Thrombocytopenia Complicating Transcatheter Aortic Valve Implantation: Differences Between Two New-Generation Devices

Immature Platelet Fraction and Clinical Outcomes in Patients Undergoing Transcatheter Aortic Valve Implantation

INTRODUCTION

Immature platelets or reticulated platelets are newly released thrombocytes. They can be identified by their large size and high RNA cytoplasm concentration. Immature platelet fraction (IPF) represents the percentage of immature circulative platelets relative to the total number of platelets. The role of IPF in patients undergoing transcatheter aortic valve implantation (TAVI) is unknown. The aim of the current trial was to assess the levels of IPF in patients undergoing TAVI and correlation with clinical outcomes.

MATERIAL AND METHODS

Immature platelet fraction levels were measured 3 times in all patients (preprocedure, 1-2 days post-procedure and 1-month post-procedure). Immature platelet fraction measurement was carried out using an autoanalyzer (Sysmex XE-2100). Patients were followed for 12 months. Primary outcomes were defined as complications during hospitalizations, rehospitalization, and mortality.

RESULTS

Fifty-one patients were included in the study. Mean age was 79.8 (±9.6), and 28 (55%) were women. Twenty-one patients (41%) had complications: Of them, 6 of 21 (29%) occurred during hospitalizations (2-vascular complications; 2-sepsis, 2-implantation of a pacemaker), 9 of 21 (43%) patients were rehospitalized after the index admission, and 6 patients died during the follow-up period. Multivariate Cox regression analysis found that IPF < 7% in at least one of the 3 tests was associated with worse outcomes (hazard ratio 3.42; 95% CI 1.11-10.5, P = .032).

CONCLUSION

Immature platelet fraction >7% in patients undergoing TAVI is associated with worse outcomes. Further studies are needed to better understand this phenomenon.

Acquired Thrombocytopenia in Contemporary Transcatheter Aortic Valve Prosthesis

BACKGROUND

 Postprocedural thrombocytopenia is a known phenomenon following transcatheter aortic valve implantation (TAVI). The aim of this study is to evaluate whether postinterventional platelet kinetics differ when comparing the current generation of balloon-expandable valve (BEV) and self-expanding valve (SEV) prostheses.

METHODS

 We performed a retrospective analysis of patients undergoing TAVI at our facility between 2017 and 2019. Patients were stratified according to the type of prosthesis used: BEV or SEV. Hematocrit-corrected platelet counts were calculated to account for dilution. Nadir platelet counts (lowest recorded platelet count), drop platelet counts (DPC; highest relative platelet drop from baseline), and severity of thrombocytopenia during the discourse and at discharge were assessed.

RESULTS

 Of the 277 included patients, 212 received SEV and 65 BEV. BEV patients were younger (81.8 ± 4.4 years vs 79.7 ± 6.8 years, p = 0.03). Further demographic characteristics were similar between groups. Implanted SEV were larger (p < 0.001) and had shorter procedural times (p < 0.01). There were no significant differences in postprocedural discourse. Postinterventional platelet drop was more pronounced in BEV patients in several evaluated metrics: mean DPC (24.3 ± 10.9% vs 18.8 ± 14.8%, p < 0.01), patients with DPC > 30% (n = 19, 29.2%, vs n = 33, 15.6%, p = 0.02), and also when comparing platelet kinetics.

CONCLUSION

 Despite improvements in outcome, the current generation of balloon-expandable TAVI prostheses carries a predisposition for postprocedural thrombocytopenia even when the effects of dilution are accounted for.