In this study based on a nationwide database, we aimed to evaluate the rates of in-hospital mortality and complications following TMVR in patients with RA. Our results show no significant difference in in-hospital mortality between patients with RA versus without RA. Moreover, both groups had similar rates of complications, although cardiac tamponade, post-procedural heart failure, and requirement for a permanent pacemaker were observed only in patients without RA. This is likely due to the low prevalence of RA in our study population and does not represent a protective role of RA against these complications. Previous studies assessing baseline characteristics of patients undergoing TMVR report comparable RA prevalence ranging from 2–4% (16, 17)
Predictably, our RA cohort was predominantly female, reflecting the known higher prevalence in females (18). Patients with RA and females have been underrepresented in the more extensive clinical trials of TMVR, which may limit our understanding of sex-specific outcome profiles following the procedure (14, 19, 20). Although recent studies showed no difference in in-hospital mortality or major complications between sexes following TMVR, one large study on transcatheter aortic valve replacement (TAVR) reported an increased risk of significant bleeding in women (21, 22). This highlights the importance of further research on sex-related outcomes following percutaneous valve interventions to help mitigate complications. Our present study, which focuses on RA patients who are also more likely to be females, thus provides a unique perspective on assessing TMVR outcomes.
Several studies evaluating the safety of TMVR in different population subgroups were published in recent years, however, no robust data exist regarding the safety of TMVR in patients with RA. One study evaluated outcomes of TAVR versus surgical aortic valve replacement in RA patients and found a non-significant trend towards better survival with TAVR. The same study also reported a significantly lower risk of complications such as acute kidney injury, need for blood transfusion, and cardiac tamponade in TAVR, although at the price of increased risk of complete heart block (23). These likely reflect the inherent risks associated with open surgical versus percutaneous procedures. Another study assessing in-hospital mortality following TAVR in patients with connective tissue disease (CTD) found no increased mortality risk. However, the risk for infectious complications was higher (24). These results were observed in all-comer CTD patients with no further subcategorization of specific conditions; thus, no conclusion can be drawn specifically regarding RA patients. Our present study is the first to evaluate in-hospital outcomes of RA patients following TMVR.
Our results show that patients with diabetes had a significantly higher risk of in-hospital complications following TMVR. This agrees with most published data regarding the effects of diabetes on percutaneous valve repair, although some studies report no increased mortality risk (25, 26). Given the known pathophysiological effects of diabetes on the cardiovascular system, it is more plausible that it would confer increased mortality risk. Our results reflect increased mortality in all-comer diabetics with no stratification for the level of glucose control or medications received, as this information is not available through the NIS. Interestingly, one study reported that the increased risk of mortality in people with diabetes following TAVR was mainly driven by the insulin-treated subpopulation (27).
Similarly, patients with CKD had increased mortality following TMVR. A prior study showed no increase in mortality but a greater risk of complications, specifically acute renal failure and need for dialysis (28). Another study showed increased 30-day mortality in CKD patients, although this was driven by the low creatinine-clearance subpopulation. Patients with a history of CABG or hypertension had greater survival to discharge following TMVR, although this was statistically significant only for CABG patients. Similar findings have been reported in a prior study (26). One plausible explanation is that these patient populations had more intensive cardioprotective drug regimens that conferred a periprocedural mortality benefit, such as beta-blockers. Furthermore, patients with mitral regurgitation have a high prevalence of CAD (29). Thus, prior CABG may have provided a mortality benefit through improved baseline myocardial perfusion and function.
Our study has several limitations. First, the number of RA patients analysed in this study is low, which affects the power of this study. This is likely due to the relatively low prevalence of RA in the general population. Additionally, the NIS database only captures in-hospital stays, and observation-only stays are not recorded, which may result in underrepresentation of RA patients undergoing TMVR. Another limitation of the NIS database is that the RA population is incompletely described (i.e. serological data, stage of disease, echocardiographic evidence of mitral valve RA involvement, and treatment). Moreover, other post-procedural parameters such as residual mitral regurgitation and mitral valve pressure gradient were not available from the NIS database. Finally, the indication for TMVR (i.e., TMVR for primary vs. secondary MR) could not be obtained from the database; thus we cannot discern if the indication of TMVR has any effect on outcomes.
In conclusion, patients with RA represent a unique population with distinct cardiac, vascular, and renal risk factors. Our study addresses a knowledge gap regarding the safety of TMVR in this specific population, and our results suggest that it is safe for RA patients to undergo TMVR without increased risk of in-hospital complications or mortality. Future studies are needed to ascertain our results and further evaluate TMVR outcomes in RA patients with varying disease severity, immunosuppressive regimens, and complications.