The acute PE in a patient with PAVM is a predisposing factor for life-threatening complications, such as stroke, and there have been few reports of cases in which they were found at the same time and how they were treated (Graves et al., 2009; Serra et al., 2015; Luis et al., 2021). Although HHT, a disease related to PAVM, has been reported to be associated with an increase in thrombotic risk due to iron deficiency (Shovlin et al., 2014), patients with both PAVM and PE are rare. This is a devastating situation, as PE itself can cause hemodynamic instability, and it is a risk for the paradoxical embolism of thromboemboli.
According to Graves et al. (Graves et al., 2009), the acute on chronic PE in a patient with multiple-infarct dementia due to a large PAVM was successfully treated with concurrent anticoagulation and endovascular embolization. Considering the nature of PE, they judged that the risk of migration through minimal catheter manipulation was not high, and the benefit from blocking the shunt was greater. In a report of Serra et al. (Serra et al., 2015), asymptomatic PE was found in the feeding artery course of residual PAVM during a follow-up consultation after multiple PAVM embolization. The remaining PAVM was treated with delayed embolization after one week of anticoagulation. It seems that a safer method was chosen because the burden and clinical significance of PE in this patient were not large.
However, in the current case, a large amount of PE was extended to the segmental artery where the feeding artery of PAVM originated, making it difficult to determine the treatment sequence. Anticoagulation was started while discussing the timing of endovascular embolization. However, stroke due to paradoxical embolism that occurred a few days after hospitalization could not be prevented. Here, several factors that influenced the occurrence of such paradoxical embolism can be postulated. First, considering the history and CT appearance of the PE, it was judged to be an acute type and unstable. Second, the location of the thromboembolus was extended to the segmental artery feeding the PAVM, so there was a possibility of migration by marginal flow or additional thrombosis. Lastly, paradoxical embolism was reported as more common in high-grade shunts on TTCE (Velthuis et al., 2013), which were more likely to be associated with identifiable PAVMs seen on CT (Velthuis et al., 2014). Grade 2 and 3 shunts had odds ratios of 4.78 and 10.4, respectively, compared to grade 1 shunt that had no increased risk. Although it was not confirmed by TTCE in this case, the presence of high grade shunting was highly suspected. Considering these circumstances, it was determined that inducing thrombus fragmentation and migration during catheter manipulation would be riskier than slowly dissolving the thrombus through anticoagulation.
APS is an autoimmune disorder that promotes a hypercoagulable state and causes vascular thrombosis like venous thrombosis, and its most common pulmonary manifestation is PE (Farmer-Boatwright et al., 2009; Sarinc Ulasli et al., 2021). Although it has been reported that an APS-induced PE rarely appears in a massive and life-threatening form (Sarinc Ulasli et al., 2021), its cumulative frequency due to its recurrent nature was reported to be as high as 14.1% (Cervera et al., 2009). Therefore, if it is accompanied by PAVM as in this case, the risk of fatal stroke due to paradoxical embolism will also increase cumulatively. Therefore, an early diagnosis and appropriate treatment are very important.