A meta-analysis of impact of low-flow/low-gradient aortic stenosis on survival after transcatheter aortic valve implantation

AIMS: To determine whether low-flow/low-gradient (LF/LG) aortic stenosis affects survival after transcatheter aortic valve implantation (TAVI), we performed a meta-analysis of currently available studies. METHODS: MEDLINE and EMBASE were searched through January 2019 using PubMed and OVID. Observational studies comparing all-cause mortality after TAVI for patients with classical LF/LG (C/LF/LG) aortic stenosis versus normal-flow/high-gradient (NF/HG) aortic stenosis, paradoxical LF/LG (P/LF/LG) aortic stenosis versus NF/HG aortic stenosis, and (3) C/LF/LG aortic stenosis versus P/LF/LG aortic stenosis were included. Study-specific estimates, risk and hazard ratios of mortality, were combined in the random-effects model. RESULTS: Our search identified nine eligible studies including a total of 5512 TAVI patients. Pooled analysis demonstrated significantly higher early mortality in C/LF/LG aortic stenosis than NF/HG aortic stenosis (risk ratio, 1.72; P = 0.02) and no statistically significant difference in early mortality between P/LF/LG aortic stenosis and NF/HG aortic stenosis (P = 0.67) and between C/LF/LG aortic stenosis and P/LF/LG aortic stenosis (P = 0.51). Midterm mortality in C/LF/LG (risk ratio/hazard ratio, 1.73; P = 0.0003) and P/LF/LG aortic stenosis (risk ratio/hazard ratio, 1.48; P < 0.0001) was significantly higher than that in NF/HG aortic stenosis. There was no statistically significant difference in midterm mortality between C/LF/LG aortic stenosis and P/LF/LG aortic stenosis (P = 0.63). CONCLUSION: After TAVI, C/LF/LG aortic stenosis is associated with increased early mortality compared with NF/HG, and C/LF/LG and P/LF/LG aortic stenosis is associated with increased midterm mortality compared with NF/HG aortic stenosis despite no difference in early mortality between P/LF/LG aortic stenosis and NF/HG aortic stenosis. There is no difference in early and midterm mortality between C/LF/LG aortic stenosis and P/LF/LG aortic stenosis.