Early and Late Leaflet Thrombosis Following TAVR A Multicenter Initiative From the OCEAN-TAVI Registry

A real-world multicenter study by Yanagisawa and his colleagues published in Circulation: Cardiovascular Interventions reported that untreated early leaflet thrombosis did not affect the cumulative event rates of death, stroke, and rehospitalization for heart failure. The investigators also stressed on the fact that late leaflet thrombosis was newly detected in patients during the 3-year follow-up period. 

The clinical relevance of leaflet thrombosis of prostheses after TAVR has long been an important unresolved issue. Symptomatic leaflet thrombosis of prostheses after TAVR is rare (0.6%–2.8%). Although previous studies reported the incidence of possible leaflet thrombosis after TAVR, little was known about the clinical impact and occurrence of leaflet thrombosis beyond 1 year after TAVR. In a multicenter transcatheter aortic valve replacement registry, the investigators analyzed data from 485 patients who underwent 4-dimensional multidetector computed tomography post-transcatheter aortic valve replacement performed to survey hypo-attenuated leaflet thickening with reduced leaflet motion compatible with thrombus at a median of 3 days, 6 months, 1 year, 2 years, and 3 years. Incidence, predictors, and clinical outcomes of early (median 3 days) and late (>30 days) leaflet thrombosis were assessed. Additional anticoagulation was not administered because of subclinical findings at the time of computed tomography in all patients.

The results showcased that early leaflet thrombosis occurred in 45 (9.3%) of 485 patients. Mean pressure gradient at discharge was higher in patients with early leaflet thrombosis than in those without. Independent predictors of early leaflet thrombosis in balloon-expandable prostheses were low-flow, low-gradient aortic stenosis, severe prosthesis-patient mismatch, and 29-mm prostheses. No predictors could be identified for self-expanding prosthesis. Moreover, cumulative event rates of death, stroke, or rehospitalization for heart failure over 2 years were 10.7% and 16.9% in patients with and without early leaflet thrombosis, respectively (P=0.63). Late leaflet thrombosis occurred late up to 3 years, and male sex and paravalvular leak less than mild were independent predictors.

Highlighting the important findings of his study, corresponding author Dr. Kentaro Hayashida Department of Cardiology, Keio University School of Medicine, Tokyo stated, “First, 45 (9.3%) of 485 patients had early leaflet thrombosis on MDCT at a median of 3 days after TAVR, and all were subclinical. Second, early leaflet thrombosis did not affect the cumulative event rates for the composite endpoint of death, stroke, or rehospitalization for heart failure during the follow-up period (mean, 1.8 years; SD, 0.9). Third, LFLG-AS, severe PPM, and 29-mm prostheses were identified as predictors for early leaflet thrombosis in balloon-expandable prostheses. Fourth, late leaflet thrombosis occurred late up to 3 years, and the independent predictors were male sex and PVL less than mild.” Thus, the study emphasized that untreated early (median 3 days) leaflet thrombosis did not affect hard endpoints, and late leaflet thrombosis occurred late up to 3 years. Secondly, independent predictors of leaflet thrombosis could be related to local hemodynamic stasis on the leaflets. Lastly, follow-up assessment of transcatheter bioprostheses in patients with predictors of leaflet thrombosis was particularly necessary. “In conclusion, our data demonstrated that untreated early leaflet thrombosis did not affect the rates of death, stroke, and rehospitalization for heart failure. The independent predictors of early leaflet thrombosis after TAVR with balloon-expandable prostheses were LFLG-AS, severe PPM, and 29-mm prostheses. Late leaflet thrombosis occurred late up to 3 years, and the independent predictors were male sex and PVL less than mild. Longer follow-up of this observation is needed to determine its occurrence and evaluate its clinical impact,” Hayashida and his co-authors noted.