Thrombocytopenia after aortic valve replacement with freedom solo bioprosthesis: a propensity study

The incidence of postoperative thrombocytopenia after aortic valve replacement with the Freedom Solo bioprosthesis remains unclear. This propensity-matched study was carried out to evaluate the incidence and clinical impact of thrombocytopenia in patients receiving the Freedom Solo bioprosthesis.

Patients who underwent aortic valve replacement with a Freedom Solo or Carpentier-Edwards Perimount pericardial prosthesis at our institution between 2006 and 2008 were screened retrospectively. Exclusion criteria included double valve replacement, redo surgery, and active endocarditis. Two hundred six patients were considered eligible for this analysis. Using propensity scores 36 matched pairs of patients with a Freedom Solo or Perimount bioprosthesis were obtained. The primary end point was the occurrence of postoperative thrombocytopenia. Secondary end points were postoperative thromboembolic or hemorrhagic events and 30-day mortality.

Before matching, severe thrombocytopenia (<30 x 10(9) platelets/L) occurred in 22% of patients with a Freedom Solo bioprosthesis and 1% with a Perimount bioprosthesis (p < 0.0001), thromboembolic or hemorrhagic events occurred in 3% and 2%, respectively (p = 0.37), and 30-day mortality was 4% and 6%, respectively (p = 0.48). Multivariate analysis identified preoperative platelet count (p = 0.01) and Freedom Solo (p < 0.0001) as independent risk factors for severe postoperative thrombocytopenia. After matching, severe thrombocytopenia occurred in 25% and 3% of patients with Freedom Solo and Perimount bioprostheses, respectively (p < 0.0001), thromboembolic or hemorrhagic events occurred in 0%, and 30-day mortality was 3% and 6%, respectively (p = 0.99).

The risk of thrombocytopenia was high after Freedom Solo implantation. However, this complication was not related to any deleterious events in our study population.