Discussion
Transcatheter aortic valve replacement (TAVR) is increasingly performed in Asia after a relatively late start.21 Several studies have now examined TAVR in an Asian population,17 22 23 with the majority of data from the Japanese Optimised transCathEter vAlvular iNtervention (OCEAN)-TAVR registry, which is specific, however, to one Asian ethnic group and to the balloon-expandable device. Data comparing gender differences in a broad geography of Asia and across various Asian ethnicities are lacking. Our study is the first description of sex-related differences in patients undergoing TAVR across Asia and across the various Asian ethnic groups.
An interesting and unique finding was the very small physical stature (eg, average height ≈149 cm) in elderly female Asians. Female patients had better LVEF and less comorbidities with respect to coronary artery disease, smoking and chronic lung disease, but were older and more likely to have had prior heart valve surgery, resulting in a trend towards a higher logistic EuroSCORE. With the smaller physical stature, smaller aortic annulus and, as shown in a previous study, smaller iliofemoral dimensions,19 the transfemoral route was used slightly less frequently, and the prostheses used in women were also smaller in size. However, mild or more paravalvular leak was also less frequent in women.
Despite more serious vascular complications occurring in female patients, the 30-day rates of stroke or mortality were low and similar between the sexes. Of note, most, if not all, centres were beginning their TAVR programmes, and most of the valves used were second-generation balloon-expandable or self-expanding valves. Functional status improved significantly and uniformly for both sexes; NYHA class III or IV at baseline was 67.5% in women versus 65.3% in men (p=0.35) to 5.7% in women and 4.8% in men at 30 days (p=0.92). At 1 year, there was no difference in survival between the sexes, despite women being older and having a trend towards a higher baseline EuroSCORE. The 1-year mortality somewhat approximated the baseline logistic EuroSCORE and is concordant with the findings from a previous Asian registry.17
Our data are consistent with several studies showing no difference in 30-day or 1-year survival between the sexes despite a higher incidence of major vascular complications,8 11–13 24 25 although some studies demonstrate that women have a better 1-year or long-term survival after TAVR.10 11 14 16 Although we did not record the iliofemoral dimensions in this study, it has been shown in a previous study by the first author that Asian women had significantly smaller iliofemoral dimensions than Asian men.19 In that study, the minimal femoral diameters were 6.3±1.5 mm versus 7.3±1.8 mm in women and men, respectively (p<0.001). The BSA of both sexes in that study was nearly identical with the current results (women vs men: 1.5±0.2 vs 1.7±0.2, p<0.001 in the previous study compared with 1.47±1.7 vs 1.67±1.7, p<0.001 in this study), indicating that the physical stature of the study populations was similar. As there was no difference in the incidence of peripheral artery disease between the sexes and interestingly because BSA or BMI was not associated with major vascular injury, the higher rate of major vascular complications in women in our study may be attributed to smaller ilio-femoral dimensions, older age and female sex itself (both of these may arguably be markers of vessel fragility).
More importantly, our study demonstrated that TAVR could achieve an equally good outcome for Asian women despite their smaller size and anatomy and higher incidence of major vascular complications. In contrast, it has been shown in some studies that a smaller height and female sex may be correlated with increased mortality after surgical TAVR25–27; thus, it is reassuring that physically small Asian women do not experience increased short-term mortality after TAVR. In concordance with Western data, women had less comorbidities associated with coronary artery disease and lung disease,8–11 13 and these could be accounted for by a much lower incidence of smoking. Women also had less mild or more paravalvular leaks, consistent with some studies9 11 12 24 25 but not others.10 It has been suggested that this is possibly due to the smaller aortic annulus in women leading to less frequently undersized prosthesis and more relative valve oversizing. It is reassuring, however, to note that the incidence of permanent pacemaker replacement was not increased in women.
It was interesting to note that although age and major vascular injury predicted overall 30-day mortality, only major vascular injury was significant for women and only age was significant for men. This implies that it is imperative to reduce major vascular injury in women to decrease short-term mortality.
The factors associated with 1-year mortality in this study—logistic EuroSCORE, hypertension, moderate or more paravalvular leak, 30-day NYHA class III or IV—reaffirm what is already well understood and are broadly consistent with a previous Asian registry.17
With the third-generation balloon-expandable (Sapien 3) valve and self-expanding (Evolut R and Pro) valves becoming commercially available in Asia in the recent years, the outcomes can be expected to improve. In particular, residual paravalvular leaks (both severity and frequency) for both sexes should be lowered, and the incidence of major vascular complications, especially in women, can be expected to be reduced.
Limitations
This study was limited to centres that agreed to participate, and hence data from many institutions in Asia were not available. These factors may have introduced bias into the study population. The data and outcomes were recorded by the individual centres, and no central adjudication was available. The data were analysed retrospectively and the possibility of unmeasured confounders that may have affected our results could not be excluded. There were missing parameters such as femoral/iliac vessel dimensions (CT measurements were unavailable or incomplete in many centres).
No information was available regarding the types of anaesthesia used (general anaesthesia vs local anaesthesia/conscious sedation) or the technique of femoral access (surgical cut-down versus fluoroscopy-guided percutaneous access). However, studies have shown that the incidence of major vascular injury was similar regardless of the access technique.28 29 The devices used in this study were second-generation Sapien or CoreValve prostheses; thus, these results may not apply to other devices or new-generation contemporary technologies.