Even though thrombocytopenia following transcatheter aortic valve implantation (TAVI)
has been described, further investigation of this phenomenon is needed.
To determine which factors may explain the fall in platelet count that occurs after
implantation of a TAVI device, including markers of platelet and blood coagulation
Material and methods
32 patients without previous indications for dual antiplatelet therapy (mean age 78.5 ± 7.9 years, 62% females) with severe aortic valve stenosis (mean gradient 54.6 ± 16.9 mm Hg) who qualified for TAVI procedure (Edwards Sapien XT) were prospectively analyzed.
Platelet counts were analyzed before the surgery, on the day of the procedure and
for the three following postoperative days (POD 1 to 3). To assess platelet activation
P-selectin (PS, serum) and platelet factor 4 (PF-4, CTAD plasma) were measured, whereas
for the evaluation of coagulation activation prothrombin fragments 1 + 2 (F1 + 2, plasma) were assessed before the procedure, on POD-1 and POD-3 (ELISA).
During the postoperative period a significant platelet count drop, the most evident
on POD-2, was observed followed by a platelet count raise. The platelet count drop
correlated directly with the amount of iodinated contrast agent (r = 0.42, p = 0.016) and inversely with baseline mean platelet volume (r = −0.37, p = 0.046). Neither clinical nor perioperative parameters, except contrast medium, influenced
platelet count decrease. No significant differences regarding the concentration of
the evaluated markers in patients with and without thrombocytopenia were found. PF-4
and F1 + 2 significantly changed during the study (p < 0.05). Greater acute PF-4 decrease correlated with greater acute platelet count drop
(r = 0.48, p = 0.043), and during the study slower PF-4 increase correlated with higher platelet
count increase on POD-3 (r = −0.505, p = 0.032). Lower baseline PS correlated with lower baseline platelet count and higher
platelet count increase on POD-3 (r = 0.45, p = 0.04 and =−0.55, p = 0.02, respectively). No significant correlations between F1 + 2 concentrations and platelet count changes have been found.
Platelet reduction shortly after TAVI procedure is related to the amount of contrast
agent applied during the procedure. Platelet activation and blood coagulation along
with impaired baseline platelet renewal might be the mechanisms of thrombocytopenia
following TAVI procedure.