Device-related thrombus (DRT) should be addressed as a chronic condition, says a new study, which identifies a larger initial DRT size as the only independent predictor of the complication’s evolution. Findings by the research team highlighted that in current practice, a third of DRT events had an “unfavorable” evolution, either persisting or recurring after initial diagnosis. DRT’s progression was also associated with a twofold increased risk of thromboembolic events and ischemic stroke. “DRT should be addressed as a chronic condition and, given its consequences, actively managed until regression,” concluded the authors of the paper, which was published Monday online. “The duration and intensity of antithrombotic management to treat DRT remain unclear, especially in high bleeding risk patients,” the authors wrote. “Ideally, DRT management should be explored in dedicated trials,” they added. “Evidence will likely come from registries and real-life experience in which a unified diagnosis and management of DRT would be of great help for both the internal and external validity of such reports.” DRT occurrence after LAA closure In the investigation, which was published in the Nov. 27 issue of JACC: Cardiovascular Interventions, the authors analyzed an international multicenter retrospective registry that included 237 patients diagnosed with DRT after left atrial appendage closure (LAAC). The team found that DRT resolved in 153 patients (71.5%) and had unfavorable evolution in 75 patients (persisted in 61 patients [28.5%] despite therapy intensification and recurred among patients with initial DRT resolution in 14 patients [6.5%]). The sole predictor of unfavorable DRT evolution was average thrombus size at the initial diagnosis (odds ratio [OR] per 1-mm increase: 1.09, 95% confidence interval [CI]: 1.03-1.16; P=0.003), with an optimal cutoff size of 7 mm (OR: 2.51; 95% CI: 1.39-4.52; P=0.002). Unfavorable evolution of DRT was associated with a higher rate of thromboembolic events compared to resolved DRT (26.7% vs 15.1%; hazard ratio [HR]: 2.13; 95% CI: 1.15-3.94; P=0.02). “In the pooled analysis from the PROTECT-AF and PREVAIL trials, ~12% of embolic events that occurred in patients with DRT took place in patients with multiple DRT episodes,” said the paper’s research team, led by Jules Mesnier, MD, from the Quebec Heart and Lung Institute, Laval University, in Quebec City, and Trevor Simard, MD, of the Mayo Clinic in Rochester, Minnesota. “This increased risk is intuitively understood because the longer the potential cardioembolic thrombus remains, the higher the risk of ischemic events is. However, the question remains regarding whether DRT is the direct cause of ischemic embolism, a marker of an increased thrombotic risk, or both. In our study, women and index DRT size were associated with an increased risk of persisting DRT. “ Study highlights knowledge contradictions In an accompanying editorial comment, Issam Moussa, MD, MBA, from the University of Illinois Urbana-Champaign, said the study’s insights highlighted the “contradictions in the current state of knowledge.” This extends to the treatment of DRT, the frequency of recurrent DRT and the impact of unfavorable evolution of DRT on clinical outcomes. Referencing the EUROC-DRT registry and a similar study, Moussa highlighted a number of observations in the incidences of unfavorable DRT evolution that he felt required further investigation. These included current literature that indicate that the frequency of DRT resolution is ~70% to 80% irrespective of whether dual antiplatelet therapy or anticoagulant therapy is used. Moussa also pointed out that the current study’s main finding, in which the sole predictor of unfavorable DRT evolution was average thrombus size at initial diagnosis, should consider that the recurrent DRT diagnosis was a result of “selective” rather than systematic repeat imaging. “Potentially, the treating physician is more likely to repeat imaging after initial resolution of DRT if the initial clot size was large, thereby creating a selection bias,” he said. Commenting on the unfavorable evolution of DRT’s link to a higher rate of thromboembolic events compared to resolved DRT, Moussa said it is noteworthy that patients with persistent DRT had different outcomes than patients with recurrent DRT. “The outcomes of patients with persistent DRT were not statistically significantly worse than those with resolved DRT,” he wrote. “The lack of statistical significance may be because of the lack of study power, but it may also be caused by the possibility that persistent DRT may become fibrosed and poses a lower risk of embolism.” Study methodology Data were obtained from an international multicenter registry including 237 patients diagnosed with DRT after LAAC. Of these, 214 patients with a subsequent imaging examination after the initial diagnosis of DRT were included. Unfavorable evolution of DRT was defined as either persisting or recurrent DRT. The mean age of these patients was 75.6±8.0 years, 61.6% were women, and the risk of stroke (for non-rheumatic atrial fibrillation) was assessed using the CHA2DS2-VASc score (mean 4.6±1.7). The primary clinical outcome was the occurrence of any thromboembolic event (a composite of ischemic stroke and peripheral embolism) after LAAC. Sources: Mesnier J, Simard T, Jung RG, et al. Persistent and Recurrent Device-Related Thrombus After Left Atrial Appendage Closure. JACC Cardiovasc Interv. 2023;22;2722–2732. Moussa I. Predicting Behavior of Device-Related Thrombus After Left Atrial Appendage Occlusion: The Heisenberg’s Uncertainty Principle Applies. JACC Cardiovasc Interv. 2023;22;2733–2735. Image Credit: Damian – stock.adobe.com