Leaflet Immobility and Thrombosis in Transcatheter Aortic Valve Replacement

Arnold C. T. Ng; David R. Holmes; Michael J. Mack; Victoria Delgado; Raj Makkar; Philipp Blanke; Jonathon A. Leipsic; Martin B. Leon; Jeroen J. Bax

Disclosures

Eur Heart J. 2020;41(33):3184-3197. 

In This Article

Clinical Consequences

Clinical consequences of THV thrombosis can be divided into haemodynamic effects of valvular obstruction, thromboembolic complications, and mortality. Due to the small number of patients with clinical events, no studies to date have systematically reported all these clinical sequelae. Haemodynamic effects of valvular obstruction often present clinically as heart failure symptoms such as exertional dyspnoea. The reported incidence of dyspnoea is higher in echocardiographic studies compared with 4D MDCT studies. As previously alluded to when comparing echocardiography vs. 4D MDCT, majority of patients diagnosed with THV thrombosis on 4D MDCT does not have significant haemodynamic obstruction on echocardiography and therefore absent heart failure symptoms (Table 2). Only one 4D MDCT study reported an incidence of heart failure as 18% (5 patients out of 28 cases of THV thrombosis).[23] Of these five patients, three had preserved LVEF, effective orifice area <1.0 cm2, and mean gradient >20 mmHg but <40 mmHg (raising the possibility of paradoxical low-flow low-gradient as cause of dyspnoea rather than severe valvular obstruction). The remaining two patients had severely reduced LVEF (but no baseline echocardiographic data available), again raising the possibility that the symptoms were due to pre-existing heart failure with reduced LVEF instead of severe valvular obstruction from THV thrombosis.[23] To date, no other 4D MDCT studies have reported their overall incidence of heart failure associated with HALT or RLM.

In contrast, echocardiographic studies identify patients with already significant obstruction secondary to THV thrombosis. Therefore, patients are more likely to be symptomatic at presentation. Currently, three echocardiographic studies identified a total of 54 cases of THV thrombosis in 6304 TAVR patients (a pooled incidence of 0.9%), with reported incidence of worsening dyspnoea ranged from 38.9% to 70% in these patients.[33,43,44] Finally, only one published study has compared clinical symptoms between patients with or without THV thrombosis and reported no significant difference in the overall incidence of heart failure.[26]

Thromboembolism, specifically transient ischaemic attack (TIA) or cerebrovascular accident (CVA), is the most likely reported clinical complication of THV thrombosis (Table 1 and Table 2). The overall incidence of thromboembolism is low and the largest reported absolute number of TIA/CVA was 8 in 106 patients with THV thrombosis on 4D MDCT, equating to an overall incidence of 7.5%.[21] To date, only 1 study has reported a significant difference in the incidence of thromboembolism in patients with and without THV thrombosis.[21] From the RESOLVE and SAVORY registries where TIA and CVA were blindly adjudicated by a stroke neurologist, Chakravarty et al.[21] reported a higher incidence of non-procedural TIA incidence (5% vs. 1%, P = 0.002) but no difference in ischaemic stroke rates (4% vs. 2%, P = 0.14) in patients with THV thrombosis. All other published studies showed no difference in TIA/CVA incidence.[22,23,26,27] In the PARTNER 3 CT substudy, patients with HALT had 8.6% combined risk of death, CVA, TIA and thromboembolic events compared with 2.9% in patients without HALT (P = 0.11).[41] Long-term implications on TAVR longevity is unknown, and further follow-up is planned at 10 years.[41] Similar results were also noted in the recently published Global Study Comparing a Rivaroxaban-Based Antithrombotic Strategy to an Antiplatelet-Based Strategy After Transcatheter Aortic Valve Replacement to Optimize Clinical Outcomes (GALILEO-4D) trial substudy where no patients with ≥50% RLM had thromboembolic complications at 90 days.[48]

Finally, all studies to date have reported a similar rate of all-cause mortality between patients with and without THV thrombosis.[21–23,26–28,40,48] In the PARTNER 3 CT substudy, no patients with HALT died within the reported study period.[41]

Based on current publications, the incidence of clinical complications associated with subclinical THV thrombosis is very low. However, all these studies are limited by a small number of patients with THV thrombosis with limited follow-up duration. With the expected growth and utilization of TAVR for intermediate- and low-risk patient groups, future research into clinical implications of THV thrombosis on long-term valve integrity and patient morbidity/mortality is needed.

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