Results

Characteristics of the studies

The steps that we followed in selecting the articles are shown in the PRISMA flow diagram in Figure 1 . In total, we found 49 articles. After the selection process, we retrieved four papers, and nine articles were added manually from the references of the formers. In the end, the final number of the included in our meta-analysis was 13 articles 14-26.
The overall population size was 2,013 patients, 1,066 (53%), and 947 (47%) in the AVR and noAVR group, respectively. The baseline characteristics of the included patients are shown in Table 1 . Twelve papers defined whether their cohort of patients presented preserved or reduced LVEF 14-21,23-26. Out of 1,533 patients, 952 (62.1%) patients had preserved LVEF, and 581 (37.9%) had low LVEF. The mean age of the total population was 74.9 [73.3-76.6] years old 14-18,20-23,25,26, particularly 73.2 [69.7-76.7] years old in the AVR group and 77.7 [74.8-80.7] years old in the noAVR group. Overall AVA was 0.81 [0.77-0.84] cm2 14-18,20-23,26; overall mean gradients was 27.21 [24.43-29.98] mmHg14-18,20-23,26; overall SVI was 34.82 [27.61- 42.04] mL/m2 15-18,20,21,23,26.
The determination of the number of patients undergoing either SAVR or TAVR was conducted on 11 papers 14-21,23,25,26. The number of patients treated with SAVR was 607 (81.7%), while 136 (18.3%) patients received TAVR (Table 2 ). In the noAVR group, the majority of patients were treated medically rather than with valvuloplasty (99.9% vs. 0.1%).