Table 1. Characteristics of included studies.
| Study (author, year) | Study design | Patient cohort | Recruitment strategy | Definition of moderate AS |
| AS: aortic stenosis; AVA: aortic valve area; LVEF: left ventricular ejection fraction. | ||||
| Amanullah, 2021[6] | Retrospective, observational, single centre | Moderate aortic stenosis on echocardiogram | Retrospective review of echocardiograms from 2001-2018 | (1) AVA: 1.0-1.5 cm2 |
| Samad, 2016[5] | Retrospective, observational, echocardiogram database | LVEF < 50%, moderate aortic stenosis on echocardiogram | Retrospective review of echocardiograms from 1995-2014 | (1) AVA: 1.0-1.5 cm2 (2) Mean aortic gradient: 25-39 mmHg (3) Peak aortic jet velocity 3-4 m/s |
| Chew, 2021[9] | Retrospective, observational, single centre | Asymptomatic, LVEF > 50%, moderate aortic stenosis on echocardiogram | Retrospective review of echocardiograms from 2001-2020 | (1) Peak aortic velocity: 3.0-4.0 m/s (2) Mean aortic gradient: 20-40 mmHg (3) Aortic valve area: 1.0-1.5 cm2; (4) Indexed AVA: 0.60-0.85 cm2/ m2 (5) Velocity ratio: 0.25-0.50 |
| Du, 2021[8] | Prospective, observational, multi-centre | Moderate aortic stenosis on echocardiogram | Prospective enrolment of patients diagnosed with moderate AS on echocardiogram | (1) Peak aortic velocity: 3.0-4.0 m/s (2) Mean aortic gradient: 20- 40 mmHg (3) Aortic valve area: 1.0-1.5 cm2; (4) Indexed AVA: 0.60-0.85 cm2/ m2 (5) Dimensionless index: 0.25-0.50 |
| Delesalle, 2019[3] | Prospective, observational, multi-centre | LVEF > 50%, moderate AS on echocardiogram | Prospective enrolment of patients diagnosed with moderate AS on echocardiogram | (1) AVA: 1.0-1.5 cm2 |
| Jean, 2021[7] | Retrospective, observational, multi-centre | LVEF < 50%, moderate AS on echocardiogram | Retrospective review of echocardiograms from 2010-2015 | (1) AVA: 1.0-1.5 cm2 (2) Peak aortic jet velocity: 2-4 m/s at rest or after dobutamine stress echocardiography |
| Moon, 2020[4] | Retrospective, observational, echocardiogram database | LVEF < 50%, moderate AS on echocardiogram | Retrospective review of echocardiograms from 2001-2017 | (1) AVA: 1.0-1.5 cm2 (2) Maximal aortic valve velocity: 2-4 m/s |