Platelet aggregometry cannot identify uremic platelet dysfunction in heart failure patients prior to cardiac surgery

Platelet Function in Acute Kidney Injury: A Systematic Review and a Cohort Study

Acute kidney injury (AKI) patients have increased bleeding risk, which could be partially due to acquired platelet dysfunction. We conducted a systematic review and a cohort study to investigate platelet function and count in AKI and their association with AKI-related bleeding and mortality. Through a systematic literature search in PubMed and Embase, we identified 9 studies reporting platelet function and 56 studies reporting platelet count or platelet indices in AKI patients. Overall, platelet aggregation was reduced in AKI patients in nonintensive care unit (ICU) settings but not in ICU settings, except that reduced aggregation was associated with renal replacement therapy. Thrombocytopenia in AKI was frequent and often predictive of mortality. In our cohort study, we prospectively included 54 adult ICU patients who developed AKI within 24 hours of ICU admission and 33 non-AKI ICU controls. Platelet function was measured with light transmission aggregometry and flow cytometry. AKI patients bled more frequently than non-AKI patients (p = 0.04), and bleeding was associated with increased 30-day mortality in AKI (p = 0.02). However, platelet function was not different between AKI and non-AKI patients (aggregation: all p > 0.52; flow cytometry: all p > 0.07) and platelet function was not associated with bleeding in AKI. In conclusion, a reduced platelet count is frequent in AKI, but the literature on platelet function in AKI is sparse. In a cohort study, we demonstrated that patients with AKI within 24 hours of ICU admission exhibited increased bleeding tendency but this was not associated with reduced platelet function.

A Prospective Observational Study on Multiplate®-, ROTEM®- and Thrombin Generation Examinations Before and Early After Implantation of a Left Ventricular Assist Device (LVAD)

Background

Heart failure patients are frequently on coagulation-active medications before LVAD implantation and perioperative bleeding is a frequent complication after left ventricular assist device (LVAD) implantation. The role of point-of-care coagulation tests in assessing bleeding risk for LVAD implantation and the early postoperative time course of these tests is not well established.

Methods

We prospectively enrolled 25 patients with terminal heart failure undergoing LVAD implantation. Study related TRAP-, ASPI- and ADP- tests of Multiplate^® platelet aggregometry, ROTEM^® rotational thromboelastometry (INTEM, EXTEM, FIBTEM), thrombin generation assay and conventional laboratory studies were measured at 11 predefined time-points during the first 21 postoperative days. We examined if preoperative TRAP-, ASPI-, ADP- and ROTEM values are correlated with estimated total blood loss (primary outcome parameter) during the first 21 days after LVAD implantation and compared the baseline values of these measurements between patients with a bleeding event to those without. We performed Spearman's correlation and non-parametric tests for paired and non-paired comparisons.

Results

7 out of 25 (28%) patients experienced a bleeding event of which 4 required surgical revision. Of the preoperatively performed measurements the TRAP test [Spearman's Rho (ρ) = −0.5, p = 0.01], INTEM CFT (ρ = 0.72, p < 0.001), INTEM alpha (−0.7, p < 0.001), EXTEM MCF (ρ = −0.63; p < 0.001), EXTEM alpha (ρ = −0.67; p < 0.001), FIBTEM MCF (ρ = −0.41; p = 0.042), Fibrinogen (Clauss) (ρ = −0.5; p = 0.011), Anti-thrombin activity (ρ = −0.49; p = 0.013) and platelet count (ρ = −0.42; p = 0.034) were significantly correlated to total blood loss. Patients undergoing a surgical bleeding revision had significantly reduced values in TRAP—[31.5 IQR (17.25–43.5U) vs. 69 IQR (52.5–87U); p = 0.004], ASPI—[16.5 IQR (5.5–35.7U) vs. 39 IQR (24.5–62.5U); p = 0.038], ADP—[30 IQR (22–69U) vs. 12.5 IQR (8.7–21.5U); p = 0.01], EXTEM MCF—[63 IQR (57.7–63.7) vs. 67 IQR (65–75.5); p = 0.019] and EXTEM alpha [74 IQR (68.75–74) vs. 79 IQR (78–80.5); p = 0.002] values before LVAD implantation.

Conclusion

Multiplate^® and ROTEM^® measurements before LVAD implantation may identify LVAD candidates with platelet dysfunction and alterations of the primary hemostasis and could guide anesthetists and intensive care practitioners in bleeding risk stratification and in the perioperative clinical management.