies (aPL). Lupus anticoagulant (LA) is one of the three laboratory parameters (the others being antibodies to either cardiolipin or β2-glycoprotein I) that defines this rare but potentially devastating condition. For the search for aCL and aβ2-GP-I, traditionally measured with immunological solid-phase assays (ELISA), several different assays and detection techniques are currently available, thus making these tests relatively reliable and widespread. On the other hand, LA detection is based on functional coagulation procedures that are characterized by poor standardization, difficulties in interpreting the results, and interference by several drugs commonly used in the clinical settings in which LA search is appropriate. This article aims to review the current state of the art and the challenges that clinicians and laboratories incur in the detection of LA.

Direct oral anticoagulant adsorption and laboratory detection of lupus anticoagulant

Direct oral anticoagulants (DOACs) interfere with many coagulation assays, mostly in lupus anticoagulant (LA) detection, causing false positive and negative results. Despite guidelines recommendations, LA testing may be important during anticoagulation when the clinician has to decide whether to prolong or discontinue the drug.

OBJECTIVES

In this study, the effect of activated charcoal (DOAC-Stop, DS) as a DOAC-adsorbent was investigated on samples from DOACs treated and untreated patients.

BASIC METHODS

165 plasma samples with a LA request were collected in three laboratories: 105 were from patients receiving DOACs and 60 were from nonanticoagulated patients with 30 LA negative and 30 LA positive. All coagulation screening assays and LA assays were evaluated before and after DS treatment.

RESULTS

The adsorption technique reduced DOACs concentration below the Lower Limit of Quantification. For nonanticoagulated patients: no significant difference in ratio results of coagulation screening (prothrombin time, activated partial thromboplastin time and thrombin time) and LA tests were observed before and after addition of DS in LA positive and negative patients. Every LA was correctly classified. For anticoagulated patients: a statistically significant difference was found for coagulation screening assays and LA assays. Final LA conclusions changed after DS addition from positive to negative in 58.9% of patients (more frequently with Rivaroxaban) and from negative to positive in 8% of patients (more frequently with Apixaban).

CONCLUSIONS

Our study suggests that DOAC-Stop can be used in daily laboratory practice to remove DOACs interference for a more accurate assessment of LA that is essential for diagnosis and management of APS patients.

Added value of antiphosphatidylserine/prothrombin antibodies in the workup of thrombotic antiphospholipid syndrome: Communication from the ISTH SSC Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies

BACKGROUND

Diagnosis of antiphospholipid syndrome (APS) requires persistent presence of lupus anticoagulant (LAC), anticardiolipin (aCL) IgG/IgM, or anti-β2 glycoprotein I (aβ2GPI) IgG/IgM antibodies. Other antiphospholipid antibodies (aPL) such as antiphosphatidylserine/prothrombin antibodies (aPS/PT) are promising in assessment of thrombotic APS (TAPS).

AIM

To evaluate the added value of aPS/PT IgG and IgM in TAPS.

MATERIAL AND METHODS

aPS/PT IgG/IgM, aCL IgG/IgM, aβ2GPI IgG/IgM, and LAC were determined in 757 patients (TAPS and controls). aPS/PT cut-off values were calculated, and aPS/PT titers and positivity were compared between TAPS and controls, type of thrombosis, and antibody profiles. Likelihood ratios (LR), odds ratios (OR), and aPL score were determined.

RESULTS

aPS/PT IgG and IgM were associated with TAPS and triple positivity. In-house calculated cut-offs were higher for IgM (43 units), compared to manufacturer's cut-off (30 units). Thresholds of 90 (IgG) and 200 (IgM) units were determined as high-titer cut-off. Higher aPS/PT titers were observed in triple positive patients and showed higher LR and OR for TAPS. aPS/PT was independently associated with TAPS when adjusted for aCL/aβ2GPI, but not when adjusted for LAC. In isolated LAC positive patients, aPS/PT was positive in 27.1% TAPS patients and in 77.3% patients with autoimmune disease. Diagnostic value of aPL score did not differ with and without including aPS/PT.

CONCLUSION

aPS/PT positivity, especially with high antibody titer, is associated with TAPS diagnosis. Analysis on top of current laboratory criteria is not essential in TAPS diagnosis, but aPS/PT could be useful in patients with thrombosis and a double positive aPL profile (aCL+/aβ2GPI+).